Sunday, June 19, 2022

Class 10 Science | Chapter-end Exercise & Answers | Chapter 16 | Sustainable Management of Natural Resources

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Class 10 Science | Chapter-end Exercise & Answers | Chapter 15 | Our Environment

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Class 10 Science | Chapter-end Exercise & Answers | Chapter 14 | Sources of Energy

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Class 10 Science | Chapter-end Exercise & Answers | Chapter 13 | Magnetic Effects of Electric Current

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Class 10 Science | Chapter-end Exercise & Answers | Chapter 12 | Electricity

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Class 10 Science | Chapter-end Exercise & Answers | Chapter 11 | The Human Eye and the Colourful World

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Class 10 Science | Chapter-end Exercise & Answers | Chapter 8 | How do Organisms Reproduce?

1.   Asexual reproduction takes place through budding in

(a) amoeba                             

(b) yeast

(c) plasmodium                      

(d) leishmania


Answer:

(b) Yeast


2.   Which of the following is not a part of the female reproductive system in human beings?

(a) Ovary                                  

(b) Uterus

(c) Vas deferens                     

(d) Fallopian tube


Answer:

(c) Vas deferens


3.   The anther contains

(a) sepals                                

(b) ovules

(c) carpel                                 

(d) pollen grains


Answer:

(d) Pollen grains


4.   What are the advantages of sexual reproduction over asexual reproduction?


Answer:

Sexual reproduction can generate more variations and speed up the making of new variants by combining DNA copies from two individuals. All these variations are accumulated and inherited from generation to generation. It produces individuals with different patterns of variations in a population. Thus the organism can adapt quickly to changes in its surroundings.


5.   What are the functions performed by the testis in human beings?


Answer:

·   Testes produce male gametes (sperms).

· Testes produce a hormone called testosterone. It controls the development of reproductive organs and secondary sexual characters.


6.   Why does menstruation occur?


Answer:

If the ovum is not fertilised, the thick and soft inner lining of uterus is no longer needed and hence breaks. So, the lining along with the blood vessels and the dead ovum comes out of the vagina in the form of blood. This is called menstruation.


7.   Draw a labelled diagram of the longitudinal section of a flower.


Answer:

8.   What are the different methods of contraception?


Answer:

a) Barrier method: E.g., condom, diaphragm and cervical caps. These prevent the entry of sperms in the female genital tract.

b) Chemical method: Use of oral and vaginal pills. The oral pills suppress the release of ovum. The vaginal pills/ creams are spermicidal.

c) Intrauterine contraceptive devices: E.g., Copper-T. It prevents the sperms to reach the uterus.

d) Surgical method: It includes vasectomy in males and tubectomy in females. In vasectomy, a small part of vas deferens is cut or tied. In tubectomy, fallopian tube is cut or tied.


9.   How are the modes for reproduction different in unicellular and multicellular organisms?


Answer:

Reproduction mode in unicellular organisms

Reproduction mode in multicellular organisms

Asexual reproduction.

Asexual or Sexual.

Only one parent is needed.

For sexual reproduction, two parents are needed.

No special cells.

Special cells are present.

No special organs are present for reproduction.

Special organs are present for reproduction.


10.  How does reproduction help in providing stability to populations of species?


Answer:

Reproduction helps to generate copies of individuals which are suited to a particular environment.

The formation of variations during reproduction provides stability to the populations to adapt various environmental conditions.


11.  What could be the reasons for adopting contraceptive methods?


Answer:

·    To control the birth rate and population explosion.

·    To reduce the adverse effects on mother’s body due to frequent pregnancy.

·    To prevent sexually transmitted diseases.


Class 10 Science | Chapter-end Exercise & Answers | Chapter 10 | Light – Reflection and Refraction

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Class 10 Science | Chapter-end Exercise & Answers | Chapter 9 | Heredity and Evolution

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Class 10 Science | Chapter-end Exercise & Answers | Chapter 7 | Control and Coordination

1.   Which of the following is a plant hormone?

(a) Insulin                  

(b) Thyroxin

(c) Oestrogen            

(d) Cytokinin


Answer:

(d) Cytokinin


2.   The gap between two neurons is called a

(a) dendrite               

(b) synapse

(c) axon                      

(d) impulse


Answer:

(b) Synapse


3.   The brain is responsible for

(a) thinking                

(b) regulating the heartbeat

(c) balancing the body           

(d) all of the above


Answer:

(b) All of the above


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 is to detect information from the environment. E.g., photoreceptors in eye detect light.

If receptors do not work properly, the information obtained from the environment will not reach the CNS. As a result, the body cannot respond to the environmental stimuli. It affects our abilities such as vision, hearing, smell, taste, touch etc.


5.   Draw the structure of a neuron and explain its function.


Answer:

Function: Neurons carry information (electrical signals called impulses) to and from the CNS.


6.   How does phototropism occur in plants?


Answer:
Phototropism is the movement of a plant part due to light. The shoot shows positive phototropism and roots show negative phototropism.

Phototropism occurs due to the hormone auxin. When light falls on one side of a plant, the secretion of auxin hormone is more in the part away from the light. Hence, auxin causes growth in length of the cells in shady part. So, the plant bends towards light.


7.   Which signals will get disrupted in case of a spinal cord injury?


Answer:

·    All the involuntary actions will be disrupted.

·    Reflex actions will be disrupted.

·    Signals to and from the brain will be disrupted.


8.   How does chemical coordination occur in plants?


Answer:

Chemical coordination in plants occurs with the help of plant hormones. In meristematic regions, cells secrete hormones such as auxins. These substances identify the information by stimulating the nearby cells and communicate the information.


9.   What is the need for a system of control and coordination in an organism?


Answer:

·    To save the body of the organisms from the harmful changes in the environment.

·    To respond to external and internal stimuli.

·    To control voluntary and involuntary actions.


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


Answer:

Involuntary action: It is a set of muscle movements that do not require thinking. It is controlled by the brain. E.g., heartbeat.

Reflex action: It is a rapid and spontaneous response to a stimulus. It is controlled by spinal cord. E.g., sudden withdrawal of hand when we touch a hot object.


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


Answer:

Nervous Mechanism

Hormonal Mechanism

It involves neurons (nerve cells).

It involves endocrine glands.

Signals are transferred in the form of electrical impulses.

Signals are transferred in the form of chemicals (hormones).

Impulses travel quickly.

Hormones travel slowly.

Quick response.

Slow response.

Signals travel along the neurons.

Signals are transmitted through blood.

The effects are short-lived.

The effects are prolonged.


12. What is the difference between the manner in which movement takes place in a sensitive plant and the movement in our legs?


Answer:

Movement in a sensitive plant

Movement in our legs

Leaves respond to touch (nastic movement).

Leg muscles respond to nerve impulses.

It is not controlled by any part of the plant.

It is controlled by brain and spinal cord.

Here, cells change their shape on changing the amount of water in them.

Water has no effect on the muscle movement.