CHAPTER -6- CONTROL AND COORDINATION

CHAPTER -6- CONTROL AND COORDINATION(VOLUME-1)

Q.NO. Multiple Choice Questions (MCQ).

The electrical impulse travels in a neuron from:
a. \( \text{Dendrite} \rightarrow \text{axon} \rightarrow \text{axonal end} \rightarrow \text{cell body} \)
b. \( \text{Cell body} \rightarrow \text{dendrite} \rightarrow \text{axon} \rightarrow \text{axonal end} \)
c. \( \text{Dendrite} \rightarrow \text{cell body} \rightarrow \text{axon} \rightarrow \text{axonal end} \)
d. \( \text{Axonal end} \rightarrow \text{axon} \rightarrow \text{cell body} \rightarrow \text{dendrite} \)
Which of the following statements is true?
i. Sudden action in response to something in the environment is called reflex action.
ii. Sensory neurons carry signals from the spinal cord to muscles.
iii. Motor neurons carry signals from receptors to the spinal cord.
iv. The path through which signals are transmitted from a receptor to a muscle or a gland is called the reflex arc.
a. 1 and 2
b. 1 and 3
c. 1 and 4
d. 1, 2 and 3
The hormone that regulates blood sugar level is:
a) Insulin
b) Thyroxine
c) Adrenaline
d) Estrogen
Which one of the following is not a tropic movement?
a) Movement of shoot towards light
b) Movement of roots toward water
c) Movement of roots toward gravity
d) Drooping of leaves of Mimosa pudica on touching
Which plant hormone is responsible for cell elongation?
a) Cytokinin
b) Auxin
c) Gibberellin
d) Abscisic acid
The growth of tendrils towards a support is an example of:
a) Hydrotropism
c) Chemotropism
d) Thigmotropism
Which of the following controls voluntary actions?
a) Spinal cord
b) Medulla
c) Cerebrum
d) Cerebellum
Which hormone is released during stress and increases blood pressure?
a) Thyroxine
b) Insulin
c) Adrenaline
d) Estrogen
Which of the following statements are correct?
(I) Hormones are released directly into the bloodstream.
(II) Endocrine glands use electrical impulses.
(III) Sex hormones regulate changes associated with puberty.
Options:
(a) (I) and (II) (b) (I) and (III) (c) (II) and (III) (d) (I), (II) and (III)
Ans. (b) (I) and (III)
The main function of abscisic acid in plants is to:
(a) increase the length of cells
(b) promote cell division
(c) inhibit growth
(d) promote growth of stem

Following questions consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:

(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.

Assertion (A): Adrenaline increases heart rate and breathing rate during emergency situations.
Reason (R): Adrenaline helps the body prepare for 'fight or flight' response.
Assertion (A): Thyroxine helps in regulating metabolism in the human body.
Reason (R): Iodine is necessary for the synthesis of thyroxine.

Diagram of a neuron labeled (a), (b), (c), (d)

Flowchart: Dendrite -> a -> b -> End point of Neuron

VERY SHORT ANSWERS QUESTIONS

Sameer was studying in his room, suddenly he smells somethings burning and sees smoke in the room. He rushes out of the room immediately. Was sameers’s action voluntary or involuntary? Why?
(a) Name one gustatory receptor and one olfactory receptor in human beings.
(b) Write a and b in the given flow chart of neuron through which information travels as an electrical impulse.
(a) Label the parts a) and c) of a neuron in Figure:-
(b) write the function of b) and d).
How do we detect the smell of an agarbatti (incense stick)?
Differentiate between central nervous system and peripheral nervous system.

SHORT ANSWERS QUESTIONS

A patient shows symptoms of high blood sugar. Which gland is likely to be malfunctioning? Explain the hormone involved.
In an experiment, a plant kept in a dark room shows bending of shoot towards the window. Explain the reason.
A cheetah, on seeing a prey, moves towards him at a very high speed. What causes the movement of his muscles? How does the chemistry of cellular components of muscles change during this event?
A person is frightened suddenly. Describe the hormonal changes that occur in his body.
For nervous and hormonal systems to control and coordinate in human beings, hypothalamus plays an important role in receiving the neural/nerve signals from brain and release hormones. In situation of iodine deficiency, hypothalamus releases hormones to stimulate pituitary gland, it further sends stimulating hormone to thyroid gland to secrete thyroxin that regulates carbohydrate metabolism. This is an example of feedback mechanism of regulation of hormones in human beings. Justify the statement.

LONG ANSWERS QUESTIONS

Diagram of Human Brain labeled A, B, C, D

Study the figure related to human brain and answer the questions that follow.
a) Name the parts A, B, C and D of human brain.
b) What is the function of the fluid filled in the brain?
c) What constitutes Peripheral Nervous System (PNS)?
d) Name the endocrine gland associated with brain.

Fig 7.2 Diagram of Reflex Arc labeled (a), (b), (c), (d)

(a) Label the parts (a) ,(b) and (c), (d) and show the direction of flow of electrical signals in the given figure
(b) Write the function of (c) and (d).
(c) Explain the process which is taking place in the given diagram.
A person while climbing up a rocky hill comes into a panic state and fear. His body starts reacting in a ‘ flight-or-flight’ condition to adjust to the dangerous and stressful situation. Based on the above facts, answer the questions that follow.
a) (i) Name the hormone secreted in this condition.
a) (ii) Name the source gland of the hormone secreted in this condition.
b) State any two responses in the body of the person as a result of the secretion of this hormone.
c) How does the action of the chemical signals in terms of the hormones differ from the electrical impulses via nerve cells?

CASE BASED QUESTIONS (CBQs)

Rajesh accidentally touched a thorn but quickly withdrew his hand. He later realized that he did this without even thinking about it! So, his reflexes were quite quick.
(a) What is the main centre for such reflex actions of Rajesh?
(b) In a neuron, the conversion of electrical signal to a chemical signal occurs at which part?
(c) What are electrical impulses? Write any two limitations of electrical impulses.
Thyroid gland is a bilobed structure situated in our neck region. It secretes a hormone called thyroxine. Iodine is necessary for the thyroid gland to make thyroxine. Thyroxine regulates carbohydrate, protein and fat metabolism in the body. It promotes growth of body tissues also. When there is an excess of thyroxine in the body, a person suffers from hyperthyroidism and if this gland is underactive it results in hypothyroidism. Hyperthyroidism is diagnosed by blood tests that measure the levels of thyroxine and Thyroid Stimulating Hormone (TSH). Hypothyroidism is caused due to the deficiency of iodine in our diet resulting in a disease called goitre.

(a) Where is thyroid gland situated in our body?
(b) State the function of thyroxine in human body.
(c) What is hyperthyroidism? How can we control hypothyroidism?

ANSWER

1. (C)
2. (C)
3. (A)
4. (C)
5. (D)
6. (B)
7. (D)
8. (C)
9. (b) (I) and (III)
10. (c) inhibit growth
11. (A)
12 (A)
13. Voluntary because rushing out of the room was under his conscious control. somkessmell’s were perceived by the receptors in the sense organ and signals are sent to the brain and then brain sent signals to effector organs i.e. muscles, to move out of the room.
14. (a) Gustatory receptors are receptors for taste present in taste buds on tongue and olfactory receptors are the receptors for smell present in nasal chambers.
(b) a is cyton and b is axon.
15 i) a. Dendrite c. Axon
ii) b is cell body which provide structure to the body and store the organelles of the cell and d is axon terminals transmit messages to other cell.
16. The smell of an agarbatti is detected by the nose. The olfactory receptors present in the nose sends electrical signal to the fore brain. The fore brain interprets this signal as the smell of the incense stick.
17.

S.No.	CNS	PNS
i	includes brain and spinal cord	includes all nerves that connect CNS to body parts.
ii	Coordinates the body’s functions.	Controls involuntary activities of organs.

18. Pancreas may not be producing enough insulin which helps regulate blood glucose levels by promoting uptake of glucose into cells.
19. This is positive phototropism. Auxins accumulate on the darker side of shoot, promoting more growth there, causing it to bend towards light.
20. A cheetah on seeing a prey generates a nerve impulse which reaches the muscles and the muscle fibre moves.
The muscle cell will then move by changing their shape so that muscle cells shorten.
Muscle cells have special proteins that change both shape and their arrangement in the cell in response to nervous electrical impulses.
When this happens new arrangements of these proteins give the muscle cells a shorter form.
21. \( \text{Adrenal glands release adrenaline} \rightarrow \text{increases heartbeat, respiration, and glucose level to prepare the body for action.} \)
22. For nervous and hormonal systems to control and coordinate in human beings, hypothalamus plays an important role in receiving the neural/nerve signals from brain and release hormones.
E.g. – In situation of iodine deficiency, hypothalamus releases hormones to stimulate pituitary gland, it further sends stimulating hormone to thyroid gland to secrete thyroxin that regulates carbohydrate metabolism.
23 a) A. Cerebrum B. Spinal cord C. medulla oblongata D. Cerebellum
b) Cushioning and protecting the brain and spinal cord from injury.
c) Cranial nerves, Spinal nerves, Autonomic nervous system
d) Pituitary gland: Often called the "master gland," it secretes hormones that regulate other glands, including the thyroid, adrenal glands, and gonads.
24. a) sensory neuron (b) spinal cord (c) motor neuron (d) effector organ bady
c) reflex action
25. a) i. Adrenaline
a) ii. adrenal glands
b) Increased heart rate: Adrenaline causes the heart to beat faster, delivering more oxygen and glucose to the muscles, preparing the body for quick action.
Dilated pupils: The pupils widen (mydriasis) to improve vision and enhance the person’s awareness of their surroundings, helping them to detect any potential threats more quickly.
c) Hormones are chemical messengers released into the bloodstream and travel throughout the body. Electrical impulses via nerve cells (neurons) are rapid, localized signals that travel along nerve fibers to communicate with other nerve cells, muscles, or glands.
26. Ans. (a) The main centre for such reflex actions of Rajesh is spinal cord.
(b) At the end of the axon, the electrical impulse sets off the release of some chemicals that cross the gap and start a similar electrical impulse in a dendrite of the next neuron.
(c) Electrical impulse is a signal which is transmitted along a nerve fibre. Any environmental change is detected by the specialized tips of nerve cells known as dendrites in the form of a message. The message acquired sets off a chemical reaction which creates an electrical impulse.
Electrical impulses have following limitations:
(i) They will reach only those cells which are connected by nervous tissue.
(ii) Electrical impulses acts for only a short period of time and the message is only sent in the presence of the stimulus.
(iii) Nerve cells cannot continuously create and transmit electrical impulses.
27. Ans. (a) Thyroid gland is situated at the front of the neck, just below the larynx (Adam’s apple).
(b) Thyroxine hormone is secreted by the thyroid gland. Thyroxine plays vital roles in increasing the basal metabolic rate, regulating long bone growth, increasing body’s sensitivity to hormone adrenaline, digestive functions, etc.
(c) Hyperthyroidism occurs when the thyroid gland produces excessive amount of hormone thyroxine. We can control hypothyroidism by including iodised salt in our diet. Deficiency of iodine in our diet reduces the levels of TSH and causes a disease called goitre.