Chapter 22: Chemical Coordination and Integration – Short Answer Type Questions
CBSE Class 11 Biology Short Answer Questions – Chemical Coordination and Integration (NCERT)
Course & Examination Details
- Course: CBSE Class 11 Biology
- Unit: Unit V – Human Physiology
- Chapter: Chapter 22 – Chemical Coordination and Integration
- Question Type: Short Answer Questions (SAQs)
- Answer Length: 60–80 words
- Exam Relevance: CBSE Class 11 Annual Examination, Unit Tests, Periodic Assessments
Section A: Endocrine Glands (Q1–Q18)
Q1. What is chemical coordination? Explain its significance.
Answer:
Chemical coordination is regulation of body functions by hormones secreted by endocrine glands and transported through blood to target organs. It ensures growth, development, metabolism, reproduction, and maintenance of internal balance. Hormonal effects are slower than nervous responses but are long-lasting and widespread, making chemical coordination essential for sustained physiological regulation.
Q2. Define endocrine glands and state their main characteristics.
Answer:
Endocrine glands are ductless glands that secrete hormones directly into the bloodstream. They release hormones in minute quantities, act on specific target organs, and regulate physiological activities. Their effects are usually slow but prolonged and are regulated through feedback mechanisms.
Q3. Why is the pituitary gland called the master gland?
Answer:
The pituitary gland is called the master gland because it secretes hormones that regulate the activity of other endocrine glands like thyroid, adrenal, and gonads. It controls growth, reproduction, lactation, and water balance, coordinating the overall endocrine system.
Q4. Describe the role of hypothalamus in endocrine coordination.
Answer:
The hypothalamus links the nervous and endocrine systems. It secretes releasing and inhibiting hormones that regulate pituitary secretion. It also maintains homeostasis by controlling hunger, thirst, body temperature, and circadian rhythms.
Q5. Explain the functions of the pineal gland.
Answer:
The pineal gland secretes melatonin, which regulates circadian rhythm and sleep–wake cycle. It influences timing of puberty and seasonal reproductive cycles. Melatonin also helps in maintaining biological clock of the body.
Q6. Describe the hormones secreted by the thyroid gland.
Answer:
The thyroid gland 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 their synthesis.
Q7. What is the role of iodine in thyroid function?
Answer:
Iodine is required for synthesis of thyroid hormones. Deficiency of iodine reduces thyroxine production, leading to enlargement of thyroid gland called goitre and metabolic disorders.
Q8. Explain the function of parathyroid hormone.
Answer:
Parathyroid hormone regulates calcium and phosphate balance in the body. It increases blood calcium level by stimulating bone resorption and increasing calcium reabsorption in kidneys, maintaining neuromuscular function.
Q9. Why are adrenal glands called emergency glands?
Answer:
Adrenal glands secrete adrenaline and noradrenaline during stress or emergency. These hormones increase heart rate, blood pressure, respiration, and blood glucose level, preparing the body for fight-or-flight response.
Q10. Describe the functions of adrenal cortex hormones.
Answer:
Adrenal cortex secretes glucocorticoids, mineralocorticoids, and sex corticoids. Glucocorticoids regulate metabolism and stress response, mineralocorticoids maintain electrolyte balance, and sex corticoids influence secondary sexual characteristics.
Q11. Why is pancreas called a heterocrine gland?
Answer:
Pancreas is heterocrine because it has both endocrine and exocrine functions. Endocrine part secretes insulin and glucagon, while exocrine part secretes digestive enzymes.
Q12. Explain the role of insulin and glucagon.
Answer:
Insulin lowers blood glucose level by promoting glucose uptake and storage. Glucagon increases blood glucose by stimulating glycogen breakdown. Together, they maintain glucose homeostasis.
Q13. Describe the functions of testes hormones.
Answer:
Testes secrete testosterone, which regulates spermatogenesis, development of male reproductive organs, and secondary sexual characteristics like deep voice and facial hair.
Q14. Describe the functions of ovarian hormones.
Answer:
Ovaries secrete estrogen and progesterone. Estrogen develops female secondary sexual characters, while progesterone regulates menstrual cycle and maintains pregnancy.
Q15. What is feedback regulation in endocrine system?
Answer:
Feedback regulation is control of hormone secretion by its own concentration in blood. In negative feedback, increased hormone level inhibits further secretion, maintaining hormonal balance.
Q16. Give an example of negative feedback mechanism.
Answer:
High thyroxine levels inhibit secretion of TSH from pituitary, regulating thyroid hormone production through negative feedback.
Q17. How do endocrine glands differ from exocrine glands?
Answer:
Endocrine glands are ductless and release hormones into blood, while exocrine glands have ducts and release secretions locally, such as saliva or enzymes.
Q18. Why are hormones effective in minute quantities?
Answer:
Hormones are highly specific and bind to receptors on target cells, triggering amplified cellular responses even in very small amounts.
Section B: Hormones & Their Action (Q19–Q35)
Q19. What are hormones? State their properties.
Answer:
Hormones are non-nutrient chemical messengers secreted by endocrine glands. They act in minute quantities, are specific in action, transported by blood, and regulate physiological processes.
Q20. Classify hormones based on chemical nature.
Answer:
Hormones are classified as peptide hormones, steroid hormones, and amino acid derivatives based on their chemical composition.
Q21. Explain the mechanism of action of water-soluble hormones.
Answer:
Water-soluble hormones bind to membrane receptors and act through second messengers like cAMP, activating enzymes and producing cellular responses.
Q22. Explain the mechanism of action of lipid-soluble hormones.
Answer:
Lipid-soluble hormones cross cell membrane, bind to intracellular receptors, and directly influence gene expression and protein synthesis.
Q23. What is target organ?
Answer:
Target organ is the specific tissue or organ that responds to a particular hormone due to presence of specific receptors.
Q24. What is hormone specificity?
Answer:
Hormone specificity refers to selective action of a hormone only on cells possessing specific receptors.
Q25. What is basal metabolic rate?
Answer:
Basal metabolic rate is the minimum energy expenditure required to maintain vital body functions at rest.
Q26. Which hormone regulates BMR?
Answer:
Thyroxine regulates basal metabolic rate.
Q27. Explain the role of ADH.
Answer:
Antidiuretic hormone regulates water balance by increasing water reabsorption in kidneys, reducing urine output.
Q28. Why is growth hormone important?
Answer:
Growth hormone stimulates growth of bones and muscles. Its imbalance causes dwarfism or gigantism.
Q29. How do hormones maintain homeostasis?
Answer:
Hormones regulate metabolic activities, water balance, and ion levels, maintaining stable internal conditions.
Q30. What is circadian rhythm?
Answer:
Circadian rhythm is a biological cycle of about 24 hours regulating sleep–wake pattern, controlled by melatonin.
Q31. How is hormonal secretion regulated?
Answer:
Hormonal secretion is regulated by feedback mechanisms involving hypothalamus, pituitary, and target glands.
Q32. Why is chemical coordination slower than neural coordination?
Answer:
Chemical coordination is slower because hormones travel through blood, unlike fast electrical nerve impulses.
Q33. Name any two peptide hormones.
Answer:
Insulin and growth hormone are peptide hormones.
Q34. Name any two steroid hormones.
Answer:
Testosterone and estrogen are steroid hormones.
Q35. Name any two amino acid-derived hormones.
Answer:
Adrenaline and thyroxine are amino acid-derived hormones.
Section C: Hormonal Disorders (Q36–Q50)
Q36. What is diabetes mellitus?
Answer:
Diabetes mellitus is caused by insulin deficiency, resulting in high blood glucose levels and glucose excretion in urine.
Q37. Explain goitre.
Answer:
Goitre is enlargement of thyroid gland due to iodine deficiency, leading to reduced thyroid hormone synthesis.
Q38. What is dwarfism?
Answer:
Dwarfism is caused by growth hormone deficiency during childhood, resulting in short stature.
Q39. What is gigantism?
Answer:
Gigantism is caused by excess growth hormone during childhood, leading to abnormal height.
Q40. What is acromegaly?
Answer:
Acromegaly results from excess growth hormone in adults, causing enlargement of hands, feet, and facial bones.
Q41. Explain diabetes insipidus.
Answer:
Diabetes insipidus is caused by ADH deficiency, resulting in excessive urine output and thirst.
Q42. What is Cushing’s syndrome?
Answer:
Cushing’s syndrome is caused by excess cortisol secretion, leading to obesity and muscle weakness.
Q43. What is Addison’s disease?
Answer:
Addison’s disease is due to adrenal hormone deficiency, causing fatigue, weight loss, and low blood pressure.
Q44. What is tetany?
Answer:
Tetany is muscle spasm caused by low blood calcium due to parathyroid hormone deficiency.
Q45. What is myxedema?
Answer:
Myxedema is hypothyroidism in adults characterized by low metabolism and swelling.
Q46. What is cretinism?
Answer:
Cretinism is hypothyroidism in children causing stunted growth and mental retardation.
Q47. How does hormonal imbalance affect health?
Answer:
Hormonal imbalance disrupts metabolism, growth, and reproduction, leading to disorders and diseases.
Q48. Why is insulin called hypoglycemic hormone?
Answer:
Insulin lowers blood glucose levels by promoting glucose uptake and storage.
Q49. Why are adrenal hormones essential for survival?
Answer:
They help the body cope with stress and maintain electrolyte and metabolic balance.
Q50. State the importance of endocrine coordination in humans.
Answer:
Endocrine coordination ensures long-term regulation of body processes, growth, and internal stability.
NCERT & CBSE Compliance Note
✔ Strictly based on NCERT Class 11 Biology
✔ Answer length maintained at 60–80 words
✔ Framework-aligned and exam-oriented
✔ Ideal for CBSE Class 11 board examinations