৪৯তম বিসিএস ⎯ প্রাণ রসায়ন [৬০১]

Answer: B) Thyroxine and epinephrine
Explanation:
Amino acid–derived hormones are synthesized from tyrosine or tryptophan. Examples: thyroxine (T4), epinephrine, norepinephrine.

Answer: B) Cholesterol
Explanation:
Steroid hormones (e.g., cortisol, testosterone, estrogen) are all derived from cholesterol.

Answer: C) Glucagon
Explanation:
Peptide hormones are made of amino acid chains, such as glucagon, insulin, and growth hormone.

Answer: C) Thyroxine
Explanation:
Thyroid hormones and steroid hormones are lipid-soluble, allowing them to cross cell membranes easily.

Answer: C) Require high concentrations to be effective
Explanation:
Hormones are highly potent and effective even at very low concentrations.

Answer: C) Hormone acting on nearby target cells
Explanation:
Paracrine hormones act locally, affecting neighboring cells (e.g., growth factors).

Answer: A) Peptide hormone
Explanation:
Insulin is a peptide hormone composed of two polypeptide chains.

Answer: C) Directly regulating gene transcription
Explanation:
Steroid hormones cross the cell membrane, bind to intracellular receptors, and modulate gene expression.

Answer: D) Insulin
Explanation:
Second messengers like cAMP, IP3, and DAG relay hormone signals inside the cell, but insulin itself is a first messenger.

Answer: B) FSH
Explanation:
FSH acts on Sertoli cells to promote sperm production.

Answer: C) Peptide and catecholamine signaling
Explanation:
Most peptide hormones and catecholamines bind to GPCRs to trigger intracellular signaling cascades.

Answer: C) Phosphodiesterase
Explanation:
Phosphodiesterase terminates cAMP signaling by breaking it down into AMP.

Answer: C) Thyroxine
Explanation:
Thyroid hormones are lipid-soluble and bind to intracellular nuclear receptors.

Answer: C) Tyrosine kinase receptor
Explanation:
Insulin binds to a tyrosine kinase receptor, triggering phosphorylation cascades.

Answer: C) Oxytocin
Explanation:
The posterior pituitary releases oxytocin and ADH, synthesized in the hypothalamus.

Answer: C) Somatotrophs
Explanation:
Somatotrophs in the anterior pituitary secrete growth hormone (GH).

Answer: B) Thyroid gland
Explanation:
TSH stimulates the thyroid gland to produce T3 and T4.

Answer: B) Cortisol
Explanation:
ACTH acts on the adrenal cortex, stimulating cortisol and glucocorticoid production.

 Answer: B) Diabetes insipidus
Explanation:
Lack of ADH causes excessive urine output and dehydration, characteristic of diabetes insipidus.

Answer: B) Milk production
Explanation:
Prolactin stimulates milk synthesis in mammary glands after childbirth.

Answer: B) FSH and LH
Explanation:
FSH and LH control gametogenesis and sex steroid production in the gonads.

Answer: B) Hypothalamus
Explanation:
ADH and oxytocin are produced in the hypothalamus and stored in the posterior pituitary.

Answer: A) Follicle
Explanation:
The thyroid follicle is the structural and functional unit, consisting of follicular cells that secrete thyroid hormones.

Answer: C) Iodine
Explanation:
Iodine is required for the synthesis of thyroxine (T4) and triiodothyronine (T3).

Answer: B) T3
Explanation:
T3 is more active than T4 because it binds more strongly to thyroid receptors.

Answer: C) Basal metabolic rate (BMR)
Explanation:
Thyroid hormones increase BMR by stimulating energy production and oxygen consumption.

Answer: C) TSH
Explanation:
Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to produce T3 and T4.

Answer: C) Myxedema
Explanation:
Myxedema is a condition with low thyroid hormone levels in adults, leading to lethargy, weight gain, and swelling.

Answer: C) Thyroglobulin
Explanation:
Thyroid hormones are stored in the colloid as part of the protein thyroglobulin

Answer: B) Parathyroid hormone (PTH)
Explanation:
PTH regulates calcium and phosphate balance in the blood.

Answer: B) Blood calcium is low
Explanation:
PTH is secreted in response to low calcium levels to increase blood calcium.

Answer: D) All of the above
Explanation:
PTH increases calcium through three mechanisms: intestinal absorption, bone resorption, and kidney reabsorption.

Answer: B) Calcitonin
Explanation:
Calcitonin lowers blood calcium by inhibiting bone resorption, opposing PTH.

Answer: A) Liver and kidneys
Explanation:
Vitamin D is first hydroxylated in the liver and then activated in the kidneys.

Answer: B) Glucagon
Explanation:
Alpha cells secrete glucagon, which raises blood glucose.

Answer: B) Insulin
Explanation:
Beta cells release insulin to lower blood glucose.

Answer: B) Insulin
Explanation:
Insulin promotes glucose uptake and storage, reducing blood glucose levels.

Answer: B) Liver
Explanation:
Glucagon stimulates glycogenolysis and gluconeogenesis in the liver.

Answer: B) Insulin deficiency or resistance
Explanation:
Diabetes is caused by lack of insulin or inability of cells to respond to it.

Answer: B) Somatostatin
Explanation:
Somatostatin suppresses the secretion of both insulin and glucagon.

Answer: B) Decrease blood glucose
Explanation:
Insulin promotes glucose uptake into tissues, reducing blood glucose.

Answer: B) Leydig cells
Explanation:
Leydig cells in the testes secrete testosterone.

Answer: B) Granulosa cells
Explanation:
Granulosa cells of the ovaries secrete estrogen.

Answer: B) LH
Explanation:
The LH surge triggers ovulation.

Answer: B) Corpus luteum
Explanation:
After ovulation, the corpus luteum produces progesterone.

Answer: B) Progesterone
Explanation:
Progesterone maintains the uterine lining and prevents contractions during pregnancy.

Answer: A) Iodine deficiency
Explanation:
Iodine deficiency leads to thyroid enlargement as the gland tries to compensate by increasing hormone synthesis.

Answer: B) LH
Explanation:
LH stimulates Leydig cells to produce testosterone.

Answer: B) Development of female reproductive organs
Explanation:
Estrogen promotes growth of female secondary sexual characteristics and reproductive organs.

Answer: B) Insulin resistance in target cells
Explanation:
Type 2 diabetes occurs when cells become resistant to insulin.