CBSE Important Questions Class 10 Science Chapter 6 – Control and Coordination
Class 10 Science Chapter 6 Control and Coordination is part of the CBSE Class 10 Science syllabus. It explains how animals and plants control their activities and respond to the world around them. Students learn about the nervous system, the structure of a neuron, how a nerve impulse travels, reflex action, the parts of the human brain, the sense organs such as the eye, ear and nose, and the hormones made by the endocrine glands in both animals and plants.
These CBSE important questions for Class 10 Science Chapter 6 cover the mechanism of smell, the working and structure of the human eye, the parts of the brain and their functions, the dendrite and axon of a neuron, thermoregulation, how local anaesthesia works at the synapse, hormones and target organs, and a question on PCOS. Every question has a clear step-by-step answer in simple English with figures, so students can practise on their own, parents can check the answers, and teachers can use them for class tests.
CBSE Important Questions Class 10 Science Chapter 6
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Q1. Write a short note on the mechanism of smell.
Answer: The nose is the sense organ that lets us smell.
• The upper part of the nasal cavity is lined by a layer called the olfactory epithelium.
• About 20 million mucus-coated olfactory receptors lie on this layer.
• The dendrites of these receptor cells end as fine olfactory hairs (cilia).
• Bowman's glands produce mucus.
• The mucus dissolves the smell molecules in the air, and these molecules trigger the olfactory receptors.
• Nerve impulses then travel from the receptors through the olfactory nerve to the brain, which tells us what the smell is.
Q2. Describe the functioning of the human eye.
Answer: Light enters the eye through the pupil and falls on the lens. The lens forms a real and inverted image of the object on the retina.
The cells of the retina contain photopigments called rhodopsin and iodopsin, each made of opsin and retinal. When the image falls on the retina, the retinal separates from the opsin, which changes the shape of the opsin. This change creates an electrical signal (action potential).
The optic nerve carries this signal to the visual cortex of the brain, where it is processed, and we recognise what we are seeing.
Q3. Draw the structure of the human eye and label the part where:
(i) Maximum refraction occurs
(ii) Sharpest image formation takes place
(iii) Curvature of lens is altered
(iv) Focuses light rays
(v) Optic nerve emerges
Answer: (i) Maximum refraction occurs at the cornea.
(ii) The sharpest image is formed at the fovea.
(iii) The curvature of the lens is changed by the ciliary body.
(iv) Light rays are focused by the lens.
(v) The optic nerve leaves the eye at the blind spot.
Q4. Name the researcher who established the role of the eye as a sense organ.
Answer: Johannes Kepler established the role of the eye as a sense organ.
Q5. Mark the given statements as True or False. If they are false, rewrite the correct statement.
i. The ear acts as a video camera.
ii. The stimulus of a lower level is masked by the same stimulus of a higher level.
iii. All stimuli are able to generate responses.
iv. The stimulants carry the information to receptors, which convert it into nerve signals.
v. The ear helps in maintaining the equilibrium of the body besides hearing.
Answer: i. False. The eye acts as a video camera.
ii. True.
iii. False. All stimuli are not able to generate responses.
iv. True.
v. True.
Q6. Mike had a body temperature of 37.9 °C. After one hour, his body temperature was recorded as 37.5 °C. Can you tell how thermoregulation caused this reduction in Mike's body temperature?
Answer: When Mike's body temperature rose to 37.9 °C, the homeostasis system of his body started thermoregulation to bring it back to normal. The brain signalled the sweat glands, so his skin produced sweat. As the sweat evaporated from the skin, it took heat away from the body, and the temperature came down to 37.5 °C.
Q7. Observe the diagram of the human brain. Identify the parts labelled I, II, III and IV, and state one primary function for each part.
Answer: Part I – Cerebrum: controls voluntary actions such as writing, climbing and playing.
Part II – Cerebellum: controls the balance of the body.
Part III – Pons: regulates facial expressions.
Part IV – Medulla oblongata: controls the rate of respiration (and other involuntary actions such as heartbeat and blood pressure).
Q8. Observe the diagram of a neuron. Identify the parts labelled (S) and (R) and describe the specific function of each in the transmission of a nerve impulse.
Answer: (S) is the dendrite. Its job is to receive electrical or chemical signals from other neurons or from sensory receptors and carry them towards the cell body.
(R) is the axon. Its job is to carry the nerve impulse, as an electrical signal, away from the cell body towards the axon terminals, from where it is passed on to the next cell.
Q9. Read the given assertion and reason and select the correct answer.
Assertion (A): Damage to the cerebellum can result in difficulty in walking and maintaining the posture of the body.
Reason (R): The cerebellum is responsible for coordination and balance of body movements.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Answer: (a) Both A and R are true and R is the correct explanation of A.
The cerebellum controls the balance and coordination of body movements. So if it is damaged, the person loses balance and finds it hard to walk or stand straight. The Reason therefore correctly explains the Assertion.
Q10. During the extraction of a tooth, the dentist gives an injection of local anaesthesia to the patient before the extraction. Which of the following stands correct regarding the above case?
(a) It blocks the signals coming from the cyton of the neuron.
(b) It enhances the transmission of impulse from the neuron to the muscles.
(c) It inhibits the functioning of neurons in the mouth during extraction.
(d) It arrests the transmission of impulse at the synapse of the neurons.
Answer: (d) It arrests the transmission of impulse at the synapse of the neurons.
A local anaesthetic works at the synapse, the tiny gap between two neurons. It stops the chemical signal from crossing this gap, so the pain impulse never reaches the brain and the patient feels no pain during the extraction.
Q11. Ritu observed excessive growth of hair on her face and body, weight gain, oily skin and irregular periods. The gynaecologist told her that she has PCOS (polycystic ovary syndrome), a hormonal disorder in which the ovaries enlarge and many cysts form in them.
Read the given statements and find the incorrect one.
I. Estrogen is secreted by the corpus luteum that initiates the development of female secondary sex organs.
II. Progesterone is secreted by the ovarian follicles under the influence of LH from the pituitary gland.
III. In the case of Ritu, ovulation will be affected.
IV. The release of estrogen will fluctuate in the case of Ritu.
(a) I and II
(b) II and III
(c) III and IV
(d) I and IV
Answer: (a) I and II
Statement I is wrong because estrogen is secreted mainly by the ovarian follicles, not by the corpus luteum.
Statement II is wrong because progesterone is secreted mainly by the corpus luteum, not by the ovarian follicles.
Statements III and IV are correct, because in PCOS ovulation is disturbed and the hormone levels keep changing.
Q12. Hormones are chemical messengers secreted by ductless glands and carried by the blood to other parts of the body, where they act on a target organ. If the receptor molecules are removed from the target organ, what change will be detected in the hormonal action?
(a) The hormone will continue to function in its regular way.
(b) A physiological response will be triggered to inhibit the functioning of the hormone.
(c) The hormones will start responding in the opposite way.
(d) No response will be generated in the cells of the target organ.
Answer: (d) No response will be generated in the cells of the target organ.
A hormone can act only after it fits into a special receptor on the target cell, much like a key fitting into a lock. If the receptors are removed, the hormone has nowhere to attach, so it cannot pass on its message and the cell gives no response.
Related Study Material on Extramarks
- CBSE Important Questions Class 10 Science Chapter 1
- CBSE Important Questions Class 10 Science Chapter 2
- CBSE Important Questions Class 10 Science Chapter 3
- CBSE Important Questions Class 10 Science Chapter 4
- CBSE Important Questions Class 10 Science Chapter 5
- CBSE Important Questions Class 10 Science Chapter 7
- CBSE Important Questions Class 10 Science Chapter 8
- CBSE Important Questions Class 10 Science Chapter 9
- CBSE Important Questions Class 10 Science Chapter 10
- CBSE Important Questions Class 10 Science Chapter 11
- CBSE Important Questions Class 10 Science Chapter 12
- CBSE Important Questions Class 10 Science Chapter 13
Q.1 Inner wall of alimentary canal is not digested by the digestive enzymes. Why?
Marks:2
Ans
The inner wall of the alimentary canal is not digested by the digestive enzymes because the inner wall of the alimentary canal is lined by a wall of epithelial cells that secrete mucous. This mucous layer acts as the first line of defence.
Q.2 Which of the following organisms is a link between the living and the non-living organism?
(a) Bacteria
(b) Protozoa
(c) Virus
(d) Fungi
Marks:1
Ans
Viruses are considered at the borderline of living and non-living because they show both the characteristics of a living and a non-living. As they act as non-living in the free atmosphere, when they enter into a living organisms body, they show the features of a living organism and start reproduction.
Q.3 The process by which an artificial kidney removes harmful waste products from the blood is ________________.
(a) haemolysis
(b) dialysis
(c) osmosis
(d) phagocytosis
Marks:1
Ans
Artificial kidney is used in case of kidney failure. It is a device used to remove harmful waste products from the blood through dialysis.
Q.4 Kidneys are not only the organs of excretion. Their work is supplemented by
(a) liver
(b) large intestine
(c) heart
(d) skin
Marks:1
Ans
Skin also helps in the excretion of waste materials in the form of sweat.
Q.5 What will happen if CO2 is absent during the process of photosynthesis?
Marks:1
Ans
In the absence of CO2 during photosynthesis, there will neither be food production nor the release of oxygen into the atmosphere.