CBSE Class 11 Biology Chemical Coordination and Integration Assignments

Short Answer Type Questions

Question. Write any four characteristic features of hormones.

Answer. (i) Hormones are intercellular chemical messengers. (ii) They have low molecular weight. (iii) They are effective in low concentration. (iv) They may accelerate or retard the specific reactions.

Question. (a) What is intermedin?
(b) (i) Name the smallest endocrine gland of human body.
(ii) Name the hormone secreted by it.

Answer. (a) Intermedin is a substance secreted by the pars intermedia of pituitary gland. (b) (i) Pituitary is the smallest endocrine gland of human body. (ii) Hormones of pituitary gland are growth hormone (GH), prolactin, TSH, ACTH, oxytocin, antidiuretic hormone, FSH, and LH.

Question. Which two hormones regulate blood calcium levels? Briefly describe the feedback mechanism.

Answer. Calcitonin and parathormone regulate blood calcium levels. Calcitonin is secreted when blood calcium levels are high. It lowers the calcium levels by decreasing mobilisation of Ca2+ from bones and prevents Ca2+ reabsorption in nephrons. Parathormone (PTH) is secreted in response to fall in blood calcium level. The release of parathormone increases blood calcium to normal by drawing calcium from bones into the plasma, by increasing calcium absorption in the digestive tract and by reducing loss of calcium in the urine. PTH has an effect that opposes the effect of calcitonin.

Question. (a) Name the hormone which lowers the blood sugar level.
(b) From where that hormone is secreted?
(c) Describe functions of insulin.

Answer. (a) Insulin is the hormone which lowers the blood sugar level. (b) Insulin is secreted from the b-cells of islets of Langerhans of pancreas. (c) (i) It lowers blood glucose levels by stimulating the deposition of glycogen granules in the liver and muscles. (ii) It increases the glucose entry through the plasma membrane. (iii) Insulin increases protein synthesis by incorporation of amino acids into peptides. (iv) It helps in the deposition of fat in adipose tissue from glucose.

Question. Mention the chemical nature of animal hormones and give their examples.

Answer. Chemical nature of animal hormones – (i) Protein nature – TSH, ACTH, FSH (ii) Steroid nature – Testosterone, estrogen (iii) Amino nature – Thyroxine, Epinephrine (iv) Polypeptide nature – ADH, Oxytocin

Question. Write short notes on the functions of the following hormones :
(a) Thymosin
(b) Androgen
(c) Estrogen
(d) Insulin and Glucagon.

Answer. (a) Thymosin is secreted by thymus. It accelerates cell division, stimulates the development and differentiation of T-lymphocytes and also hastens attainment of sexual maturity. (b) Androgens are secreted by testis. They stimulate the development of male reproductive system, formation of sperms, development of male accessory sex characters and also determines the male sexual behaviour and the sex urge. (c) Estrogens are secreted by ovaries. It stimulates the female reproductive tract to grow to full size and become functional, differentiation of ova and development of accessory sex characters. (d) Insulin is secreted by the b-cells of the pancreas. It lowers blood glucose level, and promotes synthesis of proteins and fats. Glycogen is secreted by the a-cells of the pancreas. It increases the level of glucose in the blood.

Question. Mention the name and source of the hormone which regulates the following:
(a) Heart beat and blood pressure
(b) Maturation of Graafian follicle
(c) Milk secretion
(d) Secretion of growth hormone
(e) Lowers the level of calcium ion in blood

Answer. The name and source of the hormones are given in the table: 

Long Answer Type Questions

Question. Hypothalamus is a super master endocrine gland. Elaborate.

Answer. Hypothalamus is a super master endocrine gland as it secretes hormones that regulate the synthesis and secretion of pituitary gland which is a master gland. The hypothalamus is connected to the anterior lobe of pituitary gland by hypophysial portal veins, however, it is connected to the posterior lobe of pituitary gland mainly by axons of neurosecretory cells. The hormones produced by hypothalamus are of two types, the releasing hormones (which stimulate the secretion of pituitary hormones) and the inhibiting hormones (which inhibit secretions of pituitary hormones). The hormones secreted by hypothalamus are summarised below: (i) Adrenocorticotropic Releasing Hormone (ARH) or Corticotropin Releasing Hormone – It stimulates the anterior lobe of pituitary gland to secrete its adrenocorticotropic hormone (ACTH). (ii) Thyrotropin Releasing Hormone (TRH) – It stimulates the anterior lobe of pituitary gland to secrete its thyroid stimulating hormone (TSH) or thyrotropin. (iii) Growth Hormone-Releasing Hormone (GHRH) – It stimulates the anterior lobe of pituitary gland to release its growth hormone (GH) or somatotrophin. (iv) Growth Hormone-Inhibitory Hormone (GHIH) – This hormone is also called somatostatin (SS). It inhibits the secretion of growth hormone from the anterior lobe of pituitary gland. (v) Gonadotropin Releasing Hormone (GnRH)- It stimulates the anterior lobe of pituitary gland to secrete two gonadotropic hormones : Follicle Stimulating Hormone (FSH) and Luteinising Hormone (LH)). (vi) Prolactin Releasing hormone (PRH) – It stimulates the anterior lobe of the pituitary gland to secrete its prolactin hormone. (vii) Prolactin Inhibitory Hormone (PIH) – It inhibits the secretion of prolactin from the anterior lobe of pituitary gland. (viii) MSH Releasing Hormone (MSHRH) – It stimulates the intermediate lobe of pituitary gland to secrete its melanocyte stimulating hormone (MSH). (ix) MSH Inhibitory Hormone (MSHIH) – It inhibits the secretion of melanocyte stimulating hormone from the intermediate lobe of pituitary gland.

Solve the MCQ questions below

Question. Assertion :- Endocrine glands lack ducts and are called ductless gland.
Reason :- Exocrine glands secrete hormones through duct.
(a) A
(b) B
(c) C
(d) D
Answer: C

Question. Assertion :- Hormones are non-nutrient chemicals act as intracellular messanger and produced in trace amount.
Reason :- Metabollic activities occur only inside cell.
(a) A
(b) B
(c) C
(d) D
Answer: D

Question. Assertion :- Testis and ovaries are organised glands of body.
Reason :- All cells of testis and overy secretes hormones.
(a) A
(b) B
(c) C
(d) D
Answer: C

Question. Assertion :- Destruction of neurohypophysis without affecting hypothalamus can lead to diuresis.
Reason :- Antidiuretic hormone is secreted by neurohypopysis.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Sperm production is controlled by gonadotrophins.
Reason :- Hypothalamus promote pituitary to secrete its hormone by releasing hormone.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Somatostatin is an inhibitory hormone reach to neurohypophysis gland through blood circulation.
Reason :- Hypothalamus secretes only inhibitory hormone.
(a) A
(b) B
(c) C
(d) D
Answer: D

Question. Assertion :- Oxytocin responsible for child birth, and milk ejection from the mammary gland.
Reason :- Oxytocin acts on smooth muscles and stimulate their contraction.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Posterior lobe of pituitary gland secretes oxytocin.
Reason :- Oxytocin formed in hypothalamus also called neurohormones.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Amino acids derivative hormones binds to the receptor present on cell membrane.
Reason :- Hormone-receptor complex is essential to show their effect on target tissue.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Daily diurnal rhythm of our body is regulated by melatonin hormone.
Reason :- Melatonin is antagonistic hormone to MSH.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- A person during interview feeling anxiety, increased heartbeat & dryness of mouth.
Reason :- This condition induced stress leads to release of emergency hormones.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Follicles of thyroid is situated in stromal part.
Reason :- Ovarian follicle matures in stromal of ovary.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Thyroxine hormone regulate B.M.R. of body.
Reason :- Thyroid gland synthesize its hormone in presence of Iodine.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Calcium is essential for heart functions and neuronal depolarisation.
Reason :- Lack of iodine, affects the calcium level in body.
(a) A
(b) B
(c) C
(d) D
Answer: C

Question. Assertion :- Hypothyrodism during pregnancy causes defective development and maturation of growing baby.
Reason :- Growth hormone is essential for the proper growth of baby.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Parathormone stimulates osteoblast cells to phagocyte in bones.
Reason :- Parathormone decreases blood calcium level.
(a) A
(b) B
(c) C
(d) D
Answer: D

Question. Assertion :- Thymus gland is lobular structures located on the ventral side of aorta.
Reason :- All type of lymphocytes mature in thymus provide immunity to body.
(a) A
(b) B
(c) C
(d) D
Answer: C

Question. Assertion :- Glucocorticoid stimulate gluconeogenesis.
Reason :- Adrenaline is secreted during stress inhibits alimentary canal functions.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Adrenal medulla is ectodermal in origin.
Reason :- Adrenal medulla is a modified sympathetic ganglion.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Decrease in blood pressure stimulate secretion of mineralocorticoids.
Reason :- Blood volume and electrolytes must be in proper amount to maintain B.P.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Electrolytes and \( Na^+ \) are absorbed at tubular part of nephrones.
Reason :- Aldosterone act on both PCT and DCT of nephron.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Insulin is a hypoglyemic hormone.
Reason :- Prolonged hyperglycemia leads to complex disorder called diabetes mallitus associated with loss of glucose through urine.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Androgen is a catabolic hormone.
Reason :- Androgen secreted from seminiferous tubules.
(a) A
(b) B
(c) C
(d) D
Answer: D

Question. Assertion :- ANF is secreted from heart to decrease blood pressure.
Reason :- Non adrenaline influences blood pressure.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- The posterior pituitary is under the direct neural regulation of the hypothalamus.
Reason :- Oxytocin and vasopressin, are actually synthesised by the hypothalamus and are transported axonally to neurohypophysis.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Deficiency of iodine in our diet results in hypothyrodism and enlargement of the thyroid gland called simple goitre.
Reason :- Iodine is essential for the normal rate of hormone synthesis in the thyroid .
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Cortisol can be used in treatment of allergic diseases and inflammatory diseases.
Reason :- Cortisol produces anti inflammatory reaction and suppresses the immune response.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Hormones produce their effects on target tissues by binding to specific receptors.
Reason :- Steroid hormones interacts with intracellular receptors and regulate gene expression.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Hormones are also secreted by some tissues which are not endocrine glands.
Reason :- Hormones are intercellular messengers and are also produced by ducted glands where they are transported upto their target organs through ducts.
(a) A
(b) B
(c) C
(d) D
Answer: C

Question. Assertion :- Thymus gland is a lobular structure located between lungs behind sternum and on ventral side of aorta.
Reason :- Thymus secretes thymosin hormone that plays a major role in the differentiation of T-Lymphocytes.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Parathormone increase calcium level in blood (hypercalemic hormone).
Reason :- PTH withdraws calcium from bones.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Glucagon is a hyperglycemic hormone.
Reason :- Glucagon decrease cellular uptake and use of glucose therefore blood sugar increases.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Vasopressin is called as anti diuretic hormone.
Reason :- Vasopressin decrease loss of water in urine by absorbing water and ions in DCT.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Mineralocorticoid (Aldosterone) is a hormone of adrenal cortex.
Reason :- Secretion of mineralocorticoid is not controlled by ACTH.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Steroid hormones like cortisol and androgen directly send their information to nucleus.
Reason :- Steroid hormones are lipid soluble therefore can cross through plasma membrane.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Atrial natriuretic factor is a peptide secreted from wall of right atrium.
Reason :- ANF is a vasodialator and decrease blood pressure.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Thymosine hormone is important for immune system.
Reason :- Thymosine causes differentiation of T-lymphocytes which is important for cell mediated immunity.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Glucagon acts faster than progesterone.
Reason :- Glucagon acts through secondary messenger while progesterone act on gene.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Thyroid gland synthesize \( T_4 \) (thyroxine) and triiodothyronine.
Reason :- Hyposecretion of thyrocalcitonin causes simple goitre.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Growth hormone (GH) stimulate growth of the body and cell division.
Reason :- Hyposecretion of GH causes dwarfism as well as acromegaly.
(a) A
(b) B
(c) C
(d) D
Answer: A

Question. Assertion :- Oxytocin acts on smooth muscle of the body.
Reason :- Oxytocin causes contraction in uterine muscle & also causes ejection of milk from mammary gland.
(a) A
(b) B
(c) C
(d) D
Answer: B

Question. Assertion :- Melanocyte stimulating hormone (MSH) is secreted from the same gland which secret melatonin.
Reason :- Melatonin causes darkening of skin.
(a) A
(b) B
(c) C
(d) D
Answer: D