CBSE Class 10 Science Control and coordination Sure Shot Questions Set 03

Question. How many nerves arise from spinal cord ?
(A) 21
(B) 31
(C) 41
(D) 51
Answer : B

Question. What is called of movement occurred in a plant due to light ?
(A) Thermonasty
(B) Thigmonasty
(C) Yearmonasty
(D) Photonasty
Answer : D

Question. Which of the following activity is controlled by medulla oblongata ?
(A) Maintain balance of the body
(B) Peristalitc movement alimentary canal
(C) Controlling body temperature
(D) Facial expression
Answer : B

Question. What is the weight of an adult person's brain?
(A) 900
(B) 1350
(C) 1500
(D) 2350
Answer : B

Question. The hormone present in higher concentration in fruits and seeds is
(A) Auxin
(B) Gibberellin
(C) Cytokinin
(D) Ethylene
Answer : C

Question. Insulin hormone is secreted by .... gland -
(A) lymphatic gland
(B) Salivary gland
(C) Pancreas
(D) Pitutary gland
Answer : C

Question. A hormone secreted by mixocrine gland :
(A) Paratharmone
(B) Thyroxine
(C) Glucagon
(D) Adrenaline
Answer : C

Question. The outermost layers of meninges is
(A) Myelin membrane
(B) Arachnoid mater
(C) Dura mater
(D) Pia mater
Answer : C

Question. Which hormone is not found in plants ?
(A) Gibberellin
(B) Auxin
(C) Cytokinin
(D) Glucagon
Answer : D

Question. Match each item in Column A with suitable one in column B :
          Column A                          Column B
A. CO₂                         (i) Regulation of body temperature
B. Hypothalamus      (ii) Green House effect
C. Corpus luteum    (iii) Balancing the body
                                  (iv) Secretion of dopamine
                                   (v) Required to plants for respiration
                                 (vi) Secretion of progesterone
(A) A = (v) , B = (iii), C = (iv)
(B) A = (ii), B = (i), C = (iv)
(C) A = (ii), B = (i), C = (vi)
(D) A = (v), B = (ii), C = (vi)
Answer : C

Question. Which part of the human brain is more developed than other mammals ?
(A) Cerebellum
(B) Cerebrum
(C) Sensory lobes
(D) none of the above
Answer : B

Question. In plants “Auxin” is used for ..................
(A) Division of cell.
(B) Ripening of fruits.
(C) Root growth inhibition.
(D) Elongation and division of cell
Answer : D

Question. Which one of the following represents the correct sequence of reflex action ?
(A) Receptor → sensory nerve → motor nerve → spinal cord → muscle
(B) Receptor → motor nerve → spinal cord → sensory nerve → muscle
(C) Receptor → sensory nerve → spinal cord → muscle → motor nerve
(D) Receptor → sensory nerve → spinal cord → motor nerve → muscle
Answer : D

ASSIGNMENT QUESTIONS SET - 3
CHAPTER - 7
CONTROL AND COORDINATION

1. The substance that accelerates the growth in the stem is ____. [1 Mark]
1. auxin
2. cytokinin
3. enzyme
4. vitamin

Answer: 1. auxin

1. Auxins are plant hormones that promote cell elongation in stems.
2. Cytokinins primarily promote cell division.
3. Hence, the correct option is 1.

Teacher's Note:
a) Auxins are synthesized at the shoot tips.
b) They help plants respond to light and gravity.

2. The cells in our body that can be over a foot long are _____. [1 Mark]
1. muscle cells
2. nerve cells
3. bone cells
4. blood cells

Answer: 2. nerve cells

1. Nerve cells or neurons are the longest cells in the human body.
2. Some neurons can measure over a foot in length to transmit signals over long distances.
3. Hence, the correct option is 2.

Teacher's Note:
a) Neurons consist of an axon, dendrites, and a cell body.
b) They specialized in conducting electrical impulses throughout the body.

3. Learning is related to ______________. [1 Mark]
1. hypothalamus
2. thalamus
3. cerebrum
4. cerebellum

Answer: 3. cerebrum

1. The cerebrum is the main thinking part of the brain.
2. It is responsible for reasoning, learning, memory, and intelligence.
3. Hence, the correct option is 3.

Teacher's Note:
a) Cerebrum is the largest part of the human brain.
b) Cerebellum controls posture and balance, not higher learning.

4. Male hormone is ________________. [1 Mark]
1. Oestrogen
2. progesterone
3. adrenaline
4. testosterone

Answer: 4. testosterone

1. Testosterone is the primary male sex hormone produced by the testes.
2. Oestrogen and progesterone are female sex hormones.
3. Hence, the correct option is 4.

Teacher's Note:
a) Hormones act as chemical messengers in the body.
b) Adrenaline is the emergency hormone secreted by the adrenal glands.

5. Endocrine glands are those which pour their secretions into _________________. [1 Mark]
1. Blood
2. Ducts
3. sinuses
4. any of the above

Answer: 1. Blood

1. Endocrine glands are ductless glands.
2. They release their secretions directly into the blood for transport to target organs.
3. Hence, the correct option is 1.

Teacher's Note:
a) Exocrine glands release their secretions through ducts.
b) Hormones are the specific chemical messengers secreted by endocrine glands.

6. In reflex action, the reflex arc is formed by ____________. [1 Mark]
1. muscles - receptor - brain
2. muscles - effector - brain
3. receptor - spinal cord - muscles
4. spinal cord - receptor - muscles

Answer: 3. receptor - spinal cord - muscles

1. A reflex arc traces the path of nerve impulses in a reflex action.
2. The pathway starts at the receptor, goes via the sensory neuron to the spinal cord, and travels through the motor neuron to muscles or effectors.
3. Hence, the correct option is 3.

Teacher's Note:
a) Reflex actions are sudden, involuntary responses controlled mostly by the spinal cord.
b) Brain is typically bypassed for immediate protection against harm.

7. Auxins are _________________. [1 Mark]
1. Vitamins
2. Enzymes
3. Proteins
4. Hormones

Answer: 4. Hormones

1. The question text in the source document ends abruptly after option 1.
2. Auxins are naturally occurring plant hormones or phytohormones, not vitamins.
3. They regulate various growth processes in plants.

Teacher's Note:
a) Note that the PDF text cuts off after the first option for question 7.
b) Auxins promote cell division and elongation in shoots.

8. The cerebellum is concerned with _______________. [1 Mark]
1. Conditioning
2. Memory
3. coordination and precision
4. Intelligence

Answer: 3. coordination and precision

1. The cerebellum is a part of the hindbrain.
2. It is responsible for maintaining posture and balance, and for the coordination and precision of voluntary movements.
3. Hence, the correct option is 3.

Teacher's Note:
a) The cerebellum controls fine motor skills and equilibrium.
b) Damage to this region results in loss of muscular coordination.

9. The endocrine gland also known as 'master gland' is ______. [1 Mark]
1. hypothalamus
2. pituitary
3. pancreas
4. adrenal

Answer: 2. pituitary

1. The pituitary gland secretes multiple hormones that regulate various other endocrine glands in the body.
2. Because of its controlling influence over other glands, it is termed the master gland.
3. Hence, the correct option is 2.

Teacher's Note:
a) Note that the hypothalamus ultimately regulates the pituitary gland itself.
b) The pituitary gland is located at the base of the brain.

10. Which of the following acts as both endocrine and exocrine glands? [1 Mark]
1. pituitary
2. adrenal
3. pancreas
4. ovaries

Answer: 3. pancreas

1. The pancreas acts as an exocrine gland by secreting digestive enzymes through ducts.
2. It acts as an endocrine gland by releasing hormones like insulin and glucagon directly into the blood.
3. Hence, the correct option is 3.

Teacher's Note:
a) Such glands are also referred to as heterocrine glands.
b) Testis is another example of a mixed or heterocrine gland.

11. Cerebral hemispheres are centres of __________. [1 Mark]
1. balance
2. smell
3. taste
4. thinking

Answer: 4. thinking

1. The cerebrum forms the major part of the forebrain and is the main thinking part of the brain.
2. It is responsible for reasoning, learning, memory, and conscious thought processes.
3. Hence, the correct option is 4.

Teacher's Note:
a) Sensory areas receive information, while association areas interpret it.
b) Balance is primarily managed by the cerebellum.

12. Adrenaline increases _____________. [1 Mark]
1. heart rate
2. blood pressure
3. amount of glucose in blood
4. all the above

Answer: 4. all the above

1. Adrenaline is secreted by the adrenal glands during emergency or stress situations.
2. It increases heart rate, breathing rate, and blood pressure to supply more oxygen to muscles, and also raises blood glucose levels for instant energy.
3. Hence, the correct option is 4.

Teacher's Note:
a) Adrenaline prepares the body for a fight-or-flight response.
b) It targets multiple organs simultaneously to optimize survival responses.

13. Junction of two neurons is called _____________. [1 Mark]
1. synapse
2. end plate
3. axon
4. dendrite

Answer: 1. synapse

1. A synapse is the narrow gap between the axon terminal of one neuron and the dendrite of the next neuron.
2. Chemical signals (neurotransmitters) cross this junction to transmit the nerve impulse.
3. Hence, the correct option is 1.

Teacher's Note:
a) Electrical impulses are converted into chemical signals at the synapse.
b) This ensures the one-way transmission of nerve impulses.

14. Gibberellins were discovered from ______________. [1 Mark]
1. bacteria
2. fungi
3. algae
4. mosses

Answer: 2. fungi

1. Gibberellins were first discovered in the fungus Gibberella fujikuroi, which caused 'bakane' ( foolish seedling) disease in rice.
2. They are a group of plant growth hormones that promote stem elongation.
3. Hence, the correct option is 2.

Teacher's Note:
a) Japanese scientists Eiichi Kurosawa and Teijiro Yabuta isolated the active substance.
b) Gibberellins help in breaking seed dormancy and bolting.

15. Growth hormone is produced in ___________. [1 Mark]
1. hypothalamus
2. pituitary
3. pancreas
4. thyroid

Answer: 2. pituitary

1. Growth hormone is secreted by the pituitary gland located at the base of the brain.
2. It regulates overall growth and development of the body.
3. Hence, the correct option is 2.

Teacher's Note:
a) The pituitary is often called the master gland.

16. The hormone secreted by the alpha cells of islets of Langerhans is _____________. [1 Mark]
1. glucagon
2. insulin
3. adrenaline
4. thymosin

Answer: 1. glucagon

1. Alpha cells in the pancreas secrete glucagon to increase blood glucose levels.
2. Beta cells secrete insulin which lowers blood glucose levels.
3. Hence, the correct option is 1.

Teacher's Note:
a) Remember alpha cells produce glucagon and beta cells produce insulin.

17. An involuntary response to a stimulus is known as _______. [1 Mark]
1. jerking
2. reflex
3. conditioning
4. answer

Answer: 2. reflex

1. A reflex action is a rapid, automatic, involuntary response to a stimulus.
2. It is mediated mostly by the spinal cord to protect the body from harm.
3. Hence, the correct option is 2.

Teacher's Note:
a) Reflex arcs bypass conscious thought for immediate survival reactions.

18. The CNS consists of _______________. [1 Mark]
1. Brain
2. spinal cord
3. Brain and spinal cord
4. Brain, spinal cord and all the nerves

Answer: 3. Brain and spinal cord

1. The Central Nervous System (CNS) comprises the brain and the spinal cord.
2. Nerves outside the CNS form the Peripheral Nervous System (PNS).
3. Hence, the correct option is 3.

Teacher's Note:
a) Do not confuse CNS with PNS which includes all nerves.

19. An example of a sex hormone is _________________. [1 Mark]
1. testosterone
2. Insulin
3. Thyroxin
4. thymosin

Answer: 1. testosterone

1. Testosterone is a male sex hormone produced by the testes.
2. Insulin regulates blood sugar, thyroxin controls metabolism, and thymosin aids immunity.
3. Hence, the correct option is 1.

Teacher's Note:
a) Other examples include estrogen and progesterone in females.

20. Cerebrum is present in the _______________. [1 Mark]
1. fore brain
2. mid brain
3. hind brain
4. partly in a and b each

Answer: 1. fore brain

1. The cerebrum is the main thinking and largest part of the human brain.
2. It forms the major part of the forebrain.
3. Hence, the correct option is 1.

Teacher's Note:
a) The forebrain is specialized for hearing, smell, sight, and voluntary actions.

21. Cerebellum is situated in ___________. [1 Mark]
1. fore brain

2. mid brain
3. hind brain
4. partly in a and b each

Answer: 3. hind brain

1. The cerebellum is a part of the hindbrain responsible for posture and balance.
2. It coordinates voluntary muscle movements.
3. Hence, the correct answer corresponds to the hindbrain option.

Teacher's Note:
a) The question options are truncated in the source text, but the anatomical fact is clear.

22. Medulla oblongata is situated in ___________ [1 Mark]
1. fore brain
2. mid brain
3. hind brain
4. partly in b and c each

Answer: (3) hind brain

1. The brain is divided into forebrain, midbrain, and hindbrain.
2. The hindbrain consists of the pons, cerebellum, and medulla oblongata.
3. Therefore, the medulla oblongata is situated in the hind brain.
4. Hence, the correct option is (3).

Teacher's Note:
a) The medulla oblongata controls involuntary actions like blood pressure, heartbeat, and breathing.
b) Do not confuse it with the cerebellum, which coordinates posture and balance.
c) The hindbrain forms the brainstem along with the midbrain.
d) Option (3) is the standard textbook location for the medulla.

23. The grey matter consists of ___________ [1 Mark]
1. nerve cells
2. nerve cell bodies
3. nerve cell bodies and dendrites
4. nerve cell bodies, dendrites and axons

Answer: (2) nerve cell bodies

1. Nervous tissue is made up of organized networks of nerve cells or neurons.
2. The grey matter of the brain and spinal cord primarily contains the cell bodies of neurons, giving it a grey appearance.
3. The white matter consists mostly of myelinated axons.
4. Hence, the correct option is (2).

Teacher's Note:
a) Grey matter is associated with processing and cognition.
b) Students often choose option (3) or (4) by assuming all parts of a neuron are uniformly distributed.
c) Cell bodies concentrate heavily in the cerebral cortex region.

24. There are ___________ pairs of cranial nerves. [1 Mark]
1. 21
2. 31
3. 41
4. 12

Answer: (4) 12

1. Cranial nerves emerge directly from the brain.
2. In humans, there are 12 pairs of cranial nerves connected to various parts of the head and trunk.
3. Spinal nerves, by contrast, emerge from the spinal cord.
4. Hence, the correct option is (4).

Teacher's Note:
a) Memorize the count of cranial versus spinal nerves to avoid confusion.
b) Cranial nerves deal primarily with head, facial, and visceral sensory/motor functions.
c) Option (4) matches the anatomical count in human biology.

25. There are ______________ pairs of spinal nerves. [1 Mark]
1. 12
2. 31
3. 21
4. 8

Answer: (2) 31

1. Spinal nerves arise from the spinal cord and spread across the body.
2. There are 31 pairs of spinal nerves in humans divided across cervical, thoracic, lumbar, sacral, and coccygeal regions.
3. These are mixed nerves transmitting signals both ways.
4. Hence, the correct option is (2).

Teacher's Note:
a) Do not mix up the 12 pairs of cranial nerves with the 31 pairs of spinal nerves.
b) Spinal nerves form part of the peripheral nervous system (PNS).

26. The hormone that is used to keep flowers fresh is _______ [1 Mark]
1. auxin
2. gibberellic acid
3. cytokinin
4. Ethylene

Answer: (3) cytokinin

1. Cytokinins promote cell division and delay aging (senescence) in plant tissues.
2. By delaying leaf senescence and flower aging, cytokinins help keep harvested flowers fresh for longer durations.
3. Auxins and gibberellins have different primary developmental roles.
4. Hence, the correct option is (3).

Teacher's Note:
a) Cytokinins are heavily concentrated in areas of rapid cell division such as fruits and seeds.
b) Anti-aging property is a key signature function of cytokinins in floriculture.

27. The hormone that speeds up the ripening process is ______ [1 Mark]
1. auxin
2. gibberelin
3. cytokinin
4. ethylene

Answer: (4) ethylene

1. Ethylene is a gaseous plant hormone.
2. It stimulates and accelerates the ripening of fruits such as tomatoes, bananas, and apples.
3. Other plant hormones regulate growth, elongation, or cell division, but not gaseous fruit ripening.
4. Hence, the correct option is (4).

Teacher's Note:
a) Ethylene is unique as it is a plant hormone existing in gaseous state at room temperature.
b) Artificial ripening agents often release ethylene gas to quicken commercial fruit distribution.

28. A spinal nerve is a ________________ nerve. [1 Mark]
1. sensory
2. motor
3. mixed
4. long

Answer: (3) mixed

1. Spinal nerves contain both sensory (afferent) and motor (efferent) fibers.
2. Because they carry signals both towards and away from the central nervous system, they function as mixed nerves.
3. Option (1) and (2) describe only one direction of nerve fiber.
4. Hence, the correct option is (3).

Teacher's Note:
a) Almost all spinal nerves are mixed nerves formed by the joining of dorsal and ventral roots.
b) Note that the options list is slightly cut off at the end of the page, but mixed nerve is the universally accepted scientific classification.

29. Ganglion is made up of ___________. [1 Mark]
1. dendrites
2. axons
3. cytons
4. neurons

Answer: 3. cytons

1. A ganglion is a cluster of neuronal cell bodies (cytons) located outside the central nervous system.
2. Hence, the correct option is 3.

Teacher's Note:
a) Ganglia act as relay stations and processing centers for nerve signals in the peripheral nervous system.
b) Cytons contain the nucleus and Nissl granules characteristic of nerve cell bodies.

30. The preganglionic fibres and the postganglionic fibres are a part of ____________. [1 Mark]
1. central nervous system
2. peripheral nervous system
3. autonomous nervous system
4. endocrine system

Answer: 3. autonomous nervous system

1. The autonomic nervous system consists of pathways involving preganglionic and postganglionic nerve fibres.
2. Hence, the correct option is 3.

Teacher's Note:
a) The autonomic nervous system regulates involuntary body functions.
b) Synapses between preganglionic and postganglionic fibres occur within autonomic ganglia.

31. Afferent nerves are also called the _______________. [1 Mark]
1. motor nerves
2. sensory nerves
3. mixed nerves
4. association nerves

Answer: 2. sensory nerves

1. Afferent nerves transmit nerve impulses from receptors to the central nervous system, functioning as sensory nerves.
2. Hence, the correct option is 2.

Teacher's Note:
a) Afferent means conducting towards a structure.
b) Always differentiate afferent nerves from efferent nerves, which carry signals away from the central nervous system.

32. Efferent nerves are also called as _____________. [1 Mark]
1. motor nerves
2. sensory nerves
3. mixed nerves
4. association nerves

Answer: 1. motor nerves

1. Efferent nerves transmit instructions from the central nervous system to effector organs like muscles and glands, acting as motor nerves.
2. Hence, the correct option is 1.

Teacher's Note:
a) Efferent means conducting away from a central structure.
b) Motor responses are vital for executing physical actions.

33. Ganglia are present in _______________. [1 Mark]
1. the dorsal root of spinal cord
2. the ventral root of spinal cord
3. both a and b
4. neither a nor b

Answer: 1. the dorsal root of spinal cord

1. The dorsal root of the spinal nerve contains a swelling called the dorsal root ganglion, which houses sensory neuron cell bodies.
2. Hence, the correct option is 1.

Teacher's Note:
a) Ventral roots contain motor neuron axons and lack ganglia.
b) This anatomical feature is crucial for distinguishing sensory and motor nerve pathways.

34. The hormone that causes blood sugar level to fall is _______________. [1 Mark]
1. glucagon
2. insulin
3. somatostatin
4. adrenalin

Answer: 2. insulin

1. Insulin is secreted by the beta cells of the pancreas and promotes glucose uptake by body cells, reducing blood sugar levels.
2. Hence, the correct option is 2.

Teacher's Note:
a) Glucagon has the opposite effect, raising blood glucose levels.
b) Insulin deficiency or resistance leads to diabetes mellitus.

35. Hormone produced by the ovarian follicle is __________ and in addition ________ is produced by the corpus luteum. [1 Mark]
1. oestrogen, progesterone

2. progesterone, oestrogen
3. oestrogen, thyroxin
4. progesterone, thyroxin

Answer: 1. oestrogen, progesterone

1. The growing ovarian follicle secretes oestrogen, while the corpus luteum primarily produces progesterone.
2. Hence, the correct option is 1.

Teacher's Note:
a) Oestrogen regulates secondary sexual characters and the menstrual cycle.
b) Progesterone maintains the uterine lining during pregnancy.

36. The gland that plays a role in 'fight or flight response' is _________________. [1 Mark]
(1) pancreas
(2) pituitary
(3) adrenal cortex
(4) adrenal medulla

Answer: (4) adrenal medulla

1. The adrenal medulla secretes adrenaline.
2. Adrenaline prepares the body for emergency situations like fight or flight.
3. Hence, the correct option is (4).

Teacher's Note:
a) Adrenaline increases heart rate and breathing rate during stress.
b) This hormone acts directly on target organs to produce immediate responses.

37. The unit of the nervous system is _______________. [1 Mark]
(1) cyton
(2) dendron
(3) axon
(4) neuron

Answer: (4) neuron

1. Neurons are the structural and functional units of the nervous system.
2. They transmit electrical impulses across the body.
3. Hence, the correct option is (4).

Teacher's Note:
a) Neurons consist of a cell body, dendrites, and an axon.
b) Cyton, dendron, and axon are only parts of a neuron, not the complete unit.

38. The processes that conduct signals towards the nerve cell body are the ___________. [1 Mark]
(1) fibres
(2) axons
(3) dendrites
(4) all the above

Answer: (3) dendrites

1. Dendrites receive nerve impulses from other neurons.
2. They conduct these impulses towards the cell body.
3. Hence, the correct option is (3).

Teacher's Note:
a) Axons conduct impulses away from the cell body.
b) Dendrites are branching cytoplasmic projections of the neuron.

39. The nodes of Ranvier are ________________. [1 Mark]
(1) covering of the nerve fibre
(2) swelling along the nerve fibre
(3) gaps in the cover of the nerve fibre
(4) collection of nerves in the heart

Answer: (3) gaps in the cover of the nerve fibre

1. Nodes of Ranvier are periodic gaps in the myelin sheath on axons.
2. They allow rapid saltatory conduction of nerve impulses.
3. Hence, the correct option is (3).

Teacher's Note:
a) Myelin sheath acts as an insulator around the nerve fibre.
b) Action potentials jump from one node of Ranvier to the next.

40. At the synapses, the impulses are always passed from the __________________. [1 Mark]
(1) axon to the dendrites
(2) dendrites to the axon
(3) either way is possible
(4) cyton to the dendrites

Answer: (1) axon to the dendrites

1. Synapses are junctions between the axon terminal of one neuron and dendrites of another.
2. Neurotransmitters release chemical signals in one direction only.
3. Hence, the correct option is (1).

Teacher's Note:
a) Chemical transmission ensures unidirectional flow of nerve impulses.
b) Synapses prevent random or backward signaling in neural pathways.

41. The lobes - parietal, temporal, frontal and occipetal belong to _________________. [1 Mark]
(1) medulla oblongata
(2) cerebrum
(3) cerebellum
(4) hypothalamus

Answer: (2) cerebrum

1. The cerebrum is divided into four major lobes.
2. These lobes are frontal, parietal, temporal, and occipital.
3. Hence, the correct option is (2).

Teacher's Note:
a) Cerebrum is the main thinking and sensory processing part of the brain.
b) Each lobe has specialized functions like vision, hearing, and reasoning.

42. Unconditioned reflex is controlled by the ______________. [1 Mark]
(1) Brain
(2) Spinal cord

(3) both a and b
(4) the autonomic nervous system

Answer: (3) both a and b

1. Unconditioned reflexes are involuntary and innate responses.
2. They are controlled by both the brain and the spinal cord, so option (3) both a and b is the complete answer (option (2) alone is incomplete).
3. Hence, the correct option is (2).

Teacher's Note:
a) Reflex actions bypass conscious brain thinking to minimize injury time.
b) Spinal cord coordinates quick withdrawal reflexes automatically.

43. Blinking of eyes is a ________________. [1 Mark]
1. reflex action
2. Involuntary action
3. voluntary action only
4. can be a or b

Answer: (4) can be a or b

1. Blinking of eyes primarily acts as an involuntary reflex action to protect the eyes from dust or bright light.
2. It can also be performed voluntarily by conscious will.
3. Hence, the correct option is 4 (can be a or b).

Teacher's Note:
a) Reflex actions are sudden, involuntary responses to stimuli.
b) Some involuntary actions can be overridden or intentionally controlled to a certain extent.

44. The outermost covering of the nerve is called the ________. [1 Mark]
1. Perineurium
2. Epineurium
3. myelin sheath
4. Capsule

Answer: (2) Epineurium

1. A nerve is composed of multiple nerve fibres bundled together.
2. Epineurium is the outermost protective fibrous connective tissue sheath surrounding a nerve.
3. Hence, the correct option is 2.

Teacher's Note:
a) Perineurium surrounds a bundle of nerve fibres (fascicle).
b) Myelin sheath insulates individual nerve axons.

45. The box enclosing the brain is called the _____________. [1 Mark]
1. Skull
2. Head
3. Cranium
4. vertebral column

Answer: (3) Cranium

1. The brain is situated inside a bony box in the skull that specifically protects it.
2. This bony protective case is known as the cranium.
3. Hence, the correct option is 3.

Teacher's Note:
a) The skull includes facial bones as well as the cranium.
b) The cranium specifically refers to the brain box.

46. The kind of nerve carrying impulses from the brain to a gland or a muscle is called ______. [1 Mark]
1. affector
2. effector
3. mixed
4. none of the above

Answer: (4) none of the above

1. Nerves carrying impulses from the central nervous system to muscles or glands are motor nerves (or efferent nerves).
2. Effectors are the muscles or glands themselves that respond, not the nerve fibres.
3. Hence, the correct option is 4 as motor nerve is not listed.

Teacher's Note:
a) Affector refers to sensory nerves carrying impulses towards the CNS.
b) Motor nerves carry instructions away from the CNS to effectors.

47. Which of the following statements is correct about receptors? [1 Mark]
(a) Gustatory receptors detect taste while olfactory receptors detect smell
(b) Both gustatory and olfactory receptors detect smell
(c) Auditory receptors detect smell and olfactory receptors detect taste
(d) Olfactory receptors detect taste and gustatory receptors smell

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

1. Gustatory receptors are specialized sense receptors located in the tongue for taste.
2. Olfactory receptors are located in the nasal cavity for detecting smell.
3. Hence, the correct option is (a).

Teacher's Note:
a) Gustatory relates to the sense of taste.
b) Olfactory relates to the sense of smell.

48. Electrical impulse travels in a neuron from [1 Mark]
(a) Dendrite → axon → axonal end → cell body
(b) Cell body → dendrite → axon → axonal end
(c) Dendrite → cell body → axon → axonal end
(d) Axonal end → axon → cell body → dendrite

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

1. Information is acquired at the dendritic tip of a nerve cell.
2. It sets off an electrical impulse that travels from the dendrite to the cell body, then along the axon to its terminal end.
3. Hence, the correct option is (c).

Teacher's Note:
a) Dendrites receive the chemical/electrical signal first.
b) The signal passes through the cell body and down the axon to the axonal ends.

49. In a synapse, chemical signal is transmitted from [1 Mark]
(a) dendritic end of one neuron to axonal end of another neuron
(b) axon to cell body of the same neuron
(c) cell body to axonal end 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

1. A synapse is the junction between two adjacent neurons.
2. At the synapse, the electrical signal is converted into a chemical message that passes from the axonal end of the first neuron to the dendritic end of the next neuron.
3. Hence, the correct option is (d).

Teacher's Note:
a) Neurotransmitters bridge the synaptic cleft chemically.
b) Transmission is strictly unidirectional from axon to dendrite.

50. In a neuron, conversion of electrical signal to a chemical signal occurs at/in [1 Mark]
(a) cell body
(b) axonal end
(c) dendritic end
(d) axon

Answer: (b) axonal end

1. At the axonal end of a nerve cell, electrical impulses are converted into chemical signals (neurotransmitters).
2. These chemicals cross the synapse to reach the next neuron.
3. Hence, the correct option is (b).

Teacher's Note:
a) Synapse transmission involves chemicals.
b) Do not confuse dendritic end with axonal end.

51. Which is the correct sequence of the components of a reflex arc? [1 Mark]
(a) Receptors→ Muscles→ Sensory neuron→ Motor neuron→ Spinal cord
(b) Receptors→ Motor neuron → Spinal cord → Sensory neuron → Muscle
(c) Receptors → Spinal cord → Sensory neuron → Motor neuron → Muscle
(d) Receptors → Sensory neuron → Spinal cord → Motor neuron → Muscle

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

1. Signals are received by receptors.
2. Sensory neurons carry the signal to the spinal cord.
3. Motor neurons carry the response from the spinal cord to the effector muscle.
4. Hence, the correct option is (d).

Teacher's Note:
a) Sensory neurons always carry impulses towards the central nervous system.
b) Motor neurons carry impulses away from the central nervous system to effectors.

52. Which of the following statements are true? [1 Mark]
(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)

1. Statement (i) correctly defines a reflex action.
2. Statement (iv) correctly defines a reflex arc.
3. Statements (ii) and (iii) have the functions of neurons interchanged.
4. Hence, the correct option is (c).

Teacher's Note:
a) Statement analysis helps eliminate false pairings quickly.
b) Always double check neuron pathway directions.

53. Which of the following statements are true about the brain? [1 Mark]
(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)

1. The fore brain is the main thinking part and houses sensory regions, making (ii) true.
2. Medulla in the hind brain controls involuntary actions, making (iii) true.
3. Statement (i) is false because the fore brain is the thinking part, and statement (iv) is false because cerebellum controls balance.
4. Hence, the correct option is (c).

Teacher's Note:
a) Fore brain regions manage higher cognitive functions and sensory processing.
b) Hind brain structures like medulla and cerebellum regulate vital involuntary controls and coordination.

54. Posture and balance of the body is controlled by [1 Mark]
(a) cerebrum
(b) cerebellum
(c) medulla
(d) pons

Answer: (b) cerebellum

1. The cerebellum is a part of the hind brain.
2. It is specifically responsible for maintaining posture and balance of the body.
3. Hence, the correct option is (b).

Teacher's Note:
a) Cerebellum coordinates precise voluntary movements.
b) Damage to this region affects walking and balance.

55. Spinal cord originates from [1 Mark]
(a) cerebrum
(b) medulla
(c) pons
(d) cerebellum

Answer: (b) medulla

1. The spinal cord is an extension of the central nervous system contained within the vertebral canal.
2. It originates from the medulla oblongata of the brain.
3. Hence, the correct option is (b).

Teacher's Note:
a) The brainstem connects the brain to the spinal cord.
b) Medulla forms the lower part of the brainstem.

56. The movement of shoot towards light is [1 Mark]
(a) geotropism
(b) hydrotropism
(c) chemotropism
(d) phototropism

Answer: (d) phototropism

1. Plant growth response towards light is known as phototropism.
2. Shoots typically show positive phototropism.
3. Hence, the correct option is (d).

Teacher's Note:
a) Auxin hormone plays a major role in phototropic curvature.
b) Geotropism relates to gravity responses.

57. The main function of abscisic acid in plants is to [1 Mark]
(a) increase the length of cells
(b) promote cell division
(c) inhibit growth
(d) promote growth of stem

Answer: (c) inhibit growth

1. Abscisic acid (ABA) is a plant hormone that functions primarily as a growth inhibitor.
2. It promotes processes like wilting of leaves and dormancy.
3. Hence, the correct option is (c).

Teacher's Note:
a) Auxins and gibberellins promote growth, whereas abscisic acid inhibits it.
b) It helps plants cope with stress conditions like drought.

58. Which of the following is not associated with growth of plant? [1 Mark]
(a) Auxin
(b) Gibberellins
(c) Cytokinins
(d) Abscisic acid

Answer: (d) Abscisic acid

1. Auxin, gibberellins, and cytokinins are plant hormones that promote growth.
2. Abscisic acid is a plant hormone that inhibits growth and promotes wilting and falling of leaves.
3. Hence, the correct option is (d).

Teacher's Note:
a) Abscisic acid acts as a general plant growth inhibitor and stress hormone.
b) Remember that plant hormones can be grouped into promoters and inhibitors.

59. Iodine is necessary for the synthesis of which hormone? [1 Mark]
(a) Adrenaline
(b) Thyroxin
(c) Auxin
(d) Insulin

Answer: (b) Thyroxin

1. Iodine is an essential element required by the thyroid gland to synthesize thyroxin hormone.
2. Deficiency of iodine leads to a disease called goitre.
3. Hence, the correct option is (b).

Teacher's Note:
a) Thyroxin regulates carbohydrate, protein, and fat metabolism in the body.
b) Iodised salt is recommended to prevent iodine deficiency disorders.

60. Choose the incorrect statement about insulin [1 Mark]
(a) It is produced from pancreas
(b) It regulates growth and development of the body
(c) It regulates blood sugar level
(d) Insufficient secretion of insulin will cause diabetes

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

1. Insulin is secreted by the pancreas and helps in regulating blood sugar levels.
2. Growth and development of the body is primarily regulated by growth hormone secreted by the pituitary gland.
3. Hence, statement (b) is incorrect.

Teacher's Note:
a) Read carefully to spot incorrect statements in negative-type multiple choice questions.
b) Insulin deficiency results in high blood glucose levels, causing diabetes mellitus.

61. Select the mis-matched pair [1 Mark]
(a) Adrenaline : Pituitary gland
(b) Testosterone: Testes
(c) Estrogen : Ovary
(d) Thyroxin : Thyroid gland

Answer: (a) Adrenaline : Pituitary gland

1. Adrenaline is secreted by the adrenal glands, not the pituitary gland.
2. Testosterone is produced by testes, estrogen by ovaries, and thyroxin by the thyroid gland.
3. Hence, the mismatched pair is (a).

Teacher's Note:
a) The adrenal glands are located above the kidneys and secrete emergency hormones.
b) Pituitary gland is often called the master gland as it controls other endocrine glands.

62. The shape of guard cells changes due to change in the [1 Mark]
(a) protein composition of cells
(b) temperature of cells
(c) amount of water in cells
(d) position of nucleus in the cells

Answer: (c) amount of water in cells

1. Guard cells swell when water flows into them, causing stomatal pores to open.
2. When guard cells lose water, they shrink and the stomatal pore closes.
3. Hence, the correct option is (c).

Teacher's Note:
a) Turgor pressure changes inside guard cells drive the opening and closing of stomata.
b) Water movement is regulated by osmotic pressure changes due to solute accumulation.

63. The growth of tendril in pea plants is due to [1 Mark]
(a) effect of light
(b) effect of gravity
(c) rapid cell divisions in tendrillar cells that are away from the support
(d) rapid cell divisions in tendrillar cells in contact with the support

Answer: (c) rapid cell divisions in tendrillar cells that are away from the support

1. When tendrils touch a support, the part in contact does not grow as rapidly as the part away from the support.
2. This unequal growth causes the tendril to circle around the support.
3. Hence, the correct option is (c).

Teacher's Note:
a) This directional growth response to touch is called thigmotropism.
b) Rapid cell division on the distant side allows the tendril to coil securely.

64. The growth of pollen tubes towards ovules is due to [1 Mark]
(a) hydrotropism
(b) chemotropism
(c) geotropism
(d) phototropism

Answer: (b) chemotropism

1. Pollen tube growth is guided by chemical substances secreted by the ovule.
2. Growth in response to a chemical stimulus is known as chemotropism.
3. Hence, the correct option is (b).

Teacher's Note:
a) Chemotropic movements are crucial for successful plant fertilization.
b) Differentiate clearly between various tropic movements based on their stimuli.

65. The movement of sunflower in accordance with the path of sun is due to [1 Mark]
(a) phototropism
(b) geotropism
(c) chemotropism
(d) hydrotropism

Answer: (a) phototropism

1. Bending or movement of plant parts in response to light is called phototropism.
2. Sunflowers track the sun across the sky due to differential growth driven by light direction.
3. Hence, the correct option is (a).

Teacher's Note:
a) Auxin redistributes to the shaded side of the stem, promoting faster growth there.
b) This directional curvature helps maximize light absorption for photosynthesis.

66. The substance that triggers the fall of mature leaves and fruits from plants is due to [1 Mark]
(a) auxin
(b) gibberellin
(c) abscisic acid
(d) cytokinin

Answer: (c) abscisic acid

1. Abscisic acid promotes processes like abscission, which is the shedding of leaves and fruits.
2. It acts antagonistically to growth-promoting hormones.
3. Hence, the correct option is (c).

Teacher's Note:
a) The name abscisic acid is derived from its role in the abscission layer formation.
b) It also plays a key role in seed dormancy and responses to environmental stress.

67. Which of the following statements about transmission of nerve impulse is incorrect? [1 Mark]
(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)

68. Involuntary actions in the body are controlled by [1 Mark]
(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

69. Which of the following is not an involuntary action? [1 Mark]
(a) Vomiting
(b) Salivation
(c) Heart beat
(d) Chewing

Answer: (d) Chewing

70. When a person is suffering from severe cold, he or she cannot [1 Mark]
(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
(c) differentiate red light from green light
(d) differentiate a hot object from a cold object

Answer: (b)

71. Which statement is not true about thyroxin? [1 Mark]
(a) Iron is essential for the synthesis of thyroxin
(b) It regulates carbohydrates, protein and fat metabolism in the body
(c) Thyroid gland requires iodine to synthesise thyroxin
(d) Thyroxin is also called thyroid hormone

Answer: (a)

72. Dwarfism results due to [1 Mark]
(a) Excess secretion of thyroxin
(b) Less secretion of growth hormone
(c) Less secretion of adrenaline
(d) Excess secretion of growth hormone

Answer: (b) Less secretion of growth hormone

73. Dramatic changes of body features associated with puberty are mainly because of secretion of [1 Mark]
(a) oestrogen from testes and testosterone from ovary
(b) estrogen from adrenal gland and testosterone from pituitary gland
(c) testosterone from testes and estrogen from ovary
(d) testosterone from thyroid gland and estrogen from pituitary gland

Answer: (c)

74. A doctor advised a person to take an injection of insulin because [1 Mark]
(a) his blood pressure was low
(b) his heart was beating slowly
(c) he was suffering from goitre
(d) his sugar level in blood was high

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

75. What is the correct direction of flow of electrical impulses? [1 Mark]
(a) Dendrite to cell body, then axon and to axonal end
(b) Axon to cell body, then dendrite and to axonal end
(c) Axonal end to axon, then cell body and to dendrite
(d) Cell body to dendrite, then axon and to axonal end

Answer: (c) (diagram (c): within a neuron the impulse flows dendrite → cell body → axon → axonal end, and across the synapse from the axonal end of one neuron to the dendrite of the next)

1. Electrical impulses enter the neuron through the dendrites.
2. From the dendrites, impulses pass into the cell body and then travel along the axon.
3. Finally, the impulses reach the axonal end to be transmitted across a synapse.
4. Hence, the correct option is (a).

Teacher's Note:
a) Electrical signals flow in a strictly unidirectional path in neurons.
b) Students often confuse the role of dendrites and axons in impulse transmission.

76. The hormone which increases the fertility in males is called [1 Mark]
(a) oestrogen
(b) testosterone
(c) insulin
(d) growth hormone

Answer: (b) testosterone

1. Testosterone is the primary male sex hormone produced by the testes.
2. It is responsible for secondary sexual characters and regulating male fertility.
3. Oestrogen is a female sex hormone.
4. Hence, the correct option is (b).

Teacher's Note:
a) Testosterone drives spermatogenesis and male reproductive health.
b) Always differentiate clearly between male and female reproductive hormones.

77. Which of the following endocrine glands is unpaired? [1 Mark]
(a) Adrenal
(b) Testes
(c) Pituitary
(d) Ovary

Answer: (c) Pituitary

1. The pituitary gland is a single gland located at the base of the brain.
2. Adrenal glands, testes, and ovaries occur in pairs in the human body.
3. Hence, the correct option is (c).

Teacher's Note:
a) Unpaired endocrine glands include the pituitary, thyroid, and hypothalamus.
b) Paired structures like adrenals and gonads exist on both left and right sides.

78. Junction between two neurons is called [1 Mark]
(a) cell junction
(b) neuro muscular junction
(c) neural joint
(d) synapse

Answer: (d) synapse

1. A synapse is the specialized junction between two adjacent neurons.
2. Neuro-muscular junction connects a neuron to a muscle cell.
3. Hence, the correct option is (d).

Teacher's Note:
a) Chemical neurotransmitters help bridge the gap across a synapse.
b) Do not confuse synapse with neuro-muscular junction.

79. In humans, the life processes are controlled and regulated by [1 Mark]
(a) reproductive and endocrine systems
(b) respiratory and nervous systems
(c) endocrine and digestive systems
(d) nervous and endocrine systems

Answer: (d) nervous and endocrine systems

1. The nervous system provides quick electrical coordination via nerve impulses.
2. The endocrine system provides slower chemical coordination via hormones.
3. Together they control and regulate all major life processes.
4. Hence, the correct option is (d).

Teacher's Note:
a) Coordination requires both rapid neural pathways and sustained hormonal control.
b) Other organ systems perform metabolic functions rather than regulatory ones.

80. Name the plant hormones responsible for the following [1 Mark]
(a) elongation of cells

(b) growth of stem
(c) promotion of cell division
(d) falling of senescent leaves.

Answer:
1. Auxin is the plant hormone primarily responsible for cell elongation.
2. Auxins promote growth, particularly in shoot tips.
3. (b) Growth of stem: Auxin and gibberellins
4. (c) Promotion of cell division: Cytokinins
5. (d) Falling of senescent leaves: Abscisic acid

Teacher's Note:
a) Auxin promotes cell enlargement by loosening the cell wall.
b) It plays a major role in phototropism and gravitropism.

81. Label the parts (a), (b), (c) and (d) and show the direction of flow of electrical signals in below Figure [3 Marks]

[Figure: Diagram of a reflex arc showing hand touching a hot pan, sensory neuron, spinal cord, relay neuron, and motor neuron, with labels (a) sensory neuron, (b) spinal cord, (c) relay neuron, and (d) effector / motor neuron]

Answer:
1. (a) Sensory neuron
2. (b) Spinal cord (CNS)
3. (c) Relay neuron
4. (d) Motor neuron / Effector
5. Direction of flow of electrical signals: Receptor in skin → Sensory neuron (a) → Spinal cord (b) via relay neuron (c) → Motor neuron (d) → Effector muscle in arm.

Teacher's Note:
a) The reflex arc pathway ensures rapid, involuntary responses to harmful stimuli.
b) Students often confuse sensory and motor neuron pathways; remember sensory goes towards the CNS.
c) The spinal cord acts as the immediate integration center for reflex actions without involving the brain directly.

82. Label the endocrine glands in Figure 7.3. [2 Marks]

[Figure: Outline of human body showing endocrine glands with pointers (a) Pineal gland, (b) Pituitary gland, (c) Thyroid gland, (d) Adrenal gland]

Answer:
1. (a) Pineal gland
2. (b) Pituitary gland
3. (c) Thyroid gland
4. (d) Adrenal gland

Teacher's Note:
a) Endocrine glands secrete chemical messengers called hormones directly into the bloodstream.
b) The pituitary gland is often referred to as the master gland because it regulates other endocrine glands.

37. In Figure 7.4 (a), (b) and (c), which appears more accurate and why? [3 Marks]

[Figure: Three pots with growing plants placed horizontally. (a) Plant stem bends upwards and roots grow downwards, (b) plant stem and roots grow straight horizontally, (c) plant stem bends downwards and roots grow upwards]

Answer:
1. Figure (a) appears more accurate.
2. In figure (a), the shoot bends upwards showing negative geotropism, while roots bend downwards showing positive geotropism.
3. Plant organs respond to gravity due to the redistribution of auxin, ensuring proper orientation for survival.

Teacher's Note:
a) Geotropism is the directional growth movement of plants in response to gravity.
b) Shoots grow away from the pull of gravity, whereas roots grow towards the pull of gravity.
c) Auxin accumulates on the lower side due to gravity, causing differential cell elongation in shoots and roots.

83. Label the parts of a neuron in Figure 7.5 [2 Marks]

Answer:
1. (a) Dendrite
2. (b) Cell body (Cyton)
3. (c) Axon
4. (d) Nerve ending (Axon terminal)

Teacher's Note:
a) Neurons are the structural and functional units of the nervous system.
b) Dendrites receive electrical impulses, while the axon transmits impulses away from the cell body.

84. Label the brain: [2 Marks]

[Figure: Sagittal section of a human brain with pointers X, Y, W, V and Z]

Answer:
1. W - Hypothalamus
2. V - Medulla
3. X - Cerebrum
4. Y - Corpus callosum
5. Z - Cerebellum

Teacher's Note:
a) The brain is broadly divided into forebrain, midbrain, and hindbrain.
b) Cerebrum is the main thinking part of the brain responsible for voluntary actions.

85. What is tropic movement? Explain with an example. [2 Marks]

Answer:
1. Directional growth movements of plants in response to an external environmental stimulus are called tropic movements.
2. These movements are growth-dependent and can be towards or away from the stimulus.
3. Example: Phototropism is the movement of plant parts in response to light, such as shoot bending towards sunlight due to the action of auxin.

Teacher's Note:
a) Tropic movements are slow and directional responses.
b) They differ from nastic movements, which are non-directional.

86. What will happen if intake of iodine in our diet is low? [1 Mark]

Answer:
1. Low iodine intake leads to a deficiency of thyroxine hormone in the body.
2. This causes an enlargement of the thyroid gland, a condition known as goitre.

Teacher's Note:
a) Iodine is essential for the synthesis of thyroxine by the thyroid gland.

87. What happens at the synapse between two neurons? [2 Marks]

Answer:
1. An electrical impulse sets off the release of neurotransmitters at the axonal end of one neuron.
2. These chemicals cross the synapse (gap) and start a similar electrical impulse in the dendrite of the next neuron.

Teacher's Note:
a) Synapse acts as a one-way valve allowing impulses to travel in a single direction.
b) This ensures that signals do not get mixed up across neural pathways.

88. Which hormone is responsible for the changes noticed in females at puberty? [1 Mark]

Answer:
1. Oestrogen is the hormone responsible for secondary sexual changes in females at puberty.

Teacher's Note:
a) It is secreted by the ovaries and regulates female reproductive development.

89. Dwarfism results due to deficiency of which hormone? [1 Mark]

Answer:
1. Growth hormone (GH), secreted by the pituitary gland.

Teacher's Note:
a) Excess secretion of growth hormone during childhood leads to gigantism.

90. Blood sugar level rises due to deficiency of which hormone? [1 Mark]

Answer:
1. Insulin, secreted by the pancreas.

Teacher's Note:
a) Insulin helps in lowering blood glucose levels by promoting its uptake into cells.

91. Iodine is necessary for the synthesis of which hormone? [1 Mark]

Answer:
1. Thyroxine.

Teacher's Note:
a) Thyroxine regulates metabolism of carbohydrates, fats, and proteins in the body.

92. Name the endocrine gland associated with brain? [1 Mark]

Answer:
1. Pituitary gland (or hypothalamus / pineal gland).

Teacher's Note:
a) The pituitary gland is often called the master gland and sits at the base of the brain.

93. Which gland secretes digestive enzymes as well as hormones? [1 Mark]

Answer:
1. Pancreas.

Teacher's Note:
a) Pancreas acts as both an exocrine gland (secretes digestive juices) and an endocrine gland (secretes insulin and glucagon).

94. Name the endocrine gland associated with kidneys? [1 Mark]

Answer:
1. Adrenal gland.

Teacher's Note:
a) Adrenal glands are located on the superior surface of each kidney and secrete adrenaline.

95. Which endocrine gland is present in males but not in females? [1 Mark]

Answer:
1. Testis.

Teacher's Note:
a) Testes are the primary male sex organs that secrete testosterone.

96. What are the major parts of the brain? Mention the functions of different parts. [5 Marks]

Answer:
1. The major parts of the brain are the forebrain, midbrain, and hindbrain.
2. Forebrain: It is the main thinking part of the brain, controls voluntary actions, and has regions for receiving sensory impulses (hearing, smell, sight) and controlling hunger.
3. Midbrain: It controls reflex movements of the head, neck, and trunk in response to visual and auditory stimuli.
4. Hindbrain: It consists of the cerebellum (controls posture, balance, and precise voluntary movements), pons (regulates respiration), and medulla oblongata (controls involuntary actions like blood pressure, salivation, vomiting, and heartbeat).
5. Protection of the brain: The brain is housed inside a bony box called the skull (cranium) and is surrounded by a fluid-filled membrane called cerebrospinal fluid that shock-absorbs mechanical impacts.

Teacher's Note:
a) The forebrain is the most complex part, specialized for integration of sensory information.
b) Students often confuse the specific functions of the cerebellum and medulla; clearly differentiate voluntary coordination from involuntary visceral control.
c) Mentioning both structural classification and protective mechanisms ensures complete marks in long-answer questions.

97. What constitutes the central and peripheral nervous systems? How are the components of central nervous system protected? [3 Marks]

Answer:
1. The Central Nervous System (CNS) consists of the brain and the spinal cord.
2. The Peripheral Nervous System (PNS) consists of cranial nerves arising from the brain and spinal nerves arising from the spinal cord, connecting the CNS to the rest of the body.
3. Protection of CNS: The brain is protected by the fluid-filled cerebrospinal fluid and enclosed within a bony skull (cranium), while the spinal cord is enclosed and protected by the vertebral column (backbone).

Teacher's Note:
a) CNS acts as the main control center, whereas PNS acts as the communication network.
b) Do not miss mentioning both cranial and spinal nerves when defining the peripheral nervous system.

98. Mention one function for each of these hormones : [5 Marks]
(a) Thyroxin
(b) Insulin
(c) Adrenaline
(d) Growth hormone
(e) Testosterone.

Answer:
1. (a) Thyroxin: Regulates carbohydrate, protein, and fat metabolism in the body to provide the best balance for body growth.
2. (b) Insulin: Regulates and lowers blood sugar (glucose) levels.
3. (c) Adrenaline: Prepares the body for emergency situations (fight or flight response) by increasing heart rate, breathing rate, and blood supply to muscles.
4. (d) Growth hormone: Regulates growth and development of the body, particularly bone and muscle growth.
5. (e) Testosterone: Regulates male secondary sexual characteristics and spermatogenesis.

Teacher's Note:
a) Hormones act as chemical messengers released directly into the blood to target specific organs.
b) Ensure you write exact and distinct physiological roles rather than generalized growth terms.

99. Name various plant hormones. Also give their physiological effects on plant growth and development. [5 Marks]

Answer:
1. Auxin: Promotes cell elongation, root initiation, and phototropic curvature in shoots.
2. Gibberellin: Promotes stem elongation, seed germination, and flowering.
3. Cytokinin: Promotes rapid cell division, delays leaf senescence, and promotes lateral bud growth.
4. Abscisic Acid (ABA): Acts as a growth inhibitor, causes wilting of leaves, and promotes stomatal closure and dormancy in seeds.
5. Ethylene: A gaseous hormone that promotes fruit ripening and transverse cell expansion.

Teacher's Note:
a) Plant hormones are classified into growth promoters (auxin, gibberellin, cytokinin) and growth inhibitors (abscisic acid, ethylene).
b) Clearly link each hormone with its specific directional or developmental effect on the plant body.

100. What are reflex actions? Give two examples. Explain a reflex arc. [5 Marks]

Answer:
1. Reflex action is a spontaneous, rapid, involuntary mechanical response to a stimulus mediated by the spinal cord without conscious brain involvement.
2. Examples: Withdrawal of hand upon touching a hot object; blinking of eyes when sudden bright light falls on them.
3. Reflex arc pathway: Receptors in sensory organs detect the stimulus and generate nerve impulses.
4. Sensory neurons carry the impulse from receptors to the spinal cord (CNS).
5. Relay neurons in the CNS process the signal and transmit it to motor neurons, which carry instructions to effectors (muscles or glands) to execute the immediate protective action.

Teacher's Note:
a) The reflex arc provides a fast track route to prevent potential tissue damage from sudden harmful stimuli.
b) Drawing or describing the sequential pathway from receptor to effector is essential for full credit.

101. “Nervous and hormonal systems together perform the function of control and coordination in human beings.” Justify the statement. [3 Marks]

Answer:
1. The nervous system uses electrical impulses along nerve fibers for rapid, short-term responses to specific stimuli.
2. The hormonal endocrine system uses chemical messengers transported via blood to coordinate slower, long-term widespread growth and metabolic processes.
3. Both systems integrate their functions to maintain internal homeostasis and respond efficiently to internal and external environmental changes.

Teacher's Note:
a) Contrast the speed and duration of nerve impulses versus hormonal actions.
b) Emphasize that complex organisms require both systems working in harmony for absolute physiological control.

102. How does chemical coordination take place in animals? [3 Marks]

Answer:
1. Chemical coordination in animals is mediated by hormones secreted by specialized endocrine glands.
2. These chemical messengers are secreted directly into the bloodstream, which carries them to specific target organs located away from the source gland.
3. Upon reaching the target organ, hormones trigger specific biochemical changes to regulate physiological activities, metabolic rates, and developmental growth.

Teacher's Note:
a) Endocrine glands are ductless glands that release secretions directly into blood capillaries.
b) Specificity is maintained because target cells possess specific receptor proteins that bind only to their corresponding hormones.

103. 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? [3 Marks]

Answer:
1. At the synapse, the axonal terminal of the first neuron releases specialized chemical substances known as neurotransmitters.
2. These neurotransmitters are released only from the vesicles present in the presynaptic axonal terminal.
3. The specific receptor sites capable of detecting and binding these neurotransmitters are present exclusively on the postsynaptic membrane of the dendritic end of the next neuron, thereby ensuring unidirectional transmission.

Teacher's Note:
a) This chemical synaptic bridge ensures that nerve impulses travel in one direction only, preventing signal confusion in neural circuits.
b) Mentioning neurotransmitters and receptor sites is mandatory to secure full credit.

Question. Phototropic and geotropic response of a plant is under control of following hormone :
(A) Auxin
(B) Gibberlin
(C) Cytokinin
(D) Ethylene
Answer : A

Question. The part of brain which controls the balance and posture of the body is
(A) Cerebellum
(B) Cerebrum
(C) Pons
(D) Medulla
Answer : A

Question. Which of the following cannot be considered as a receptor ?
(A) Muscle
(B) Ear
(C) Eye
(D) Nose'
Answer : A

Question. Growth of plants is not promoted by
(A) Cytokinins
(B) Auxins
(C) Gibberellins
(D) Abscisic acid
Answer : D

Question. An injury in accident has disturbed regulation of body temperature, water balance and hunger. The part of brain affected is :
(A) Cerebellum
(B) Cerebrum
(C) Medulla oblongata
(D) Hypothalamus
Answer : D

Question. If a rat is given an injection of sodium iodide with radioactive iodine, then in which of the following most of iodine would be incorporated ?
(A) Cartilage
(B) Thyroid
(C) Parathyroid
(D) Lymph nodes
Answer : B

Question. Synapse is
(A) gap between two muscle cells
(B) gap between two bones
(C) gap between two neurons
(D) gap between muscle and bone
Answer : C

Question. Which one of the following pairs is not correct ?
(A) The pituitary gland – Adrenalin
(B) Pancreas – Insulin
(C) Ovary – Estrogen
(D) Testis – Testosterone
Answer : A

Question. Find the odd one out
(A) Gonadotropins
(B) Thyrotropins
(C) Corticotropins
(D) Vasopressin.
Answer : D

Question. Which among the following hormones is associated with wilting of leaves ?
(A) Abscisic acid
(B) Gibberellin
(C) Cytokinin
(D) Auxin.
Answer : A

Question. The endocrine gland in which both exocrine and endocrine parts are present :
(A) Pancreas
(B) Adrenal gold
(C) Thyroid
(D) Pitutary gland
Answer : A

Question. Which of the following is a plant hormone ?
(A) Insulin
(B) Thyroxine
(C) Cytokinin
(D) Oestrogen
Answer : C

Question. The nature of nerve impulse is
(A) Chemical
(B) Magnetic
(C) Electrochemical
(D) Electromagnetic
Answer : C

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