NCERT Exemplar Class 11 Biology Solutions Chapter 22 Chemical Coordination and Integration

Multiple Choice Questions:

Question:1

Select the right match of the endocrine gland and their hormones amongst the options given below.

Options:
(a) A – (iv), B – (ii), C – (iii), D – (i)
(b) A – (ii), B – (iv), C – (i), D – (iii)
(c) A – (iv), B – (ii), C – (i), D – (iii)
(d) A – (ii), B – (iv), C – (iii), D – (i)

Answer:

(d) A – (ii), B – (iv), C – (iii), D – (i) is the correct option

Question:2

Which of the following hormones is not secreted by anterior pituitary gland?
(a) Growth hormone
(b) Follicle stimulating hormone
(c) Oxytocin
(d) Adrenocorticotropic hormone

Answer:

The answer is the option (c) Oxytocin.
Explanation: Oxytocin is produced by the posterior pituitary gland.

Question:3

Mary is about to face an interview. But during the first five minutes before the interview she experiences sweating, increased rate of heartbeat, respiration etc. Which hormone is responsible for her restlessness?

(a) Estrogen and progesterone
(b) Oxytocin and vasopressin
(c) Adrenaline and noradrenaline
(d) Insulin and glucagon

Answer:

Ans. The answer is the option (c) Adrenaline and noradrenaline.

Explanation: Adrenaline and noradrenaline are also called stress hormones and can be responsible for restlessness.

Question:4

The steroid hormone responsible for balance of water and electrolytes in our body is
(a) Insulin
(b) Melatonin
(c)Testosterone
(d) Aldosterone

Answer:

The answer is the option (d) Aldosterone.
Explanation: Aldosterone stimulates reabsorption of Na+ and water and excretion of K+ and phosphate ions; thus it is responsible for maintaining water balance and electrolytes in our bodies.

Question:5

Thymosin is responsible for

(a) Raising the blood sugar level

(b) Raising the blood calcium level

(c) Differentiation of T lymphocytes

(d) Decrease in RBC

Answer:

The answer is the option (c) Differentiation of T lymphocytes.

Question:6

In the mechanism of action of a protein hormone, one of the second messengers is
a. Cyclic AMP
b. Insulin
c. T3
d. Gastrin

Answer:

The answer is the option (a) Cyclic AMP
Explanation: Hormones which react with membrane-bound receptors and generally do not enter the target cell, but creates second messengers (Cyclic AMP, IP3, Ca++, etc.)

Question:7
Leydig cells produce a group of hormones called
(a) Androgens
(b) Estrogens
(c) Aldosterone
(d) Gonadotropins

Answer:

The answer is the option (a) Androgens.

Question:8

Corpus luteum secretes a hormone called
(a) Prolactin
(b) Progesterone
(c) Aldosterone
(d) Testosterone

Answer:

The answer is the option (b) Progesterone.

Question:9

Cortisol is secreted from
(a) Pancreas
(b) Thyroid
(c) Adrenal
(d) Thymus

Answer:

The answer is the option (c) Adrenal

Question:10

A hormone responsible for normal sleep-wake cycle is
(a) Epinephrine
(b) Gastrin
(c) Melatonin
(d) Insulin

Answer:

The answer is the option (c) Melatonin.

Question:11

Hormones are called chemical signals that stimulate specific target tissues.Which is the correct location of these receptors in case of protein hormones?

(a) Extracellular matrix
(b) Blood
(c) Plasma membrane
(d) Nucleus

Answer:

The answer is the option (c) Plasma membrane.

Question:12

Choose the correct option among the following:

Options:
(a) A—(ii), B—(i), C—(iii), D—(iv)
(b) A—(iv), B—(i)„ C—(iii), D—(ii)
(c) A—(i), B—(ii), C—(iii), D—(iv)
(d) A—(i), B—(iv), C—(ii), D—(iii)

Answer:

The answer is the option (b) A—(iv), B—(i), C—(iii), D—(ii).

Question:13

Which of the following do not play any role in calcium balance in the human body?
(a) Vitamin D
(b) Parathyroid hormone
(c) Thyrocalcitonin
(d) Thymosin

Answer:

The answer is the option (d) Thymosin.
Explanation: Thymosin is responsible for differentiation of T-lymphocyte in the body.

Question:14

Which of the following organs in mammals does not consist of a central 'medullary' region surrounded by a cortical region?
(a) Ovary
(b) Liver
(c) Adrenal
(d) Kidney

Answer:

The answer is the option (b) Liver.

Question:15

Which of the following conditions is not linked to deficiency of thyroid hormone?
(a) Cretinism
(b) Goitre
(c) Myxedema
(d) Exophthalmos

Answer:

The answer is the option (d) Exophthalmos.
Explanation: Exophthalmos happens due to hyperthyroidism.

Very Short Answer Type Questions:

Question:1

There are many endocrine glands in the human body. Name the gland which is absent in male and the one which is absent in females.

Answer:

Ovaries are glands which are absent in males and testis is absent in females.

Question:2

Which of the two adrenocortical layers, zona glomerulosa and zona reticularis lies outside enveloping the other?

Answer:

Ans.
The outermost layer is the Zona glomerulosa, and the innermost layer of the adrenal gland is the zona reticularis.

Question:3

What is erythropoiesis? Which hormone stimulates it?

Answer:

The process of formation of RBCs from the bone marrow is known as erythropoiesis. It is stimulated by the hormone called erythropoietin.

Question:4

Name the only hormone secreted by pars intermedia of the pituitary gland.

Answer:
Melanocyte Stimulating Hormone (MSH) is the only hormone secreted by pars intermedia of the pituitary gland.

Question:5

Name the endocrine gland that produces calcitonin and mention the role played by this hormone.

Answer:

The thyroid gland produces calcitonin or thyrocalcitonin. Calcitonin hormone regulates blood calcium levels in the body.

Question:6

Name the hormone that helps in cell-mediated immunity.

Answer:
Thymosin is the hormone that helps in cell-mediated immunity.

Question:7

What is the role of the second messenger in the mechanism of protein hormone action?

Answer:
The Second messenger helps in regulating cell metabolism. The hormones which react with the membrane-bound receptors generally do not enter the cell. Instead of that, they create second messengers and in doing so, affect the functioning of the target cells.

Question:8

State whether true or false:
(a) Gastrointestinal tract, kidney and heart also produce hormones.
(b) Pars distalis produces six trophic hormones.
(c) B-lymphocytes provide cell-mediated immunity.
(d) Insulin resistance results in a disease called diabetes mellitus.

Answer:
(a) True
(b) True
(c) False
(d) True

Question:9

A patient complains of constant thirst, excessive passing of urine and low blood pressure. When the doctor checked the patient's blood glucose and blood insulin level, the levels were found to be normal or slightly low. The doctor diagnosed the condition as diabetes insipidus. But he decided to measure one more hormone in the patient's blood. Which hormone does the doctor intend to measure?

Answer:
The doctor intends to measure Vasopressin or Antidiuretic hormones because low levels of these hormones can cause excessive passing of urine and low blood pressure in humans.

Question:10

Correct the following statements by replacing the term underlined.
(a) Insulin is a steroid hormone.
(b) TSH is secreted from the corpus luteum.
(c) Tetraiodothyronine is an emergency hormone.
(d) The pineal gland is located on the anterior part of the kidney.

Answer:
(a) Insulin is a peptide hormone.
(b) TSH is secreted from anterior pituitary gland.
(c) Tetraiodothyronine is a maintenance hormone.
(d) The adrenal gland is located on the anterior part of the kidney.

Question:11

Rearrange the following hormones in Column I so as to match with their chemical nature in Column II.

Answer:

The answer is the option (a) - (iii), (b) - (i), (c ) - (ii), (d) - (iv)

Short Answer Type Questions:

Question:1

What is the role played by luteinizing hormones in males and females respectively?

Answer:

Luteinizing hormones play the following roles: -

• In Males: They help in stimulating the Leydig cell production of testosterone.

• In Females: They help in stimulating the process of ovulation.

Question:2

What is the role of the second messenger in hormone action?

Answer:

Extracellular substances such as some hormones which do not cross the plasma membrane are called the first messenger. In cases like these, second messengers are produced so that they can enter the cell. Second messengers trigger various physiological changes in a cell. Hence, second messengers play the role of connecting the signals from first messengers.

Question:3

On an educational trip to Uttaranchal, Ketki and her friends observed that many local people were having swollen necks. Please help Ketki and her friends to find out the solutions to the following questions.
(a) Which probable disease are these people suffering from?
(b) How is it caused?
(c) What effect does this condition have on pregnancy?

Answer:
(a) The people are suffering from a health condition called the goitre.
(b) Goitre is caused by dietary iodine deficiency.
(c) If a pregnant woman is suffering from goitre, which is associated with hypothyroidism; it can have adverse effects on the foetus. Goitre causes defective development and maturation of the growing baby leading to stunted growth, mental retardation, abnormal skin and deaf-mutism.

Question:4

George comes on a vacation to India from the US. The long journey disturbs his biological system, and he suffers from jet lag. What is the cause of his discomfort?

Answer:
Body's biological clock follows a set pattern during the 24 hours called the circadian rhythm. If a person travels through different time zones through long hours of journey, his circadian rhythm gets troubled. As a result, the person suffers from jet lag.
This causes sleep disturbance, bowel habits, anorexia, etc.

Question:5

Inflammatory responses can be controlled by a certain steroid. Name the steroid, the source from which it is obtained and also mention its other important functions.

Answer:

Inflammatory responses are controlled by a steroid called cortisol. Cortisol hormone is secreted by the adrenal cortex. Cortisol is one of the many corticoids secreted by the adrenal gland. It also stimulates the RBC production and also influences or modulates a lot of changes that happen in the body in response to stress etc.

Question:6

Old people have weak immune systems What could be the reason.

Answer:

The thymus gland in the body does the job of secreting the hormone called thymosin which plays a big role in the differentiation of T-lymphocytes. T-lymphocytes are responsible for cell mediation for immune response. In old people, because of their age, their thymus gland starts to degenerate, which results in reduced production of thymosin. Thus, old people have weak immune systems.

Question:7

What are the effects of hypothyroidism (observed during pregnancy) on the development and maturation of a growing baby?

Answer:

If a pregnant woman is suffering from hypothyroidism; it can have adverse effects on the development and maturation of the foetus. Their foetus's growth can be stunted, which can result in an underweight newborn. The effects of hypothyroidism remain after birth and do not go away. The baby's brain may not develop, and they may show signs of mental retardation. The baby can also develop abnormal skin and deaf-mutism.

Question:8

Mention the difference between hypothyroidism and hyperthyroidism.

Answer:

Question:9

You have learnt that a characteristic feature of endocrine systems is the presence of feedback loops. By what is meant if hormone A stimulates gland 'X' to secrete hormone B, the production of 'A' could be modified when the level of B changes in our blood. An example is the relationship between hormones LH and estrogen (E2). An old woman exhibits the following features.

High levels of LH in blood but low levels of E2 in the blood. Another woman exhibits high level of LH in blood and also high level of E2 in the blood. Where lies the defect in both these women? Provide a suitable diagram to support the answer.

Answer:

In the body, the level of LH in the blood is generally low before puberty, and it starts to increase during the reproductive phase. LH levels in the blood during the reproductive phase are dependent on the specific phase of the ovulation cycle that the woman is going through. When ovulation is about to happen, the LH level peaks, and so does the level of E2. This displays normal conditions.

But in the case of older women, LH level in the bodies is higher, and it goes along with the low levels of E2. Low level of E2 displays the end of the reproductive phase. It is known that menopause marks the end of the reproductive phase for the woman. After menopause, no or negligible oocytes are left in the ovary. Hence, LH is not being utilized the way it was during the reproductive phase. This explains the reason of the increased level of LH in blood in older women.

Long Answer Type Questions:

Question:1

A milkman is very upset one morning as his cow refuses to give any milk. The milkman's wife gets the calf from the shed. On fondling by the calf, the cow gave sufficient milk. Describe the role of endocrine gland and the pathway associated with this response?

Answer:

Ans. Milk secretion in mammals is provoked by the hormone known as oxytocin which works on positive feedback mechanisms.
(a) When the calf suckles on the cow's udder; it stimulates the nerve impulses.
(b) Nerve impulses in order to send signals to the hypothalamus, which starts producing oxytocin in the body.
(c) Therefore, Oxytocin results in the contraction of the smooth muscles around the alveoli (in the cow's udder) and hence milk is released.

Udder (suckling stimulus) Hypothalamus Posterior lobe of pituitary Oxytocin (in the blood) Udder (Smooth muscles) Milk flow.

Question:2

A sample of urine was diagnosed to contain a high content of glucose and ketone bodies. Based on this observation, answer the following:

(a) Which endocrine gland and hormone is related to this condition?
(b) Name the cells on which this hormone acts.
(c) What is the condition called, and how can it be rectified?

Answer:
(a) The pancreas is the endocrine gland and insulin is the hormone which is related to this condition.
(b) Insulin acts on hepatocytes and adipocytes.
(c) This condition is called diabetes. This can be controlled by changing some dietary habits, medications etc. In some cases, the patient may need to take insulin on a daily basis.

Question:3

Calcium plays a very important role in the formation of bones. Elaborate the role of endocrine glands and hormones responsible for maintaining Calcium homeostasis.

Answer:

The movement of calcium ions between the body fluids and cells is known as calcium homoeostasis. Calcium plays a critical role in different metabolic processes and is also an important part of the bones. Hence, to maintain the levels of calcium in body fluids, cells and bones are very highly important. Both the thyroid and parathyroid hormones play great roles in calcium homeostasis.

Question:4

Illustrate the differences between the mechanism of action of a protein and a steroid hormone.

Answer:

Question:5

Hypothalamus is a super master endocrine gland. Elaborate.

Answer:

Ans. The hypothalamus consists of many groups of neurosecretory cells which are called nuclei which produces hormones. These hormones control the synthesis and production of pituitary hormones. The hypothalamus produces two types of hormones, i.e. releasing hormones (that revivify secretion of pituitary hormones) and inhibiting hormones (which inhibits the secretion of pituitary hormones) The Pituitary gland produces the maximum number of hormones in the body, But many hormones secreted from the pituitary gland regulate the function of other endocrine glands in the body. In fact, all the other endocrine glands are controlled by the hormones which are produced by the pituitary gland. Thus, the pituitary gland is popularly known as the 'Master Gland' But the hormones secreted by hypothalamus regulates the production of hormones from the pituitary gland. Due to this, the hypothalamus can also be known as the 'Super Master Gland' of the body.