CBSE Class 10 Science Control and Coordination Assignment Set 06

This is Set 06 of mixed practice assignment questions for CBSE Class 10 Science Chapter 6, Control and Coordination, with marks, step-by-step answers and a Teacher's Note for every question. It focuses on the nervous system: neurons and synapse, reflex action, the parts of the brain, the spinal cord, and how nerves and hormones work together.

Very Short Answer Questions (1 Mark)

Question 1. Name the systems in animals which help in the process of control and coordination.
Answer:
(i) The nervous system and (ii) the hormonal (endocrine) system help in control and coordination in animals.
In simple words: Animals use nerves and hormones to coordinate their body.

Teacher's Note:
1. Plants have only the chemical (hormonal) system.
2. Mention both systems for the mark.

Question 2. What is a neuron?
Answer:
A neuron (nerve cell) is the structural and functional unit of the nervous system. It consists of a cell body (cyton), dendrites and an axon.
In simple words: A neuron is the basic nerve cell that carries messages.

Teacher's Note:
1. Neuron is also the longest cell of the human body.
2. Name its three parts.

Question 3. What are the main divisions of the nervous system?
Answer:
The nervous system is broadly divided into two parts: (i) the central nervous system (brain and spinal cord) and (ii) the peripheral nervous system (cranial and spinal nerves).
In simple words: The nervous system has a central part and a peripheral part.

Teacher's Note:
1. Give the organs of each division in brackets.
2. CNS is the control room and PNS is the wiring.

Question 4. Which part of the brain maintains posture and equilibrium of the body?
Answer:
The cerebellum of the hind brain maintains the posture and equilibrium (balance) of the body.
In simple words: The cerebellum keeps the body balanced.

Teacher's Note:
1. The cerebellum is the 'little brain' at the back.
2. Walking in a straight line and riding a bicycle depend on it.

Question 5. Give one function of hypothalamus.
Answer:
The hypothalamus regulates the secretion of hormones from the pituitary gland. It also has the centres of hunger and thirst.
In simple words: The hypothalamus links the brain with the hormone system.

Teacher's Note:
1. The hypothalamus is part of the forebrain.
2. Feeling full or hungry is controlled here.

Question 6. Name the two components of the peripheral nervous system.
Answer:
The two components of the peripheral nervous system are the cranial nerves, arising from the brain, and the spinal nerves, arising from the spinal cord.
In simple words: Nerves from the brain and nerves from the spinal cord make the peripheral system.

Teacher's Note:
1. Cranial means head and spinal means backbone.
2. Write the origin of each.

Question 7. Mention the part of the brain which controls the involuntary actions like blood pressure, salivation etc.
Answer:
The medulla oblongata in the hind brain controls involuntary actions such as blood pressure, salivation, heartbeat and vomiting.
In simple words: The medulla runs the actions we cannot control.

Teacher's Note:
1. Medulla controls involuntary actions, cerebellum controls balance.
2. Name the region of the brain too.

Question 8. List two body functions that will be affected if the cerebellum gets damaged.
Answer:
(i) Walking in a straight line (maintaining the body balance and posture). (ii) Picking up a thing from the ground (precision of voluntary movements).
In simple words: Damage to the cerebellum makes movements unsteady.

Teacher's Note:
1. The cerebellum is responsible for balance and fine control of muscles.
2. Give examples of daily actions.

Question 9. (i) Name one gustatory receptor and one olfactory receptor present in human beings.
(ii) Write a and b in the given flow chart of neuron through which information travels as an electrical impulse. Dendrite → a → b → End point of Neuron
Answer:
(i) The tongue contains the gustatory receptors (for taste) and the nose contains the olfactory receptors (for smell).
(ii) Dendrite → Cell body (a) → Axon (b) → End point of neuron.
In simple words: The tongue tastes, the nose smells, and the impulse goes from dendrite to cell body to axon.

Teacher's Note:
1. Receptors are present in the sense organs.
2. Remember the order dendrite, cell body, axon.

Short Answer Questions (2 and 3 Marks)

Question 10. What happens at the synapse between two neurons?
Answer:
Step 1: The synapse is the small gap between the axon terminal of one neuron and the dendrite of the next neuron.
Step 2: When the electrical impulse reaches the end of the axon, it releases chemicals (neurotransmitters) into the gap.
Step 3: These chemicals cross the gap and start a similar electrical impulse in the dendrite of the next neuron.
Final answer: The electrical signal changes to a chemical signal and back to an electrical signal, in one direction only.
In simple words: At the synapse a chemical carries the message across the gap to the next neuron.

Teacher's Note:
1. The chemicals are released only from the axonal end.
2. Write the signal change: electrical to chemical to electrical.

Question 11. Name the system which facilitates communication between the central nervous system and the other parts of the body. Mention two types of nerves it consists of along with their organs of origin.
Answer:
The peripheral nervous system facilitates the communication between the central nervous system and the other parts of the body.
It consists of (i) cranial nerves, which arise from the brain and spread to the head region, and (ii) spinal nerves, which arise from the spinal cord and spread through the rest of the body.
In simple words: Nerves from the brain and spinal cord connect the body with the control centres.

Teacher's Note:
1. Name the system, the two nerve types and where they arise.
2. CNS cannot reach the body without the PNS.

Question 12. What is the role of brain in reflex action?
Answer:
Step 1: A reflex arc is formed in the spinal cord, so the response to the stimulus is given without the brain's thinking.
Step 2: The information about the stimulus still travels to the brain, where it is interpreted, but the brain does not take part in the quick response.
Final answer: The brain does not control the reflex response. It only receives the information about it afterwards.
In simple words: A reflex is finished by the spinal cord before the brain even thinks about it.

Teacher's Note:
1. Reflex arcs save time by not involving the brain.
2. Some reflexes such as watering of mouth are controlled by the brain.

Question 13. What do you mean by voluntary and involuntary actions? Categorise the following actions as voluntary or involuntary.
(i) Shivering when it is too cold.
(ii) Peristaltic movement in oesophagus when swallowing food.
(iii) Changing channels on TV to watch your favourite programme.
(iv) Tears flushing out from eyes when foreign particles fall on them.
Answer:
Actions performed according to our will, under conscious thought, are voluntary actions. Actions performed without our will and without conscious control are involuntary actions.
(i) Involuntary action.
(ii) Involuntary action.
(iii) Voluntary action.
(iv) Involuntary action.
In simple words: If you choose to do it, it is voluntary; if the body does it by itself, it is involuntary.

Teacher's Note:
1. Ask whether you decide to do the action.
2. Reflexes are involuntary actions.

Question 14. How do we detect the smell of an agarbatti (incense stick)?
Answer:
Step 1: The smell molecules of the incense stick spread in the air and reach the olfactory receptors in the nose.
Step 2: The receptors generate an impulse, which is carried by the sensory neurons to the olfactory region of the forebrain.
Step 3: The forebrain interprets the impulse along with the information stored in the brain.
Final answer: The olfactory receptors detect the smell and the forebrain interprets it.
In simple words: The nose picks up the smell and the brain tells us what it is.

Teacher's Note:
1. Name the receptor, the nerve and the brain part.
2. Olfactory receptors are for smell and gustatory receptors for taste.

Question 15. 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:
Step 1: Receptors are specialised cells (tips of nerve cells) in the sense organs, which detect the changes in the environment (stimuli) and send the information as impulses to the spinal cord or brain.
Step 2: If receptors do not work properly, impulses are not formed and the body cannot respond properly to the stimulus. For example, if the pain receptors of the skin are damaged, a person may touch a hot object and get burnt without realising it.
Final answer: Receptors detect stimuli; failure of receptors makes the body unable to sense and respond to the surroundings.
In simple words: Receptors are the body's sensors; without them we cannot sense danger.

Teacher's Note:
1. Give an example of a sense that can be lost.
2. A person with a cold cannot smell properly.

Teacher's Note:
1. Write the answer in a two-column table.
2. Include at least three points.

Teacher's Note:
1. Use a table with the same points for both parts.
2. Do not mix up the names; cerebellum has the word 'bell' at the back.

Question 18. How are involuntary action and reflex action different from each other?
Answer:
Involuntary actions cannot be controlled even if we want to do so. They take place on their own, without a sudden stimulus, for example the beating of the heart, which goes on all the time without our thinking about it.
Reflex action is also a kind of involuntary action, but it takes place in response to a stimulus. For example, the pupil of the eye becomes smaller on stepping out in bright light. Reflex actions are controlled by the spinal cord.
In simple words: Every reflex is involuntary, but heartbeat shows that not every involuntary action is a reflex.

Teacher's Note:
1. Give one example of each type.
2. Reflexes always need a stimulus.

Teacher's Note:
1. Both types belong to the peripheral nervous system.
2. Remember the numbers 31 and 12.

Question 20. Why have reflex arcs evolved in animals?
Answer:
Step 1: Many animals have very little or none of the complex network of neurons needed for thinking, and even in complex animals the thinking process of the brain is not fast enough.
Step 2: A reflex arc gives a quick response to a sudden, harmful stimulus without involving the brain.
Final answer: Reflex arcs have evolved as an efficient way of functioning in the absence of true thought processes, to protect the body quickly.
In simple words: Reflex arcs give a fast safety response when there is no time to think.

Teacher's Note:
1. Link the answer with the speed of the response.
2. Give the example of touching a hot object.

Question 21. The brain directs our body's internal functions. It also integrates sensory impulses and information to form perceptions, thoughts and memories. The brain gives us self-awareness and the ability to speak and move in the world.
(i) The brain is divided into three major subparts. Name these subparts.
(ii) Name the part of the brain that is responsible for maintaining body posture?
(iii) Name the part of the brain that has the reflex centres for sneezing and vomiting?
(iv) The brain is the part of the central nervous system or peripheral nervous system?
Answer:
(i) The three subparts are the forebrain, the midbrain and the hindbrain.
(ii) The cerebellum controls the body posture and coordinates the movement of the limbs.
(iii) The medulla oblongata (hind brain) has the reflex centres for sneezing, vomiting, coughing and swallowing.
(iv) The brain is a part of the central nervous system, along with the spinal cord.
In simple words: The brain has three parts and each part looks after a particular group of jobs.

Teacher's Note:
1. Learn the three regions and one function from each.
2. The medulla also regulates breathing and heartbeat.

Long Answer Questions (3 and 5 Marks)

Question 22. What constitutes the central and peripheral nervous systems? How are the components of the central nervous system protected?
Answer:
Step 1: The central nervous system (CNS) consists of the brain and the spinal cord. It receives information from all parts of the body and decides the response.
Step 2: The peripheral nervous system (PNS) consists of the nerves that connect the CNS with the rest of the body: the cranial nerves from the brain and the spinal nerves from the spinal cord.
Step 3: Protection of the brain: It is enclosed in a bony box called the cranium. Inside the box, it is contained in a fluid-filled balloon (cerebrospinal fluid), which acts as a shock absorber.
Step 4: Protection of the spinal cord: It is enclosed in the vertebral column (backbone) and is also covered with membranes and fluid.
Final answer: CNS = brain + spinal cord; PNS = cranial and spinal nerves; the brain is protected by the cranium and the spinal cord by the vertebral column.
In simple words: The brain and spinal cord are the control centre and the nerves are the cables, and bones protect the centre.

Teacher's Note:
1. Draw a small flow chart of the nervous system for revision.
2. Name the bony protection of both organs.

Question 23. Following are the two examples of plant movement. One is dropping of leaves in touch-me-not plant and second is attaching of pea plant to a support with the help of tendrils.
(i) What is the stimulus which is common for movement in both the cases?
(ii) What is the difference in movement in both the plants? Explain.
(iii) Give appropriate scientific terms for the movements described in both cases.
Answer:
(i) Touch is the stimulus common to both cases.
(ii) The dropping of leaves of the touch-me-not plant is a growth-independent movement. It occurs due to the change in the turgor (water content) of the cells. The attachment of the pea plant to a support by tendrils is a growth-dependent movement. The part of the tendril away from the support grows faster, because of the hormone auxin, so the tendril coils round the support.
(iii) The dropping of leaves of the touch-me-not plant is a nastic movement (seismonasty or thigmonasty). The movement of the tendril is a tropic movement (thigmotropism).
In simple words: Both movements are caused by touch, but one is a fast water change and the other is slow growth.

Teacher's Note:
1. Compare the two movements under growth, speed and direction.
2. Tendrils are positively thigmotropic.

Question 24. Nervous and hormonal systems together perform the function of control and coordination in human beings. Justify this statement with the help of an example.
Answer:
Step 1: The nervous system carries information quickly through neurons as electrical impulses, but nerves do not reach every part of the body and the effect is short lived.
Step 2: The hormonal system uses chemical messengers that travel in the blood to all the parts. The effect is slower but lasts longer.
Step 3: Example: In an emergency, the sense organs and the brain detect the danger and the nervous system sends the response to the muscles. At the same time the adrenal glands secrete adrenaline, which increases the heartbeat and breathing and sends more blood to the muscles.
Final answer: Both systems work in harmony to deal with the situation, so they together perform control and coordination.
In simple words: Nerves give the fast signal and hormones keep the body prepared for longer.

Teacher's Note:
1. Use adrenaline or insulin as the example.
2. State one point of difference between the two systems.