CBSE Class 10 Biology Control and Coordination Previous Year Questions
Help your child master CBSE Class 10 Biology Control and Coordination with this expertly curated collection of previous year board exam questions spanning 2014–2024. Every question comes with a detailed answer and explanation — covering the nervous system, hormones, tropic movements, and reflex arcs — so your child walks into the exam fully prepared.
CBSE Class 10 Biology Control and Coordination — Questions with Solutions

Explanation: The figure “C” depicts the phenomenon of geotropism appropriately. Geotropism is the growth of the parts of plants in response to the force of gravity. The upward growth of plant shoots is an instance of negative geotropism, while the downward growth of roots is an instance of positive geotropism.
Explanation: When a tendril touches an object, the side in contact with the object grows slower than its other side (i.e., rapid cell divisions occur in the cells that are away from the support). This causes the tendril to bend towards the object, grow around it, and finally cling to it.
Explanation: The cerebellum controls voluntary movements such as walking, posture, balance coordination, eye movements, and speech. This control results in smooth and balanced muscular activity.
Explanation: A synapse is a microscopic gap between two neurons where a chemical signal is transmitted from the axonal end of one neuron to the dendritic end of another neuron.
Explanation: The gustatory receptors, which detect taste, are present in the tongue.
Explanation: Cytokinin regulates cell division by promoting it in plants.
Explanation: The sensory nerve of a reflex arc carries information from the receptor cells to the spinal cord. It is also called an afferent neuron.
Explanation: Auxin becomes more concentrated on the side of the plant that is not facing the light (the shaded side). In the shoots, this causes the shaded side to grow more quickly, which results in the bending of the shoot towards the light.
It is a plant growth regulator that inhibits growth.
Action:
It is responsible for promoting ageing and senescence in plants.
This concentration of auxin stimulates the cells to grow longer on the side of the shoot away from light. Thus, the plant appears to bend towards the light while growing.
This phenomenon is called phototropism.
(b) Plant hormones are also referred to as growth regulators and can be controlled by a number of stimuli. Mention one point of difference between the functioning of animal growth hormones and plant growth regulators with respect to such control.
When light comes from one side, auxin diffuses to the shaded side of the shoot. The higher concentration of auxin on the shaded side causes those cells to grow longer, making the shoot bend towards the light — this is phototropism.
(b) Animal growth hormones cannot promote growth under the influence of external stimuli like light, gravity, etc., while plant growth regulators can.
(i) Positive phototropism
(ii) Negative geotropism
(iii) Positive hydrotropism
(i) Positive phototropism – Shoot
(ii) Negative geotropism – Shoot
(iii) Positive hydrotropism – Root
(a) Which hormone facilitated the ripening of tomatoes?
(b) Why did the tomatoes in the paper bag ripen faster?
(b) Ethylene is a gaseous hormone, and the paper bag prevented it from diffusing into the air. Hence, the tomatoes ripened faster.
The movement of the shoot towards light is known as a tropic movement. This movement depends on the direction of light and is directional and involves growth development.
Walking away was a voluntary slow action.
| Beating of Heart (Involuntary Actions) | Reflex Actions |
|---|---|
| Involuntary actions are not controlled by our will. | Reflex actions are sudden actions in response to something. |
| They do not need any external stimulus to work. | They require a stimulus for their action. |
| These actions are regulated by the brain. | These actions are regulated by the spinal cord. |
| They do not involve skeletal muscles. | They involve skeletal muscles. |
Examples of Involuntary Actions: Beating of heart, salivating, blinking of eyes, breathing.
Examples of Reflex Actions: Quick withdrawal of hand from a hot object, coughing, sneezing, shivering.
(a) Sensation of feeling full
(b) Vomiting
(c) Picking up a pencil
(d) Riding a bicycle
(b) Medulla / Hind Brain
(c) Cerebellum / Hind Brain
(d) Cerebellum / Hind Brain
(i) Maintaining posture and balance
(ii) Beating of heart
(iii) Thinking
(iv) Blood pressure
(ii) Medulla
(iii) Cerebrum
(iv) Medulla
The three responses that enable the animal body to deal with it are:
(i) Increased heart rate:
Adrenaline increases heart rate, enabling the animal to pump more blood and oxygen to the muscles. This helps the animal to react quickly to the perceived danger.
(ii) Dilated pupils:
Adrenaline causes the pupils to dilate, which helps the animal to see more clearly in low light conditions. This is essential for detecting potential threats and reacting quickly.
(iii) Increased blood sugar:
Adrenaline increases the release of glucose from the liver into the bloodstream, providing the animal with a quick source of energy. This helps the animal to perform physical activities required to defend itself or escape from danger.
(b) How do auxins promote the growth of a tendril around a support?
It is the directional movement of a plant organ in response to an external stimulus.
(b)
Auxins produced in the shoot tip move downwards in the plant. These auxins cause cell elongation in the growing tissues. In the tendrils, auxins move away from the point of contact with the supporting object, while more growth occurs on the side away from the support. As a result of this unequal growth on the two sides, the tendril coils around the support.

- The adrenaline hormone is secreted into the blood.
- The heart beats faster resulting in supply of more oxygen to the muscles.
- Blood is diverted to skeletal muscles.
- The breathing rate increases.
- The blood supply to digestive systems and skin is reduced.
- Electrical impulses have limited access to only those cells that are connected by nervous tissue/neurons, whereas chemical signals can reach each and every cell of the body.
- Cells need time to reset in order to create repeated/new electrical impulses whereas no such time is required for chemical communication.
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What is the term given to the sequence of events occurring in the diagram?
(b) – Sensory neuron
(c) – Spinal cord
(d) – Relay neuron
(e) – Motor neuron
The term given to the sequence of events occurring in the diagram is reflex arc.
Receptor → Sensory neuron → Spinal cord → Brain → Motor neuron → Eye → Contraction of eye muscles
Example:
- When sugar level rises, insulin secretion increases.
- When sugar level falls, insulin secretion reduces.
(i) You observe swollen neck in people living in the hills.
(ii) Over secretion of Growth Hormone takes place during childhood.
(iii) Facial hair develop in boys aged 13.
(ii) Will lead to gigantism.
(iii) Timely secretion of testosterone.
(i) Mid brain
(ii) Pituitary gland
(iii) Cerebellum
(iv) Cerebrum

Experiment:
- Soak the seeds in water overnight.
- Place moist cotton in a perforated petri dish.
- Put the soaked seeds in the petri dish and place it on a beaker.
- Roots pass through pores and grow downwards.
- After some time, roots will bend towards the base of the petri dish having moisture.
(b) In the absence of muscle cells, how do plant cells show movement?
- Auxin: It is synthesised in the young tip of roots and shoots. It promotes elongation and division of cells and root formation.
- Gibberellins: They help in the growth of the stem.
- Cytokinins: They promote cell division and delay leaf ageing.
(b) In the absence of muscle cells, plant cells show two types of movements:
(i) Tropic movements are growth movements in response to an environmental stimulus. This type of movement may occur in response to gravity (geotropism), light (phototropism), water (hydrotropism), chemical (chemotropism), etc.
(ii) Nastic movements are independent of the direction of stimulus. This type of movement may occur in response to chemicals, temperature, touch, etc.
This shows that a plant cell can show movements in response to different stimuli although they do not have muscle cells.
(b) How do nerve impulses travel in the body? Explain.
Iodine is essential for the functioning of the thyroid / formation of thyroxine hormone.
Disease: Goitre.
One symptom of Goitre: Swollen neck.
(b)
- Impulse travels from dendrite to the cell body, then along the axon to its end.
- At the end of the axon, some chemicals (neurotransmitters) are released, which cross the synapse and initiate a similar electrical impulse in the next neuron.
- The impulse then travels further in the body.
(b) How do nerve impulses travel in our body?
Receptor: Specialized tips of some nerve cells that receive information from the surroundings.
Location: Sense organs (such as the eyes, ears, nose, tongue, and skin).
Examples of receptors in the forebrain and their functions:
- Gustatory receptor: Detects taste.
- Olfactory receptor: Detects smell.
(b)
Nerve impulses travel through neurons in a sequence of steps:
- Stimulus: A stimulus is detected by receptors and converted into an electrical impulse.
- Dendrites: The electrical impulse travels along the dendrites towards the cell body of the neuron.
- Axon: The impulse then moves down the axon, the long extension of the neuron.
- Synapse: When the impulse reaches the end of the axon, neurotransmitters are released across the synapse.
- Next neuron: The neurotransmitters trigger an electrical impulse in the next neuron, and the process continues until the impulse reaches its destination, such as the brain or muscles.
Sequence of events during sneezing:
- Nerve endings located in the nasal passage identify the irritant that has entered the nose.
- Receptors send the information or nerve impulses to the sneezing centre located in the brain stem.
- The brain stem sends instructions to the lungs or diaphragm for a response.
- The diaphragm moves abruptly, and chest muscles contract in response to the instructions received.
- Air blows out from the nose and mouth instantly and rapidly.
- Sneezing occurs as a response to the irritant.
(b) Which hormone is present in the areas of rapid cell division in a plant and which hormone inhibits the growth?
Sameer is suffering from diabetes.
The hormone responsible for this disease is insulin.
The organ producing the hormone is the pancreas.
(b)
The hormone present in the areas of rapid cell division in a plant is cytokinins.
The hormone that inhibits growth is abscisic acid.
(b) Are all involuntary actions reflex actions? Justify.
Similarities:
- In both cases, the signal is initiated by receptors located at the specific sense organ.
- In both cases, neurotransmitters are released and accepted by neurons to carry the impulse.
Differences:
- The action of smelling the rose is voluntary whereas pulling the hand away is involuntary in nature.
- While smelling the rose, the nerve impulse reaches the brain and back, whereas on touching a thorn, the nerve impulse travels only to the spinal cord and back.
(b)
No, not all involuntary actions are reflex actions. Most involuntary actions do not require a stimulus to occur, as is necessarily required in the case of a reflex action.

1. What does the graph indicate?
2. A student suggested a different title for the graph — ‘Height of boys and girls from birth to adulthood’. Is the title correct? Explain your answer.
3. Which of the following statements are correct? Circle ‘Yes’ or ‘No’ to mark your response.
| Statement | Yes/No |
|---|---|
| Hormones are released directly into the bloodstream. | Yes/No |
| Endocrine glands use electrical impulses. | Yes/No |
| Sex hormones regulate changes associated with puberty. | Yes/No |
2. The title is incorrect because the height of boys and girls from 0 to 3 years is not given.
3.
- Hormones are released directly into the bloodstream. — Yes
- Endocrine glands use electrical impulses. — No
- Sex hormones regulate changes associated with puberty. — Yes

