Class-X Question Bank 1

Question Bank

Endocrine System

1. Differentiate between :

(i) Nervous control and Hormonal control

(ii) Endocrine gland and Exocrine gland

(iii) Hormone and Enzyme

(iv) Simple goitre and Exopthalmic goitre

(v) Diabetes mellitus and Diabetes insipidus

(vi) Cretinism and Myxodema

(vii) Gigantism and Acromegaly

Ans. (i)

Nervous Control Hormonal Control (a) The information is sent in the form of electric signals.

The information is sent in the form of chemical signals.

(b) The signals travel through nerve fibres to specific target cells like muscle fibres and glands.

The signals travel through bloodstream to cells in different organs.

(c) The nervous system causes muscles to contract or relax, glands to secrete more or less. But it cannot bring about growth.

Endocrine system brings about changes in metabolic activities of all body tissues. It affects growth.

(d) Action is immediate (within few milliseconds).

Action is slow (can take hours or days to produce response).

(e) Effect lasts for a short time. Effect is more lasting and permanent.

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(ii)

Endocrine Glands Exocrine Glands (a) These are ductless glands. They may or may not have ducts. (b) They pour secretion directly into the blood.

The secretion is poured directly at the site of action.

(c) They secrete hormones. They secrete enzymes. (d) They control long-term activities of target organs, e.g., thyroid glands.

They control short-term activity, e.g., gastric gland.

(iii)

Hormone Enzyme (a) They are produced by endocrine glands.

They are produced by exocrine glands.

(b) Chemically they may be proteins, steroids or their derivatives.

All enzymes are proteins.

(c) They are secreted at one site and act at another.

They act at their site of secretion or pass through ducts to their site of action.

(d) Hormone-regulated processes are not reversible.

Enzyme-mediated reactions are reversible.

(e) They are effective in low concentration. Their under- secretion or over-secretion affects body metabolism and growth.,

They act in low concentration. An increase or decrease in their concentration affects the rate of the process.

(f) They act either slowly or rapidly. They act quickly.

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(iv)

Simple Goitre Exopthalmic Goitre (a) Caused due to the enlargement of thyroid gland because of deficiency of iodine.

Caused due to the enlargement of thyroid gland because of hypersecretion of thyroxine.

(b) Eyes do not bulge out. Eyes bulge out. (c) Less thyroxine is produced, hence low metabolic rate.

Excessive thyroxine produced, hence increased metabolic rate.

(d) It may cause decrease in body temperature, heartbeat and lack of alertness.

It causes rise in blood pressure and body temperature, nervousness, irritability and loss of body weight.

(e) Increased intake of iodine can prevent and cure this disorder.

This can be rectified by surgical removal of a part of thyroid gland.

(v)

Diabetes insipidus Diabetes mellitus (a) This is due to under-secretion of anti-diuretic hormone.

This is due to failure of secretion of insulin.

(b) It is marked by loss of excess water in urine.

It is marked by loss of excess glucose in urine.

(c) Osmotic balance of the body is disturbed.

Total metabolism of the body is disturbed.

(d) Healing power is not affected. Body’s healing capacity is impaired.

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(vi)

Cretinism Myxoedema (a) Caused by hyposecretion of thyroxine in infants.

Caused by hyposecretion of thyroxine in adults.

(b) It is characterised by stunted growth, pot belly, protruding tongue and pigeon chest.

It is characterised by puffy appearance, due to accumulation of fat in the sub- cutaneous tissue and oedema (accumulation of water in tissue space).

(c) Mental and sexual retardation takes place.

Mental and sexual development is not affected but patients lack alertness.

(vii)

Gigantism Acromegaly (a) Caused by oversecretion of somatotropin in childhood.

Caused by oversecretion of somatotropin after adolescence.

(b) Due to abnormal elongation of bones and muscles, person is of abnormally large height.

Abnormal increase of bones of hands and legs, and the lower jaw, person has gorilla-like appearance but is not a giant.

2. Give general characterstics of hormones.

Ans. (i) Hormones are produced by endocrine glands and are distributed all through

the body by blood.

(ii) They are information molecules or chemical regulators secreted in response

to environmental changes in or outside the body.

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(iii) Chemically they may be large proteins (anterior pituitary hormone)

or small peptides (posterior pituitary hormone) or modified amino

acids (thyroid hormones) or amines (adrenal medulla hormones) or

steroids (adrenal-cortical hormones).

(iv) They have low molecular weight and diffuse readily through the cell

membrane.

(v) They regulate body functions along with nerves.

(vi) They don’t catalyse specific reactions but instead help in synthesis,

activation or inhibition of some enzymes in their target organs.

(vii) Abnormal production (more or less production) of hormones severely

affects body metabolism and growth.

3. Explain :

(i) Why some women develop beard and some men develop breasts?

(ii) Effects of sex hormones at puberty.

(iii) People of hilly region usually develop goitre.

(iv) High stature of male body than the female body.

(v) Older people tend to feel more cold.

(vi) Pituitary gland is called the ‘master gland’.

(vii) Adrenaline is known as an ‘emergency hormone’.

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Ans. (i) The cause of the development of beard in females and breasts in males

with normal karyotype is due to excessive secretion of sex corticoids.

(ii) The sex hormones are secreted by the gonads. In males the hormones

secreted are testosterone and androsterone. They are responsible for

(a) normal maturation of sperms, (b) stimulation of secondary sex characters

i.e. facial hair (beard), pattern of body hair, low pitch of voice

(c) broadening of shoulders, (d) influence sex instinct and reflexes.

In females, the hormone oestrogen stimulates the development of

secondary sexual characterstics at puberty, i.e., development of hair in

pubic region and in the armpits, development of breast, fat deposits in

hips and high pitch of voice.

(iii) People in the hilly region usually develop goitre because of the enlargement

of thyroid gland. Deficiency of iodine in diet causes the thyroid to enlarge to

produce inadequate amount to thyroxine.

(iv) Male sex hormone stimulates the development of external male characters.

It also promotes the growth of many parts of the body tissues, including

bones and muscles. Since females do not have these hormones (androgens),

they do not grow as tall and or have strong statue.

(v) The thyroid gland regulates the body metabolism, including causing an

increase in basal metabolic rate which raises the body temperature.

With advancing age, the activity of thyroid gland slows down and body

heat production is lowered. That is why older people tend to feel colder

than youngsters.

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(vi) The pituitary gland is referred to as the ‘master gland, because the activities

and growth of the endocrine glands and somatic cells are under the influence

of secretions of the pituitary gland. Nearly 50,000 nerves fibres enter this

fragment of tissue, and an enormously rich blood supply carries its hormones

to the rest of the body.

(viii) Adrenaline is a hormone which prepares the body to meet any emergency

situation to ‘fight’, i.e., to face the danger of for ‘flight’, to run away from it,

and extra energy and strength are provided to the body for the situation. Extra

hormone is released into the blood at the time of emotional stress. The gland

itself is stimulated by the nerve endings of the autonomic nervous systems.

4. Match the items in Column A with those in Column B.

Column A Column B (i) Diabetes mellitus (ii) Myxoedema (iii) Demineralisation of bones (iv) Addison’s disease (v) Dwarfism (vi) Cretinism (vii) Tetany (viii) Exopthalmic goitre (ix) Darkening of skin (x) Diabetes insipidus

(a) Hyposecretion of thyroxine in adults. (b) Hyposecretion of human growth hormone.(c) Hyposecretion of thyroxine in children. (d) Hyposecretion of parathormone. (e) Hypersecretion of Thyroxine. (f) Hyposecretion of Insulin (g) Hypersecretion of MSH. (h) Hyposecretion of vasopressin. (i) Hyposecretion of glucocorticoid. (j) Hypersecretion of parathormone.

Ans. (i) (f) (ii) (a) (iii) (j) (iv) (i) (v) (b) (vi) (c) (vii) (d) (viii) (e) (ix) (g)

(x) (h).

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5. Given below is an outline diagram of human body showing position of certain

organs.

Ans.

6. Complete the following table by filling in the blank spaces numbered 1 to 10.

Gland Secretions Effect on body 1. ___________ Oestrogen 2. ___________ Alpha cells of Pancreas 3. ___________ 4. ___________ 5. ___________ 6. ___________ Protruding eyes Lachrymal 7. ___________ 8. ___________ 9.___________ 10. ___________ Gigantism

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Ans.

Gland Secretions Effect on body 1.Ovary Oestrogen 2. Controls secondary sexual

charactersAlpha cells of Pancreas 3. Glucagon 4. Raises blood sugar level by

stimulating conversion of glycogen to glucose.

5.Thyroid 6. Thyroxin Protruding eyes Lachrymal 7. Lachrymal fluid (tears) 8. Serves as lubricants and

washes away dust particles.9.Pituitary 10. STH or GH (somato

trophic or growth hormone)

Gigantism

7. The hormone that releases glucose into the blood.

Ans. Glucagon.

8. (a) Name the hormone produced by the thyroid gland and state its function in

the body.

(b) What would a child suffer from if there was hyposecretion from the thyroid?

(c) (i) The three hormones produced by the pancreas.

(ii) The hormones produced by adrenal medulla.

(iii) The condition caused by oversecretion of insulin.

Ans. (a) Thyroid gland secretes thyroxin and calcitonin.

Thyroxin promotes tissue metabolism, growth and differentiation.

Calcitonin promotes movement of calcium ions from blood to bones.

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(b) Hyposecretion of thyroid leads to simple goitre, cretinism in children and

myxodema in adults.

(c) (i) Three hormones produced by pancreas are insulin, glucagon and

somatostatin.

(ii) The hormone produced by adrenal medulla is adrenalin. It causes

stimulation of sympathetic nervous system.

(iii) The condition caused by oversecretion of insulin is diabetes mellitus.

9. Name the following:

(a) The hormone secreted by β -cells of islets of Langerhans.

(b) Hormone which increases blood sugar.

(c) Hormone which causes secretion of more urine.

(d) The hormone which stimulates the entire sympathetic nervous system.

Ans. (a) Insulin (b) Glucagon (c) Insulin (d) Adrenalin

10. Complete the following table by filling in blank space 1 to 8:

Name of gland Substance produced One important function Islets of Langerhans 3.................. 5.................. 7..................

1 ................. Adrenaline Thyroxine LH

2................. 4.................. 6.................. 8..................

Ans. 1. Insulin.

2. Regulates blood sugar level. Stimulates deposition of extra glucose in

liver as glycogen.

3. Adrenal gland.

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4. Prepares the body for ‘fight’ or ‘flight’ actions by stimulating

sympathetic nervous systems.

5. Thyroid gland.

6. Promotes tissue metabolism, growth and differentiation.

7. Anterior Pituitary gland.

8. Stimulates ovulation, maintenance of corpus luteum and secretion of

progesterone in female and secretion of testosterone in males.

11. Why is iodine important for our body?

Ans. Iodine is the active ingredient in the production of thyroxin. And thyroxin,

in turn promotes tissue metabolism, growth and differentiation. Thus, it is

important.

12. If you stand to make your maiden speech before a large audience, your

mouth dries up and heart rate increases. What brings about these

changes?

Ans. The hormone responsible for this is adrenalin. It is a hormone, which prepares

the body to meet any emergency situation, for “Fight” i.e. to face danger or for

“flight”, i.e. to run away from it. Extra hormone is released into the blood at the

time of emotional stress.

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13. Compare the hormonal response with the nervous response with respect

to speed.

Ans. Hormonal response is slow, whereas, nervous response is immediate/

spontaneous.

14. How do endocrine glands differ from other glands?

Ans. Apart from endocrine glands, there are exocrine glands. Unlike, exocrine

glands, endocrine glands “secrete internally”, also called ductless glands

because their secretions are poured directly into the blood and not through

any special duct. These glands activate each other and work as a system of

organs called endocrine system.

15. Mention any two differences between a hormone and an enzyme.

Ans. (i) Hormones are secreted by glands. Enzymes are not secreted by any gland.

(ii) Hormones have a direct effect on the target organs.

Enzymes only catalyse the reaction, they are not used up during the reaction.

16. Do you agree with the statement — “All hormones are chemical signals”?

Yes/No. Justify your answer.

Ans. Yes. Hormones are transmitted chemically through blood. They can bring about

specific chemical changes and regulate metabolism. They activate each other

and work in a coordinated manner. As for example, the hormone insulin acts on

liver and muscle cells and deposit extra glucose in the form of glycogen.

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17. If one adrenal gland is removed, the other one gets enlarged to some extent.

How do you explain this change.

Ans. The one remaining adrenal gland performs the function of two glands.

Therefore it gets slightly enlarged for enhanced secretion of hormones.

18. Given alongside is a portion from the human body showing some

important structure in ventral view.

(a) Where is this portion located in the body?

(b) Name the structures numbered 1 – 3.

(c) State one main function of each of the structures named above.

Ans. (a) In the neck

(b) 1 – Larynx

2 – Thyroid gland

3 – Trachea

(c) 1 – Production of sound

2 – Production of thyroxine

3 – Breathing

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19. Given below are two diagrams (one is correct, the other is somewhat incorrect)

showing the transport of a hormone from its source gland/cell to the target

organ/cell.

(a) Which one has the error – A or B? _________

(b) What is the error? _______________________

[Hint : Look at all the arrows indicating the direction of flow of hormone

inside blood stream.]

Ans. (a) B has error.

(b) Trap between gland and blood vessel. The hormone molecules are absorbed

directly into the blood stream.