Month: October 2024

Students must go through these JAC Class 10 Science Notes Chapter 2 Acids, Bases and Salts to get a clear insight into all the important concepts.

JAC Board Class 10 Science Notes Chapter 2 Acids, Bases and Salts

→ Acid: Acids are sour in taste. Acid turns wet blue litmus paper to red. It releases H⁺ ions in an aqueous solution. Acid has a pH value lower than 7. H⁺(aq) ions in the solution are responsible for acidic character.

→ Base: Bases are bitter in taste. Base turns wet red litmus paper to blue. It releases OH^– ions in an aqueous solution. Base has a pH value higher than 7. OH^–(aq) ions in the solution are responsible for basic character.

→ Indicator: Indicator changes colour in presence of acid or base or it changes odour (smell) in presence of acid or base.

• Synthetic indicators : Methyl orange and Phenolphthalein.
• Natural indicators : Extract of red cabbage leaves, turmeric, vanilla extract, onion, starch.

→ On reaction with metal, acid liberates dihydrogen (H₂) gas and forms corresponding salt, while, base reacts with active metal to form dihydrogen gas and a salt is formed which has a negative ion (anion) consisting of metal and oxygen.

→ Acid reacts with metal carbonate, or metal hydrogen carbonate and forms the corresponding salt, carbon dioxide gas and water.

→ Aqueous solutions (solutions prepared in water) of acids and bases conduct electricity because they produce hydrogen ions (H⁺(aq)) and hydroxide ions (OH^–(aq)) responsible for conducting electricity.

→ pH scale: pH scale is useful to determine the nature of the solution whether acidic or basic.

• For acidic solution : pH < 7, pOH > 7
• For basic solution : pH > 7, pOH < 7
• For neutral solution : pH = 7, pOH = 7

→ Most of the metabolic reactions taking place in living bodies are within a narrow pH range of 7.0 to 7.8.

→ Mixing of a concentrated acid or a base with water is a highly exothermic reaction.

→ Neutralisation reaction: The chemical reaction in which acid and base neutralise each otiier to form corresponding salt and water is called neutralisation reaction. Salts have various uses in daily life and in industries.

→ Substance (Compound) and its uses:

• Vanilla, onion, clove : As olfactory indicator
• Milk of magnesia : As an antacid
• Sodium chloride (NaCl) : In the preparation of sodium hydroxide, baking soda, washing soda, bleaching powder and in various substances used in daily life.
• Sodium hydroxide (NaOH) : For making soaps, detergent, in purification of petroleum, in laboratory.
• Bleaching powder (CaOCl₂) : Used as bleaching agent, as disinfectant and as an oxidising agent.
• Baking soda (NaHCO₃): Used as an antacid, as disinfectant, in laboratory, making food soft and spongy and used in soda-acid fire-extinguishers.
• Washing soda (Na₂CO₃) : Used in making glass, soaps, as cleansing agents for domestic purposes, in paper and textile industries and in laboratory.
• Plaster of paris (CaSO₄.\(\frac { 1 }{ 2 }\)H₂O) : Used in construction industry, as plaster for supporting fractured bones, chalk for blackboard, making toys, in decoration material, making moulds and in laboratory.

Jharkhand Board JAC Class 10 Science Solutions Chapter 7 Control and Coordination Textbook Exercise Questions and Answers.

JAC Board Class 10 Science Solutions Chapter 7 Control and Coordination

Jharkhand Board Class 10 Science Control and Coordination Textbook Questions and Answers

Question 1.
Which of the following is a plant hormone?
A. Insulin
B. Thyroxin
C. Estrogen
D. Cytokinin
Answer:
Cytokinin

Question 2.
The gap between two neurons is called a ………………..
A. dendrite
B. synapse
C. axon
D. impulse
Answer:
synapse

Question 3.
The brain is responsible for ……………….
A. thinking
B. regulating the heartbeat
C. balancing the body
D. all of the above
Answer:
all of the above

Question 4.
What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?
Answer:
The function of receptors : To receive collect information about changes in the environment around us in form of stimuli. This information pass to central nervous system through sensory nerves in form of impulse.

If receptors do not work properly, external stimuli cannot be received and body will not respond towards it.

Question 5.
Draw the structure of a neuron and explain its function.
Answer:
Structure of neuron:

Function of neuron:
The information is acquired at the end of the dendritic tip of a nerve cell and sets off a chemical reaction that creates an electrical impulse. This impulse travels from the dendrite to the cell body and then along the axon to its end. At the end of the axon, the electrical impulse sets off the release of some chemicals (Neurotransmitters) which cross the synapse and start a similar electrical impulse in a dendrite of the next neuron.

Thus, neuron is specialised for conducting information via electrical impulses from one part of the body to another.

Question 6.
How does phototropism occur in plant?
Answer:
To observe the response of plant parts to light OR To study phototropism in plants.
Materials: Conical flask, wire mesh, cardboard box open from one side, water, two-three freshly germinated bean seeds.

Procedure:

• Fill a conical flask with water.
• Cover the neck of the flask with a wire mesh.
• Keep two-three freshly germinated bean seeds on the wire mesh.
• Take a cardboard box which is open from one side.
• Keep the flask in the box in such a manner that the open side of the box faces light coming from a window.
• Observe after two or three days and note down your observation.
• Now turn the flask and leave it undisturbed in this condition for a few days and then observe.
  

Observation: In the initial position of flask, the shoot bends towards light and roots turn away from light.
After turning the flask, position of shoot and roots change, i.e., shoot goes away from light and roots turn towards light but after a few days shoot again shows bending towards light and roots move away from light.

Questions:

Question 1.
Have the old parts of the shoot and root changed direction?
Answer:
Yes, shoot always grows towards light as it positively phototropic and root goes in opposite direction of light.

Question 2.
Are there differences in the direction of the new growth?
Answer:
No, growth pattern or direction follows environmental stimulus.

Question 3.
What can we conclude from this activity?
Answer:
We can conclude from this activity that shoot shows positive phototropism and roots show negative phototropism.

Question 7.
Which signals will get disrupted in case of a spinal cord injury?
Answer:
In case of a spinal cord injury following signals will get disrupted :

• Reflex action
• Sensory impulses from different organs of body to brain through spinal cord will not be conducted
• Motor impulses from brain to different organs of body through spinal cord will not be transmitted.

Question 8.
How does chemical coordination occur in plants?
Answer:
The chemical coordination occurs in plants by means of plant hormones. They help to coordinate growth, development and. responses to the environment. They are synthesised at places away from where they act and reach to the areas of action by simple diffusion.

Question 9.
What is the need for a system of control and coordination in an organism?
Answer:
In multicellular organisms, body organisation is complex. Different organs s and tissues perform different specialised functions. Therefore, it is necessary that all the organs work together in a proper coordinating way, it needs a system of control and coordination.

In human beings, well-developed nervous and endocrine system were evolved for control and coordination.

Question 10.
How are involuntary actions and reflex actions different from each other?
Answer:

Involuntary actions	Reflex actions
These are controlled by medulla a part of hind-brain.	These are controlled by spinal cord in general.
Functioning of internal body parts are involuntary actions.	It is involuntary response to external stimuli without the knowledge of cerebrum.
Such actions go on continued under normal condition also, e.g., heartbeats, breathing, peristalsis, etc.	It is shown under a condition of emergency. Such as to pull hand away on touching to hot object.
It occurs in controlled rhythmic way.	It is a quick action.

Question 11.
Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Answer:

Nervous mechanism	Hormonal mechanism
Neuron is the main functional unit in nervous mechanism.	Hormone acts as chemical messenger in hormonal mechanism.
Impulse is generated at dendrite and it passes along the axon through cell body.	Hormone is secreted from endocrine gland and is transported through blood circulation.
The neural responses are quick.	The hormonal actions are slow.
Its effect is short lasting.	Its effect is long lasting.
Impulse is delivered to other neuron, gland or muscle cells.	Information is received by target cells who have specific molecules on their surfaces.

Question 12.
What is the difference between the manner in which movement take place in a sensitive plant and the movement in our legs?
Answer:

Movement in a sensitive plant	Movement in our legs
It occurs in response to touch.	It is voluntary action as per our need.
Neural signals are not involved in such movement.	Neural signals from cerebellum are involved in such movements.
No specific protein is present in plant cells for it.	A specific protein is present in our muscle cells for it.
Plant cells change their shape by changing the amount of water in it.	A special proteins change both their shape and their arrangement in response to nervous impulses due to which the muscle cells shorten.

Jharkhand Board Class 10 Science Control and Coordination InText Questions and Answers

Question 1.
What is the difference between a reflex action and walking?
Answer:
Reflex action is an involuntary action controlled by spinal cord. Thinking is not involved in such action.

Walking is a voluntary action and is controlled by a cerebellum, a part of hind-brain. This action is shown as per wish of an individual.

Question 2.
What happens at the synapse between two neurons?
Answer:
Synapse is the gap between nerve endings of axon of one neuron and dendrites of another neuron. At the end of axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the synapse and start a similar electrical impulse in a dendrite of the next neuron.

Question 3.
Which part of the brain maintains posture and equilibrium of the body?
Answer:
Cerebellum is the part of the brain that maintains posture and equilibrium of the body.

Question 4.
How do we detect the smell of an agarbatti (incense stick)?
Answer:
Olfactory receptors in our nose are stimulated by the smell of agarbatti. This causes generation of impulse which is received at dendrite of sensory neuron. Such impulse is transmited to brain. In cerebrum message is interpreted and we detect the smell.

Question 5.
What is the role of the brain in reflex action?
Answer:
Generally reflex action is shown by spinal cord and there is no active role of brain in it. However the information input also goes to the brain.

In some reflex actions such as mouth watering on seeing delicious food, heartbeats, breathing, movement of diaphragm, yawning, blinking of eyes, sneezing, etc. brain is involved.

Question 6.
What are plant hormones?
Answer:
Plant hormones are chemical compounds produced by plant itself and help to coordinate growth, development and responses to the environment.

Question 7.
How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light?
Answer:

Question 8.
Give an example of a plant hormone that promotes growth.
Answer:
An example of a plant hormone that promotes growth : Auxin.

Question 9.
How do auxins promote the growth of a tendril around a support?
Answer:
Auxins are growth promoting plant hormones that induce cell elongation. When tendril comes in contact with a support, auxin stimulates faster growth on to a part of tendril away from the support. This causes the tendril to coil around the support.

Question 10.
Design an experiment to demonstrate hydrotropism.
Answer:
The type of movement of the growing plant organ, which is induced by stimulus of water is called hydrotropism.

To demonstrate hydrotropism.

Apparatus-Materials: clay, two plants, two glass

Procedure: Take two glass troughs each filled to about 1/3 with clay. Label the trough as (A) and (B). Plant two, almost equal sized cuttings, S one in each of the troughs. Add water in trough (A) and keep the clay of trough (B) dry. However in trough (B) place a small clay pot (or a cup of clay) filled with water quite close to the cutting. (See the figure) Add daily a small quantity of? water in trough (A) but not in trough (B). Dig out the clay carefully in both the troughs after about a week or more.

Observation : It will be seen that the cutting in trough (A) shows a simple and straight growth of the root, while that in trough (B) shows the root curved in the direction of clay pot filled with water.

Conclusion: It can be concluded that the root grows and elongates in the direction of source of water. It means that the root shows positive hydrotropism.

Question 11.
How does chemical coordination take place in animals?
Answer:
In animals, endocrine glands secretes S chemical substances (Hormones) in precise quantities. They are directly released in blood and through blood circulation they reach to their target (Functional) site. Specific cells of body have specific molecules with which hormone molecules bind and transmit information.

Thus, chemical coordination take place in animals.

Question 12.
Why is the use of iodised salt advisable?
Answer:
The use of iodised salt is advisable because iodine is essential for the synthesis of thyroxin hormone in thyroid gland. Deficiency of iodine causes goitre. Iodised salt fulfills the requirement of iodine of body and protects agains goitre disease.

Question 13.
How does our body respond when adrenaline is secreted into the blood?
Answer:
Adrenaline prepares our body in an emergency situation. When adrenaline is secreted into the blood body shows following responses:
The heart beats faster, breathing rate increases, blood pressure increases, skeletal muscles become more active, etc. This is known as fight or flight response.

Question 14.
Why are some patients of diabetes treated by giving injections of insulin?
Answer:
Insulin is a pancreatic hormone which helps in regulating blood sugar level. In the patients of diabetes, the blood sugar level rises due to deficiency of insulin. So, some patients of diabetes are treated by giving injections of insulin to maintain blood sugar level.

Activity 7.1 [T. B. Pg. 115]

To detect the taste bud (gustatory receptor) and its function.

• Put some sugar on your tongue In the mouth.
• Block your nose by pressing it between your thumb and index finger.
• Now eat sugar again.
• While eating lunch, block your nose in the same way and notice If you can fully appreciate the taste of food you are eating.

Questions:

Question 1.
How does the sugar taste?
Answer:
The taste of sugar is sweet.

Question 2.
Is there any difference in the taste of sugar while you block your nose?
Answer:
When we eat sugar after blocking our nose, we find no difference in the taste of sugar.

Question 3.
Is there a difference in how sugar and food taste If your nose Is blocked? If so, why might be happening?
Answer:
If we block our nose, we feel the taste but cannot fully appreciate because the olfactory receptors are not stimulated. We cannot feel the smell.

Question 4.
Do you come across a similar situation when you have a cold?
Answer:
Yes, when we have a cold, olfactory receptors are covered with excessive secreted mucus.

Activity 7.2 [T. B. Pg. 121]

To observe the response of plant parts to light OR To study phototropism in plants.

Materials: Conical flask, wire mesh, cardboard box open from one side, water, two-three freshly germinated bean seeds.

Procedure:

• Fill a conical flask with water.
• Cover the neck of the flask with a wire mesh.
• Keep two-three freshly germinated bean seeds on the wire mesh.
• Take a cardboard box which is open from one side.
• Keep the flask in the box in such a manner that the open side of the box faces light coming from a window.
• Observe after two or three days and note down your observation.
• Now turn the flask and leave it undisturbed in this condition for a few days and then observe.
  

Observation: In the initial position of flask, the shoot bends towards light and roots turn away from light.

After turning the flask, position of shoot and roots change, i.e., shoot goes away from light and roots turn towards light but after a few days shoot again shows bending towards light and roots move away from light.

Questions:

Question 1.
Have the old parts of the shoot and root changed direction?
Answer:
Yes, shoot always grows towards light as it positively phototropic and root goes in opposite direction of light.

Question 2.
Are there differences in the direction of the new growth?
Answer:
No, growth pattern or direction follows environmental stimulus.

Question 3.
What can we conclude from this activity?
Answer:
We can conclude from this activity that shoot shows positive phototropism and roots show negative phototropism.

Activity 7.3 [T. B. Pg. 123]

Identify the endocrine glands mentioned in the diagram.

Activity 7.4 [T. B. Pg. 125]

To know some important hormones and their functions.
Complete the following given table:

No.	Hormone	Endocrine Gland	Function
1.	Growth hormone	Pituitary gland	Stimulates growth in all organs.
2.	Thyroxin	Thyroid gland	Regulates metabolism for body growth.
3.	Insulin	Pancreas	Regulate blood sugar level
4.	Testosterone	Testes	Development of secondary sexual characters in male
5.	Estrogen	Ovaries	Development of female sex organs, regulates menstrual cycle, etc.
6.	Adrenaline	Adrenal gland	Prepares body for an emergency condition, i.e., either fight or flight.
7.	Releasing hormones	Hypo-thalamus	Stimulates pituitary gland to release hormones

Jharkhand Board JAC Class 10 Science Solutions Chapter 11 मानव नेत्र एवं रंगबिरंगा संसार Textbook Exercise Questions and Answers.

JAC Board Class 10 Science Solutions Chapter 11 मानव नेत्र एवं रंगबिरंगा संसार

Jharkhand Board Class 10 Science मानव नेत्र एवं रंगबिरंगा संसार Textbook Questions and Answers

अभ्यास प्रश्न (पृष्ठ संख्या-219-220)

प्रश्न 1.
मानव नेत्र अभिनेत्र लेंस की फोकस दूरी को समायोजित करके विभिन्न दूरियों पर रखी वस्तुओं को फोकसित कर सकता है। ऐसा हो पाने का करण है-
(a) जरा दूरदृष्टिता
(b) समंजन
(c) निकट-दृष्टि
(d) दीर्घ-दृष्टि
उत्तर:
(b) समंजन

प्रश्न 2.
मानव नेत्र जिस भाग पर किसी वस्तु का प्रतिबिम्ब बनाते हैं वह है-
(a) कॉर्निय
(b) परितारिका
(c) पु
(d) दृष्टिपटल
उत्तर:
(d) दृष्टिपटल।

प्रश्न 3.
सामान्य दृष्टि के वयस्क के लिए सुस्पष्ट दर्शन की अल्पतम दूरी होती है, लगभग-
(a) 25 m
(b) 2.5 cm
(c) 25 cm
(d) 2.5 m
उत्तर:
(c) 25 em.

प्रश्न 4.
अभिनेत्र लेंस की फोकस दूरी में परिवर्तन किया जाता है-
(a) पुतली द्वारा
(b) दृष्टिपटल द्वारा
(c) पक्ष्माभी द्वारा
(d) परितारिका द्वारा
उत्तर:
(c) पक्ष्माभी द्वारा।

प्रश्न 5.
किसी व्यक्ति को अपनी दूर की दृष्टि को संशोधित करने के लिए 5.5 डाइऑप्टर क्षमता के लेंस की आवश्यकता है। अपनी निकट की दृष्टि को संशोधित करने के लिए उसे +1.5 डाइऑप्टर क्षमता के लेंस की आवश्यकता है। संशोधित करने के लिए आवश्यक लेंस की फोकस दूरी क्या होगी – (i) दूर की दृष्टि के लिए (ii) निकट की दृष्टि के लिए।
हल:
(i) दूर की दृष्टि के लिए-
फोकस दूरी =

(ii) निकट की दृष्टि के लिए-
फोकस दूरी =

उत्तर:
(i) 18.2 सेमी
(ii) 66.7 सेमी।

प्रश्न 6.
किसी निकट दृष्टिदोष से पीड़ित व्यक्ति का दूर बिन्दु नेत्र के सामने 80 cm दूरी पर है। इस दोष को संशोधित करने के लिए आवश्यक लेंस की प्रकृति तथा क्षमता क्या होगी?
उत्तर:
व्यक्ति को दीप संशाधित करने के लिए अवतल लेंस चाहिए।
लेंस की क्षमता,

प्रश्न 7.
चित्र बनाकर दर्शाइए कि दीर्घ दृष्टिदोष कैसे संशोधित किया जाता है? एक दीर्घ दृष्टि दोषयुक्त नेत्र का निकट बिन्दु 1 mm है। इस दोष को संशोधित करने के लिए आवश्यक लेंस की क्षमता क्या होगी? यह मान लीजिए कि सामान्य नेत्र का निकट बिन्दु 25 em है।
उत्तर:

(ii) संशोधन के लिए उत्तल लेंस उपयुक्त होता तथा प्रश्नानुसार,
u = – 25cm
v = – 1m = – 100 cm
लेंस सूत्र से,
\(\frac{1}{v}-\frac{1}{u}=\frac{1}{f}\)
⇒ \(\frac{1}{-100}-\frac{1}{-25}=\frac{1}{f}\)
f = \(\frac { 100 }{ 3 }\) cm
f = \(\frac { 1 }{ 3 }\)m
लैस क्षमता P = \(\frac { 1 }{ f }\)
P = \(\frac{\frac{1}{3}}{\frac{3}{3}}\)
P = + 3 डाइऑप्टर

प्रश्न 8.
सामान्य नेत्र 25 cm से निकट रखी वस्तुओं को सुस्पष्ट क्यों नहीं देख पाते?
उत्तर:
25 cm से कम दूरी पर रखी हुई वस्तु से आने वाली प्रकाश की किरणों को दृष्टिपटल पर फोकस करने के लिए मानव नेत्र की क्षमता में जितनी वृद्धि होनी चाहिए उतना नहीं हो पाता है, क्योंकि मानव नेत्र की फोकस दूरी 25 cm से कम नहीं हो सकती है। इसलिए उस वस्तु का प्रतिबिम्ब दिखाई नहीं देता है।

प्रश्न 9.
जब हम नेत्र से किसी वस्तु की दूरी को बढ़ा देते हैं, तो नेत्र में प्रतिबिम्ब दूरी का क्या होता है?
उत्तर:
प्रतिबिम्ब दूरी स्थिर रहती है क्योंकि मानव नेत्र के लेंस की फोकस दूरी इस प्रकार से समायोजित होती है कि प्रतिबिम्ब हमेशा दृष्टिपटल पर ही बने।

प्रश्न 10.
तारे क्यों टिमटिमाते हैं?
उत्तर:
गर्म और ठंडी हवाओं के कारण पृथ्वी के वायुमण्डल का अपवर्तनांक लगातार परिवर्तित होता रहता है। तारों से आने वाली प्रकाश किरणों का इस प्रकार लगातार अपवर्तन होता है, तो प्रकाश किरणें निरीक्षक की आँखों तक अनियमित रूप से आती हैं। इसके कारण तारों की आभासी स्थिति बदलती है और तारे टिमटिमाते नजर आते हैं।

प्रश्न 11.
व्याख्या कीजिए कि यह क्यों नहीं टिमटिमाते हैं?
उत्तर:
ग्रह पृथ्वी के बहुत नजदीक है। यह प्रकाश के वृहद स्रोत माने जाते हैं। अतः ग्रहों से आने वाली प्रकाश किरणों में औसत परिवर्तन न के बराबर होता है। इसलिए ग्रहों की आभासी स्थिति स्थिर होती है एवं ग्रह नहीं टिमटिमाते।

प्रश्न 12.
सूर्योदय के समय सूर्य रक्ताभ क्यों प्रतीत होता है?
उत्तर:
दृश्य प्रकाश किरणों के तरंगदैर्ध्य से भी छोटे धूलकणों या जल कणों की वायुमण्डल में उपस्थिति के कारण प्रकाश किरणों का प्रकीर्णन होता है।

सूर्योदय या सूर्यास्त के समय सूर्य क्षितिज पर होता है। इस समय सूर्य से आने वाला प्रकाश हमारे नेत्रों तक पहुँचने से पहले पृथ्वी के वायुमण्डल में वायु की मोटी परतों से गुजरता है अतः कम तरंगदैर्ध्य वाले रंग यथा नीला, बैंगनी आदि का प्रकीर्णन हो जाता है तथा केवल लंबी प्रकाश तरंगें जैसे – लाल हमारे नेत्रों तक पहुँचती है। अतः सूर्योदय या सूर्यास्त के समय सूर्य रक्ताभ प्रतीत होता है।

प्रश्न 13.
किसी अंतरिक्षयात्री को आकाश नीले की अपेक्षा काला क्यों प्रतीत होता है?
उत्तर:
अंतरिक्षयात्री के लिए ऊँचाई पर कोई भी वायुमण्डल नहीं होता है। इसलिए प्रकाश किरणों का प्रकीर्णन नहीं होता है और अंतरिक्षयात्री को आकाश काला नजर आता है।

Jharkhand Board Class 10 Science मानव नेत्र एवं रंगबिरंगा संसार InText Questions and Answers

पाठगत प्रश्न (पृष्ठ संख्या – 211)

प्रश्न 1.
नेत्र की समंजन क्षमता से क्या अभिप्राय है?
उत्तर:
नेत्र की वह क्षमता जिसके कारण वह विभिन्न दूरियों पर स्थित वस्तुओं के प्रतिबिम्ब रेटिना पर बना सकती है, उसकी समंजन क्षमता कहलाती है।

प्रश्न 2.
निकट दृष्टिदोष का कोई व्यक्ति 1.2 m से अधिक दूरी पर रखी वस्तुओं को सुस्पष्ट नहीं देख सकता। इस दोष को दूर करने के लिए प्रयुक्त संशोधक लेंस किस प्रकार का होना चाहिए?
उत्तर:
यह निकट दृष्टिदोष है, जिसे दूर करने के लिए उचित क्षमता का अवतल लेंस लेना चाहिए।

प्रश्न 3.
मानव नेत्र की सामान्य दृष्टि के लिए दूर बिन्दु तथा निकट बिन्दु नेत्र से कितनी दूरी पर होते हैं?
उत्तर:
मानव नेत्र की सामान्य दृष्टि के लिए दूर बिन्दु अनन्त पर तथा निकट बिन्दु नेत्र से 25 cm की दूरी पर होता है, जिसे सुस्पष्ट दर्शन की न्यूनतम (या अल्पतम) दूरी भी कहते हैं।

प्रश्न 4.
अंतिम पंक्ति में बैठे किसी विद्यार्थी को श्यामपट्ट पढ़ने में कठिनाई होती है। यह विद्यार्थी किस दृष्टिदोष से पीड़ित है? इसे किस प्रकार संशोधित किया जा सकता है?
उत्तर:
यह विद्यार्थी निकट दृष्टिदोष से पीड़ित है। इसे उचित क्षमता के अवतल लेंस द्वारा संशोधित किया जा सकता है।

क्रिया-कलाप – 11.1

• एक ड्राइंग बोर्ड पर ड्राइंग पिनों की सहायता से सफेद कागज की एक शीट लगाइए।
• इस शीट पर काँच का प्रिज्म इस प्रकार रखिए कि इसका त्रिभुजाकार फलक आधार बन जाए। एक पेंसिल का प्रयोग करके प्रिज्म की सीमा रेखा खींचिए।
• प्रिज्म के किसी एक अपवर्तक पृष्ठ AB से कोई कोण बनाती हुई एक सरल रेखा PE खींचिए।
• रेखा PE पर दो पिनें, बिन्दु P तथा Q पर गाड़िए जैसा कि चित्र में दर्शाया गया है।
• फलक AC की ओर से P तथा Q पिनों के प्रतिबिम्बों को देखिए।
• R तथा S बिन्दुओं पर दो और पिनें इस प्रकार गाड़िए कि पिन R तथा S एवं पिन P तथा Q के प्रतिबिम्ब एक सीधी रेखा में दिखाई दें।
  
• पिनों तथा काँच के प्रिज्म को हटाइए।
• रेखा PE प्रिज्म की सीमा रेखा के बिन्दु E पर मिलती है (चित्र देखिए)। इसी प्रकार, बिन्दुओं, R तथा S को एक रेखा से जोड़िए तथा इस रेखा को इस प्रकार आगे बढ़ाइए कि यह प्रिज्म के फलक AC से F पर मिले। हम पहले ही देख चुके हैं कि पिनों P तथा Q को मिलाने वाली रेखा फलक AB से E पर मिलती है। E तथा F को मिलाइए।
• प्रिज्म के अपवर्तक पृष्ठों AB तथा AC पर क्रमशः बिन्दुओं E तथा F पर अभिलम्ब खींचिए।

क्रिया-कलाप के प्रश्नोत्तर

प्रश्न 1.
आपतित किरण, अपवर्तित किरण, निर्मर्त किरण तथा विचलन कोण को दर्शाने के लिए एक चित्र बनाइए।
उत्तर:
PE – आपतित किरण ∠i – आपतन कोण
EF – अपवर्तित किरण ∠r – अपवर्तन कोण
FS – निर्गत किरण ∠e – निर्गत कोण
∠A – प्रिज्म कोण ∠D – विचलन कोण

प्रश्न 2.
एक प्रकाश की किरण कितनी बार अपवर्तित होती है और प्रत्येक बार अपवर्तित किरण की दिशा क्या होगी?
उत्तर:
जब प्रकाश की किरण प्रिज्म से गुजरती यह दो बार अपवर्तित होती है। एक बार तब, जब यह हवा से काँच में प्रवेश करती है तथा दूसरी बार तब, जब यह काँच से हवा में प्रवेश करती है। प्रत्येक बार यह प्रिज्म के आधार की तरफ मुड़ती है।

प्रश्न 3.
विचलन कोण क्या है?
उत्तर:
आपतित किरण की दिशा तथा निर्गत किरण की दिशा के बीच बनने वाले कोण को विचलन कोण कहते हैं।

प्रश्न 4.
किस प्रकार के प्रकाश के लिए विचलन कोण सबसे कम एवं किस प्रकार के प्रकाश के लिए यह सबसे अधिक होता है?
उत्तर:
लाल प्रकाश के लिए सबसे कम तथा नीले प्रकाश के लिए विचलन कोण सबसे अधिक होता है।

क्रिया-कलाप – 11.2

• गत्ते की एक मोटी शीट लीजिए तथा इसके मध्य में एक छोटा छिद्र या एक पतली झिर्री बनाइए।
• पतली झिर्री पर सूर्य का प्रकाश पड़ने दीजिए। इससे श्वेत प्रकाश का एक पतला किरण पुंज प्राप्त होता है।
  
• अब काँच का एक प्रिज्म लीजिए तथा चित्र में दर्शाए अनुसार झिर्री से प्रकाश को इसके एक फलक पर डालिए।
• प्रिज्म को धीरे से इतना घुमाइए कि इससे बाहर निकलने वाला प्रकाश पास रखे किसी परदे पर दिखाई देने लगे।

क्रिया-कलाप के प्रश्नोत्तर

प्रश्न 1.
आप क्या देखते हैं? आप वर्णों की एक आकर्षक पट्टी देखेंगे। ऐसा क्यों होता है?
उत्तर:
ऐसा प्रकाश के विक्षेपण के कारण होता है। काँच में प्रकाश के अलग-अलग अवयवी वर्णों की चाल अलग-अलग होने के कारण ये अलग-अलग कोणों पर विक्षेपित हो जाते हैं।

क्रिया-कलाप – 11.3

• कोई अभिसारी लेंस L₁ ( उत्तल लेंस) लेकर इसके फोकस पर श्वेत प्रकाश का तीव्र स्रोत (S) रखिए। लेंस, प्रकाश का एक समांतर किरण पुंज प्रदान करता है।
• प्रकाश के समांतर किरण पुंज को स्वच्छ जल से भरे एक पारदर्शी काँच के टैंक (T) से गुजारिए।
  
• किसी एक गत्ते में बने एक वृत्ताकार छिद्र (C) से इस प्रकाश किरण पुंज को गुजरने दीजिए। चित्र में दर्शाए अनुसार एक दूसरे अभिसारी लेंस (L₂) का प्रयोग करके वृत्ताकार छिद्र का स्पष्ट प्रतिबिम्ब परदे (MN) पर बनाइए।

क्रिया-कलाप के प्रश्नोत्तर

प्रश्न 1.
टैंक में लगभग 2 L स्वच्छ जल लेकर 200 g सोडियम थायोसल्फेट (हाइपो) घोलिए। जल में लगभग 1 से 2 mL सांद्र सल्फ्यूरिक अम्ल डालिए। आप क्या देखते हैं?
उत्तर:
लगभग 2-3 मिनट के पश्चात् सल्फर के सूक्ष्म कणों द्वारा प्रकाश का अवक्षेपण होता है एवं काँच के टैंक से नीला प्रकाश दिखाई देता है। यह घटना कोलाइडी घोल के कणों द्वारा प्रकाश के प्रकीर्णन के कारण होता है।

Jharkhand Board JAC Class 10 Science Important Questions Chapter 8 How do Organisms Reproduce? Important Questions and Answers.

JAC Board Class 10 Science Important Questions Chapter 8 How do Organisms Reproduce?

Additional Questions and Answers

Question 1.
Distinguish between :
(1) Asexual reproduction and Sexual reproduction
OR
What is the basic difference between asexual reproduction and sexual reproduction?
Answer:

Asexual reproduction	Sexual reproduction
1. In asexual reproduction, a single individual is involved, whose certain body part forms the new individual of the same kind.	1. In sexual reproduction, two gametes of opposite sex fuse to form a fertilized egg (zygote) that develops into a new individual.
2. The sex of an organism does not play any role in the reproductive process.	2. The organisms involved are either bisexual or the two individuals are of opposite sex.
3. The new organism has all the characters of the parent organism without any change in the hereditary characters.	3. The new individual follows laws of inheritance and therefore, differs from its parent organisms.
4. Asexual reproduction is of different types such as fission, regeneration, budding, sporulation, fragmentation, etc.	4. No specific types of sexual reproduction.
5. With changing environment asexual reproduction is not sufficient to sustain life.	5. With changing environment, sexual reproduction is essential to sustain life.

(2) Binary fission and Multiple fission
Answer:

Binary fission	Multiple fission
1. Binary fission forms only two offsprings from a single parent.	1. Multiple fission forms many offsprings from a single parent.
2. This method of reproduction occurs in normal condition.	2. This method of reproduction occurs in unfavourable condition.
3. In this method the nucleus divides once.	3. The nucleus divides several times.
4. In this cytoplasm also divides into two parts.	4. In this, small amount of cytoplasm collects around each daughter nuclei after multiple divisions.
5. The parent cell does not get destroyed but it gets divided into two parts.	5. In this with breaking of cyst, the parent cell also break.

(3) Budding and Sporulation
Answer:

Budding	Sporulation
1. In this method of asexual reproduction, a small part of the body of the parent animal grows out as a ‘Bud’.	1. In this method of asexual reproduction, sporangium is produced in the parent plant.
2. The forming bud grows and differentiates in daughter animal.	2. The spore germinates to produce new plant.
3. The forming bud is not a reproductive unit.	3. The spore is the microscopic reproductive unit, which is covered by protective coat.
4. Example: Hydra, Yeast.	4. Example: Mucor, Rhizopus.

(4) Puberty stage in male and Puberty stage in female
Answer:

Puberty stage in male	Puberty stage in female
1. Boys reach puberty at the age of 13 to 14 years.	1. Girls attain puberty at the age of 10 to 12 years.
2. Muscles grow more in boys.	2. Muscles are soft in girls.
3. Voice becomes deep.	3. Voice remains shrilled.
4. Shoulder and chest broadens.	4. The hip region widens.
5. The penis becomes larger and it is capable of becoming erect.	5. Mammary glands, vagina and uterus are developed.

(5) Male reproductive system and Female reproductive system
Answer:

Male reproductive system	Female reproductive system
1. Testes, vas deferens, seminal vesicle, prostate gland and penis are included in it.	1. Ovary, oviduct, uterus and vagina are included in it.
2. Male reproductive system is formed by the organs related to production of sperms and transfer of sperms to the place of fertilisation.	2. Female reproductive system is formed by the organs related to production of ovum, implantation of embryo and child birth.
3. Testes are located in the scrotal sac outside the abdominal cavity.	3. Ovaries are located in the abdominal cavity.
4. The vas deferens, joins with urinary duct coming from urinary bladder to form urethra.	4. The oviducts from two sides open in the muscular uterus.
5. The urethra is common passage for sperms and urine.	5. In female, the urinaiy opening and genital opening are separate.

(6) Contraceptive mechanical method and Contraceptive chemical method
Answer:

Contraceptive mechanical method	Contraceptive chemical method
1. In this method, copper-T, loop, diaphragm worn in vagina and condom are used.	1. In this method, the pills are used which are made up of hormones.
2. This method is useful for both male and female.	2. This method is useful only for females.
3. Sperms are prevented from entering in female genital tract or unable to reach in oviduct due to barrier.	3. Release of ova is inhibited.
4. This method does not affect the production of gametes.	4. This method can disturb the balance of female sex hormones.

Question 2.
Give scientific reasons for the following tatements:
(1) The offsprings formed through asexual : reproduction have same genetic constitution as their parent cell.
Answer:
In asexual reproduction, the union of male and female gametes does not occur.

• Single parent is involved in asexual reproduction. The process of formation of new cell begins s with the creation of DNA copies.
• Two offsprings are formed from the single parent cell which possess equal proportion of DNA.

Hence, the offsprings formed through asexual reproduction have same genetic constitution as their parent cell.

(2) Variation is necessary for the maintenance of existence of any species.
Answer:
Specific species or its population live in the particular environment or habitat which is suitable to them.

• There are changes taking place on earth e.g., fluctuation in temperature, variation in the water level, etc.
• Organisms possesing variations get a chance to urvive in the changing environment.
• Due to variation, organisms can adapt to the environment and hence they can exist through adaptations.
• With the help of variation geographical distribution of organisms increase.

Hence, variation is necessary for the maintenance of existence of any species.

(3) Testes are situated outside the abdominal cavity.
Answer:
Sperms are produced by the testis.

• The temperature of testis remains 2-3°C lower than the body temperature which is optimal for the formation of sperms.
• If testis remain in abdominal cavity, then at the higher temperature, testes are unable to produce sperms.

Hence, testes are situated outside the abdominal cavity.

(4) The number of bryophyllum keep on increasing in garden.
Answer:
In some plants, parts like root, stem and leaves can give rise to buds in dormant state which acts as reproductive unit.

• When suitable moisture and temperature are provided to these dormant structures, they form new plants.
• Buds found on the leaves of bryophyllum induce vegetative propagation.
• In garden, the detatched buds germinate under favourable conditions such as moisture, nutrients, suitable temperature.

Hence, the number of bryophyllum keep on increasing in garden.

(5) The property of vegetative propagation is useful in agricultural purposes.
Answer:
In many plants root, stem and leaves develop into new plants under appropriate condition. Such a mode of reproduction is called vegetative propagation.

Advantages of vegetative propagation are as follow:

• Vegetative propagation is used in layering or grafting methods to grow many plants like sugarcane, roses or grapes for agricultural purposes.
• Plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds.
• The plants that have lost the capacity to produce seeds can also be produced by vegetative propagation, e.g., banana, orange, rose, jasmine
• All plants produced by vegetative propagation are genetically similar to the parent plant.

(6) Extinction of species can be prevented in sexually reproducting organisms.
Answer:
In sexual reproduction, a zygote is formed s by the union of sexual reproductive cells through fertilisation.

• The male reproductive cell is formed in father’s body and female reproductive cell is formed in mother’s body.
• Thus, offspring gets genetic material (DNA) of two different parents. So, there is variation in offspring.
• This variation helps the individual to get adapted to the changing environment. So, organism can live better.
• Through variation and adaptation, species extinction can be prevented and continuity of life is maintained.

So, extinction of species can be prevented in sexually reproducting organisms.

(7) Contraceptive pills are helpful to prevent pregnancy.
Answer:
Pills used for contraception form contraceptive chemical method.

• The female uses oral contraceptive pills.
• The oral pills contain a combination of hormones (progesterone) which stop the release of eggs and fertilisation cannot occur.
• By using, such pills fertilisation can be prevented.

Hence, contraceptive pills are helpful to prevent pregnancy.

(8) The use of ultrasound technique should be banned for the sex determination.
OR
Prenatal sex determination has been prohibited by law.
Answer:
The ultrasound technique should be used for detection of genetic and other structural abnormalities in embryo.

• Some people use the ultrasound technique (sonography) illegally for sex determination of embryo.
• Due to preference to male child the female embryo is aborted.
• The killing of the unborn girl child is known as female foeticide. This sex-selective abortion is unethical and illegal.
• By female foeticide, female sex ratio is reducing at an alarming rate in India.

Hence, the use of ultrasound technique should be banned for the prenatal sex determination.

(9) Each new generation through sexual mode of reproduction will end up in equal number of chromosomes and the DNA content instead of double to its parents.
Answer:
In sexual mode of reproduction, each new generation is the combination of the DNA copies from two parents. Each new generation gets twice the amount of DNA compared to that with the previous generation.

But reduction division i.e., meiosis occurs during gamete formation. As a result germ cells have half the number of chromosomes and half the amount of DNA set as compared to the non- reproductive body cells.

When haploid germ cells from two parents fuse during sexual reproduction, it results in diploid zygote. Chromosomes and the DNA content in new generation is thus reestablished.

Question 3.
Carefully observe the given diagram and answer the questions related with it:

Questions :
(1) Write name of a, b, c, d and e in given diagram.
(2) Where do given events occur?

• Formation of ovum and its release
• Fertilisation
• Implantation of fertilised ovum

(3) The inner wall of uterus….

• Before ovulation and
• What happens if ovum does not get fertilised?

Answer:
(1) a-oviduct, b-ovary, c-uterus, d-cervix, e-vagina

(2)

Event	Organ
(i) Formation of ovum and its release	by ovary
(ii) Fertilisation	in oviduct
(iii) Implantation of fertilised ovum	in uterus

(3) (i) Before ovulation, the inner wall of uterus becomes thick, spongy and with full of blood supply.
(ii) If ovum does not get fertilised, then thick and spongy wall of uterus along with blood and dead ovum comes out of the vagina in the form of bleeding, i.e., Menstruation.

Questions:
(1) Do labelling of a, b, c, d and e in given diagram.

(2) Where do the given events occur?

• Both sperms and urine pass.
• Sperms delivered through in it.
• Add their fluid secretion with sperms.

(3) ‘d’ part passes through which organ?
What changes are noticed in such organ during adolescence?

(4) State the characteristics of cells produced by e in the given diagram.
Answer:
(1) a-seminal vesicle, b-prostate gland, c – vas deferens, d – urethra, e – testis.

(2)

Event	Related organ / part
(i) Both sperms and urine pass	Urethra
(ii) Sperms delivered in it.	Vas deferens
(iii) Add their fluid secretion with sperms	Seminal vesicle, Prostate gland

(3) ‘d’ part is urethra passes through penis. The penis begins to become enlarged and erect. This changes are noticed after puberty.

(4) Sperms are produced by ‘e’ (Testis). The sperms are motile male gametes that consist of mainly genetic material and a long tail.

(1) Identify ‘a’ and state what it carries.
(2) Identify ‘b’ and state the changes in its structure after fertilisation.
(3) Identify ‘c’ and mention from where is it released and by which process does it reach here.
(4) Identify ‘d’ and state how seeds are formed?
Answer:
(1) a – Pollen tube, it carries male germ cell.
(2) b – Ovary, it grows rapidly and ripens to form a fruit after fertilisation.
(3) c – Pollen grain, it is released from anther of stamen and by the process of pollination it reaches on the stigma.
(4) d – Female germ cell, male germ cell fuses with it to form zygote. Zygote divides several times to form an embryo within the ovule. The ovule develops a tough coat and it is gradually converted into seed.

Objective Questions and Answers

Question 1.
Answer the following questions in short:
(1) Write down the name of different methods of asexual reproduction.
Answer:
The various methods of asexual reproduction are:

• Fission (Binary fission and multiple fission)
• Fragmentation
• Regeneration
• Spore formation and
• Vegetative propagation.

(2) Name two animals which reproduce asexually through fission.
Answer:
Animals that reproduce asexually through fission : Amoeba. Plasmodium.

(3) Name the asexual method of reproduction in (a) Hydra and (b) Plasmodium.
Answer:

• In hydra methods of asexual reproduction are regeneration and budding.
• In plasmodium method of asexual reproduction is multiple fission.

(4) What is the meaning of regeneration? Name two animals which can regenerate from their body parts.
Answer:
Meaning of regeneration : A small cut part of the body can regenerate to form a complete new organism.
Example: Hydra and Planaria.

(5) What is the meaning of vegetative propagation?
Answer:
Vegetative propagation means production of new plants from the roots, stem or leaves of parental plant without taking help of any reproductive orgAnswer:

(6) How do we know that two different individual organisms belong to the same species?
Answer:
Due to similarities among organisms it is clear that they belong to the same species.

(7) What will lead to change in body designs?
Answer:
The DNA in the cell nucleus is the information source for making proteins. If the information is changed, different proteins are formed leading changes in body designs.

(8) What does most basic level in reproduction involve?
Answer:
The most basic level in reproduction involves making of DNA copies for the blueprints of body design.

(9) When does the newly formed DNA copies separate?
Answer:
Newly formed DNA copies separate when additional cellular apparatus is formed at the time of cell division.

(10) Are the two cells formed by a cell division absolutely identical?
Answer:
No, the process of copying the DNA will have some variations each time. As a result, the DNA copies generated may not be identical to \ the original. So, the two cells are not absolutely identical.

(11) How is reproduction to be achieved from a single type, if the organism itself consists of many cell types?
Answer:
Organism may contain many cells but only specialized cells are able to perform reproduction.

(12) Why regeneration is not the same as reproduction?
Answer:
Reproduction is a complex process using specialised cells or organs but regeneration is basically a repair process in which torn out part can heal.

(13) Which parts of flowers fall off after fertilisation?
Answer:
The petals, sepals, stamens, style and stigma may shrivel and fall off after fertilisation.

(14) What are the functions of petals and sepals?
Answer:

• Function of petals : To attract insects for pollination.
• Function of sepals : To protect petals, stamens and pistils.

(15) Which part of flower persists in the fruit of which plant?
Answer:
Dry sepals persist in some fruits such as brinjals, apple, guava. Some of sepals persist in strawberry.

(16) State any two changes that can be included under the general process of growth in human beings.
Answer:
Increase in height and weight, replacement of milk teeth by permanent teeth, etc.

(17) How are new combinations of variants produced generation after generation?
Answer:
Each new variation is made in a DNA copy that already has variation accumulated from previous generations. During sexual reproduction, variations from two individuals are recombined.

(18) Name the methods in which property of vegetative propagation is used? Give the examples for the same.
Answer:
The property of vegetative propagation is used in layering and grafting methods. Sugarcane, roses, grapes are grown for agricultural purposes by this methods.

(19) By which agents is cross-pollination achieved?
Answer:
Cross-pollination is achieved by agents like wind, water or animals.

(20) State any two common changes that appear in both sexes during the period of adolescence?
Answer:
Thick hair growing in armpits and the genital area, the skin frequently becomes oily and pimples begin to develop.

(21) Secretion of which glands makes transport and nutrition of sperms easier?
Answer:
The fluid secretion of prostate gland and seminal vesicles makes transport and nutrition of sperms easier.

(22) State the difference in meaning between zygote, embryo and foetus.
Answer:

Zygote	Embryo	Fbetus
1. The ferti-lised egg is called zygote. 2. It is formed by fusion of sperm and egg cell.	The zygote starts dividing and form a ball of cells called embryo.	The em-bryo is implanted in the lining of the uterus where it continues to grow organs then it is called foetus.

(23) What is called placenta?
Answer:
A disc-like special tissue embedded in uterine wall through which the embryo gets nutrition from mother’s blood is called placenta.

(24) How is body of mother designed to undertake the development of the child?
Answer:
The uterus in mother prepares itself every month to receive and nurture the growing embryo.

(25) How the transmission of sexually transmitted diseases can be prevented during the sexual act?
Answer:
Using a condom diming sexual act can help to prevent transmission of sexually transmitted diseases.

(26) State the names of STDs caused by bacteria and virus.
Answer:
Bacterial STDs : Gonorrhoea, Syphilis.
Viral STDs: Warts, HIV-AIDS

(27) What is the misuse of prenatal sex determination?
Answer:
Parents terminate the pregnancy after knowing the sex of their unborn child; usually a daughter. This is illegal and unethical to carry out prenatal sex determination for aborting female foetus.

Question 2.
Define : OR Explain the terms :
(1) Reproduction
Answer:
The process producing new organism of its own kind during their maturity stage is known as reproduction.

(2) Variation
Answer:
The difference in the characters of individuals of a same species or its population is known as variation.

(3) Asexual reproduction
Answer:
The mode of reproduction allows new generation to be created from a single individual without the formation and fusion of gametes is known as asexual reproduction.

(4) Sexual reproduction
Answer:
A mode of reproduction that depend on the involvement of two individuals (male and female) to create new generation is known as sexual reproduction.

(5) Multiple fission
Answer:
A mode of asexual reproduction in which the division of parent cell forms small, nearly equal sized daughter offsprings is known as multiple fission.

(6) Fragmentation
Answer:
The breaking up of the body of a multi-cellular organism into two or many pieces and on maturing, each piece grows to form a complete new organism is known as fragmentation.

(7) Bud
Answer:
A bulging structure that develops as an outgrowth due to repeated cell division at one specific site, which develops into tiny individual is called a bud.

(8) Vegetative propagation
Answer:
In certain plants, root, stem and leaves develop into new plants under favourable conditions. This property is called as vegetative c propagation.

(9) Sporangia
Answer:
In fungus e.g., Rhizopus, tiny blob-like structure producing spores for reproduction is called sporangia.

(10) Spore
Answer:
A microscopic reproductive unit produced in sporangia and covered by thick protective wall is called spore.

(11) Meiosis
Answer:
A type of cell division in germ cells in which chromosome number is reduced to half is called meiosis.

(12) Flower
Answer:
A sexual reproductive structure produced in flowering plants, especially in angiosperms is called flower.

(13) Seed germination
Answer:
The development of new plant from the seed upon getting favourable conditions, is known as seed germination.

(14) Pollination
Answer:
A process of transfer of pollen from anther of a stamen to the stigma of a pistil in the same or in different flower is called pollination.

(15) Puberty
Answer:
The age at which reproductive organs become functional and attaining the sexual maturity is known as ‘puberty’.

(16) Female foeticide
Answer:
Illegal sex-selective abortion of female foetuses or killing the female foetus is called female foeticide.

(17) Fertilisation
Answer:
A process of a fusion of male gamete and female gamete to form a zygote is called fertilisation.

(18) Menstruation
Answer:
Menstruation is the periodic event taking place after every 28 days in mature woman. This is a cyclic process, interrupted only by pregnancy. During menstruation there is bleeding through vaginal opening. The cell debris and unfertilised ovum is given out of the body during menstruation.

If the egg is not fertilised, it lives for about one day. Since the ovary releases one egg every month, the uterus also prepares itself every month to receive a fertilised egg. Uterine lining becomes thick, spongy and richly supplied with blood. But if fertilisation does not occur then this lining is not needed any longer. So, the lining slowly breaks and comes out through the vaginal opening as blood and mucous.

This cycle takes place roughly every month and is called menstruation. It usually lasts for about two to eight days.

some degree of sexual maturation does not necessarily mean that the body or the mind is ready for sexual acts or for having and bringing up children.

Question 3.
Fill in the blanks :

1. ……………….. undergoes continuous cell division to produce multicellular embryo.
2. ……………….. is the causative agent responsible for sexual diseases like gonorrhea and syphilis.
3. ……………….. type of cell division reduces chromosome number to half in germ cells.
4. In plasmodium, asexual reproduction occurs through ………………..
5. On the surface of potato tuber, there are many ……………….. present for the asexual reproduction.
6. A small cut part of organism’s body can form complete new organism. This process is known as ………………..
7. In flowering plant, fertilisation of egg cell occur in ………………..
8. In sexual reproduction, creation of diversity in characters are fulfilled by ………………..
9. In female, every ……………….. days ovum is released from the ovary.
10. To prevent pregnancy, copper-T is placed in ………………..
11. The temperature of scrotum remains ……………….. below the body temperature.
12. The genetic variation created during reproduction is the basis for ………………..
13. In flowering plant, ……………….. is most important part for continuity of life.
14. The cells involved in sexual reproduction are known as ………………..
15. When sperms reach in urethra from testes, secretions from ……………….. and ……………….. are added with them.
16. If fertilisation of ovum does not occur in female, then ……………….. happens.
17. The size of ……………….. is determined by the rates of birth and death.
18. The uterus opens into the vagina through the ………………..
19. A ……………….. is a future shoot and a ……………….. is a future root in the structure of seed.
20. The DNA in the cell nucleus is the information source for making ………………..

Answer:

1. Zygote
2. Bacteria
3. Meiosis
4. multiple fission
5. buds
6. regeneration
7. ovule
8. Genetic variation
9. 28
10. uterus
11. 2-3°C
12. evolution
13. ovule
14. gametes/germ cells
15. seminal vesicles, prostate gland
16. menstruation
17. population
18. cervix
19. plumule, radicle
20. proteins

Question 4.
State whether the following statements are true or false:

1. Number of organisms increase rapidly through asexual reproduction under unfavourable condition.
2. Fragmentation is the simplest method of reproduction in unicellular animals like amoeba and leishmania.
3. The information of protein synthesis is stored in DNA of a cell nucleus.
4. Variation is useful for the survival of species.
5. Budding is an asexual reproduction method observed only in animals.
6. Condom is a mechanical barrier.
7. In sexual reproduction, DNA content is doubled in zygote than the DNA content of parents.
8. The pollen grains produced in stamen are male reproductive cells.
9. Secretion of the sex hormones starts at the puberty stage.
10. Fallopian tubes come out from the vas deferens.
11. In human, fertilisation occurs in vagina of female and embryo development occurs in uterus.
12. The ovaries contain thousands of immature eggs in newborn girl.
13. Menstruation usually lasts for about two to eight days.
14. Prenatal sex determination is legal in our country.
15. The size of population is determined through birthrate and deathrate of organisms.
16. Syphilis is a STD.
17. Copying of DNA is a part of cellular reproduction.
18. Plants such as banana, orange, rose and jasmine that have lost the capacity to produce s seeds can reproduce by vegetative propagation.
19. Self-pollination is considered better than cross-pollination as far as variation is concerned.
20. Reproduction by production of bud is a common in yeast, hydra and bryophyllum.

Answer:

1. False
2. False
3. True
4. True
5. False
6. True
7. False
8. False
9. True
10. False
11. False
12. True
13. True
14. False
15. True
16. True
17. True
18. True
19. False
20. True

Question 5.
Match the following :
(1)

Column I	Column II
1. Fragmentation	p. Planar ia
2. Budding	q. Potato
3. Vegetative propagation	r. Spirogyra
4. Regeneration	s. Yeast

Answer:
(1 – r), (2 – s), (3 – q), (4 – p).

(2)

Column I	Column II
1. Testis	p. Mouth of uterus
2. Ovary	q. Testosterone
3. Prostate gland	r. Fertilisation
4. Cervix	s. Disc-like special tissue develops between embryo and the uterus wall.
5. Oviduct	t. Progesterone
6. Placenta	u. Secretory gland in the passage of sperms

Answer:
(1 – q), (2 – t), (3 – u), (4 – p), (5 – r), (6 – s).

(3)

Column I	Column II
1. Binary fission	p. Hydra
2. Multiple fission	q. Amoeba
3. Budding	r. Rhizopus
4. Spore formation	s. Plasmodium

Answer:
(1 – q), (2 – s), (3 – p), (4 – r).

(4)

Column I	Column II
1. Ovary	p. Fertilisation of ovum by a sperm
2. Oviduct	q. Passage of sperms
3. Uterus	r. Secretion of sex hormones
4. Vagina	s. Growth of fertilised ovum and development of embryo

Answer:
(1 – r), (2 – p), (3 – s), (4 – q).

(5)

Column I	Column II
1. Life of unfertilised egg	p. 2 to 8 days
2. Puberty in girls	q. About 1 day
3. Menstruation in female	r. At least 9 months
4. Development of embryo in uterus of female	s. 10 to 12 years

Answer:
(1 – q), (2 – s), (3 – p), (4 – r).

(6)

Column I (Contraceptive methods)	Column II (Uses)
1. Barrier method in male	p. Oral pills
2. Chemical method	q. Condom
3. Surgical method	r. Copper-T
4. Barrier method in female	s. Fallopian tubes blocked

Answer:
(1 – q), (2 – p), (3 – s), (4 – r).

Question 6.
Diagram based questions:
1. Identify organisms in the diagram. Which asexual reproduction method is seen? Write it.

Answer:

• Leishmania – Binary fission
• Plasmodium – Multiple fission
• Spirogyra – Fragmentation
• Planaria – Regeneration

2. Draw labelled diagram of (b) and (c) steps of budding in hydra.

Answer:

3. In amoeba, binary fission’s some diagrams are given. Give its proper sequence.

Answer:
(3) → (2) → (1) → (4)

4. Carefully observe the given diagrams and give answer of following questions:

(1) Identify organisms (a), (b), (c), (d) and write their names.
(2) Give names of biological processes seen in all the four diagrams.
(3) How is this biological process useful for organisms?
Answer:
(1)

• Hydra
• Rhizopus
• Bryophyllum
• Planaria

(2) Asexual reproduction

• Budding
• Spore formation
• Vegetative propagation
• Regeneration

(3 ) To maintain continuity of life and to increase their number

5. Identify the given diagram and label the parts a, b and c.

Answer:
Spore formation in Rhizopus
a-Sporangium, b-Spore and c-Hyphae

6. Observe the diagram and answer the questions :

Which part give rise to shoot when seed germinates?
(1) Is the seed dicot or monocot?
(2) Which part give rise to shoot when seed germinates?
(3) Identify ‘a’ in the diagram.
Answer:
(1) Dicot
(2) Plumule
(3) a – Radicle

Question 7.
Select the correct option from those given below each question:
1. A simple multicellular animal having tentacles and lives in fresh water reproduces by the asexual method of ………………………
A. binary fission
B. spore formation
C. budding
D. fragmentation
Answer:
C. budding

2. In which of the following living organism spore formation takes place?
A. Rhizopus
B. Planaria
C. Spirogyra
D. Potato
Answer:
A. Rhizopus

3. Method of asexual reproduction in spirogyra….
A. division of a cell into two cells
B. breaking up of filaments into smaller bits
C. division of a cell into many cells
D. formation of a large number of buds
Answer:
B. breaking up of filaments into smaller bits

4. The filaments of certain algae breaks again and again and each part develops as individual algae. Which type of process is this?
A. Budding
B. Fragmentation
C. Binary fission
D. Multiple fission
Answer:
B. Fragmentation

5. Which kind of reproduction methods are fission, budding, spore formation, etc.?
A. Vegetative propagation
B. Asexual reproduction
C. Sexual reproduction
D. None of these
Answer:
B. Asexual reproduction

6. Which parts of plant produce new plant through vegetative propagation?
A. Root, stem and flower
B. Stem, flower and fruit
C. Stem, leaf and flower
D. Root, stem and leaf
Answer:
D. Root, stem and leaf

7. For how many days does the menstruation period last in woman?
A. 2 to 8
B. 10 to 12
C. 13 to 18
D. 28 to 32
Answer:
A. 2 to 8

8. Which unicellular fungus shows budding?
A. Mucor
B. Yeast
C. Amoeba
D. None of these
Answer:
B. Yeast

9. Which of the following organism shows regeneration?
A. Amoeba
B. Paramoecium
C. Hydra (or Planaria)
D. Rhizopus
Answer:
C. Hydra (or Planaria)

10. Where are testes located in male?
A. In abdominal cavity
B. In vas deferens
C. In scrotum
D. In penis
Answer:
C. In scrotum

11. If the normal temperature of the body is 37 °C, then the ideal temperature of the scrotum is ………………
A. 37 °C
B. 36 °C
C. 39 °C
D. 34 °C
Answer:
D. 34 °C

12. Where does the fertilisation of sperm and ovum occur in human?
A. In uterus
B. In cervix
C. In vagina
D. In oviduct
Answer:
D. In oviduct

13. Where does the implantation and development of the embryo take place?
A. In uterus
B. In vagina
C. In ovary
D. In oviduct
Answer:
A. In uterus

14. Duration from time of fertilisation in human female to the birth of a child :
A. 100 days
B. 180 days
C. 210 days
D. 280 days
Answer:
D. 280 days

15. Which structure develops between uterine wall and foetus to fulfill the need of nutrition?
A. Placenta
B. Umbilical cord
C. Amnion
D. Amniotic fluid
Answer:
A. Placenta

16. In asexual reproduction, offsprings are similar, because…
A. only one parent is involved in reproduction.
B. two parents are involved in reproduction.
C. reproductive cells are involved.
D. reproductive cells are not involved.
Answer:
A. only one parent is involved in reproduction.

17. From the following, which fungus does not undergo asexual reproduction through spore formation?
A. Rhizopus
B. Penicillium
C. Yeast
D. Mucor
Answer:
C. Yeast

18. What is the similarity in reproduction between amoeba and bacteria?
(1) They are multicellular.
(2) They are unicellular.
(3) They only undergo sexual reproduction.
(4) They only undergo asexual reproduction.
(5) They mainly undergo binary fission.
A. (1), (3) and (4)
B. (2) and (3)
C. (2) and (4)
D. (2), (4) and (5)
Answer:
D. (2), (4) and (5)

19. Which is a necessity of cellular reproduction?
A. Changes in niche
B. Continuity of life
C. Copying of DNA
D. Transportation of hereditary characters
Answer:
C. Copying of DNA

20. Which of the following is true for the flower?
(1) Flowers are always bisexual.
(2) They possess sexual reproductive part.
(3) They are produced in all plant groups.
(4) Its ovule after fertilisation is converted into seed.
A. (1) and (3)
B. (2) and (3)
C. (1) and (4)
D. (2) and (4)
Answer:
D. (2) and (4)

21. Variation is observed more in the offsprings produced through sexual reproduction, because…
A. sexual reproduction is a long and complicated process.
B. genetic material of two parents of different species is inherited in offspring.
C. genetic material of two parents of same species is inherited in offspring.
D. genetic material in the offspring is double than that in the parent.
Answer:
C. genetic material of two parents of same species is inherited in offspring.

22. In which part of the flower male reproductive cells and female reproductive cells are produced I respectively?
A. Pollen grain, ovule
B. Anther, Stigma
C. Stigma, style
D. Ovary, ovule
Answer:
A. Pollen grain, ovule

23. What will be produced from the fertilised egg cell In a flower?
A. Embryo
B. Spore
C. Fruit
D. All of given
Answer:
A. Embryo

24. In which type of reproduction there is seed formation?
A. Vegetative propagation
B. Asexual reproduction
C. Sexual reproduction
D. Budding
Answer:
C. Sexual reproduction

25. At the stage of puberty in boy there are secondary sexual changes. Which of the following is these?
A. Increase in height and weight
B. Hair growth in armpits
C. Hair growth in genital area
D. Larger and erect penis
Answer:
D. Larger and erect penis

26. For the formation of sperms in testes, the temperature…
A. must be lower than the body temperature.
B. must be higher than the body temperature.
C. must be same as the body temperature.
D. temperature is not an affecting factor.
Answer:
A. must be lower than the body temperature.

27. Which of the following are not the functions of testes, at puberty?
(1) Formation of reproductive cells
(2) Development of placenta
(3) Secretion of testosterone
(4) Secretion of progesterone
A. (1) and (4)
B. (2) and (4)
C. (3) and (4)
D. (2) and (3)
Answer:
B. (2) and (4)

28. Which of the following group of sexual diseases occur through the bacteria?
A. AIDS-Herpes of reproductive organs
B. Syphilis-Gonorrhea
C. Syphilis-AIDS
D. Gonorrhea-AIDS
Answer:
B. Syphilis-Gonorrhea

29. Offsprings formed by organisms showing asexual reproduction have greater range of similarity because …
(1) only one parent is involved in asexual reproduction.
(2) reproductive cells does not involve in asexual reproduction.
(3) asexual reproduction is faster than sexual reproduction.
(4) more offsprings are produced in asexual reproduction.
A. (1) and (2)
B. (1) and (3)
C. (2) and (4)
D. (3) and (4)
Answer:
B. (1) and (3)

30. Stamen in flower:
A. They produce new seeds.
B. They produce new fruit.
C. They produce pollen grains.
D. They develops fertilised ovum.
Answer:
C. They produce pollen grains.

31. The responsible factors for rapid spread of rhizopus on piece of bread are….
(1) more amount of spores.
(2) getting moist and mineral nutrients from the bread.
(3) presence of branched tubular hyphae.
(4) round spores having sporangium.
A. (1) and (3)
B. (2) and (4)
C. (1) and (2)
D. (3) and (4)
Answer:
C. (1) and (2)

32. What is indicated by the given figure?

A. Budding in yeast
B. Formation of pseudopodia in amoeba
C. Binary fission in amoeba
D. Cyst-formation in amoeba
Answer:
C. Binary fission in amoeba

33. Which is the sign of initiation of reproductive maturity in girl?
A. When menstruation occurs
B. When embryo is carried
C. When she arrives at menopause stage
D. Before ovulation
Answer:
A. When menstruation occurs

34. Which part of flower becomes mature and modified into fruit?
A. Ovule
B. Carpel
C. Ovary
D. Female gamete
Answer:
C. Ovary

35. When plants lose the capacity of seed formation then how does reproduction occur in them?
A. By spore formation
B. By vegetative propagation
C. By fission
D. By regeneration
Answer:
B. By vegetative propagation

36. In which contraceptive method, condom is used?
A. Surgical method
B. Hormonal method
C. Chemical method
D. Mechanical method
Answer:
D. Mechanical method

37. Statement A: Prenatal sex determination has been prohibited by law.
Reason R : Illegal sex-selective abortion of female foetuses increased.
Which is the correct option for A and R?
A. Both A and R correct, R is correct explanation of A.?
B. Both A and R correct, but R is not explanation of A.?
C. A is correct, R is incorrect.
D. A is incorrect, R is correct.
Answer:
A. Both A and R correct, R is correct explanation of A.

Question 7.
Answer as directed : (Miscellaneous)
(1) Give full form : HIV – AIDS
Answer:
HIV : Human Immunodeficiency Virus
AIDS: Acquired Immuno Deficiency Syndrome

(2) Following events in flowering plants given below:
(a) Pollen tube develops in style
(b) Plumule develops as shoot system
(c) Ovule modified in seed
(d) Anther releases pollen and stigma receives it.
Arrange them in correct sequence.
Answer:
(d) → (a) → (c) → (b)

(3) Identify me : I am a type of cell division, significant during sexual reproduction and helping to maintain constant chromosome number generation after generation in particular species.
Answer:
Meiosis

(4) Stamen : Pollen grains : : Testes : ………………
Answer:
Sperms

(5) Find mismatched pair :
A. Hydra → Budding, Regeneration
B. Binary fission → Amoeba, Leishmania
C. Pistil → Anther, Filament
D. Sperms → Genetic material, Long tail
Answer:
C. Pistil → Anther, Filament

(6) Identify me : I am a disc like specialised tissue developed after implantation of embryo in a uterine wall.
Answer:
Placenta

(7) Arrange following events in correct sequence:
(a) Menstruation lasts for two to eight days.
(b) Ovary releases one egg every month.
(c) Uterus lining becomes thick and spongy.
(d) Egg is not fertilised.
Answer:
(b) → (c) → (d) → (a)

(8) Differentiate the word pair : Uterus and urethra
Answer:
Uterus is an elastic bag like structure in female reproductive system where embryo is implanted and nourished.
Urethra is a common passage for passing sperms and urine in males.

(9) Plasmodium : malaria : ………………….. : :
Leishmania : ………………….. : Binary fission
Answer:
Multiple fission, Kala-azar

(10) Arrange following events in correct sequence :
(a) Division of zygote to form embryo.
(b) Rhythmic contractions of muscles in the uterus.
(c) The lining of uterus thicken and richly supplied with blood.
(d) Embryo develops organs to become foetus.
(e) Embryo gets nutrition with the help of placenta.
Answer:
(c) → (a) → (e) → (d) → (b)

(11) Find mismatched pair :
(I) Viral infection Warts
(II) Bacterial infection – Syphilis
(III) Fungal infection – Kala-azar
(IV) Protozoan infection – Malaria
Answer:
(III) Fungal infection Kala-azar

(12) Identify me : I am an external organ of male reproductive system essential for sexual intercourse, but due to covering on me, unwanted pregnancy and transmission of many infection can be prevented.
Answer:
Penis

Value Based Questions With Answers

Question 1.
In higher level multicellular animals, the capacity of regeneration is seen or not? Justify your answer with an example of human body. Is it a type of reproduction?
Answer:
Yes, in human being hair and nails grow after cutting. At a site of injury, new cells are formed and healing of cut body part takes place. But this is not a type of reproduction.

Question 2.
A woman has undergone surgical contraceptive method. Will she show the menstruation or not? Justify your answer.
Answer:
Yes, she will show menstruation till 45 – 48 years. Because oviducts are surgically s blocked whereas menstruation flow takes place mainly due to breakage of lining of uterine wall. This is under the influence of ovarian hormones.

Question 3.
A man has undergone surgical contraceptive method. Will he be able to participate in sexual act? On which structure/part, surgical process s is done? Will he now be safe against sexually transmitted diseases?
Answer:
Yes, man will be able to participate in sexual act even after he has undergone surgical contraceptive method.
Vas deferens is surgically blocked.
He will not be safe against sexually transmitted diseases unless he uses condom.

Question 4.
Why in sexual reproduction variation is observed even though the DNA and chromosomes do not get doubled?
Answer:
Variation is observed in offsprings produced through sexual reproduction because off-springs receive DNA and chromosomes from two different parents.
New variation is made in DNA copying in parental generation and during gamete formation, meiosis is also responsible for new combinations.

Question 5.
Vegetative propagation is seen in which plants? Flowering or non-flowering plant?
Artificial vegetative propagation is practised in which plants? Seed bearing or seedless plants?
Answer:
Vegetative propagation is seen mainly in flowering plants. But non-flowering plants such as moss, fern also show vegetative propagation.

Artificial vegetative propagation is practised in seed bearing plants such as rose, sugarcane, grapes, jasmine, orange, etc.

Practical Skill Based Questions With Answers

Question 1.
Collect different flowers such as Maize, Sunflower, Papaya, Hibiscus, Datura, Rose, Crinum, etc. Which of them are bisexual? Draw diagram of any one bisexual flower and state function of each parts.
Answer:
Bisexual flowers: Hibiscus, Sunflower, Datura, Rose, Crinum.

Question 2.
You are given following seeds :
Maize, Bean, Wheat, Green gram (Mung), Rice, Groundnut.
Classify them into monocot and dicot seeds. Select any one dicot seed and dip in water for about 4 to 5 hours. Press it and observe the part of embryo.
Questions:
(1) Are the basic structural parts of an embryo equal in all dicot seeds?
(2) What is the function of cotyledons?
(3) Is there any change in size of cotyledon as seed germination progresses?
Answer:
Monocot seeds : Maize, Wheat, Rice
Dicot seeds : Bean, Green gram (Mung). Groundnut

(1) Yes
(2) Cotyledons of dicot seeds are food storing. It provies nutrients to germinating seeds.
(3 ) The size of cotyledons is reduced as the seed germination progresses. The food stored in cotyledons is used for

Question 3.

Identify diagram (a), (b), (c) and (d) and give its name.
Out of these, which one is effective for preventing unwanted pregnancy as well as for protection against sexually transmitted diseases ?
Answer:
(a) Condom
(b) Copper-T
(c) Surgical contraceptive for male (vasectomy)
(d) Surgical contraceptive for female (tubectomy).
Only condom is effective for preventing unwanted pregnancy as well as for protection against sexually transmission of diseases.

Memory Map

Students must go through these JAC Class 10 Science Notes Chapter 6 Life Processes to get a clear insight into all the important concepts.

JAC Board Class 10 Science Notes Chapter 6 Life Processes

→ Indication of life : Showing movements is an indication of life. Movements can be visible or invisible. They can be related to growth or not concerned with growth.

• Viruses are said to be connecting link between living and non-living.

→ Life processes: The main processes, that are carried out by all the living organisms in order to sustain their existence as living beings, are called life processes.

• Common life processes: The common life processes occurring in all the living organisms are nutrition, respiration, excretion or removal of metabolic wastes, growth, transportation, movement, control and coordination, reproduction, etc.

→ Nutrition: A process to transfer a source of energy from outside the body of the organism to the inside is called nutrition.

→ Modes of nutrition: There are mainly two modes of nutrition:
(i) Autotrophic nutrition : The organisms, that possess chlorophyll utilize solar energy, water and carbon dioxide and synthesize their own food as glucose -a simple form of carbohydrate. This process is called photosynthesis.

• The photosynthetic organisms show autotrophic nutrition. Green plants and certain photosynthetic bacteria are autotrophic organisms.
• Equation of photosynthesis:
  
• The carbohydrates, i.e., glucose which are not used immediately are stored in . form of starch, in case of plants.

(ii) Heterotrophic nutrition : Organisms which consume complex food material prepared by other organisms are called heterotrophic organisms. They lack chlorophyll and thus cannot synthesise their own food. All animals, fungi, cuscuta, etc. are heterotrophic organisms.

→ Digestion : Process of converting complex food components into simple and soluble form with the help of enzymes is called digestion. The resulting nutrients can be easily absorbed after digestion.

• Digestion is essential for nutrition especially. for animals.
• In single celled animals example : (Amoeba, Paramoecium), intracellular digestion takes place and in human beings digestion is extracellular in alimentary canal.
• Human alimentary canal: It extends from mouth to anus consisting of buccal cavity, oesophagus, stomach, small intestine, large intestine. There are associated glands with alimentary canal which help in digestion.
• Salivary glands, liver and pancreas are accessory glands.
• In human beings five different digestive juices, i.e., saliva, gastric juice, bile juice, pancreatic juice and intestinal juice play significant role in the process of digestion.
• Small intestine is the longest part of the alimentary canal of a human. However the length of the small intestine depends on the food consumed by the animal. Example: Herbivores have a longer small intestine, carnivores have a shorter small intestine.
• Villi: The inner lining of the small intestine has numerous finger like projections called villi which increase the surface area for absorption of simple nutrients formed by digestion.

→ Respiration : A process of breakdown of simple carbohydrates such as glucose to liberate energy is called respiration. As this process occurs inside the living cells, it is also known as cellular respiration. The energy released during respiration is stored in ATP.

• ATP is the energy currency for most of cellular processes.

→ Types of respiration: (1) Aerobic respiration: Respiration in presence of oxygen. (2) Anaerobic respiration : Respiration in absence of oxygen.
The release of energy in the aerobic respiration is greater than in the anaerobic respiration.

• Aerobic organisms need sufficient O₂ and they expell CO₂ during the process.
• Plants exchange gases through stomata. Stomata are tiny pores present on the lower surface of the leaves.
• Breathing is an important process in animals for aerobic respiration. The rate of breathing in aquatic animals is much faster than that seen in terrestrial animals.

→ Human respiratory system : This system consists nostrils, pharynx, larynx, trachea bronchi and bronchioles and lungs. Each bronchiole ends in alveolus. In lungs, large number of balloon-like structure alveoli are present. The alveoli provide a surface for gaseous exchange. In human beings a respiratory pigment haemoglobin present in red blood corpuscles take up oxygen from the air in the lungs and carry it to tissues.

→ Blood : Blood is a fluid connective tissue that carries out transportation of many substances in human beings. Blood consists of plasma which is fluid in which blood corpuscles i.e., red blood corpuscles, white blood corpuscles and platlets are suspended. Red blood corpuscles carry oxygen. Platelets plug blood leakage by helping to clot the blood at the point of injury.

• Human heart is conical, muscular organ which is four chambered, consisting of two atria (auricles) and two ventricles. There is oxygenated blood in left chambers of the heart whereas there is deoxygenated blood in right chambers.
• Fishes have only two chambered heart. Amphibians and most of the reptiles have three chambered hearts.
• Blood vessels : The blood vessels are arteries, veins and blood capillaries. In the arteries, the blood flows from the heart towards different organs and in the veins, blood flows from different organs towards the heart.

→ Lymph: It is another type of fluid involved in transportation similar to the blood plasma but it is colourless and contains less protein.

→ Transportation in plants:

• In higher plants, the transportation of water and mineral elements takes place through xylem and that of synthesized organic substances takes place through phloem.
• Conducting components of xylem: Tracheids and tracheae (vessels).
• Conducting components of phloem: Sieve tubes and companion cells.
• In xylem the conduction of materials starts from the root in upward direction, while in phloem the conduction of materials occurs in both the directions viz. downward from above and upward from roots.
• In higher plants, the water in the tracheids and tracheae is pulled upwards due to the suction force created as a result of transpiration.
• The effect of root pressure in transport of water is more important at night.
• Transpiration : The loss of water in form of water vapour from the aerial parts of the plant is called transpiration.
• Translocation of organic food : The transport of soluble products of Photosynthesis through the phloem tissue is called translocation. In this process ATP is used.

→ Excretion : The biological process of removal of harmful nitrogenous metabolic wastes from body is called excretion. Many unicellular organisms remove nitrogenous wastes by simple diffusion from the body surface.

→ Human excretory system : It consists of a pair of kidneys, a pair of ureters, urinary bladder and a urethra.
Each kidney has large number of the basic filtration units called nephrons.

→ Excretion in plants: Plants use completely different strategies for excretion than those of animals.
Waste material may be stored in the cell- vacuoles or as gum and resin, removed in the falling leaves, or excreted into the surrounding soil.

Jharkhand Board JAC Class 10 Maths Solutions Chapter 14 सांख्यिकी Ex 14.2 Textbook Exercise Questions and Answers.

JAC Board Class 10 Maths Solutions Chapter 14 सांख्यिकी Exercise 14.2

प्रश्न 1.
निम्नलिखित सारणी किसी अस्पताल में एक विशेष वर्ष में भर्ती हुए रोगियों की आयु को दर्शाती है :

उपर्युक्त आँकड़ों से बहुलक और माध्य ज्ञात कीजिए। दोनों केन्द्रीय प्रवृत्ति की मापों की तुलना कीजिए और उनकी व्याख्या कीजिए।
हल :
बहुलक के लिए :
यहाँ अधिकतम बारम्बारता 23 है। इसका संगत वर्ग अन्तराल 35-45 है।
∴ बहुलक वर्ग 35-45 होगा
∴ l = 35, f₁ = 23, f₀ = 21, f₂ = 14 और h = 10

अतः बहुलक = 36.8 वर्ष

माध्य के लिए-

माना कल्पित माध्य (A) = 40 है।

अतः आँकड़ों का बहुलक = 36.8 वर्ष तथा माध्य = 35.375 वर्ष
अस्पताल में भर्ती अधिकतम् रोगी 36.8 वर्ष आयु (लगभग) के हैं। जबकि औसतन अस्पताल में भर्ती किए गए रोगियों की आयु 35.57 वर्ष है।

प्रश्न 2.
निम्नलिखित आँकड़े, 225 बिजली उपकरणों के प्रेक्षित जीवन काल (घण्टों में) की सूचना देते हैं:

उपकरणों का बहुलक जीवन काल ज्ञात कीजिए।
हल :
यहाँ अधिकतम बारम्बारता 61 है। इसका संगत वर्ग अन्तराल 60-80 हैं:
∴ बहुलक वर्ग = 60-80
l = 60, f₁ = 61, f₀ = 52, f₂ = 38 और h = 20

अतः परिवारों का बहुलक मासिक व्यय = ₹ 1847.83
तथा माध्य मासिक व्यय = ₹ 2662.50

प्रश्न 4.
निम्नलिखित बंटन भारत के उच्चतर माध्यमिक स्कूलों में, राज्यों के अनुसार, शिक्षक-विद्यार्थी अनुपात को दर्शाता है। इन आँकड़ों के बहुलक और माध्य ज्ञात कीजिए। दोनों मापकों की व्याख्या कीजिए।

प्रति शिक्षक विद्यार्थियों की संख्या	राज्य / संघीय क्षेत्रों की संख्या
15-20 20-25 25-30 30-35 35-40 40-45 45-50 50-55	3 8 9 10 3 0 0 2

हल :
बहुलक के लिए :
यहाँ, अधिकतम बारम्बारता 10 है। इस बारम्बारता का संगत वर्ग अन्तराल 30-35 है।
∴ बहुलक वर्ग = 30-35
∴ l = 30, f₁ = 10, f₀ = 9, f₂ = 3 और h = 5

माध्य के लिए :

माना कल्पित माध्य (A) = 27.5 है।

अतः बहुलक 30.6 तथा माध्य = 29.2, अधिकांश राज्यों / UT. में छात्र और अध्यापक का अनुपात 30.6 और औसतन अनुपात 29.2 है।

प्रश्न 5.
दिया हुआ बंटन विश्व के कुछ श्रेष्ठतम बल्लेबाजों द्वारा एक दिवसीय अन्तर्राष्ट्रीय क्रिकेट मैचों में बनाए गए रनों को दर्शाता है:

बनाए गए रन	बल्लेबाजों की संख्या
3000-4000 4000-5000 5000-6000 6000-7000 7000-8000 8000-9000 9000-10000 10000-11000	4 18 9 7 6 3 1 1

इन आंकड़ों का बहुलक ज्ञात कीजिए।
हल :
बहुलक के लिए दिए गए आँकड़ों में अधिकतम बारम्बारता 18 है। इसका संगत वर्ग अन्तराल 4000 – 5000 है।
∴ बहुलक वर्ग = 4000 – 5000
∴ l = 4000; f₁ = 18; f₀ = 4; f₂ = 9 और h = 1000

अतः दिए गए आँकड़ों का बहुलक = 46087 रन

प्रश्न 6.
एक विद्यार्थी ने एक सड़क के किसी स्थान से होकर जाती हुई कारों की संख्याएँ नोट कीं और उन्हें नीचे दी हुई सारणी के रूप में व्यक्त किया। सारणी में दिया प्रत्येक प्रेक्षण 3 मिनट के अन्तराल में उस स्थान से होकर जाने वाली कारों की संख्याओं से सम्बन्धित है। ऐसे 100 अन्तरालों पर प्रेक्षण लिए गए। इन आँकड़ों का बहुलक ज्ञात कीजिए ।

हल :
दिए गए आँकड़ों में अधिकतम बारम्बारता 20 है। इस बारम्बारता का संगत वर्ग अन्तराल 40-50 है।
∴ बहुलक वर्ग = 40-50
∴ l = 40; f₁ = 20; f₀ = 12; f₂ = 11 और h = 10

अतः दिए गए आँकड़ों का बहुलक 44.7 कारें

Students must go through these JAC Class 10 Science Notes Chapter 8 How do Organisms Reproduce? to get a clear insight into all the important concepts.

JAC Board Class 10 Science Notes Chapter 8 How do Organisms Reproduce?

→ Reproduction: A process by which an organism produces new organism of its own kind is known as reproduction.

• Reproduction unlike other life processes, is not necessary to maintain the life of an individual organism.
  Reproduction involves creation of a DNA copy.
• Variations formed during reproduction are the basis for evolution.
• Reproduction is linked to the stability of population of species.
• Variation is useful for the survival of species over time.

→ Asexual Reproduction : When a single parent is involved in the formation of new generations, without the fusion of gametes it is called asexual reproduction.
Types of Asexual Reproduction :

• Fission
• Budding (e.g., Hydra)
• Spore formation (e.g., Rhizopus)
• Regeneration (e.g., Planaria)
• Fragmentation (e.g., Spirogyra)
• Vegetative propagation.

→ Fission :

• Binary fission (e.g., Amoeba, Leishmania) and
• Multiple fission (e.g., Plasmodium).

→ Vegetative Propagation :

• Natural vegetative propagation and
• Artificial vegetative propagation.

→ Natural vegetative propagation example the adventitious buds developing from the tuberous roots of sweet potato, leaf margins of bryophvllum and normal buds (eyes) on the surface of potato tuber.

• Cutting
• Layering
• Grafting, etc., are the artificial methods for vegetative propagation.

→ Advantage of vegetative propagation : All the plants produced are genetically similar to the parent plant.

→ Sexual Reproduction : A mode of reproduction in which both sexes, male and female are involved to produce new generations is known as sexual reproduction.

Germ cells have half the number of chromosome and half the amount of DNA due to meiosis. When both male and female gamete are fused, there is reestablishment of the number of chromosomes and the DNA content in the new generation. This may be similar to their parents or may be recombined to some extent.

→ Sexual reproduction in flowering plant: Flower is the sexual reproductive organ of flowering plants. The stamen is male reproductive part and the carpel is female reproductive part in flower.

• Pollen grains are produced within the anther of stamen. Male gametes are produced within the pollen grain.
• Female gametes are produced within the ovule of ovary of carpel.
• Fertilised ovule is transformed into seed while fertilised ovary forms the fruit.
• The seed germinates to produce new plant (offspring).

→ Sexual reproduction in human:

• Boys generally attain puberty at the age of 13-14 years and girls attain it at the age of 10-12 years.
• Male gonad – testis, produces sperms as well as sex hormone – testosterone.
• Female gonad – ovary, produces ova as well as sex hormones – estrogen and progesterone.

Sex hormones are responsible for attaining sexual maturity.

→ Male reproductive system in human beings : A pair of testis, vasa deferentia, seminal vesicles, prostate gland, urethra, bulbourethral glands or cowper’s glands and penis. Male reproductive cells, i.e., sperms are tiny bodies that consist mainly of genetic material and a long tail.

→ Female reproductive system in human beings: A pair of ovary, a pair of oviduct (fallopian tubes), uterus, cervix and vagina.

• Female reproductive cell, i.e., egg cell/ovum is large and contains the nutrients.
• If the fertilisation does not occur, then the thick wall of uterus (endometrium) breaks down. The thick wall of uterus along with the blood vessels and dead ovum comes out through vaginal opening in the form of a bleeding known as menstruation. Menstruation lasts for 2 to 8 days.

→ Contraceptive methods used for the control of population :

• Mechanical barriers of contraception : The loop or the copper-T are used in females and condom for males.
• Chemical barriers of contraception : Oral pills for females. By changing the hormonal balance of the body, eggs are not released.
• Surgical methods : Vasectomy, i.e., vas deferens in male is blocked or tubectomy, i.e., fallopian tubes in female is blocked surgically. In both cases fertilisation will not take place.

Students must go through these JAC Class 10 Science Notes Chapter 5 Periodic Classification of Elements to get a clear insight into all the important concepts.

JAC Board Class 10 Science Notes Chapter 5 Periodic Classification of Elements

→ There are 118 elements which are known at present and out of these, 98 elements are naturally occurring.

→ The classification of elements is made on the basis of similarity of their properties.

→ Dobereiner, Newlands, Mandeleev, Lothar Meyer and Henry Moseley made attempt of the classification of elements.

→ Dobereiner’s triads When he observed that three elements were arranged in the order of their increasing atomic masses, the atomic mass of the middle element was roughly the average of the atomic masses of the other two elements. These groups of three elements are called triads.

→ Newlands’ law of octaves When elements are arranged in the order of their increasing atomic masses, the every eighth element (starting from a given element) had properties similar to that of the first element.

→ Mendeleev’s periodic law: The properties of elements are the periodic function of their atomic masses.

→ Mendeleev classified the elements in increasing order of their masses in –

• vertical columns called groups and,
• horizontal rows called periods.

→ Mandeleev named scandium, gallium and germanium as Eka-boron, Eka-aluminium and Eka-silicon respectively.

→ Isotopes : Atoms of the same element having same atomic number but different atomic masses are known as isotopes of each other.

→ Henry Moseley showed that the atomic number of an element is a more fundamental property than its atomic mass.

→ The modem periodic law: The properties of elements are a periodic function of their atomic number.

→ Elements in the modern periodic table are arranged in 18 vertical columns called groups and 7 horizontal rows called periods.

Period number	Number of elements
1	2
2	8
3	8
4	18
5	18
6	32
7	Incomplete period

→ The position of an element in the periodic table provides information to predict its chemical properties and reactivity.

→ Periodic properties : Properties of the elements which are periodic function of their electronic configuration and are repeated after definite interval of atomic numbers.

→ Valency: The valency of an element is determined by the number of valence electrons present in the outermost shell of its atom.
OR
The valency is the combining capacity of an atom of an element to acquire noble gas configuration.

→ In a period, on moving from left to right, the valency of the elements first increases from 1 to 4 and then decreases from 4 to 0, while the valency of all elements in a group remain the same.

→ Atomic size (Atomic radius) : The distance between the centre of the nucleus and the outermost shell of an isolated atom is called atomic size (atomic radius).

→ Trend of atomic radii in a period and in a group The atomic radius decreases on moving from left to right in a period while on moving down in a group, the atomic radius of elements increases.

→ In a periodic table, metallic elements are arranged on left while non-metals are arranged on right and semi-metals or metalloids are arranged in the middle.

→ In the modern periodic table, boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po) have intermediate properties between metals and non-metals and hence called metalloids or semi-metals.

→ Metallic elements are electropositive in nature, while non-metals are electronegative in nature.

→ Generally, oxides of non-metals are acidic, while oxides of metals are basic in nature.

→ Atomic number (Z) : The number of protons in the nucleus of an atom of an element is known as the atomic number.

Students must go through these JAC Class 10 Science Notes Chapter 4 Carbon and Its Compounds to get a clear insight into all the important concepts.

JAC Board Class 10 Science Notes Chapter 4 Carbon and Its Compounds

→ All the living structures (plants and animals) are made-up of (or based on) carbon.

→ The earth’s crust contains 0.02 % carbon in the form of minerals.

→ The reactivity of elements is explained as their tendency to attain a completely filled outermost shell, i.e., attains a noble gas configuration.

→ Covalent bond : A chemical bond formed between two or more atoms by mutual sharing of valence electrons is known as a covalent bond.

→ There are three allotropes of carbon:

• Diamond
• Graphite and
• Fullerene

→ Catenation: Carbon has the unique ability to form bonds with other atoms of carbon giving rise to large number of molecules. This property of carbon is called catenation.

→ Compounds of carbon, which are linked by only single bonds between the carbon atoms are called saturated compounds while compounds of carbon having double or triple bonds between the carbon atoms are called unsaturated compounds.

→ Unsaturated organic compounds are more reactive than saturated organic compounds.

→ Structural isomers : The organic compounds having the same molecular formula but different structures are known as structural isomers.

→ Hydrocarbons : The compounds containing carbon and hydrogen only are called hydrocarbons. They may be saturated or unsaturated.

→ Saturated hydrocarbons which contain only single bond between carbon atoms are called alkanes. The unsaturated hydrocarbons which contain one or more double bonds between carbon atoms are called alkenes and those containing one or more triple bonds are called alkynes.

→ Functional group : An atom or a group of atoms which imparts specific properties to the compound is called a functional group. Based on functional group the compounds are classified as alcohol, carboxylic acid, etc.

→ Homologous seeries : A series of organic compounds in succession which differ by a definite group (like – CH₂ -) is called homologous series.
For example,

→ Oxidising agent: Some substances are capable of adding oxygen to other substances, or remove hydrogen are known as oxidising agents. For example, alkaline potassium permanganate, acidified potassium dichromate.

→ Addition reaction : Unsaturated hydrocarbons adds hydrogen in the presence of catalysts such as palladium or nickel to form saturated hydrocarbons. This reaction is known as addition reaction.

→ Substitution reaction: The reaction in which hydrogen atom of saturated hydrocarbon is replaced by functional group is called a substitution reaction.

→ Esterification: A reaction in which a carboxylic acid and an alcohol react in the presence of acid catalyst forming esters and water is known as an esterification reaction.

→ Saponification : The reaction of forming alcohol and sodium salt of carboxylic acid from ester is known as saponification.

→ The action of soaps and detergents are based on the presence of both hydrophobic and hydrophilic groups in the molecule which helps in emulsifying the oily dirt.

Students must go through these JAC Class 10 Science Notes Chapter 3 Metals and Non-metal to get a clear insight into all the important concepts.

JAC Board Class 10 Science Notes Chapter 3 Metals and Non-metal

→ Metals : Metals possesses lustre in their pure state. Metals are hard. It possesses property of malleability and ductility. Metals are good conductors of heat and electricity and their melting points are high. Metals are sonorous.

→ Non-metals: Non-metals are either solids or gases (Exception: Bromine, it is a liquid). They are neither malleable, nor ductile. They are non-conductors of heat and electricity (Exception: Graphite, it is conductor). Their melting points and boiling points are low (Exception : Diamond, it has the highest melting point).

→ Metals combine with oxygen to form metal oxides.

→ Oxides of alkali metals are soluble in water.

→ Metals form basic (For example, Na₂O, MgO) and amphoteric oxides (For example, ZnO, Al₂O₃), while non-metals form acidic and neutral oxides (For example, H₂O, CO, Cl₂O₇).

→ Metals react with acid and water forming hydrogen gas. Non-metals do not release hydrogen gas by reaction with acid and water.

→ When metals reacts with nitric acid, hydrogen gas is not evolved, because nitric acid is a strong oxidising agent.

→ Reactivity series of metals is an arrangement of metals in the descending order of their reactivity. In reactivity series, more reactive metals (elements) are placed at top while less reactive metals (elements) are placed at bottom.

→ A more reactive metal displaces a less reactive metal from its salt solution or from its molten state.

→ Metallurgy The various processes involved in the extraction of metals from their ores in different steps and finally refining the metals.

→ Ionic compounds: The compounds formed by the transfer of electrons from a metal species to a non-metal species forming ions are known as ionic compounds.

→ Properties of ionic compounds : Ionic compounds are brittle. They have high melting point and boiling point. They are soluble in water but insoluble in petrol and kerosene (non-polar solvents). These compounds do not conduct electricity in solid state but they conduct electricity in an aqueous solution or in their molten state.

→ Roasting: The process of strongly heating the sulphide ores in excess of air and converting them into oxides is called roasting.

→ Calcination: The process of strongly heating the carbonate (or hydroxide) ores in a limited supply of air and converting them into metal oxides is called calcination.

→ Alloys: The homogenous mixture of two or more metals or metal and non-metal is called an alloy. For example, brass, bronze, stainless steel, etc.

Jharkhand Board JAC Class 10 Maths Solutions Chapter 8 त्रिकोणमिति का परिचय Ex 8.4 Textbook Exercise Questions and Answers.

JAC Board Class 10 Maths Solutions Chapter 8 त्रिकोणमिति का परिचय Exercise 8.4

प्रश्न 1.
त्रिकोणमितीय अनुपातों sin A, sec A और tan A को cot A के पदों में व्यक्त कीजिए।
हल:

प्रश्न 2.
∠A के अन्य सभी त्रिकोणमितीय अनुपातों को sec A के पदों में लिखिए।
हल:
(i) ∵ sin² A + cos² A = 1
⇒ sin² A = 1 – cos² A

(ii) cos A = \(\frac{1}{\sec A}\)
(iii) 1 + tan² = sec² A
⇒ tan²A = sec² A – 1
⇒ (tan A)² = sec² A – 1
अत: tan A = \(\sqrt{\sec ^2 A-1}\)

प्रश्न 3.
मान निकालिए:
(i) \(\frac{\sin ^2 63^{\circ}+\sin ^2 27^{\circ}}{\cos ^2 17^{\circ}+\cos ^2 73^{\circ}}\)
(ii) sin 25° cos 65° + cos 25° sin 65°
हल:

= \(\frac{\cos ^2 27^{\circ}+\sin ^2 27^{\circ}}{\cos ^2 17^{\circ}+\sin ^2 17^{\circ}}\)
{∵ sin (90° – θ) = cos θ
और a cos (90° – θ) = sin θ}
= \(\frac{1}{1}\) = 1 = (∵ sin² θ + cos² θ = 1)

(ii) sin 25° cos 65° + cos 25° sin 65° = sin 25° cos (90° – 25°) + cos 25° sin (90° – 25°)
= sin 25°.sin 25° + cos 25°.cos 25°
[∵ cos (90° – 25°) = sin 25°
और sin (90° – 25°) = cos 25°]
= sin² 25° + cos² 25°
= 1

प्रश्न 4.
सही विकल्प चुनिए और अपने विकल्प की पुष्टि कीजिए:
(i) 9 sec² A – 9 tan² A बराबर है:
(A) 1
(B) 9
(C) 8
(D) 0
(ii) (1 + tan θ + see θ) (1 + cot θ – cosec θ) बराबर है:
(A) 0
(B) 1
(C) 2
(D) -1
(iii) (sec A + tan A) (1 – sin A) बराबर है:
(A) sec A
(B) sin A
(C) cosec A
(D) cos A
(iv) \(\frac{1+\tan ^2 A}{1+\cot ^2 A}\) बराबर है:
(A) sec² A
(B) -1
(C) cot² A
(D) tan² A
हल:
(i) 9 sec² A – 9 tan² A
= 9(sec² A – tan² A)
(∵ sec² A = 1 + tan² A)
= 9(1 + tan² A – tan² A)
= 9 × (1) = 9
अत: सही विकल्प (B) है।

(ii) (1 + tan θ + sec θ) (1 + cot θ – cosec θ)


(∵ sin² θ + cos² θ = 1)
अत: सही विकल्प (C) है।

(iii) (sec A + tan A) (1 – sin A)

अत: सही विकल्प (D) है।

अत: सही विकल्प (D) है।

प्रश्न 5.
निम्नलिखित सर्वसमिकाएँ सिद्ध कीजिए, जहाँ वे कोण, जिनके लिए व्यंजक परिभाषित हैं, न्यूनकोण हैं:

हल:

(viii) (sin A + cosec A)² + (cos A + sec A)² = 7 + tan² A + cot² A
L.H.S.
= (sin A + cosec A)² + (cos A + sec A)²
= (sin² A + cosec² A + 2 sin A cosec A) + (cos² A + sec² A + 2 cos A sec A)
= (sin² A + cosec² A + 2 sin A × \(\frac{1}{\sin A}\)) + (cos² A + sec² A + 2 × cos A × \(\frac{1}{\cos A}\))
= (sin² A + cosec² A + 2) + (cos² A + sec² A + 2)
= sin² A + cosec² A + cos² A + sec² A + 4
= sin² A + cos² A + cosec² A + sec² A + 4
= 1 + cosec² A + sec² A + 4 [∵ sin² θ + cos² θ = 1]
= cosec² A + sec² A + 5
= (1 + cot² A) + (1 + tan² A) + 5
[∵ cosec² θ = 1 + cot² θ]
sec² θ = 1 + tan² θ]
= tan² A + cot² A + 7 = R.H.S.
∴ L.H.S. = R.H.S.

(ix) (cosec A – sin A) (sec A – cos A) = \(\frac{1}{\tan A+\cot A}\)