SELINA Solutions for Class 10 Biology Chapter 12 - The Endocrine System

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Chapter 12 - The Endocrine System Exercise Ex. 1

Question A.1
A gland having endocrine as well as exocrine function

(a) Pituitary

(b) Thyroid

(c) Pancreas

(d) adrenal
Solution A.1
(c) pancreas
Question A.2
Exophthalmic goiter is caused due to the overactivity of

(a) thymus

(b) thyroid

(c) parathyroid

(d) adrenal cortex
Solution A.2
(b) thyroid
Question A.3

The deficiency of ADH causes:

(a) diabetes mellitus

(b) diabetes insipidus

(c) dwarfism

(d) acromegaly

Solution A.3

(b) diabetes insipidus

Question B.1

Name the following:

(a) The hormone produced by adrenal medulla.

(b) The condition caused by the over secretion of insulin.

(c) The hormone secreted by beta cells of the islets of Langerhans.

(d) The interconnection between the two lobes of thyroid gland (technical term).

(e) The hormone whose under secretion causes more urine formation.

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

Solution B.1

(a) Adrenaline

(b) Hypoglycemia

(c) Insulin

(d) Isthmus

(e) Anti-diuretic hormone (Vasopressin)

(f) Adrenaline

Question B.2
What would a child suffer from, if there was hypo secretion from his thyroid?
Solution B.2
If there was hyposecretion of the thyroid gland in a child; the child will suffer from cretinism. The symptoms of cretinism are dwarfism, mental retardation, etc.
Question B.3
Choose the odd one out from each series:

(a) The glands - thyroid, adrenal, pituitary, prostate

(b) The conditions - cretinism, myxoedema, goiter, scurvy

(c) The hormones- insulin, glucagon, cretinism, thyroxine

(d) The hormonal sources - adrenal cortex, adrenal medulla, cortisone, pituitary
Solution B.3
(a) Prostate

(b) Scurvy

(c) Cretinism

(d) Cortisone
Question B.4

Match the conditions in column A with the cause in column B.

A (Condition)

B (Cause)

(a) Dwarfism and mental retardation

i. Excess of glucose in blood

(b) Diabetes mellitus

ii. Over secretion of growth hormone

 

(c) Shortage of glucose in blood

iii. Insulin shock

(d) Gigantism

iv. Over secretion of thyroxine

(e) Enlargement of breasts in adult males

v. Hypothyroidism

 

(f) Exophthalmic goitre

vi. Over secretion of cortical hormones

 

Solution B.4

A (Condition)

B (Cause)

(a) Dwarfism and mental retardation

v. Hypothyroidism

(b) Diabetes mellitus

i. Excess of glucose in blood

(c) Shortage of glucose in blood

iii. Insulin shock

(d) Gigantism

ii. Over secretion of growth hormone

 

(e) Enlargement of breasts in adult males

vi. Over secretion of cortical hormones

 

(f) Exophthalmic goitre

iv. Over secretion of thyroxine

Question B.5

Identify the odd one in each of the following and mention what the rest are:

(a) Larynx; glucagon; testosterone; prolactin

(b) Adrenaline; penicillin; insulin; thyroxin

(c) Stomach; ileum; liver; adrenaline

(d) TSH; GH; ADH; insulin

(e) Iodine; cretinism; goiter; myxoedema

Solution B.5

(a) Larynx

Reason- Larynx is the sound box while the rest three i.e. glucagon; testosterone and prolactin are hormones.

(b) Penicillin

Reason - Penicillin is an antibiotic while adrenaline; insulin; thyroxine are hormones.

(c) Adrenaline

Reason - Adrenaline is a hormone while the stomach, ileum and liver are the organs of the digestive system.

(d) Insulin

Reason- Insulin is secreted by the pancreas while TSH, GH, ADH are the hormones secreted by the pituitary gland.

(e) Iodine

Reason- Iodine is required for the synthesis of thyroxine hormone. While cretinism, goitre, myxoedema are the deficiencies occur due to the deficiency of thyroxine.

Question B.6

Match the items of column I with those of column II.

Column I

Column II

1. Beta cells of islets of Langerhans

(a) condition due to under secretion of thyroxine in adults

2. Thyroid

(b) Undersecretion of glucocorticoids

3. Cretinism

(c) Exophthalmic goitre

4. Addison's disease

(d) Increases heart beat

5. Hypothyroidism

(e) Thyroxine

6. Myxoedema

(f) Adrenal cortex

7. Adrenaline

(g) Insulin

8. Cortisone

(h) Under secretion of thyroxine in a child

Solution B.6

Column I

Column II

1. Beta cells of islets of Langerhans

(g) Insulin

2. Thyroid

(c) Exophthalmic goitre

3. Cretinism

(h) Under secretion of

thyroxine in a

child

4. Addison's disease

(b) Undersecretion of glucocorticoids

5. Hypothyroidism

(e) Thyroxine

6. Myxoedema

(a) condition due to under     secretion of thyroxine in adults

7. Adrenaline

(d) Increases heart beat

8. Cortisone

(f) Adrenal cortex

Question B.7

Given below are group of terms. In each group the first pair indicates the relationship between the two terms. Suggest the suitable word(s) for the fourth place.

(a) Beta cells : Insulin :: Alpha cells : ………………….

(b) Children : Cretinism :: Adults : ………………….

(c) Undersecretion : Dwarfism :: Oversecretion : ………………….

(d) Diabetes mellitus : Insulin :: Diabetes insipidus : ………………….

Solution B.7

(a) Beta cells : Insulin :: Alpha cells : Glucagon.

(b) Children : Cretinism :: Adults : Myxoedema.

(c) Undersecretion : Dwarfism :: Oversecretion : Gigantism.

(d) Diabetes mellitus : Insulin :: Diabetes insipidus : Antidiuretic hormone (ADH). 

Question C.1

Mention the name of diseases based on the clues/ symptoms given below:

(a) Urine is loaded with sugar.

(b) Swelling in the neck.

(c) Dwarfism and mental retardation in children.

(d) Eyes are protruded.

(e) Excessive growth of bones in the face, hands and feet.

Solution C.1

a) Hyperglycemia

b) Simple goitre

c) Cretinism

d) Exophthalmic goitre

e) Acromegaly in adults and gigantism in children

Question C.2

Write the exact location of each of the following glands:

(a) Thyroid

(b) Adrenal

(c) Pancreas

(d) Pituitary

Solution C.2

(a) Thyroid: It is situated in the front part of the neck just below the larynx.

(b) Adrenal: It is present as a cap on the top of each kidney.

(c) Pancreas: It is located behind the stomach in the upper left abdomen.

(d) Pituitary: It hangs from the base of the mid-brain below the hypothalamus.

Question C.3

Name the following:

(a) Three hormones secreted from islets of Langerhans of pancreas.

(b) Two types of cortical hormones.

(c) Six hormones secreted from anterior pituitary.

(d) Two hormones secreted from posterior pituitary.

(e) The emergency hormone.

Solution C.3

(a) Three hormones secreted from islets of Langerhans of pancreas:

  1. Insulin
  2. Glucagon
  3. Somatostatin

 

(b) Two types of cortical hormones:

1. Glucocorticoids

2. Mineralocorticoids

 

(c) Six hormones secreted from anterior pituitary:

1. Growth hormone (somatostatin)

2. Prolactin

3. Adreno-corticotropic hormone (ACTH)

4. Thyroid stimulating hormone (TSH)

5. Follicle stimulating hormone (FSH)

6. Luteinizing hormone (LH)

 

(d) Two hormones secreted from posterior pituitary:

1. Vasopressin

2. Oxytocin

 

(e) The emergency hormone:

1. Adrenaline 

Question C.4

Write the main function of each of the following hormones.

Hormones

Functions

(a) Thyroxine

……………………………

(b) Adrenaline

……………………………

(c) Insulin

……………………………

(d) Glucagon

……………………………

(e) Vasopressin

……………………………

 

Solution C.4

Hormones

Functions

(a) Thyroxine

Regulates the basal metabolism

(b) Adrenaline

Increases heart beat and blood pressure

(c) Insulin

Reduces the blood sugar level

(d) Glucagon

Increases the blood sugar level

(e) Vasopressin

Constricts blood vessels and raises blood pressure

 

Question C.5

Name the hormones responsible for the given functions.

Functions

Hormones

(a) Contraction of uterine muscles during child birth

……………………………

(b) Maintenance of corpus luteum

……………………………

(c) Milk formation and secretion

……………………………

(d) Development of external sex characters in males

……………………………

(e) Stimulation of sympathetic nervous system

……………………………

 

Solution C.5

Functions

Hormones

(a) Contraction of uterine muscles during child birth

Oxytocin

(b) Maintenance of corpus luteum

Luteinizing hormone (LH)

(c) Milk formation and secretion

Prolactin

(d) Development of external sex characters in males

Testosterone

(e) Stimulation of sympathetic nervous system

Adrenaline

 

Question C.6
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?
Solution C.6
Adrenaline is the hormone which prepares the body to meet any emergency situation. Adrenaline makes the heart beat faster. At the same time, it stimulates the constriction of the arterioles of the digestive system reducing the blood supply of the digestive system which makes the mouth dry.
Question C.7

Given below is a table designed to give the names of the glands, the hormones produced, their chief functions, the effects of over secretion and under secretion in respect of thyroid, pituitary and pancreas. Fill up the blanks 1-13.

S.No.

Source

Gland cells

Hormone produced

Chief function

Effect of over secretion

Effect of under secretion

1.

(1) --------

thyroxine

(2) ----

(3)----

(4)---

2.

Beta cells of Islets of Langerhans

(5) ------

Promotes glucose utilization by the body cells

(6) ----

(7)    ------

3.

(8) --------

Growth hormone

(9) ----

(10) ---

Dwarfism

4.

(11) ------

Vasopressin

Increases reabsorption of water from kidney tubules

(12)    -------

(13)  ------

Solution C.7

S.No.

Source

Gland cells

Hormone produced

Chief function

Effect of over secretion

Effect of under secretion

1.

Thyroid

thyroxine

Regulates basal metabolism

Exophthalmic goiter

Simple goiter, cretinism in children and myxoedema in adults

2.

Beta cells of Islets of Langerhans

Insulin

Promotes glucose utilization by the body cells

Hypoglycemia

Diabetes mellitus

3.

Anterior pituitary

Growth hormone

Promotes growth of the whole body

Gigantism

Dwarfism

4.

Posterior pituitary

Vasopressin

Increases reabsorption of water from kidney tubule

More concentrated and less amount of urine

Diabetes insipidus

Question C.8

Complete the following table by filling in the blanks numbered 1 to 7.

Gland

Hormone secreted

Effect on body

(1) -----------

(2) -------

Regulates basal metabolism

Pancreas ("beta" cells)

(3) -------

Controls blood sugar

(4) ------------

(5) --------

Increases heart beat

(6) ------------

Thyroid stimulating hormone

(7) ------------

Solution C.8

Gland

Hormone secreted

Effect on body

Thyroid

Thyroxine

Regulates basal metabolism

Pancreas ("beta" cells)

Insulin

Controls blood sugar level

Adrenal gland

Adrenaline

Increases heart beat

Anterior pituitary

Thyroid stimulating hormone

Stimulates thyroxine secretion

Question C.9

Complete the following table by filling in the blank spaces numbered 1 to 8.

Gland

Secretions

Effect on body

(1)------------

oestrogen

(2) ---------------

Alpha cells of islets of Langerhans

(3) -------

(4) ---------------

(5) ----------

(6) -------

Protruding eyes

(7) ----------

(8) -------

Gigantism

Solution C.9

Gland

Secretions

Effect on body

Ovary

oestrogen

development of secondary sexual characteristics

Alpha cells of islets of Langerhans

Glucagon

Raises blood sugar level

Thyroid

Hypersecretion of thyroxine

Protruding eyes

Anterior pituitary

Hypersecretion of Growth hormone

Gigantism

Question D.1

Define the following terms:

(a) Endocrine system

(b) Hormones

(c) Myxoedema

Solution D.1

(a) Endocrine system: Endocrine system consists of several endocrine glands/glandular cells which activate each other and work as a system to bring about chemical coordination in the body.

 

(b) Hormones: Hormones are secretions from specific cells or glands in the body, which are carried to all body parts through the blood, but exert their effect only on one or more specific body parts (target organ or cells).

 

(c) Myxoedema: Myxoedema is a condition which occurs in adults due to hypothyroidism in which the person becomes sluggish with swelling of the face and hands. 

Question D.2

Distinguish between the following pairs:

(a) Exocrine and endocrine glands (manner of secretion)

(b) Enzymes and hormones (chemical composition and mode of action)

(c) Nervous control and hormonal control (transmission and effect)

(d) Diabetes mellitus and diabetes insipidus (cause and symptoms)

(e) Addison's disease and Cushing's syndrome (cause and sugar level)

Solution D.2

(a) Differences between exocrine and endocrine glands (manner of secretion):

Exocrine glands

Endocrine glands

Secretions are carried through special ducts.

Secretions are poured directly into the blood.

 

(b) Differences between enzymes and hormones (chemical composition and mode of action):

Enzymes

Hormones

Enzymes are protein in nature.

Hormones are peptides, amines or steroids.

Enzymes are substrate specific. These are present in all cells and show their activity there

Hormones are specific to the target cell, tissue, or system. They are produced at one site and show their activities at other sites.

 

(c) Differences between nervous control and hormonal control (transmission and effect):

Nervous control

Hormonal control

Transmitted electro-chemically through nerve fibres and chemically across synapses.

Transmitted chemically through blood.

Effect is only short-lived.

Effect is short term or long lasting.

 

(d) Differences between diabetes mellitus and diabetes insipidus (cause and symptoms):

Diabetes mellitus

Diabetes insipidus

Caused due to insufficient secretion of insulin.

Caused due to insufficient secretion of anti-diuretic hormone (ADH)

High concentration of sugar in blood.

No sugar in urine

 

(e) Differences between Addison's disease and Cushing's syndrome (cause and sugar level):

Addison's disease

Cushing's syndrome

Caused due to hyposecretion of cortisone

Caused due to hypersecretion of cortisone

Low blood sugar level

High blood sugar level

 

Question D.3

Give reason:

(a) Adrenaline is often described as the emergency hormone.

(b) Pituitary is popularly called as the master gland.

(c) People living in the low Himalayan hilly regions often suffer from goitre.

(d) Simple goitre can be prevented by using iodised salt in food.

Solution D.3

(a) Adrenaline is often described as the emergency hormone because it prepares the body to meet any emergency situation, for fight and face the danger or flight and run away from it. More adrenaline is secreted which makes the heart beat faster, increases the breathing, releases more glucose into the blood stream to fulfill the energy requirement.

 

(b) Pituitary is popularly called as the master gland because it controls the functioning of all the other endocrine glands.

 

(c) People living in the low Himalayan hilly regions often suffer from goitre because iodine is deficient in soil and hence, in the food grown there. Insufficient iodine produces less thyroxine which results in goitre.

 

(d) Iodised salt contains iodine which is an active ingredient in the production of thyroxine. Hence, it is recommended to use iodised salt in food to prevent simple goitre.

Question D.4

Do you agree with the statement- "All hormones are chemical signals"? Yes/No. Justify your answer.

Solution D.4

Chemically hormones are peptides, amines or steroids. They are involved in regulating the metabolism of the body. They can bring about specific chemical changes during metabolic process. Therefore hormones can be termed as 'chemical messengers'.

Question E.1

Study the diagram given below and then answer the questions that follow:

Selina Solutions Icse Class 10 Biology Chapter - The Endocrine System 

a. Name the cells of the pancreas that produce (1) glucagon (2) insulin.

b. State the main function of (1) glucagon and (2) insulin.

c. Why is the pancreas referred to as an exo-endocrine gland?

d. Why is insulin not given orally but is injected into the body?

e. What is the technical term for the cells of the pancreas that produce endocrine hormones?

f. Where in the body is the pancreas located?

Solution E.1

a. Glucagon: Alpha cells of the islets of Langerhans

Insulin: Beta cells of the islets of Langerhans

 

b. Insulin: It maintains the levels of glucose (sugar) in the blood.

Glucagon: It raises the blood glucose levels by stimulating the breakdown of glycogen to glucose in the liver.

 

c. An endocrine gland is one which does not pour its secretions into a duct, while an exocrine gland is a gland which pours its secretions into a duct. Because the pancreas produces hormones such as insulin, glucagon and somatostatin directly into the blood and not into a duct, it functions as an endocrine gland. Because it secretes the pancreatic juices for digestion via a duct, it functions as an exocrine gland. Hence, the pancreas is an exo-endocrine gland.

 

d. Insulin is not administered orally because the digestive juices degrade insulin, and thus the insulin is ineffective in the body.

 

e. Islets of Langerhans

 

f. The pancreas is located in the abdomen behind the stomach.

Question E.2

Given below is a portion from the human body showing some important structure in ventral (front) view.

Selina Solutions Icse Class 10 Biology Chapter - The Endocrine System

(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.

(d) Is there any duct to carry the secretions from the structure numbered 2? If so, give its name.

Solution E.2

(a) This portion is located in the neck region above the sternum.

(b) 1- Larynx, 2 - Thyroid gland, 3 - Trachea

(c) Larynx is the voice box containing vocal cords. It helps in producing sound.

Thyroid gland produces thyroxine and calcitonin which are essential hormones.

Trachea is the wind pipe that helps in passing air to and from the respiratory system while breathing.

(d) Structure 2 is the thyroid gland. It is an endocrine gland, so it is ductless and pours its secretions directly into the blood. Hence, there is no duct.

Question E.3

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

Selina Solutions Icse Class 10 Biology Chapter - The Endocrine System

(a) Name the parts numbered 1 to 4.

(b) What is common to all these parts in regard to the nature of their functions?

(c) Name the nutrient element which is essential for the normal working of part 2.

Solution E.3

(a) 1- Pituitary gland, 2 - thyroid gland, 3 - pancreas, 4 - adrenal glands

(b) All the glands shown in the above diagram are endocrine glands. They secrete essential hormones and pour their secretions directly into the blood.

(c) Iodine is essential for the normal working of thyroxine.

Question E.4

Given below are two diagrams (one is correct, the other one 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?

Selina Solutions Icse Class 10 Biology Chapter - The Endocrine System

Solution E.4

(a) A

(b) Hormone secreted by the endocrine gland is shown in the image A to be moving only in one direction i.e. towards the target organ. But actually the hormones poured into the blood stream may have one or more target sites at a time. The arrows shown are carried to all parts by the blood and their effect is produced only in one or more specific parts.

Question F.1

Compare the hormonal response with the nervous response with respect to their speed, transmission and general nature of changes brought about.

Solution F.1

Hormonal Response

Nervous Response

Hormonal response is slow.

Nervous response is immediate.

Hormones are chemical messengers transmitted through blood stream.

Nerve impulses are transmitted in the form of electro-chemical responses through nerve fibres.

This response brings about a specific chemical changes. Therefore it regulates the metabolism.

This response does not bring any chemical change during metabolism.

Question F.2

Mention three important differences between the action of hormones and that of nerves in the regulatory mechanism of our body.

Solution F.2

Action of Hormones

Action of Nerves

The effect of hormones is wide spread in the body. They can show their effect on more than one target site at a time.

The nerve response affects only particular glands.

The effect of hormones can be short-lived or long lasting.

The effect of nervous response is always short-lived.

Cannot be modified by the previous learning experiences.

Can be modified by the previous learning experiences.