SSLC Biology: Chapter 03 Chemical Messages for Homeostasis - Questions and Answers


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Class 10 Biology Questions and Answers- Chapter 03 Chemical Messages for Homeostasis
* Study Notes
• Homeostasis is maintained by the complementary activities of both the quick neural and slow hormonal systems.

1. The chemical substances, secreted by the endocrine glands?
Answer: Hormones.

2.  Hormone secreting endocrine glands are also known as 'ductless glands'. Why?
Answer: The hormones secreted by these glands are discharged directly into the blood, not through particular ducts.

3. Though hormones reach all parts of the body, each hormone act at its own target cells. How is this possible?
Answer: Though hormones reach all body parts through the bloodstream,  each hormone acts only in its target cells, having specific receptors for accepting the same hormone. When the hormone-receptor complex is formed in the plasma membrane, the enzymes in the cells become active.
 
4. The table and illustration showing the endocrine glands, site and producing hormones.

5. What is the normal level of glucose in the blood? Name the hormones which maintain this rate?
Answer: 
• 70 – 110 mg /100 ml blood.
• Insulin,  Glucagon.

6. How is the normal blood glucose level maintained?
Answer: This rate is maintained by the antagonistic activities of insulin and glucagon, released from Islets of Langerhans of the pancreas.
When glucose increases in the blood, beta cells in the Islets of Langerhans secrete insulin. It accelerates the process of glucose intake by the cells and the conversion of the excess glucose into glycogen.
When glucose decreases in blood, alpha cells in the Islets of Langerhans secrete glucagon, which converts glycogen and amino acids into glucose.

7. Islets of Langerhans: Alpha cells: Glucagon ;  
  Islets of Langerhans : Beta cells   : …..............?
Answer: Insulin.

8. The reason for --------------, (the blood glucose level more than 126mg/100ml)  is the deficiency or inactivity of the hormone insulin.
Answer: Diabetes mellitus / പ്രമേഹം. (Symptom: Increased appetite and thirst and frequent urination)

9. A test to detect the presence of glucose in the urine?
Answer: Benedict Test.
Take 2ml of urine in a test tube. Add 2ml of Benedict solution and heat for 2 minutes. We can understand the level of glucose by observing its colour change.

10. Patients having diabetes mellitus usually takes insulin injection. Why?
Answer: Insulin maintains the normal rate of glucose in our blood. 

11. World Diabetics Day?
Answer: November 14.

12. Name the endocrine glands  A and B shown in the figure.

Answer: A- Thyroid gland,  B- Parathyroid gland.

13. The chief metabolic hormone?
Answer: Thyroxine.

14. The element needed for the proper functioning of the thyroid gland?
Answer: Iodine. (Deficiency of iodine may cause a disorder, Goitre, the abnormal growth of thyroid gland)

15. Mention the functioning of hormones secreted by the thyroid gland.
Answer: 
•Thyroxine – increases the rate of metabolism and energy production, Accelerates the growth and development of the brain in the foetal stage and infancy and also regulates growth in children.
• Calcitonin – Maintains the level of calcium in the blood by depositing excess calcium in bones or by preventing the mixing of calcium with blood.
16.  Under secretion of thyroxine:  Hypothyroidism, 
Over secretion of thyroxine:  …......................?              
Answer:  Hyperthyroidism.

17. Deficiency of thyroxine during infancy may cause ---------, stunted physical-mental growth in children? 
Answer: Cretinism.

18. Deficiency of thyroxine in adults may cause ---------?        
Answer: Myxoedema.

19. Symptoms seen in person with myxoedema (Hypothyroidism)?
Answer: Low metabolic rate, sluggishness, increase in body weight, hypertension and inflammation in body tissues.

20. Symptoms seen in a person having Hypothyroidism?
Answer: High metabolic rate, rise in body temperature, excessive sweating, increased heartbeat, weight loss and emotional imbalance.

21. Give examples of the conditions due to hyperthyroidism and hypothyroidism.
Hypothyroidism in children:  Cretinism, 
Hypothyroidism in adults:  ----- ? ----          
Answer: Myxoedema

22. The hormones which maintain the normal rate of calcium in our blood?
Answer: Calcitonin of thyroid gland, Parathormone of the parathyroid gland.

23. What is the normal level of calcium in blood?  How is it maintained?
Answer: 9-11 mg /100 ml blood.                                                 
When the calcium level in blood increases, the thyroid gland secretes calcitonin, which lowers the calcium level in the blood by depositing excess calcium in bones or preventing the mixing of calcium with blood (from the bones).
When the level of calcium decreases, the parathyroid gland secretes parathormone, which increases the level of calcium by helping in its re-absorption from kidneys or by preventing the deposition of calcium in bones. 

24.The endocrine gland that is active during infancy?  Name its hormone?
Answer: Thymus gland (situated below the sternum/chest bone). Secretes the hormone thymosin.


25. Thymosin is also known as the 'youth hormone'. Why?
Answer: During infancy, thymosin helps in the maturation and activities of T-lymphocytes.

26. Name the gland that prepares our body to overcome emergencies.
Answer: Adrenal.

27. The outer part of the adrenal gland:  Cortex,
The inner part of the adrenal gland:  --------?             
Answer: Medulla.

28. Table which shows the functions of adrenal hormones.

29. Name the hormone that can be used as medicine against allergy and inflammation. Is it advisable for diabetic patients? Why?
Answer:  Cortisol of the adrenal gland.
Since cortisol increases the synthesis of glucose, it is not advisable for diabetic patients.

30. How is epinephrine or norepinephrine prepare our body to overcome emergencies?
Answer: When the sympathetic nervous system gets stimulated, the action of epinephrine or norepinephrine prolongs the body activities for more time. Due to these activities, we get the energy to resist or withdraw from such situations.
31. Why does the pineal gland, seen in the centre of our brain, called a 'biological clock'?
Answer: Melatonin, the hormone of the pineal gland, helps to maintain the rhythm of our daily activities like sleeping, and waking up. So the pineal gland is called a 'biological clock'.
(Melatonin also controls the reproductive activities of organisms that have definite reproductive periods)

32. Name the bilobed gland situated just below the hypothalamus.
Answer: Pituitary.

33.The hormones secreted by the anterior lobe of the pituitary. Mention their functions too.
Answer: 
• Tropic hormones.
 - TSH (Thyroid-stimulating hormone)- Stimulates the activity of the thyroid gland.
 - ACTH (Adreno Cortico tropic hormone)-  Stimulates the activity of the adrenal
cortex.
 - GTH (Gonadotropic hormone)-  Stimulates the activity of sex organs.
• STH (Somato tropic hormone /GH -Growth hormone)-  Promotes the growth of the body. 
• Prolactin – Production of milk.

34.Hormones which are stored in the posterior lobe of the pituitary? Their functions?
Answer: 
• Oxytocin - Facilitates childbirth by stimulating the contraction of smooth muscles in the uterine wall
    - Facilitates lactation.
• Vasopressin - Helps in the re-absorption of water in the kidneys and thus act as Anti Diuretic hormone (ADH). Thus, it regulates the level of water in the body.

35. Name the hormones of the hypothalamus.
Answer:  Releasing and Inhibitory hormones (towards the anterior lobe of pituitary to stimulate hormone production).
Oxytocin and vasopressin or ADH (towards the posterior lobe of the pituitary)

36. How can the hypothalamus control the entire endocrine system?
Answer: Through the releasing and inhibitory hormones, the hypothalamus induces the anterior lobe of the pituitary to produce various tropic hormones, which in turn stimulate certain other endocrine glands.
(Releasing hormones stimulate the production of the pituitary, but inhibitory hormones suppress hormones from the pituitary). 

37. What are the tropic hormones?
Answer: Tropic hormones are stimulating hormones of the pituitary to control the production of hormones of certain other glands.
TSH, ACTH, GTH are tropic hormones.

38. Why is the hypothalamus considered the ‘chief controller’ of the endocrine system?
Answer: Through the releasing and inhibitory hormones, the hypothalamus induces the pituitary to produce tropic hormones, which in turn stimulate certain other endocrine glands.

39. Name the growth disorders related to the pituitary's growth hormone (somatotropin / STH).
Answer:
• Dwarfism - The condition characterised by stunted physical growth due to decreased production.
• Gigantism – Excessive growth of the body due to increased production of Somato Tropic Hormone.
• Acromegaly – Excessive growth of the bones on the face, jaws and fingers due to the prolonged production of STH even after the growth phase.

40. Mention the symptoms of acromegaly.
Answer: Excessive physical growth with excessive growth of the bones on the face, jaws and fingers.

41. Describe the reason for decreased production of urine during the summer season.
Answer: During the summer season, the production of vasopressin(ADH) increases and therefore re-absorption of water in the kidneys increases,  to lower the quantity of urine.
42. The condition in which excess amount of urine is excreted, even in the summer season, due to the insufficient production of vasopressin, is known as ----------?
Answer: Diabetes insipidus.

43. Insulin:  Diabetes mellitus: Glucose,   
      Vasopressin:  --------?----------: water.                    
Answer: Diabetes insipidus.

44. Table showing sex organs, hormones and their functions.?

45.  Hormonal disorders.

46. Define pheromones. How is it useful to animals?
Answer: Pheromones are chemical substances that are secreted by certain animals to the surroundings to facilitate communication. It helps in attracting mates, informing about food, determining the path of travel, signalling dangers, help honey bees and termites to live in colonies etc.

47. Give examples of pheromones
Answer: 
• The musk in the musk deer,
• The civeton in civet cat ,
• Bombycol in female silkworm.

48. Ants can follow one after another during their trial. How is this possible?
Answer: Because of the chemicals, pheromones, that are released to their surroundings.

49. How are pheromones helpful in agricultural fields?
Answer: Pheromone traps are used for pest control in agricultural fields.

50. How the life activities are controlled and coordinated in plants?
Answer: Certain plant hormones (plant growth regulators) control and coordinate life activities in plants.

51. Table showing the natural plant hormones and their activities.

52. Name the plant hormone in gaseous form.
Answer: Ethylene.

53. The uses of artificial plant hormones in the agricultural sector.

54. Give examples of situations where artificial plant hormones are applied.
Answer: 
• Ethylene is used for the flowering of pineapple plants at a time and for the ripening of tomato, lemon, orange etc.
• Ethyphon, in liquid form, gets transformed into ethylene, increases the production of latex.
• Gibberellins are used for increasing fruit size in grapes and apples and also for preventing the ripening of fruits to assist in marketing.

55. Though artificial plant hormones are useful, their application should be with utmost care. What is your opinion?
Answer: True. The majority of synthetic plant hormones are strong chemicals.





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