7. Control and coordination SEBA/ASSEB Class 10 Science– Important Questions and Answers | Assam HSLC

SEBA/ASSEB Class 10 Science Chapter 7: Control and coordination Important Questions and Answers | HSLC Assam

Chapter 7: Control and coordination

Multiple Choose Question And Answer :

Question: Which of the following statements is correct about receptors?

(a) Gustatory receptors detect taste while olfactory receptors detect smell

(b) Both gustatory and olfactory receptors detect smell

(d) Olfactory receptors detect taste and gustatory receptors smell .

Answer: (a) Gustatory receptors detect taste while olfactory receptors detect smell.

[ Gustatory receptors are responsible for taste perception, while olfactory receptors detect odors in the sense of smell.]

Question: Electrical impulse travels in a neuron from

(a) Dendrite → axon → axonal end → cell body

(b) Cell body → dendrite → axon → axonal end

(d) Axonal end → axon → cell body → dendrite

Answer: (c) Dendrite → cell body → axon → axonal end.

Question: In a neuron, conversion of electrical signal to a chemical signal occurs at/in

(a) cell body (b) axonal end (c) dendritic end (d) axon

Answer: (b) axonal end of a neuron.

[ At the axonal end, neurotransmitters are released into the synapse to transmit the signal to the next neuron or target cell. ]

Question: Which of the following statements are true?

(i) Sudden action in response to something in the environment is called reflex action

(ii) Sensory neurons carry signals from spinal cord to muscles

(iii) Motor neurons carry signals from receptors to spinal cord

(iv) The path through which signals are transmitted from a receptor to a muscle or a gland is called reflex arc

(a) (i) and (ii) (b) (i) and (iii) (c) (i) and (iv) (d) (i) , (ii) and (iii)

Answer: (c) (i) and (iv)

[ (i) Sudden action in response to something in the environment is called reflex action.

(iv) The path through which signals are transmitted from a receptor to a muscle or a gland is called a reflex arc. ]

Question: Which of the following is a plant hormone?

(a) Insulin (b) Thyroxin (c) Oestrogen (d) Cytokinin.

Answer: (d) Cytokinin

[ Cytokinins are a class of plant hormones that promote cell division, growth, and development in plants.]

Question: The gap between two neurons is called a

(a) dendrite. (b) synapse. (c) axon. (d) impulse.

Answer: (b) synapse

[ The small gap between two neurons where nerve impulses pass is called a Synapse.]

Question: Which of the following statements are true about the brain?

(i) The main thinking part of brain is hind brain

(ii) Centres of hearing, smell, memory, sight etc are located in fore brain.

(iii) Involuntary actions like salivation, vomiting, blood pressure are controlled by the medulla in the hind brain

(iv) Cerebellum does not control posture and balance of the body

(a) (i) and (ii) (b) (i), (ii) and (iii) (c) (ii) and (iii) (d) (iii) and (iv)

Answer: (c) (ii) and (iii)

[ (ii) Centers of hearing, smell, memory, sight, etc., are located in the forebrain. (iii) Involuntary actions like salivation, vomiting, blood pressure are controlled by the medulla in the hindbrain. ]

Question: Posture and balance of the body is controlled by

(a) cerebrum (b) cerebellum (c) medulla (d) pons

Answer: (b) cerebellum.

[ The cerebellum is responsible for coordinating voluntary movements and maintaining posture and balance in the body.]

Question: The brain is responsible for

(a) thinking. (b) regulating the heart beat. (c) balancing the body. (d) all of the above.

Answer: (d) all of the above

[ The brain controls multiple vital functions such as: (a) thinking and decision-making

(b) regulating the heartbeat (through the nervous system)

So, all the given options are functions of the brain. ]

Question : The plant hormone which stimulates cell division is : [SEBA 2015]

(a) Auxin (b) Cytokinin (c) Abscisic acid (d) Gibberelin

Answer: (b) Cytokinin .

Question: The part of the brain which is responsible for maintaining equilibrium and posture of the body is : [SEBA2016]

(a) Cerebellum (b) Medulla (c) Pons (d) Cerebrum

Answer: (a) Cerebellum .

[The part of the brain that is responsible for maintaining equilibrium and posture of the body is Cerebellum. ]

Question: The hormone which causes wilting of leaves is : [SEBA 2017]

(a) Auxin (b) Gibberellin (c) Abscisic acid (d) Cytokinin

Answer: (c) Abscisic acid .

[The hormone which causes wilting of leaves is abscisic acid. ]

Question: Spinal cord originates from

(a) cerebrum (b) medulla (c) pons (d) cerebellum

Answer: (b) medulla

[ The spinal cord originates from the medulla, which is part of the brainstem.]

Question: The movement of shoot towards light is

(a) geotropism (b) hydrotropism (c) chemotropism (d) phototropism

Answer: (d) phototropism

[ The movement of a shoot towards light is phototropism. ]

Question: The main function of abscisic acid in plants is to

(a) increase the length of cells (b) promote cell division (c) inhibit growth (d) promote growth of stem

Answer: (c) inhibit growth

[ The main function of abscisic acid in plants to inhibit growth.]

Question: The hormone produced by the pancreas that helps in regulating the blood sugar level is :[SEBA 2018]

(a) adrenalin (b) thyroxin (c) insulin (d) testosterone

Answer: (c) insulin .

[The hormone produced by the pancreas that helps in regulating the blood sugar level is insulin.]

Question: The part of the brain responsible for the sensation of hunger and thirst is :[SEBA 2018]

(a) forebrain (b) midbrain (c)hindbrain (d) hypothalamus

Answer: (d) hypothalamus .

[The part of the brain responsible for the sensation of hunger and thirst is hypothalamus. ]

Question: The part of the brain that controls the posture and equilibrium of our body is [SEBA 2019]

(a) diencephalon (b) cerebrum (c) cerebellum (d) medulla oblongata

Answer: (c) cerebellum .

[The part of the brain that controls the posture and equilibrium of our body is cerebellum. ]

Question: Which of the following disease is caused due to the insufficient secretion of thyroxin hormone ?

(a) Beriberi (b) Goiter (c) Diabetes (d) Dwarfism

Answer: (b) Goiter .

[The disease caused due to the insufficient secretion of thyroxin hormone is goiter. ]

Question: The growth inhibiting hormone found to be present in plants is : [SEBA 2021]

(a) Auxin (b) gibberellin (c) cytokinin (d) abscisic acid

Answer: (d) abscisic acid .

[The growth inhibiting hormone found to be present in plants is abscisic acid.]

Question: The gap between the two neurons is called a [SEBA 2023 ]

(a) dendrite (b) synapse (c) axon (d) nerve ending

Answer: (b) synapse .

[The gap between two neurons is called a synapse .]

Question: Iodine is necessary for the synthesis of which hormone?

(a) Adrenaline (b) Thyroxin (c) Auxin (d) Insulin

Answer: (b) Thyroxin

[ Iodine is necessary for the synthesis of the thyroxin, which is a thyroid hormone.]

Question: The growth of tendril in pea plants is due to

(a) effect of light

(b) effect of gravity

(d) rapid cell divisions in tendrillar cells in contact with the support

Answer: (d) rapid cell divisions in tendrillar cells in contact with the support

[ The growth of tendril in pea plants is due to rapid cell divisions in tendrillar cells in contact with the support. ]

Question: The gap between two neurons is called ………….. [2024]

(a) dendrite (b) synapse (c) axon (d) impulse

Answer: (b) synapse

Question: Involuntary actions in the body are controlled by

(a) medulla in fore brain (b) medulla in mid brain (c) medulla in hind brain (d) medulla in spinal cord

Answer : (c) medulla in hind brain .

[ Involuntary actions in the body are primarily controlled by medulla in the hindbrain.]

Question: Which of the following is not an involuntary action?

(a) Vomiting (b) Salivation (c) Heart beat (d) Chewing

Answer: (d) Chewing

[ Chewing is not an involuntary action. ]

Question: Which of the following hormones promotes cell division in plants ? [2024]

(a) Cytokinin (b) Oestrogen (c) Thyroxin (d) Insulin

Answer: (a) Cytokinin

Question: Dwarfism results due to

(a) Excess secretion of thyroxin (b) Less secretion of growth hormone

Answer: (b) less secretion of growth hormone.

[ Insufficient production of growth hormone during childhood can lead to a slower rate of growth and result in dwarfism.]

Question: Some of the voluntary actions like walking in a straight line, riding a bicycle, picking up a pencil ,etc., are controlled by part of the hind brain called . [2024]

(a) cerebellum (b) cerebrum (c) pons (d) medulla

Answer: (a) cerebellum

Question: Which of the following is a plant hormone ? [SEBA 2023]

(a) Insulin (b) Thyroxin (c) Oestrogen (d) Cytokinin

Answer: (d) Cytokinin .

Question: Which of the following is a plant hormone ? [SEBA 2025]

(a) Insulin (b) Cytokinin (c) Thyroxin (d) Oestrogen

Answer: (b) Cytokinin

Question: A feedback mechanism regulates the action of the . [SEBA 2023]

Answer: Endocrine system .

Question: In humans, the life processes are controlled and regulated by

(a) reproductive and endocrine systems (b) respiratory and nervous systems

Answer: (d) nervous and endocrine systems

[ Nervous and endocrine systems are primarily responsible for controlling and regulating life processes in humans.]

Question: Which part of the neuron receives information from the surroundings?

(a) Axon (b) Dendrite (c) Nerve ending (d) Cell body only

Answer: (B) Dendrite

[ Dendrites receive information and carry electrical impulses towards the cell body.]

Question: Which part of the brain controls posture and balance of the body?

(a) Cerebrum (b) Medulla (c) Cerebellum (d) Spinal cord

Answer: (C) Cerebellum

[The cerebellum maintains posture, balance and precision of voluntary movements.]

Question: Which hormone is responsible for the fight-or-flight response?

(a) Insulin (b) Adrenaline (c) Thyroxine (d) Oestrogen

Answer: (b) Adrenaline

[ Adrenaline prepares the body to respond to an emergency.]

Question: Which hormone regulates blood sugar levels?

(a) Insulin (b) Adrenaline (c) Thyroxine (d) Growth hormone

Answer: (a) Insulin

[ Insulin, secreted by the pancreas, helps regulate blood glucose levels.]

Question: Which part of the brain controls involuntary actions such as blood pressure and salivation?

(a) Cerebrum (b) Cerebellum (c) Medulla (d) Forebrain only

Answer: (c) Medulla

[ The medulla controls several involuntary actions.]

Question: Which hormone is secreted by the thyroid gland?

(a) Insulin (b) Thyroxine (c) Adrenaline (d) Testosterone

Answer: (b) Thyroxine

[ The thyroid gland secretes thyroxine, which helps regulate metabolism.]

Question: Which plant hormone inhibits growth and helps in responses to stress?

(a) Auxin (b) Gibberellin (c) Cytokinin (d) Abscisic acid

Answer: (d) Abscisic acid

[ Abscisic acid generally inhibits growth and helps plants respond to stress.]

Question: Which gland is known as the master gland?

(a) Thyroid (b) Pituitary (c) Adrenal (d) Pancreas

Answer: (b) Pituitary

[ The pituitary gland secretes hormones that regulate several other endocrine glands.]

Answer following the Questions:

Question: Which part of the brain maintains posture and equilibrium of the body? [1M]

Answer: The cerebellum maintains posture and equilibrium of the body.

Question: Give an example of a plant hormone that promotes growth. [1M]

Answer: An example of a plant hormone that promotes growth is auxin.

Question: What are plant hormones ? [1M]

Answer: Plant hormones (also called phytohormones) are chemical substances which are produced in the plants and help to control and coordinate the growth and development of plants.

Question: Name the structural and functional unit of the nervous system.

Answer: The neuron is the structural and functional unit of the nervous system.

Question: Name the hormone that controls the development of male secondary sexual characteristics.

Answer: Testosterone.

Question: Which hormone controls metamorphosis in frogs?

Answer: Thyroxine.

Question: What is coordination?

Answer: Coordination is the process by which different organs and systems of the body work together to produce a proper response to a stimulus.

Question: What is a stimulus?

Answer: A stimulus is any change in the surroundings or inside the body that produces a response.

Question: Which gland secretes insulin?

Answer: The pancreas secretes insulin.

Question: What is the function of receptors?

Answer: Receptors detect stimuli from the environment or inside the body and help initiate an appropriate response.

Question: Name the plant hormone responsible for the bending of a shoot towards light.

Answer: Auxin.

Assertion and Reasoning Questions

Choose the correct option for each question:

(A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.

(B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.

(D) Assertion is false, but Reason is true.

Question: Assertion: Reflex actions are generally controlled by the spinal cord.

Reason: The spinal cord can coordinate quick responses without waiting for the brain to process the information first.

Answer: (A) Both statements are true and the Reason correctly explains the Assertion.

Question: Assertion: Auxin helps the shoot bend towards light.

Reason: Auxin accumulates on the illuminated side of the shoot and causes faster growth on that side.

Answer: (C) Assertion is true, but Reason is false. Auxin generally accumulates on the shaded side of a shoot, causing faster growth on that side.

Question: Assertion: The brain is protected by the skull.

Reason: The brain is also protected by three membranes called meninges.

Answer: (B) Both statements are true, but the Reason does not explain the protection provided specifically by the skull.

Question: Assertion: Adrenaline prepares the body to deal with emergency situations.

Reason: Adrenaline increases heart rate and breathing rate.

Answer: (A) Both statements are true, and the Reason correctly explains the Assertion.

Question: Assertion: Plants do not have a nervous system like humans.

Reason: Plants coordinate their responses mainly through chemical substances and changes in growth or cell activity.

Answer: (A) Both statements are true, and the Reason correctly explains the Assertion.

Question: Assertion: Iodine is necessary for the synthesis of thyroxine.

Reason: A deficiency of iodine may cause goitre.

Answer: (B) Both statements are true, but the Reason does not directly explain why iodine is necessary for thyroxine synthesis.

Question: Assertion: The pancreas acts as both an endocrine and an exocrine gland.

Reason: The pancreas secretes hormones into the blood and digestive juice through a duct.

Answer: (A) Both statements are true, and the Reason correctly explains the Assertion.

Question: Assertion: Chemical coordination in animals is generally slower than nervous coordination.

Reason: Hormones are transported to their target organs, whereas nervous coordination uses electrical impulses along neurons.

Answer: (A) Both statements are true, and the Reason correctly explains the Assertion.

Short Question and Answer [ 2Marks ]:

Question: Differentiate between a reflex action and a voluntary action.

Answer: The difference between a reflex action and a voluntary action:

Reflex action	Voluntary action
It is quick and automatic.	It is performed under conscious control.
Example: withdrawing a hand from a hot object.	Example: writing in a notebook.

Question: Differentiate between nervous coordination and hormonal coordination.

Answer: The difference between nervous coordination and hormonal coordination :

Nervous coordination	Hormonal coordination
It involves electrical impulses transmitted through neurons.	It involves hormones carried mainly through the blood.
Its effects are generally rapid and short-lived.	Its effects are often slower and longer-lasting.

Question: What is a reflex arc? Draw its pathway.

Answer: A reflex arc is the pathway through which nerve impulses travel during a reflex action, from the receptor to the sensory neuron, spinal cord, motor neuron and finally to the effector .

The pathway is: Receptor → Sensory neuron → Spinal cord (relay neuron) → Motor neuron → Effector

For example, when we touch a hot object, the hand is quickly withdrawn.

Question: Why is the use of iodised salt recommended?

Answer: The use of iodised salt is recommended because:

(i) Iodine is required by the thyroid gland to produce thyroxine.

(ii) Iodine deficiency can reduce thyroxine production and may lead to goitre.

Question: What are tropic movements? Give two examples.

Answer: Tropic movements are directional growth movements of plant parts in response to external stimuli.

Example: (a) Phototropism: Growth of a shoot towards light.

(b) Geotropism: Growth of roots towards gravity.

Question: State two functions of the cerebrum.

Answer: The two functions of the cerebrum are :

(i) It controls voluntary actions such as walking and writing.

(ii) It is involved in thinking, memory, learning and interpreting sensory information.

Question: How does adrenaline help the body during an emergency?

Answer: Adrenaline prepares the body to deal with emergency situations. It increases the heartbeat and breathing rate, raises blood pressure and directs more blood towards the skeletal muscles. This provides more oxygen to the muscles and prepares the body for a fight-or-flight response.

Question: What is the role of insulin? What happens when it is deficient?

Answer: Insulin is a hormone secreted by the pancreas that helps regulate blood sugar levels by allowing glucose to enter cells for energy.

When insulin is deficient or does not function properly, blood sugar levels rise, which may lead to diabetes mellitus.

Question: Differentiate between a reflex action and a voluntary action.

Answer: The difference between a reflex action and a voluntary action:

Reflex action	Voluntary action
It is quick and automatic.	It is performed under conscious control.
Example: withdrawing a hand from a hot object.	Example: writing in a notebook.

Question: What is the function of the synapse?

Answer: A synapse is the junction between two neurons. It helps transmit nerve signals from one neuron to another through chemical messengers called neurotransmitters.

Question: Why are chemical signals in plants usually slower than nervous signals in animals?

Answer: Chemical signals in plants are slower because they travel through the vascular system (xylem and phloem) by diffusion and bulk flow, whereas nervous signals in animals travel as electrical impulses along specialised nerve cells, which is much faster.

Question: What happens in Reflex Actions? [2M]

Answer: In reflex action, the body gives a quick and automatic response to a stimulus without thinking. When we touch something hot or sharp, receptors in the skin send a message through sensory nerves to the spinal cord. The spinal cord immediately sends a response through motor nerves to the muscles. The brain is informed after the action is done. Reflex actions are very fast and help protect the body from injury.

Question: How are these Tissues protected? [2M]

Answer: The brain and spinal cord are protected by strong structures. The brain is protected by the skull (cranium), while the spinal cord is protected by the vertebral column. Both are covered by three protective membranes called meninges. In addition, cerebrospinal fluid surrounds them and acts as a shock absorber. These protections prevent injury and help the nervous tissues function safely.

Question: How does the Nervous Tissue cause Action? [2M]

Answer: Nervous tissue causes action by transmitting electrical signals called nerve impulses. When a stimulus is received, receptors generate an impulse that travels through neurons to the brain or spinal cord. The nervous system processes this information and sends impulses through motor neurons to muscles or glands. As a result, muscles contract or glands release substances, producing a response or action in the body.

Question: What is the difference between a reflex action and walking? [2M]

Answer: The difference between a reflex action and walking are :

Reflex action	Walking
(i) It is an automatic and quick response to a stimulus.	(i) It is a voluntary action done by our own will.
(ii) It does not need thinking or decision-making.	(ii) It needs thinking and control by the brain.
(iii) It is controlled mainly by the spinal cord.	(iii) It is controlled by the brain.
(iv) It happens very fast to protect the body.	(iv) It is comparatively slower and planned.
Example: pulling hand away from hot object.	Example: walking to school.

Question: What happens at the synapse between two neurons? [2M]

Answer: At the synapse, the nerve impulse cannot jump directly from one neuron to another. When an impulse reaches the end of the first neuron, it releases chemical substances called neurotransmitters. These chemicals cross the small gap (synaptic cleft) and stimulate the next neuron. This starts a new electrical impulse in the second neuron, allowing the message to continue.

Question: How do we detect the smell of an agarbatti (incense stick)? [2M]

Answer: We detect the smell of an agarbatti when its aroma spreads in the air. The smell particles enter our nose and dissolve in the mucus lining. They stimulate the olfactory receptors present in the nose. These receptors send nerve impulses to the brain, and the brain recognises the smell of the agarbatti.

Question: What is the role of the brain in reflex action? [2M]

Answer: The brain does not control reflex action directly. Reflex actions are controlled by the spinal cord to give a quick response. However, the brain receives the information after the reflex action is completed. It helps us understand what happened and can control future actions if needed.

Question: How is the movement of leaves of the sensitive plant different from the movement of a shoot towards light? [2M]

Answer: The movement of the leaves of a sensitive plant is a rapid, automatic response to touch, called a nastic movement. It does not depend on the direction of the stimulus. In contrast, the movement of a shoot towards light is a slow, directional growth movement called phototropism, where the plant grows towards the light source. While leaf movement is quick and temporary, shoot movement is gradual and permanent.

Question: How do auxins promote the growth of a tendril around a support? [2M]

Answer: Auxins promote the growth of a tendril around a support by causing cells on the side away from the support to grow faster than the side touching the support. This unequal growth makes the tendril bend and curl around the support, helping the plant climb and secure itself.

Question: What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise? [3M]

Answer: Receptors in our body detect changes in the environment, called stimuli, like touch, light, sound, taste, or temperature, and send signals to the brain or spinal cord. If receptors do not work properly, the body cannot sense these changes correctly. For example, if touch receptors fail, one might not feel pain from injuries; if taste or smell receptors are damaged, food may lose its flavour; and if light receptors in the eyes are affected, vision problems can occur. This can lead to accidents or health issues.

Question: How muscle cells change their shape ? [SEBA 2020]

Answer: Muscle cells contain special proteins that can change both their shape and arrangement in the cell in response to nerve impulses. When these proteins contract and relax, the muscle cells become shorter or return to their original shape, producing movement.

Question: How Mimosa plant responses to stimulus ? [SEBA 2015]

Answer: The Mimosa pudica plant responds to the stimulus of touch by folding its leaves. This movement occurs due to the change in the amount of water in its cells, which causes the cells to shrink and the leaves to droop. This movement does not depend on growth and is a rapid response to touch.

Question: How nervous tissue maintains muscular movement ? [SEBA 2016]

Answer: Nervous tissue controls muscular movement by transmitting electrical impulses from the brain or spinal cord to the muscles. When the impulses reach the muscle cells, special proteins change their shape and arrangement, causing the muscles to contract. This produces movement in our body.

Question: Write two difference between axon and dendrite . [SEBA 2019]

Answer: The difference between axon and dendrite :

Axon	Dendrite
(i) It is a long single fibre that carries impulses away from the cell body.	(i) They are short, branched fibres that carry impulses towards the cell body.
(ii) It transmits impulses from the cell body to the next neuron or effector.	(ii) It receives impulses from the environment or from other neurons.

Question: How does nerve impulse travel in our body ? [SEBA 2018]

Answer: A nerve impulse travels through a neuron from the dendrites to the cell body and then along the axon to its nerve endings. At the nerve endings, chemicals are released, which cross the synapse and transmit the signal to the next neuron or muscle cell. In this way, nerve impulses travel throughout our body.

Question: Write the function of Adrenaline hormone . [SEBA 2017]

Answer: Adrenaline is secreted by the adrenal glands directly into the blood. It prepares our body to deal with emergency situations. It increases the heartbeat and breathing rate, thereby supplying more oxygen to the muscles. It also directs more blood towards the skeletal muscles and less towards the digestive system.

Question: How does leaf movement of the sensitive plants differ from the shoot movement towards light ?

Answer: The leaf movement of a sensitive plant, such as Mimosa pudica, is a response to touch. It occurs due to changes in the amount of water in its cells and does not depend on growth. However, the movement of a shoot towards light is a growth-dependent movement controlled by the plant hormone auxin. It is a directional response to light, called phototropism.

Question: Name two growth promoting hormones in plants and state their specific functions . [2025 2M]

Answer: Two growth-promoting hormones in plants are:

(a) Auxin: It promotes cell elongation and helps the stem bend towards light.

(b) Gibberellin: It helps in the growth of the stem by promoting cell elongation .

Question: Define a reflect arc [2025 2M]

Answer: A reflex arc is the pathway through which nerve impulses travel during a reflex action, from the receptor to the sensory neuron, spinal cord, motor neuron and finally to the effector .

Question: What happens when adrenaline is secreted into our blood ? [2025 2M]

Answer: When adrenaline is secreted into our blood, it prepares our body to deal with emergency situations. The heart beats faster, increasing the supply of oxygen to the muscles. The blood supply to the digestive system and skin is reduced, while more blood flows to the skeletal muscles. The breathing rate also increases to provide more energy to the body.

Question: Why are some of the patients of diabetes treated by giving insulin injections ? [SEBA 2025 2M]

Answer: Some patients of diabetes have a condition in which the pancreas does not produce enough insulin, or the insulin produced is not effective in controlling blood sugar levels. Since insulin helps regulate blood glucose, these patients are given insulin injections from an external source to keep their blood sugar levels normal.

Long Question and Answer :

Question: What is synapse ? How nerve impulse passes across synapse ? [3M SEBA 2015]

Answer: A synapse is the small gap or junction between two adjacent neurons or between a neuron and a muscle cell, across which nerve impulses pass.

When an electrical impulse reaches the end of the axon (nerve ending), it sets off the release of some chemicals. These chemicals cross the gap (synapse) and start a similar electrical impulse in the dendrite of the next neuron. In this way, the nerve impulse passes from one neuron to the next across the synapse.

Question: What is auxin ? How does it aid in the growth of a plant ? [SEBA 2020]

Answer: Auxin is a plant hormone which is synthesised at the shoot tip of the plant.

Auxin helps the cells to grow longer. When light is coming from one side of the plant, auxin diffuses towards the shady side of the shoot. This concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light. Thus, the plant appears to bend towards light.

Question: What is reflex ? Why reflex are developed in animals ? Write the components of reflex arc .

Answer: A reflex is a sudden, rapid and involuntary response of the body to a stimulus. It is controlled by the spinal cord and not by the brain.

Reflexes are developed in animals because in many situations, thinking and deciding takes time, and the response needs to be immediate to protect the body from harm.

The components of reflex arc are : (i) Receptor (ii) Sensory neuron (iii) Relay neuron (iv) Motor neuron (v) Effector

Question: What are the endocrine glands ? What is the difference an endocrine and exocrine gland ? Name the gland that performs both endocrine as well as exocrine functions .

Answer: Endocrine glands are ductless glands that release hormones directly into the bloodstream. These hormones help in controlling and coordinating various activities of the body.

The difference an endocrine and exocrine gland :

Endocrine glands	Exocrine glands
(a) These are ductless glands.	(a) These glands have ducts.
(b) They release hormones directly into the bloodstream.	(b) They release their secretions through ducts.
Example: Thyroid gland.	Example: Salivary gland.

The pancreas performs both endocrine and exocrine functions.

Question: What is a neuromuscular junction ? How does a nerve impulse travels from one part to the other part of the body ?[SEBA 2023]

Answer: A neuromuscular junction is the point of contact between the nerve ending of a motor neuron and a muscle cell, where the electrical impulse is transmitted from the neuron to the muscle, causing it to contract.

A nerve impulse travels through a neuron from the dendrites to the cell body and then along the axon to its nerve endings. At the nerve ending, chemicals are released that cross the synapse and start a similar electrical impulse in the next neuron. In this way, nerve impulses travel from one part of the body to another.

Question: Draw a net labeled diagram of a nerve cell and state its function . [SEBA 2023]

Answer:

A nerve cell receives and transfers information from one part of the body to another in the form of electrical impulses. It helps in coordinating and controlling the activities of the body.

Question: Draw a nerve cell with proper labeling . How is an electrical impulse created and in which direction does this impulse travel ? What function do these impulses perform ?[SEBA 2024]

Answer:

An electrical impulse is created when a stimulus acts on a neuron and causes changes in the electrical potential across its membrane. The impulse travels from the dendrites to the cell body and then along the axon to its nerve endings.

These impulses carry information from one part of the body to another. They help in transmitting messages between neurons and enable the body to respond to different stimuli.

Question: What are plant hormones ? Give an example of a plant hormone that promotes growth and the one that inhibits growth. [SEBA 2024]

Answer: Plant hormones (also called phytohormones) are chemical substances which are produced in the plants and help to control and coordinate the growth and development of plants.

Example of a plant hormone that promotes growth is Auxin .

Example of a plant hormone that inhibits growth is Abscisic acid .

Question: What is hormone ? Give an example of a growth-promoting plant hormone. How does movement of the leaves of a sensitive plant differ from the movement of a shoot towards light ? [3 M SEBA 2019]

Answer: A hormone is a chemical substance which is produced by specialised glands or tissues in one part of the body and is transported to other parts of the body through the blood to control and coordinate growth, development and various metabolic activities.

Auxin is an example of a growth-promoting plant hormone.

Difference between the movement of leaves of a sensitive plant and the movement of a shoot towards light:

Movement of leaves of a sensitive plant (Mimosa pudica)	Movement of a shoot towards light
(i) It is a nastic movement.	(i) It is a tropic movement .
(ii) It is a rapid, non-directional response to touch or stimulus, not related to the direction of the stimulus.	(ii) It is a slow, directional growth movement towards the direction of light.
(iii) It occurs due to changes in turgor pressure of cells at the base of the leaflets, causing them to lose water and droop.	(iii) It occurs due to differential growth caused by the hormone auxin, which accumulates on the shaded side and causes more elongation there.
(iv) It is a growth-independent movement.	(iv) It is a growth-dependent movement .

Question: What is hydrotropism ? How would you demonstrate hydrotropism with the help of an experiment ? [3 M SEBA2019]

Answer: Hydrotropism is the directional growth movement of a plant part in response to water. For example, the roots of a plant grow towards water and show positive hydrotropism.

Take a trough containing dry soil and place a porous pot filled with water in it. Sow some seeds in the soil near the porous pot and allow them to germinate. After a few days, observe the growth of the roots. The roots bend towards the porous pot containing water.

This shows that roots grow towards water and exhibit positive hydrotropism.

Question: Explain how a shoot bends towards light.

Answer: When light falls on one side of a growing shoot, the plant hormone auxin moves towards the shaded side, away from the light. This causes a higher concentration of auxin to accumulate on the shaded side. Auxin promotes cell elongation, so the cells on the shaded side grow longer than those on the illuminated side. As a result, the shoot bends towards the direction of light. This response is called phototropism, and since the shoot grows towards the light, it is known as positive phototropism.

Question: Explain the role of different plant hormones.

Answer: Plant hormones control the growth and development of plants. Auxins promote cell elongation and help shoots bend towards light. Gibberellins promote stem growth, while cytokinins help in cell division. Abscisic acid (ABA) inhibits growth and helps plants respond to stressful conditions. These hormones coordinate various activities in plants.

Question: How does the nervous system bring about a response to a stimulus?

Answer: When a stimulus acts on a receptor, it generates a nerve impulse. This impulse travels along the sensory neuron to the spinal cord or brain, where it is processed. From there, the impulse is passed to a motor neuron through a relay neuron. The motor neuron carries the impulse to an effector, such as a muscle or gland, which produces the response. This pathway from receptor to effector is called a reflex arc.

Stimulus → Receptor → Sensory neuron → Spinal cord (relay neuron) → Motor neuron → Effector → Response

Question: Explain how hormones regulate activities in the human body. Give three examples.

Answer: Hormones are chemical messengers secreted by endocrine glands directly into the bloodstream. They travel to specific target organs and regulate their activities by controlling growth, metabolism, development, and reproduction. Even a small amount of hormone can bring about a big change in the body.

For example, insulin from the pancreas regulates blood sugar levels by helping cells absorb glucose. Thyroxine from the thyroid gland controls the rate of metabolism and body growth. Adrenaline from the adrenal glands prepares the body to face emergencies by increasing heartbeat, breathing rate, and blood supply to muscles.

Question: What is the importance of coordination in plants? Explain with examples.

Answer: Coordination in plants helps them respond to changes in their surroundings. Plants use chemical substances called hormones to control their growth and other responses. For example, shoots grow towards light due to phototropism, roots grow towards gravity due to geotropism, and tendrils coil around a support in response to touch.

Question: What is feedback regulation? Explain it with the example of thyroxine.

Answer: Feedback regulation is a mechanism that controls the amount of hormones released by endocrine glands. For example, when the level of thyroxine in the blood is low, the pituitary gland stimulates the thyroid gland to produce more thyroxine. When the thyroxine level becomes sufficient, the stimulation decreases. In this way, feedback regulation helps maintain the proper level of thyroxine in the body.

Question: Explain the hormonal control of blood sugar levels.

Answer: The pancreas secretes the hormone insulin, which regulates blood sugar levels. When the blood sugar level rises, the pancreas releases more insulin, which helps the body cells take up glucose from the blood. This helps to lower the blood sugar level. If the pancreas does not produce enough insulin, it may lead to diabetes, in which the blood sugar level becomes high.

Question: Describe the main parts of the human brain and their functions.

Answer: The human brain has three main parts are the forebrain, midbrain and hindbrain. The forebrain includes the cerebrum, which is the largest part and controls thinking, memory, intelligence and voluntary actions. It also contains the thalamus, which relays sensory impulses, and the hypothalamus, which controls body temperature, hunger and thirst. The midbrain controls reflex movements of the eyes and head in response to sound and light. The hindbrain includes the pons, medulla and cerebellum. The medulla controls involuntary actions such as heartbeat, breathing and blood pressure. The cerebellum maintains posture and balance and coordinates body movements. The pons relays impulses between the forebrain and hindbrain.

Posted 2 weeks ago

7. Control and coordination SEBA/ASSEB Class 10 Science– Important Questions and Answers | Assam HSLC

SEBA/ASSEB Class 10 Science Chapter 7: Control and coordination Important Questions and Answers | HSLC Assam

Chapter 7: Control and coordination

Multiple Choose Question And Answer :

Answer following the Questions:

Assertion and Reasoning Questions

Short Question and Answer [ 2Marks ]:

Long Question and Answer :

Contact Info

Address

E-mail

Start Your Learning Journey