Chapter 22: Chemical Coordination and Integration – Long Answer Type Questions
CBSE Class 11 Biology Long Answer Questions – Chemical Coordination and Integration (NCERT)
Course & Examination Details
- Course: CBSE Class 11 Biology
- Prescribed By: Central Board of Secondary Education
- Based On: NCERT
- Unit: Unit V – Human Physiology
- Chapter: Chapter 22 – Chemical Coordination and Integration
- Question Type: Long Answer Questions (LAQs)
- Answer Length: 120–150 words
- Exam Relevance: CBSE Class 11 Annual Examination, Unit Tests, School Assessments
Section A: Endocrine Glands (Q1–Q8)
Q1. Explain chemical coordination in humans and state its importance.
Answer:
Chemical coordination in humans is carried out by the endocrine system through hormones. Hormones are chemical messengers secreted by ductless endocrine glands and transported through blood to target organs. They regulate long-term processes such as growth, development, metabolism, reproduction, and maintenance of internal balance. Chemical coordination is slower than neural coordination but its effects are prolonged and widespread. It plays a crucial role in adapting the body to internal and external changes, ensuring proper functioning of organs, and maintaining homeostasis. Without chemical coordination, processes like puberty, pregnancy, stress response, and metabolic regulation would not occur efficiently.
Q2. Describe the main characteristics of endocrine glands.
Answer:
Endocrine glands are ductless glands that secrete hormones directly into the bloodstream. Hormones are released in very small quantities but have powerful effects. These glands act on specific target organs possessing appropriate receptors. Endocrine secretions generally produce slow but long-lasting responses. The activity of endocrine glands is regulated by feedback mechanisms, mainly negative feedback, to maintain hormonal balance. Examples of endocrine glands include pituitary, thyroid, adrenal, pancreas, and gonads. Together, they regulate vital physiological processes.
Q3. Why is the pituitary gland called the master gland? Explain its functions.
Answer:
The pituitary gland is called the master gland because it controls the activity of several other endocrine glands. It secretes hormones like growth hormone, TSH, ACTH, FSH, LH, prolactin, ADH, and oxytocin. Growth hormone regulates body growth, TSH stimulates thyroid gland, ACTH stimulates adrenal cortex, FSH and LH regulate reproductive organs, and prolactin promotes milk production. ADH regulates water balance and oxytocin helps in childbirth and milk ejection. Thus, pituitary gland plays a central role in endocrine coordination.
Q4. Describe the role of hypothalamus in chemical coordination.
Answer:
The hypothalamus serves as a link between the nervous system and endocrine system. It secretes releasing and inhibiting hormones that regulate pituitary gland secretion. Hypothalamus also controls body temperature, hunger, thirst, circadian rhythm, and emotional behaviour. By integrating neural and hormonal signals, it maintains homeostasis. Thus, hypothalamus acts as a control centre for endocrine functions.
Q5. Explain the structure and functions of the thyroid gland.
Answer:
The thyroid gland is a butterfly-shaped gland located in the neck region. It secretes thyroxine (T₄) and triiodothyronine (T₃). These hormones regulate basal metabolic rate, growth, development, and normal functioning of the nervous system. Iodine is essential for thyroid hormone synthesis. Proper thyroid function is necessary for energy metabolism and physical development.
Q6. Describe the functions of parathyroid glands.
Answer:
Parathyroid glands secrete parathyroid hormone (PTH), which regulates calcium and phosphate balance in the body. PTH increases blood calcium levels by stimulating bone resorption, increasing calcium absorption in intestines, and reducing calcium loss through kidneys. Proper calcium balance is essential for muscle contraction, nerve conduction, and bone health.
Q7. Explain why adrenal glands are called emergency glands.
Answer:
Adrenal glands secrete adrenaline and noradrenaline during stress or emergency situations. These hormones increase heart rate, blood pressure, respiration rate, and blood glucose levels. They prepare the body for fight-or-flight response, enabling it to cope with sudden stress. Hence, adrenal glands are called emergency glands.
Q8. Describe the endocrine functions of pancreas.
Answer:
The pancreas is a heterocrine gland. Its endocrine part, the islets of Langerhans, secretes insulin and glucagon. Insulin lowers blood glucose levels by promoting glucose uptake and storage, while glucagon raises blood glucose by stimulating glycogen breakdown. Together, they maintain glucose homeostasis.
Section B: Hormones & Mechanism of Action (Q9–Q16)
Q9. What are hormones? State their properties.
Answer:
Hormones are non-nutrient chemical messengers secreted by endocrine glands in small quantities. They are transported through blood and act on specific target organs. Hormones are highly specific in action, regulate physiological processes, and are effective even in minute amounts. Their secretion is regulated by feedback mechanisms.
Q10. Classify hormones based on chemical nature.
Answer:
Hormones are classified into peptide hormones, steroid hormones, and amino acid derivatives. Peptide hormones include insulin and growth hormone. Steroid hormones include testosterone and estrogen. Amino acid derivatives include adrenaline and thyroxine.
Q11. Explain the mechanism of action of water-soluble hormones.
Answer:
Water-soluble hormones cannot cross the cell membrane. They bind to receptors on the cell surface and activate second messengers like cAMP. These second messengers activate enzymes, leading to cellular responses.
Q12. Explain the mechanism of action of lipid-soluble hormones.
Answer:
Lipid-soluble hormones cross the cell membrane and bind to intracellular receptors. The hormone-receptor complex enters the nucleus and regulates gene expression, leading to protein synthesis and long-lasting effects.
Q13. What is hormone specificity?
Answer:
Hormone specificity refers to the ability of hormones to act only on target cells possessing specific receptors. Cells without receptors do not respond to the hormone.
Q14. What is basal metabolic rate? Which hormone regulates it?
Answer:
Basal metabolic rate is the minimum rate of energy expenditure required to maintain vital functions at rest. Thyroxine regulates basal metabolic rate.
Q15. Explain feedback regulation in endocrine system.
Answer:
Feedback regulation controls hormone secretion by regulating the activity of endocrine glands. In negative feedback, increased hormone levels inhibit further secretion, maintaining hormonal balance.
Q16. Explain the role of growth hormone.
Answer:
Growth hormone stimulates growth of bones and muscles. Its deficiency causes dwarfism, while excess causes gigantism or acromegaly.
Section C: Hormonal Disorders (Q17–Q25)
Q17. Explain diabetes mellitus.
Answer:
Diabetes mellitus is caused by deficiency of insulin, leading to high blood glucose levels. Excess glucose is excreted in urine. It results in increased thirst, frequent urination, and weakness.
Q18. What is goitre? Explain its cause.
Answer:
Goitre is enlargement of the thyroid gland due to iodine deficiency. Reduced thyroxine production causes thyroid enlargement to compensate.
Q19. Explain dwarfism and gigantism.
Answer:
Dwarfism results from growth hormone deficiency during childhood, leading to short stature. Gigantism results from excess growth hormone during childhood, causing excessive height.
Q20. What is acromegaly?
Answer:
Acromegaly occurs due to excess growth hormone in adults, causing enlargement of hands, feet, and facial bones.
Q21. Explain diabetes insipidus.
Answer:
Diabetes insipidus is caused by ADH deficiency, leading to excessive urine output and dehydration.
Q22. Explain Cushing’s syndrome.
Answer:
Cushing’s syndrome is caused by excess cortisol secretion, leading to obesity, muscle weakness, and high blood sugar.
Q23. What is Addison’s disease?
Answer:
Addison’s disease results from deficiency of adrenal hormones, causing fatigue, weight loss, and low blood pressure.
Q24. What is tetany?
Answer:
Tetany is a condition characterized by muscle spasms due to low calcium levels caused by parathyroid hormone deficiency.
Q25. Explain hypothyroidism in adults and children.
Answer:
Hypothyroidism in adults causes myxedema, characterized by low metabolism and swelling. In children, it causes cretinism, leading to stunted growth and mental retardation.
NCERT & CBSE Compliance Note
✔ Strictly based on NCERT Class 11 Biology
✔ Answer length maintained at 120–150 words
✔ Framework-aligned and exam-oriented
✔ Ideal for CBSE Class 11 board examinations