6. Control and Coordination

Class 10 Chapter 6 Control and Coordination

Class 10 Chapter 7 Control and Coordination

Multiple Choice Questions

1. 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.]

2. 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.

[ The impulse typically starts at the dendrites, moves through the cell body, travels down the axon, and reaches the axonal end where it can transmit signals to other neurons or cells.]

3. In a synapse, chemical signal is transmitted from

(a) dendritic end of one neuron to axonal end of another neuron

(b) axon to cell body of the same neuron

(d) axonal end of one neuron to dendritic end of another neuron .

Answer : (d) axonal end of one neuron to dendritic end of another neuron.

[ In a synapse, the chemical signal (neurotransmitters) is transmitted from the axonal end of one neuron to the dendritic end of another neuron.]

4. In a neuron, conversion of electrical signal to a chemical signal occurs at/in

(a) cell body

(b) axonal 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. ]

5. Which is the correct sequence of the components of a reflex arc?

(a) Receptors→ Muscles→ Sensory neuron→ Motor neuron→ Spinal cord

(b) Receptors→ Motor neuron → Spinal cord → Sensory neuron → Muscle

(d) Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle

Answer: (d) Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle.

[ The signal starts with the receptors detecting a stimulus, and the information is then transmitted through the sensory neuron to the spinal cord, where a quick response is generated through the motor neuron to the effector muscle.]

6. 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)

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. ]

7. 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)

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. ]

8. Posture and balance of the body is controlled by

(a) cerebrum

(b) cerebellum

(d) pons

Answer : (b) cerebellum.

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

9. Spinal cord originates from

(a) cerebrum

(b) medulla

(d) cerebellum

Answer : (b) medulla

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

10. The movement of shoot towards light is

(a) geotropism

(b) hydrotropism

(d) phototropism

Answer : (d) phototropism

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

11. The main function of abscisic acid in plants is to

(a) increase the length of cells

(b) promote cell division

(d) promote growth of stem

Answer : (c) inhibit growth

[ The main function of abscisic acid in plants to inhibit growth. It plays a role in inducing dormancy and promoting abscission (shedding of leaves and fruits). ]

12. Which of the following is not associated with growth of plant?

(a) Auxin

(b) Gibberellins

(d) Abscisic acid

Answer : (d) Abscisic acid .

[ Abscisic acid is not associated with the promotion of growth in plants. It is involved in inhibiting growth, inducing dormancy, and promoting abscission (shedding of leaves and fruits).]

13. Iodine is necessary for the synthesis of which hormone?

(a) Adrenaline

(b) Thyroxin

(d) Insulin

Answer : (b) Thyroxin

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

14. Choose the incorrect statement about insulin

(a) It is produced from pancreas

(b) It regulates growth and development of the body

(d) Insufficient secretion of insulin will cause diabetes

Answer : (b) It regulates growth and development of the body.

[ Insulin primarily regulates blood sugar levels and does not directly control the growth and development of the body. ]

15. Select the mis-matched pair

(a) Adrenaline : Pituitary gland

(b) Testosterone: Testes

(d) Thyroxin : Thyroid gland

Answer : (a) Adrenaline: Pituitary gland.

[ Adrenaline is produced by the adrenal glands, not the pituitary gland.]

16. The shape of guard cells changes due to change in the

(a) protein composition of cells

(b) temperature of cells

(d) position of nucleus in the cells

Answer : (c) amount of water in cells.

[ The turgidity of guard cells, influenced by the water content, is crucial in controlling the opening and closing of stomata in plant leaves. ]

17. 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. Tendrils typically exhibit thigmotropism, a response to touch or contact with a support, which triggers the rapid cell division and coiling around the support.]

18. The growth of pollen tubes towards ovules is due to

(a) hydrotropism

(b) chemotropism

(d) phototropism

Answer : (b) chemotropism.

[ Chemotropism is the growth or movement of an organism in response to a chemical stimulus, and in this case, it involves the attraction of pollen tubes toward chemicals released by ovules. ]

19. The movement of sunflower in accordance with the path of sun is due to

(a) phototropism

(b) geotropism

(d) hydrotropism

Answer : (a) phototropism.

[ Phototropism is the growth or movement of an organism in response to light, and in the case of sunflowers, it causes them to follow the sun across the sky. ]

20. The substance that triggers the fall of mature leaves and fruits from plants is due to

(a) auxin

(b) gibberellin

(d) cytokinin

Answer : (c) abscisic acid.

[ Abscisic acid is involved in promoting abscission, which is the shedding of leaves and fruits from a plant.]

21. Which of the following statements about transmission of nerve impulse is incorrect?

(a) Nerve impulse travels from dendritic end towards axonal end

(b) At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron

(c) The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in a dendrite of another neuron

(d) A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells

Answer : (b) At the dendritic end electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron.

[ This statement is inaccurate because, in a synapse, it is the release of chemicals (neurotransmitters) from the axonal end that influences the generation of an electrical impulse in the dendrite of another neuron.]

22. Involuntary actions in the body are controlled by

(a) medulla in fore brain

(b) medulla in mid 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.]

23. Which of the following is not an involuntary action?

(a) Vomiting

(b) Salivation

(d) Chewing

Answer : (d) Chewing

[ Chewing is not an involuntary action. It is a voluntary action that can be consciously controlled by an individual. The other options—vomiting, salivation, and heart beat—are examples of involuntary actions that occur without conscious control.]

24. When a person is suffering from severe cold, he or she cannot

(a) differentiate the taste of an apple from that of an ice cream

(b) differentiate the smell of a perfume from that of an agarbatti

(d) differentiate a hot object from a cold object

Answer : (b) differentiate the smell of a perfume from that of an agarbatti .

[ When a person is suffering from severe cold, he or she cannot differentiate the smell of a perfume from that of an agarbatti. This is because a blocked or congested nose can affect the sense of smell.]

25. What is the correct direction of flow of electrical impulses?

Answer : (c)

26. Which statement is not true about thyroxin?

(a) Iron is essential for the synthesis of thyroxin

(b) It regulates carbohydrates, protein and fat metabolism in the body

(d) Thyroxin is also called thyroid hormone

Answer : (a) Iron is essential for the synthesis of thyroxin.

[ Iodine is essential for the synthesis of thyroxin, not iron.]

27. Dwarfism results due to

(a) Excess secretion of thyroxin

(b) Less secretion of growth hormone

(d) Excess 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.]

28. Dramatic changes of body features associated with puberty are mainly because of secretion of

(a) oestrogen from testes and testosterone from ovary

(b) estrogen from adrenal gland and testosterone from pituitary gland

(d) testosterone from thyroid gland and estrogen from pituitary gland

Answer: (c) testosterone from testes and estrogen from ovary.

[ Puberty-related changes in body features are primarily driven by the increased secretion of sex hormones, with testosterone being more prominent in males and estrogen in females.]

29. A doctor advised a person to take an injection of insulin because

(a) his blood pressure was low

(b) his heart was beating slowly

(d) his sugar level in blood was high

Answer : (d) his sugar level in blood was high .

[ The doctor advised the person to take an injection of insulin because his sugar level in the blood was high. Insulin is a hormone that helps regulate blood sugar levels.]

30. The hormone which increases the fertility in males is called

(a) oestrogen

(b) testosterone

(d) growth hormone

Answer : (b) testosterone

[ The hormone that increases fertility in males is testosterone.]

31. Which of the following endocrine glands is unpaired?

(a) Adrenal

(b) Testes

(d) Ovary

Answer : (c) Pituitary.

[ The pituitary gland is a single, pea-sized gland located at the base of the brain.]

32. Junction between two neurons is called

(a) cell junction

(b) neuro muscular junction

(d) synapse

Answer : (d) synapse

[ The junction between two neurons is called synapse. ]

33. In humans, the life processes are controlled and regulated by

(a) reproductive and endocrine systems

(b) respiratory and nervous systems

(d) nervous and endocrine systems

Answer : (d) nervous and endocrine systems

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

Short Answer Questions

34. Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in Figure 7.2.

Answer : (a) Sensosory neuron .

(b) Spinal cord (CNS).

(d) Effector = Muscle in arm.

35. Name the plant hormones responsible for the following

(a) elongation of cells

(b) growth of stem

(d) falling of senescent leaves.

Answer : The plant hormones responsible for the following functions are:

(a) Elongation of cells: Auxins.

(b) Growth of stem: Gibberellins.

(d) Falling of senescent leaves: Abscisic acid.

36. Label the endocrine glands in Figure 7.3.

Answer : (a) Pineal gland .

(b) Pituitary gland .

(d) Thymus.

37. In Figure 7.4 (a), (b) and (c), which appears more accurate and why?

Answer: In diagram (a), the roots grow downwards (positive gravitropism), and the shoots grow upwards (negative gravitropism). This aligns with the natural growth patterns of plants responding to gravity, making it the most accurate representation among the three diagrams. In diagram (b) and (c) are inaccurate because roots growing upwards and shoots growing downwards contradict these natural growth patterns observed in plants.

38. Label the parts of a neuron in Figure 7.5.

Answer: (a) Dendrite .

(b) Cell body .

(d) Nerve ending .

39. Match the terms of Column (A) with those of Column (B)

Column (A)	Column (B)
(a) Olfactory receptors	(i) Tongue
(b) Thermo receptors (temperature receptors)	(ii) Eye
(c) Gustatoreceptors	(iii) Nose
(d) Photoreceptors	(iv) Skin

Answer : (a) Olfactory receptors (iii) Nose

(b) Thermoreceptors (temperature receptors) (iv) Skin

(d) Photoreceptors (ii) Eye

40. What is a tropic movement? Explain with an example.

Answer : Tropic movement, or tropism, is a directional growth response in plants to external stimuli, where the direction of the growth depends on the direction of the stimulus.

For instance, phototropism is a type of tropic movement where a plant grows toward a light source. This response is controlled by plant hormones called auxins, which accumulate on the side of the plant away from the light, causing those cells to elongate and the plant to bend towards the light. This adaptation helps the plant maximize light absorption for photosynthesis.

41. What will happen if intake of iodine in our diet is low?

Answer : If iodine intake is low, there is a possibility of developing goitre, a condition characterized by a swollen neck. This occurs due to the thyroid gland enlarging as it tries to produce sufficient thyroid hormones despite the iodine deficiency.

42. What happens at the synapse between two neurons?

Answer : At the synapse between two neurons, an electrical signal triggers the release of neurotransmitters from the presynaptic neuron. These chemicals cross the synaptic gap and bind to receptors on the postsynaptic neuron, converting the signal back into an electrical impulse.

43. Answer the following :

(a) Which hormone is responsible for the changes noticed in females at puberty?

(b) Dwarfism results due to deficiency of which hormone?

(d) Iodine is necessary for the synthesis of which hormone?

Answer : (a) The hormone responsible for the changes noticed in females at puberty is estrogen.

(b) Dwarfism results due to the deficiency of growth hormone.

(d) Iodine is necessary for the synthesis of thyroxine.

44. Answer the following :

(a) Name the endocrine gland associated with brain?

(b) Which gland secretes digestive enzymes as well as hormones?

(d) Which endocrine gland is present in males but not in females?

Answer : (a) The endocrine gland associated with the brain is the pituitary gland.

(b) The gland that secretes digestive enzymes as well as hormones is the pancreas.

(d) The endocrine gland present in males but not in females is the prostate gland.

Long Answer Questions

45. Draw the structure of a neuron and explain its function.

Answer : Neurons are specialized cells in the nervous system responsible for transmitting and processing information throughout the body. They receive stimuli through their dendrites, convert these stimuli into electrical impulses, and then propagate these signals along their axons to communicate with other neurons, muscles, or glands. Neurons facilitate complex functions such as sensory perception, motor control, and cognitive processes by integrating and relaying information, thus enabling organisms to respond to their environment and coordinate internal activities.

46. What are the major parts of the brain? Mention the functions of different parts.

Answer : The brain is divided into three major parts: the fore-brain, mid-brain, and hind-brain.

The Function of the parts are :

The forebrain is the largest part of the brain and includes the cerebrum, which is responsible for higher cognitive functions such as thinking, reasoning, and emotions. It also contains the thalamus and hypothalamus, which regulate sensory and motor signals and maintain homeostasis by controlling bodily functions such as temperature, hunger, and thirst.

The midbrain, located below the forebrain, plays a crucial role in sensory processing and motor control. It includes structures such as the tectum and tegmentum, which are involved in visual and auditory reflexes, and the substantia nigra, which is important for movement coordination and reward.

The hindbrain consists of the cerebellum, pons, and medulla oblongata. The cerebellum coordinates voluntary movements and maintains balance and posture. The pons acts as a bridge between different parts of the nervous system and regulates breathing and communication between the cerebellum and the cerebrum. The medulla oblongata controls essential autonomic functions such as heart rate, blood pressure, and respiration.

47. What constitutes the central and peripheral nervous systems? How are the components of central nervous system protected?

Answer : The central nervous system (CNS) comprises the brain and spinal cord, while the peripheral nervous system (PNS) includes all nerves outside the central nervous system, connecting it to limbs and organs.

The central nervous system is protected by the skull and vertebral column, which shield the brain and spinal cord, respectively. Additionally, the central nervous system is encased in three protective layers called meninges and surrounded by cerebrospinal fluid, which cushions and nourishes the neural tissues.

48. Mention one function for each of these hormones :

(a) Thyroxin

(b) Insulin

(d) Growth hormone

(e) Testosterone.

Answer: (a) Thyroxin: Regulates metabolism and energy production in the body.

(b) Insulin: Lowers blood sugar levels by facilitating glucose uptake into cells.

(d) Growth hormone: Stimulates growth and cell repair throughout the body.

(e) Testosterone: Promotes the development of male secondary sexual characteristics and influences muscle growth.

49. Name various plant hormones. Also give their physiological effects on plant growth and development.

Answer: The plant hormones are : auxin , cytokinins , gibberellins and abscisic acid .

The plant hormones and their physiological effects:

Auxins: These hormones promote cell elongation, root formation, and the development of fruit. They also play a role in phototropism (growth towards light) and gravitropism (growth in response to gravity). Auxins are essential for apical dominance, which is the suppression of lateral bud growth by the main shoot.

Gibberellins: Gibberellins stimulate stem elongation, seed germination, and flowering. They are crucial for breaking seed dormancy and promoting growth in various plant tissues. Gibberellins also influence fruit development and can lead to increased fruit size.

Cytokinins: These hormones promote cell division and shoot formation. They work in conjunction with auxins to regulate the growth of lateral buds and can delay leaf senescence (aging). Cytokinins are involved in nutrient mobilization and improve plant response to environmental stresses.

Abscisic Acid (ABA): ABA helps regulate plant responses to environmental stress, such as drought, by inducing stomatal closure to reduce water loss. It also plays a role in seed dormancy and the inhibition of seed germination under unfavorable conditions.

50. What are reflex actions? Give two examples. Explain a reflex arc.

Answer : Reflex actions are automatic, rapid responses to specific stimuli that occur without conscious thought. They are controlled by the nervous system and are meant to protect the body from harm or to maintain homeostasis. Reflex actions involve a reflex arc, which includes a receptor, sensory neuron, interneuron (in the spinal cord), motor neuron, and an effector.

Two examples of reflex actions are the knee-jerk reflex, where tapping the patellar tendon causes the leg to kick involuntarily, and the withdrawal reflex, where touching a hot object results in an immediate pull back of the hand. Both are automatic responses that protect the body from harm without conscious thought.

A reflex arc is the neural pathway that mediates a reflex action. It involves a sensory neuron detecting a stimulus and sending a signal to the spinal cord, where it synapses with an interneuron. The interneuron then connects to a motor neuron, which sends a signal to a muscle or gland to produce an immediate response, bypassing the brain for faster reaction.

51. “Nervous and hormonal systems together perform the function of control and coordination in human beings.” Justify the statement.

Answer: The nervous and hormonal systems work together to ensure control and coordination in human beings by complementing each other's functions. The nervous system uses electrical impulses to provide rapid, precise control over muscles and sensory organs, allowing immediate responses to stimuli. In contrast, the hormonal system uses chemical messengers (hormones) that travel through the bloodstream to regulate slower, longer-lasting processes such as growth, metabolism, and reproduction. By integrating these systems, the body maintains homeostasis, adapts to changes, and coordinates complex activities efficiently, ensuring overall functionality and well-being.

52. How does chemical coordination take place in animals?

Answer : Chemical coordination in animals is primarily achieved through the endocrine system, which consists of glands that secrete hormones directly into the bloodstream. Hormones are chemical messengers that travel to target organs and tissues, regulating various physiological processes.

For example, the pituitary gland releases growth hormone to stimulate growth, the thyroid gland secretes thyroxine to regulate metabolism, and the pancreas produces insulin to control blood sugar levels. This hormonal regulation ensures that bodily functions such as growth, metabolism, reproduction, and stress responses are coordinated and maintained in a balanced state.

53. Why is the flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron but not the reverse?

Answer: The flow of signals in a synapse is from the axonal end of one neuron to the dendritic end of another due to the specific structure and function of synapses and the mechanisms of neurotransmitter release. The axon terminals contain synaptic vesicles filled with neurotransmitters, which are released into the synaptic cleft when an electrical signal arrives. These neurotransmitters bind to receptors on the dendrites of the next neuron, initiating a new electrical signal. Dendrites lack the necessary vesicles and machinery to release neurotransmitters, and axons lack the receptors to receive them, ensuring one-way communication. This unidirectional flow ensures precise and orderly signal transmission across the nervous system.