Selina Concise Solutions for ICSE Class 8 Biology Chapter 5 Endocrine System and Adolescence

REVIEW QUESTIONS

Multiple Choice Questions:

1. Put a tick mark (✓) against the correct alternative in the following statements:

(a) Cortisone hormone is secreted by:
1. Medulla of adrenal
2. Cortex of adrenal
3. Pancreas
4. Thyroid

Answer: 2. Cortex of adrenal
The adrenal cortex is the outer layer of the adrenal gland located on top of the kidneys. It produces cortisone, which plays a major role in regulating how the body uses fats, proteins, and carbohydrates.
Teacher's Tip: Remember that "C" stands for "Cortex" and "Cortisone."
Exam Tip: Don't confuse the adrenal cortex with the adrenal medulla, as they secrete different hormones.

(b) Which one of the following hormones stimulates the breakdown of glycogen in the liver into glucose:
1. Insulin
2. Adrenaline
3. Glucagon
4. Thyroxine

Answer: 3. Glucagon
Glucagon is produced by the pancreas and acts on the liver to turn stored energy back into sugar for the blood. This process is essential for keeping our blood sugar levels stable when we haven't eaten for a while.
Teacher's Tip: Think of Glucagon as "Glucose-is-gone," so it makes more glucose appear in the blood.
Exam Tip: Be sure to distinguish Glucagon from Insulin, as they have opposite effects on blood sugar.

(c) Which one of the following hormones converts excess of glucose into glycogen:
1. Glucagon
2. Thyroxine
3. Insulin
4. Adrenaline

Answer: 3. Insulin
Insulin is the hormone that helps cells take in sugar from the blood to use for energy or store as glycogen. Without enough insulin, sugar levels in the blood become dangerously high.
Teacher's Tip: Think of Insulin as the "In-sulin" that puts sugar "In" the cells for storage.
Exam Tip: Mention the pancreas as the source of insulin if the question asks for the gland.

(d) Which one of the following glands is also called master gland:
1. Pituitary gland
2. Adrenal gland
3. Thyroid gland
4. Ovary

Answer: 1. Pituitary gland
The pituitary gland is called the master gland because it controls the activities of most other endocrine glands. It is a tiny gland about the size of a pea located at the base of the brain.
Teacher's Tip: Think of the Pituitary gland as the "Principal" of the gland school, giving orders to everyone else.
Exam Tip: Always remember that "Master Gland" is the specific nickname for the Pituitary.

(e) The emergency hormone to face the danger or to fight is secreted by:
1. Islets of Langerhans
2. Adrenal cortex
3. Pituitary
4. Adrenal medulla

Answer: 4. Adrenal medulla
The adrenal medulla secretes adrenaline, which prepares the body for sudden physical activity or stress. This response is often called the "fight or flight" reaction because it helps you run away from danger or stay and face it.
Teacher's Tip: Associate "Medulla" with "Middle" and "Muscle" for the energy to fight.
Exam Tip: If the question asks for the hormone name, write "Adrenaline."

(f) Which one of the following endocrine glands produces its hormone in large quantities as a result of emotional stimulation?
1. Thyroid
2. Islets of Langerhans
3. Adrenal medulla
4. Adrenal cortex
Adrenal medulla produces its hormone in large quantities as a result of emotional stimulation.

Answer: 3. Adrenal medulla
When you feel scared, angry, or excited, the adrenal medulla quickly releases hormones into your bloodstream. This sudden surge is what makes your heart beat faster and your breathing increase during emotional moments.
Teacher's Tip: Think of the Adrenal Medulla as the body's "Emotional Turbo Boost."
Exam Tip: Emotional stimulation is a key phrase to look for when identifying the adrenal medulla's role.

(g) In humans, increased thyroxine production results in (tick the correct answer):
1. Increased metabolism
2. Decreased metabolism
3. Dwarfism
4. Cretinism

Answer: 1. Increased metabolism
Thyroxine controls the rate at which your body uses energy, which is known as metabolism. When there is too much thyroxine, your body's "engine" runs too fast, leading to weight loss and increased heart rate.
Teacher's Tip: Link "Thyroxine" with "Throttle"—it controls how fast the body runs.
Exam Tip: If the question asks about a decrease in thyroxine, remember it leads to "Cretinism" in children.

Short Answer Questions:

Question 1: What is a hormone?
Answer: The secretions of the endocrine glands are called Hormones, which are poured directly into the blood and are carried to the target organs.
Hormones act as chemical messengers that travel throughout the body to regulate various biological processes. They only affect specific parts of the body known as target organs, where they fit like a key into a lock.
Teacher's Tip: Think of hormones as "Wi-Fi signals" sent by glands to different body parts.
Exam Tip: Make sure to mention that they are poured "directly into the blood" because endocrine glands are ductless.

Question 2: In table given below, fill in the blanks by naming endocrine glands, the hormones they secrete, and the function they perform, in a normal person.
Answer:
S.No. 1.
Name of the gland: Thyroid
Produced: Thyroxine
Function: Control of metabolic rate

S.No. 2.
Name of the gland: Pancreas
Produced: Insulin
Function: Regulation of sugar in blood.

S.No. 3.
Name of the gland: Adrenal
Produced: Adrenaline and cortisone
Function: Preparing the body for action

S.No. 4.
Name of the gland: Pituitary
Produced: (i) Growth hormone (ii) Thyroid stimulating hormone
Function: (i) For growth (ii) Stimulates thyroid gland to secrete thyroxine
This table summarizes how different glands work together to keep the human body balanced. Each gland has a specific hormone that performs a unique and vital job for our health.
Teacher's Tip: Create a mental map: Head (Pituitary), Neck (Thyroid), Stomach (Pancreas), Kidneys (Adrenal).
Exam Tip: When filling out tables, ensure you match the hormone correctly with its specific function.

Question 3: Match the items in Column A with those in Column B.
Column A   Column B
(a) Cretinism (i) Pituitary gland
(b) Diabetes mellitus (ii) Under development of infant
(c) Increased metabolic rate (iii) Over secretion of thyroxine
(d) Simple goitre (iv) Insufficient iodine in food
(e) Growth hormone (v) Insufficient insulin in blood.

Answer: Column A Column B
(a) Cretinism (ii) Under development of infant
(b) Diabetes mellitus (v) Insufficient insulin in blood.
(c) Increased metabolic rate (iii) Over secretion of thyroxine
(d) Simple goitre (iv) Insufficient iodine in food
(e) Growth hormone (i) Pituitary gland

Question 4: Name the source and the function of each of the following hormones:
Hormone Source Function
(a) Glucagon Pancreas Breakdown of glycogen to glucose. Raises sugar in the blood.
(b) Thyroxine Thyroid gland Control of metabolic rate
(c) Adrenaline Adrenal gland Prepare the body to face emergency, stress
(d) Insulin Pancreas Regulation of sugar in blood.
(e) Cortisone Adrenal cortex Regulates carbohydrate metabolism. Its deficiency causes Addison’s disease.
Answer: Follow the table data provided above for the correct source and function of each hormone.
Each of these hormones is essential for maintaining "homeostasis," which is the stable state of the body. Knowing the specific gland is important because that is where the chemical is manufactured.
Teacher's Tip: Focus on the Pancreas as a "Double Agent" because it makes two hormones: Insulin and Glucagon.
Exam Tip: Be specific with "Adrenal cortex" for Cortisone rather than just saying "Adrenal gland."

Question 5: What is the difference between an exocrine gland and an endocrine gland?
Answer: The salivary glands, pancreas, etc., are exocrine glands, they send their secretions through ducts directly to the target orgOn the other hand, the endocrine glands are ductless glands. Their secretions are called hormones, which are poured directly into the blood and are thus carried to the target organs.
Exocrine glands use tubes or "ducts" to send things like sweat or saliva to specific surfaces. Endocrine glands are "ductless" and use the entire bloodstream as their delivery system.
Teacher's Tip: Think of Exocrine as a "Garden Hose" (duct) and Endocrine as "Wireless" (bloodstream).
Exam Tip: The word "ductless" is the most important keyword to include in this answer.

Question 6: Why is pitnitary gland is called “master gland”?
Answer: The pituitary gland is called “master gland” because it produces hormones that control other glands and many body functions including growth (growth hormone, Thyroid and Gonad stimulating hormone).
It acts as a control center that monitors body conditions and tells other glands when to start or stop working. For example, it sends a signal to the thyroid to produce thyroxine when energy levels are low.
Teacher's Tip: Imagine the Pituitary gland as the "Remote Control" for the rest of the body's glands.
Exam Tip: List at least one or two specific hormones it produces, like Growth Hormone, to show deeper knowledge.

Question 7: Briefly write about the importance of physical hygiene during adolescence.
Answer: Physical hygiene also named as Personal hygiene plays a crucial role in maintaining healthy during adolescence. The teenager should follow the below mentioned activities to promote their health:
1. Proper and Safe Food: Adolescence is a stage of rapid growth and development. Hence, a teenager should take proper care of their diet. They should take proper balanced diet that provides protiens, carbohydrates, fats, minerals and vitamins. They should take freshly prepared food and avoid stale food. They should take milk, fruits and fresh vegetables.
2. Proper life Style: Regular Exercise and sleep are necessary for maintaining good health. Teenager should avoid long hours of continous table work, television watching. Teenager should not consume alcohol, drugs or smoking.
3. Cleanliness: Teenager should take bath regularly. They should always wash their hands before and after having meals. Brushing up teeths after every meal. They should always change and wear washed clothes especially undergarments. Regular toilet habits should be adopted for maintaining good health. Teenager must keep their feet cleaned and protected. Injuries due to bacteria like tetanus, hookworms and insects may be issued if barefoot walk is undertaken. They must wash and comb their hairs regularly. All body parts must be washed and cleaned everyday. If cleanliness is not maintained there may occur chances of catching bacterial infection. Girls should take special care of cleanliness during the time of menstrual period.
4. Physical Exercise: Inorder to keep the body fit and healthy, teenager’s should walk, exercise and play outdoor games regularly in fresh air. Playing Outdoor games reduces the stress and strain of adolescence.
Good hygiene prevents infections and helps teenagers feel more confident as their bodies change. Habits like regular bathing are especially important now because sweat glands become more active during puberty.
Teacher's Tip: Use the acronym "BEEF" to remember: Bathing, Eating well, Exercise, and Fresh food.
Exam Tip: Structure your answer with clear points like the ones provided to make it easy for the examiner to read.

Question 8: Briefly discuss any four activities which can be practiced to overcome stress.
Answer: Stress is a state of mental or emotional strain and in simple terms it is called as tension. The stress can be controlled or reduced by following the below mentioned steps:
1. Yoga: It is a mind-body practice that combines physical poses, controlled breathing, and meditation or relaxation. Yoga helps in reducing steps by:
(a) Increasing Flexibility
(b) Increasing muiscle strength and tone.
(c) Improving respiration, energy and vitality.
2. Exercise: Exercise or Running or Jogging for 30 to 45 minutes at least three times a week reduce stress and keep’s the body much healthier.
3. Proper sleep schedule: Improving your sleep schedule also helps in reducing the stress.
4. Reading is a great way to calm your mind and to gain more knowledge.
5. Practice Hobbies of your interest: One should must keep practicing their hobbies as it helps in reducing the stress. Enjoy playing guitar, paino or listening music or doing riddles.
Stress management is vital for maintaining both mental and physical health during the busy teenage years. Engaging in these activities helps lower the levels of stress hormones in the body.
Teacher's Tip: Think of stress as "full storage" and these activities as the "delete" button for tension.
Exam Tip: Mentioning "Yoga" and "Exercise" as two distinct points often helps in gaining more marks.

ADDITIONAL QUESTIONS

I. Multiple choice questions. Tick (✓) the correct choice:

1. Chemical control in organisms is brought about by
1. enzymes
2. neurons
3. hormones
4. all the above.

Answer: 3. hormones
While neurons handle electrical control, hormones are responsible for the chemical messages that regulate our bodies. This chemical system works more slowly than nerves but the effects usually last much longer.
Teacher's Tip: Remember: Nerves = Electrical, Hormones = Chemical.
Exam Tip: Be careful not to pick "all of the above" just because you see neurons and enzymes; only hormones are the primary chemical control messengers.

2. Master endocrine gland
1. thyroid
2. pituitary
3. pancreas
4. adrenal

Answer: 2. pituitary
This is a repeat question because it is one of the most important facts in human biology. The pituitary gland's location deep in the brain helps it stay protected while it manages the body.
Teacher's Tip: Pituitary = Pea-sized powerhouse.
Exam Tip: Learn the location (base of the brain) as it is often asked with this question.

3. The hormone thyroxine is secreted by
1. pituitary gland
2. adrenal gland
3. thyroid gland
4. pancreas

Answer: 3. thyroid gland
The thyroid gland is located in the neck, right in front of the windpipe. It uses iodine from your food to produce thyroxine, which keeps your metabolism running.
Teacher's Tip: Notice that "Thyroid" and "Thyroxine" both start with the same five letters!
Exam Tip: If asked about the shape, the thyroid gland is often described as being "butterfly-shaped."

4. Insulin is secreted by
1. pancreas
2. pituitary gland
3. thyroid gland
4. adrenal gland

Answer: 1. pancreas
The pancreas is located behind the stomach and has special cells that monitor blood sugar constantly. When sugar is high, it releases insulin; when sugar is low, it releases glucagon.
Teacher's Tip: Think of the Pancreas as a "Thermostat" for sugar.
Exam Tip: Remember the specific cells in the pancreas that produce insulin are called the "Islets of Langerhans."

II. Fill in the blanks:
1. Hormones are produced by endocrine glands.
2. The master gland in the body is pituitary glands.
3. Adrenal glands are present above kidneys.
4. The hormone insulin is secreted by pancreas.
5. The hormone thyroxine is secreted by thyroid gland.
6. Blood pressure is controlled by the endorine gland called adrenal gland.

Answer: Fill in the underlined words in the sentences above.
These sentences highlight the most critical connections between glands and their locations or functions. For example, knowing that adrenal glands sit on kidneys helps you identify them in medical diagrams.
Teacher's Tip: Memorize these six facts and you'll have the basics of the endocrine system down!
Exam Tip: Pay attention to plural or singular terms; for example, we have two "Adrenal glands" but one "Pituitary gland."

III. State whether the following statements are true (T) or false (F):
1. Hormones are secreted by ductless glands. True.
2. For hormones to be effective in their actions, they are required in sufficiently large quantities. False. For hormones to be effective in their actions, they ar-e required in extremely small quantities.
3. The adrenal gland helps the body to fight stress. True.

Answer: Follow the True/False designations provided above.
It is a common misconception that we need a lot of hormones, but actually, just a tiny drop is enough to change how the whole body works. This is because the target organs are extremely sensitive to these chemical signals.
Teacher's Tip: Think of hormones like a tiny drop of food coloring that changes the color of a whole bucket of water.
Exam Tip: When a statement is false, always write the correct version to show you understand why it was wrong.

IV. Find the odd-one out, giving reason:
Pituitary, adrenal, thyroid, salivary gland
Answer: Salivary gland is the odd-one out as it is not an endocrine gland. Rest three are ductless endocrine glands.
The salivary gland is an exocrine gland because it has a duct to carry spit into your mouth. The others release hormones directly into your blood without any tubes.
Teacher's Tip: If it has a tube/duct, it's Exocrine; if it's tubeless, it's Endocrine.
Exam Tip: When giving a reason, explain why the odd one is different AND what the others have in common.

V. Name the following:

Question 1: Five endocrine glands found in human body.
Answer:
1. Pituitary gland.
2. Thyroid gland.
3. Parathyroid gland.
4. Adrenal gland.
5. Pancreas.
These five glands are some of the most important regulators in the human body. They work in harmony to control growth, energy, and survival responses.
Teacher's Tip: Use your hand as a guide: start at the brain and move down to the abdomen.
Exam Tip: Spelling counts! Practice writing "Parathyroid" and "Pituitary" so you don't lose marks.

Question 2: Master gland in human body.
Answer: Pituitary gland.
The pituitary gland is called the master because it produces hormones that tell other glands, like the thyroid and adrenals, what to do. It ensures that all the other glands stay "on schedule."
Teacher's Tip: Think of the Pituitary as the "Conductor" of the body's endocrine orchestra.
Exam Tip: This is a very common one-mark question, so make sure you can identify it instantly.

VI. Define the following:

1. Hormones
Answer: Hormones are chemical substances in living organisms which bring about chemical coordination and are responsible for regulating growth and development.
They are produced in small amounts but have long-lasting effects on the body. Because they travel in blood, they can reach any cell in the body that has the right receptor.
Teacher's Tip: Focus on the phrase "chemical coordination"—this is what hormones do!
Exam Tip: Always mention that hormones are "chemical substances" or "chemical messengers."

2. Endocrine glands
Answer: Endocrine glands are special organs which produce hormones and pour them into the blood for chemical coordination in living beings. They are ductless glands.
These glands don't use tubes; instead, they have many tiny blood vessels running through them to pick up the hormones. This allows the hormones to be delivered anywhere the blood flows.
Teacher's Tip: "Endo" means "inside" (releasing hormones inside the blood).
Exam Tip: Use the word "ductless" to get full marks on any definition of endocrine glands.

VII. Answer the following questions:

Question 1: Describe two characteristic features of hormones.
Answer: Characteristics features of hormones are:
1. Hormones produce long term changes such as a child’s growth and sexual maturation.
2. Hormones adjust the amount of salt and water in the body tissues, sugar in the blood and salt in the sweat. They are transported in blood.
Hormones are slow-acting but their effects, like growing taller, can last a lifetime. They are very powerful chemicals, so even a tiny amount creates a big change in how you feel or grow.
Teacher's Tip: Think of hormones as "Long-term" and "Transported by blood."
Exam Tip: When asked for "features," using a numbered list makes your answer much more clear.

Question 2: Draw an outline figure of the human body and show the location of different endocrine glands.
Answer: Refer to the diagram of the Endocrine System provided in the textbook (Page 8).
Drawing a diagram helps you visualize where each gland is located in relation to major organs like the brain and kidneys. Labels should include the Pituitary, Thyroid, Adrenals, and Pancreas.
Teacher's Tip: Practice drawing a simple "gingerbread man" outline to place the glands inside.
Exam Tip: Always use a sharp pencil for diagrams and make your labeling lines straight and clear.

Question 3: What causes diabetes?
Answer: Lack of insulin causes diabetes. The pancreas produce insulin but the body is not able to use it. This causes excess glucose to build up in the blood causing diabetes.
Insulin acts like a key that lets sugar enter our cells; without it, the sugar stays stuck in the blood. Over time, high blood sugar can damage the eyes, kidneys, and heart.
Teacher's Tip: Diabetes = Too much sugar in the blood, not enough in the cells.
Exam Tip: Mention both "lack of insulin" and "high blood glucose" for a complete answer.

Question 4: Which gland secretes insulin?
Answer: Pancreas.
The pancreas is a leaf-shaped gland that sits behind the stomach. It is unique because it functions as both an endocrine gland (releasing hormones) and an exocrine gland (releasing digestive juices).
Teacher's Tip: P is for Pancreas and P is for "Sugar Processing" (Insulin).
Exam Tip: Don't forget that the pancreas also produces Glucagon, so be specific if asked about sugar regulation.

Question 5: What happens when the thyroid gland secretes less hormone?
Answer: When the thyroid gland secretes less hormone, thyroid gland swells causing goitre.
A lack of thyroxine slows down the body's metabolism, making a person feel tired and sluggish. The swelling in the neck happens because the gland is working extra hard to try and make more hormone.
Teacher's Tip: Low Thyroxine = Slow Metabolism = Swollen Neck (Goitre).
Exam Tip: Link "less thyroxine" with "Goitre" to ensure you get full credit for this question.

VIII.

Question 1: Given below is an outline of the human body. Draw and label on the diagram.
1. the gland that secretes insulin.
2. the gland that produce adrenaline.
Answer: 1. Label the Pancreas (behind the stomach). 2. Label the Adrenal Glands (on top of the kidneys).
Using an outline map of the body is a great way to test if you know the physical locations of your glands. The pancreas is leaf-shaped, while the adrenals look like small hats on top of the kidneys.
Teacher's Tip: Adrenal glands are "Kidney Hats."
Exam Tip: Make sure your labels point exactly to the correct organ to avoid losing marks on anatomy.

Question 2: Name the disease caused by failure of the gland to produce insulin.
Answer: Diabetes.
Diabetes is a chronic condition that requires careful management of diet and sometimes medicine. It occurs when the "sugar-control system" of the body stops working properly.
Teacher's Tip: Just remember: No Insulin = Diabetes.
Exam Tip: Be careful with the spelling of "Diabetes"—it is a very common spelling error in science exams.