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Concise Biology Part II - Selina Solution for Class 10 Biology Chapter 12 - The Endocrine System

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Selina Textbook Solutions Chapter 12 - The Endocrine System

Selina Textbook Solutions are a perfect way to ace your examination with high marks. These Textbook Solutions are extremely helpful for solving difficult questions in the ICSE Class 10 Biology exam. Our Selina Textbook Solutions are written by our subject experts. Find all the answers to the Selina textbook questions of Chapter 12 - The Endocrine System.

All solutions Selina textbook questions of Chapter 12 - The Endocrine System are created in accordance with the latest ICSE syllabus. These free Textbook Solutions for ICSE Class 10 Selina Concise Biology will give you a deeper insight on the fundamentals in this chapter and will help you to score more marks in the final examination. ICSE Class 10 students can refer to these solutions while doing their homework and while studying and revising for the Biology exam. 

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Concise Biology Part II - Selina Solution for Class 10 Biology Chapter 12 - The Endocrine System Page/Excercise 1

Solution A.1

(c) pancreas

Solution A.2

(b) thyroid

Solution A.3

(c) alcohol

Solution B.1

(a) Insulin, glucagon, somatostatin

(b) Adrenaline

(c) Hypoglycemia

(d) Insulin

(e) Adrenaline

(f) Anti-diuretic hormone (Vasopressin)

(g) Adrenaline

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.

Solution B.3

(a) Prostate

(b) Scurvy

(c) Cretinism

(d) Cortisone

Solution B.4

(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.

Solution B.5

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


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

Solution B.6

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

Solution C.1

(a) True

Reason- Adrenaline is described as emergency hormone because during any emergency situation 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) False

Reason- The two different kinds of diabetes are diabetes insipidus caused due to insufficient secretion of vasopressin and the other is 'diabetes mellitus' caused due to hyposecretion of insulin but they cannot be described as mild and severe.

(c) True

Reason-Iodine is an active ingredient in the production of the thyroxine hormone.

(d) True

Reason- Pituitary gland controls the functioning of all the other endocrine glands.

(e) True

Reason- Hormones are poured directly into blood the blood stream and control physiological processes by chemical means. Their action depends on the feedback mechanism.

(f) True

Reason- Gigantism and dwarfism are controlled by the growth hormone from the pituitary gland. Growth hormone is much more active in children for their normal body growth along with which necessary substance required for the synthesis of growth hormone need to be consumed.

Solution C.2

Endocrine glands are ductless glands, means they pour their secretion i.e. hormones directly into the blood stream while the other glands are exocrine glands which have ducts. Through ducts they pour their secretions (not hormones) into the blood stream.

Solution C.3

Hormones unlike enzymes are secreted by the endocrine glands only. Also the hormones unlike the enzymes are poured directly into the blood. Hormones can be peptides, steroids, amine but all enzymes are proteins.

Solution C.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'.

Solution C.5

Iodine is an active ingredient in the production of the thyroxine hormone secreted by the thyroid gland. Thyroxine hormone is a very essential hormone for our body. In case of its abnormal secretions a person may suffer certain sever disorders. Therefore, it is an important nutrient for our body.

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.

Solution C.7

If one adrenal gland is removed, the other one gets enlarged. This is to meet the requirement of hormones produced by the body.

Solution C.8

1. Diabetes mellitus:

Cause - under secretion of Insulin hormone

Symptoms - excretion of great deal of urine with sugar,

Person feels thirsty and loss of weight. In severe

cases, the person may lose the eye sight.

2. Diabetes insipidus:

Cause - Under secretion of Anti-diuretic hormone

Symptoms - frequent urination resulting in loss of water from body and the person feels thirsty.

Solution C.9

The Himalayan soil is deficient in iodine. Thus, the food grown in such soil also becomes iodine deficient. Due to this reason, when Himalayan people consume iodine deficient food, they do not get the proper intake of iodine. Therefore, people living in the low Himalayan hilly regions often suffer from goitre.

Solution C.10



Gland cells

Hormone produced

Chief function

Effect of over secretion

Effect of under secretion




Regulates basal metabolism

Exophthalmic goiter

Simple goiter, cretinism in children and myxoedema in adults


Beta cells of Islets of Langerhans


Promotes glucose utilization by the body cells


Diabetes mellitus


Anterior pituitary

Growth hormone

Promotes growth of the whole body




Posterior pituitary


Increases reabsorption of water from kidney tubule

More concentrated and less amount of urine

Diabetes insipidus

Solution C.11


Hormone secreted

Effect on body



Regulates basal metabolism

Pancreas ("beta" cells)


Controls blood sugar level

Adrenal gland


Increases heart beat

Anterior pituitary

Thyroid stimulating hormone

Stimulates thyroxine secretion

Solution C.12



Effect on body



development of secondary sexual characteristics

Alpha cells of islets of Langerhans


Raises blood sugar level


Hypersecretion of thyroxine

Protruding eyes

Anterior pituitary

Hypersecretion of Growth hormone


Solution D.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.

Solution D.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.

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.

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.

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.

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.

TopperLearning provides step-by-step solutions for each question in each chapter. Access Chapter 12 - The Endocrine System  for ICSE Class 10 Biology free of cost. The solutions are provided by our subject matter experts. Refer to our solutions for the Selina Concise Biology textbook to revise the whole chapter and clear your fundamentals before the examination. By referring to the solutions for this chapter and the others, we hope that you are able to write your exams well.

Text Book Solutions

ICSE X - Biology

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