NCERT Solutions for Class 10 Science Chapter 7 (2025-2026)

This crucial chapter of NCERT Solutions for Class 10 Science Chapter 7, How do Organisms Reproduce?, helps us understand one of the most fundamental characteristics of life - the ability to create new individuals and ensure the continuity of species. Whether it's a simple bacteria dividing into two, a plant growing from a cutting, or the complex process of human reproduction, every organism has evolved unique methods to pass on life to the next generation. This chapter is part of the comprehensive NCERT Solutions Class 1o Science series, which covers all chapters in detail.

The chapter equips students with essential skills to distinguish between asexual and sexual reproduction, understand reproductive systems in plants and animals, learn about fertilization and embryo development, and recognize the importance of reproductive health. Every solution has been designed keeping CBSE board exam patterns in mind, ensuring students develop both conceptual clarity and problem-solving confidence. By mastering this chapter, students build a strong foundation for genetics, evolution, developmental biology, and reproductive health topics in higher classes.

NCERT Solutions for Class 10 Science Chapter 7- All Exercise Questions

How do Organisms Reproduce?
Medium
Q.
Asexual reproduction takes place through budding in

1. amoeba.
2. yeast.
3. plasmodium.
4. leishmania.
How do Organisms Reproduce?
Medium
Q.
Which of the following is not a part of the female reproductive system in human beings?

1. Ovary
2. Uterus
3. Vas deferens
4. Fallopian tube
How do Organisms Reproduce?
Medium
Q.
The anther contains

1. sepals.
2. ovules.
3. carpel.
4. pollen grains.
How do Organisms Reproduce?
Medium
Q.
What are the advantages of sexual reproduction over asexual reproduction?
How do Organisms Reproduce?
Medium
Q.
What are the functions performed by the testis in human beings?
How do Organisms Reproduce?
Difficult
Q.
Why does menstruation occur?
How do Organisms Reproduce?
Medium
Q.
Draw a lebelled diagram of the longitudinal section of a flower.
How do Organisms Reproduce?
Medium
Q.
What are the different methods of contraception?
How do Organisms Reproduce?
Difficult
Q.
How are the modes for reproduction different in unicellular and multicellular organisms?
How do Organisms Reproduce?
Medium
Q.
How does reproduction help in providing stability to populations of species?
How do Organisms Reproduce?
Medium
Q.
What could be the reason for adopting contraceptive methods?

Class 10 Chapter 7 Science Questions & Answers –How do Organisms Reproduce?

Q1. Asexual reproduction takes place through budding in

1. amoeba.
2. yeast.
3. plasmodium.
4. leishmania.

Solution:

b. Yeast

Explanation: Out of the four organisms mentioned, only in yeast asexual reproduction takes place though budding. Asexually Amoeba and Leishmania reproduce through binary fission and Plasmodium reproduces by multiple fission method.

 

Q2. Which of the following is not a part of the female reproductive system in human beings?

1. Ovary
2. Uterus
3. Vas deferens
4. Fallopian tube

Solution:

Vas deferens

Explanation: Ovary, uterus and fallopian tube are the parts of the female reproductive system in human beings whereas vas deferens is the part of male reproductive system in human beings.

 

Q3. The anther contains

1. sepals.
2. ovules.
3. carpel.
4. pollen grains.

Solution:

d) Pollen grains

Explanation: The anther contains pollen grains. Sepals are generally green in colour and protect flower in bud stage. Ovules are present in ovary of the carpel (female reproductive organ of plant).

 

Q4. What are the advantages of sexual reproduction over asexual reproduction?

Solution:

Advantages of sexual reproduction over asexual reproduction are:

1. Sexual reproduction is responsible for variations in a population.
2. Variations in individuals are responsible for survival of a species in an ecosystem.
3. Sexual reproduction plays an important role in origin of new species and is a beginning for evolution.
4. Sexual reproduction helps in providing stability to populations of species.

 

Q5. What are the functions performed by the testis in human beings?

Solution:

Testes are the male reproductive organs in human beings. Functions of testis are:

1. It produces male gametes i.e., sperms.
2. It also produces male hormone called testosterone that regulates the formation of sperms and is responsible for secondary sexual characters in human males at the time of puberty.

 

Q6. Why does menstruation occur?

Solution:  Menstruation is a process in which blood and mucosal tissues are discharged periodically from the inner lining of uterus through the vagina. In human female, every month one egg is released from one ovary. Simultaneously the uterus prepares itself for pregnancy.   During this phase, the inner lining of the uterus gets thickened and new blood vessels are formed that will nourish the future embryo. If pregnancy does not occur, then the lining of the uterus breaks down slowly and the content is released in the form of blood and mucus through the vagina and the process is known as menstruation.

 

Q7. Draw a lebelled diagram of the longitudinal section of a flower.

Solution:

 

Q8. What are the different methods of contraception?

Solution:

The different methods of contraception are:

1. Barrier method: In this method, the meeting of ovum with sperm is checked with the help of a mechanical barrier. Mechanical barrier such as condoms are made of thin and flexible rubber.  The mechanical barrier is available for both males and females. These are used to cover penis in males and vagina in females and prevent sperms from entering the uterus during sexual intercourse to avoid pregnancy.

2. Oral contraceptive: This is method in which hormones are introduced in the female partner to prevent the release of egg to avoid pregnancy. The hormones are taken orally in the form of tablets or pills.

3. Intrauterine devices (IUDs): Contraceptive devices such as the loop or Copper T are placed in the uterus that prevent sperms from reaching the egg and prevent pregnancy to occur.

4. Surgical methods: Transfer of gametes can be blocked by using surgical methods. Surgical method is an irreversible method of contraception. Surgically, in males, vas deferens is blocked to stop the sperm transfer. This process is known as vasectomy. In females, surgically fallopian tubes are blocked to carry the eggs to the uterus. This surgical procedure in females is called tubectomy.

 

Q9. How are the modes for reproduction different in unicellular and multicellular organisms?

Solution:

Unicellular organisms have single cell. Generally, unicellular organisms reproduce by asexual methods like binary fission, multiple fission, budding, etc. For example, Amoeba reproduces by binary fission, yeast reproduces by budding, and Plasmodium reproduces by multiple fission method. Multicellular organisms are made up of either simple cells or complex tissues and organs. Some of their cells are specialised to perform the function of reproduction.  Multicellular organisms can employ the asexual methods of reproduction as well as sexual methods of reproduction. Asexual methods include budding, fragmentation, spore formation and vegetative propagation. Complex multicellular organisms possess a well developed reproductive system having specialised reproductive organs.

 

Q10. How does reproduction help in providing stability to populations of species?

Solution:

In an ecosystem, organisms of different species use their ability of reproduction to survive and maintain their populations in their niches.

In an ecosystem, every individual of a species struggle for food, shelter and protection for their survival and existence. Factors like death at the end of natural life cycle, competition, predation, migration and sudden environmental changes keep on reducing population of species on a regular basis. The process of reproduction is the only way to overcome this continuous depletion of individuals from the populations of diverse species. Therefore, reproduction helps in providing stability to populations of species.

 

Q11. What could be the reason for adopting contraceptive methods?

Solution:

Contraceptive methods are mainly adopted because of the following reasons:

1. These devices prevent unwanted pregnancies to occur.
2. These devices not only help in restricting the number of children but also help in maintaining age gap between children. The age gap between children help parents in good bringing up of their children and less number of children ensures the improved living standards of a family.
3. These devices also prevent the spread of sexually transmitted diseases (STDs).
4. These devices play a role in controlling increase in human population and help in reducing pressure on life supporting natural resources such as food, air, water, fuel, etc.

More Resources of NCERT Solutions for Class 10 Science

NCERT Solutions for Class 10 Science Chapter 7  – FAQs

 

Q.1 Which of the following is a plant hormone?
(a) Insulin
(b) Thyroxin
(c) Estrogen
(d) Cytokinin

Ans-

d) Cytokinin

Explanation: Insulin, thyroxin and oestrogen are animal hormones.

Q.2 The gap between two neurons is called a
(a) dendrite.
(b) synapse.
(c) axon.
(d) impulse.

Ans-

b) Synapse

Explanation: Dendrite and axon are the parts of a neuron. Impulse is the electrical signal that travels through a neuron.

Q.3 The brain is responsible of
(a) thinking
(b) regulating the heart beat
(c) balancing of the body
(d)all of the above

Ans-

d) all of the above

Explanation: Our brain is a part of the nervous system that plays an important role in the control and coordination of higher animals. Thinking, regulating heart beat and balancing of the body are some of the functions that are controlled by the brain.

Q.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?

Ans-

The receptors are the sensory structures that on receiving environmental stimuli generate a nerve impulse. For example, our skin possesses many receptors that respond to the environmental stimuli such as increase or decrease in temperature, pain, etc. Taste receptors present on tongue help in identifying different tastes.

Functions of the receptors are:

  1. They sense the external stimuli.
  2. They also trigger impulse after perceiving stimuli.

When the receptors are damaged, the external stimuli, transferring signals to the brain are not felt. For example, when we drink hot coffee or tea, taste receptors on the tongue gets damaged. These damaged taste buds do not allow us to enjoy our food for a little while as they are not able to perceive the external stimuli i.e., taste of food.

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

Ans-

Neuron is the structural and functional unit of nervous system. The parts of a neuron are cyton (cell body), axon, and dendrites.

Functions of the parts of a neuron:

Dendrite: It receives information from the axon of another neuron and conducts the message in the form of an impulse in the cyton (cell body).

Cyton (cell body): It consists of nucleus, mitochondria, and other cell organelles and concerned with the growth and maintenance of the neuron.

Axon: It helps in conducting messages in the form of impulse away from the cyton (cell body).

Q.6 How does phototropism occur in plants?

Ans-

Phototropism refers to the orientation of organisms in response to light. In plants, phototropism occurs due to the presence of a plant hormone called auxin. Auxin is synthesised at the shoot tips of the plants and help the plant cells to grow longer. In a case, when light is coming from one side of a plant, the plant hormone auxin diffuses towards the side of the plant shoot where no light is coming. The cells of the shoot which is away from the light start growing longer under the influence of plant hormone auxin and this causes bending of the plant towards light (phototropism).

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

Ans-

In case of a spinal cord injury, the signals coming from the nerves and the receptors and the signals reaching the effector organ will be disrupted.

Q.8 How does chemical coordination occur in plants?

Ans-

Plants do not possess a nervous system. Plants respond to the external and internal stimuli by showing different types of movements. In plants, growth, development and response to the stimuli is controlled and coordinated by certain chemical substances produced in their cells called hormones. A plant hormone is an organic compound which is synthesised at plant parts away from where they act and when required diffuses to the area of action. The five major types of plant hormones are auxins, gibberellins, cytokinins, abscisic acid and ethylene. These plant hormones either act as growth promoters or growth inhibitors. Auxins, gibberellins, cytokinins are growth promoters and abscisic acid and ethylene act as growth inhibitor.

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

Ans-

An organism comprises millions of cells, tissues, organs and organ systems. In an organism, all the organ systems work in coordination with each other and are responsible for the sustenance and survival of an organism in its environment. The more complex is the organism, the more coordination is required. It is very much necessary that various organ systems of an organism should work together in controlled and coordinated manner so that different body parts can function as a single unit and respond appropriately to the stimuli. In the absence of this system of control and coordination, our body will not be able to function properly. In animals, the control and coordination are provided by the nervous system and endocrine system whereas in plants nervous system is absent.

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

Ans-

Involuntary actions cannot be consciously controlled. For example, we cannot consciously control the contraction and relaxation of our heart muscles. Involuntary actions are directly under the control of the brain. On the other hand, the reflex actions such as removal of hand just after getting pricked by a thorn shows sudden response and do not involve any thinking process. This clearly shows that the reflex actions are not under the control of brain as the involuntary actions are.

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

Ans-

Character Nervous Control and Coordination Hormonal Control and Coordination
Form of Information Nerve impulse Chemical messenger
Mode of transmission of information Through axons and dendrites Through blood
Flow of information Rapid Slow
Response Quick Slow
Duration of effect Short-lived Prolonged effects

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

Ans-

The movement that takes place in a sensitive plant such as Mimosa pudica is an example of the response to touch stimulus. In response to the stimulus of touch and for this movement to occur, the plant cells change their shape by changing the amount of water in them. Movement in our legs is a voluntary action. In a voluntary action, the signals are passed to the brain and hence are consciously controlled. In animal muscle cells, when a nerve impulse reaches the muscle cells, the muscle cells move by changing their shape. Muscle cells possess special proteins that on receiving the nerve impulse change their shape and arrangement which further cause the movement of the organ.

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