All Free Biology MCQs with Answers
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19844 questions · page 710 of 1985
7091. The deficiency of which micro-nutrient causes goiter formation?
- A. Iron
- B. Zinc
- C. Iodine
- D. Sodium
Explanation: Iodine is essential for synthesis of thyroid hormones. Its deficiency leads to goiter due to overstimulation of thyroid gland by TSH.
Correct answer: Iodine7092. The action of parathormone is antagonistic to:
- A. Insulin
- B. Calcitonin
- C. FSH
- D. TSH
Explanation: Parathyroid hormone increases blood calcium by stimulating bone resorption. Calcitonin lowers calcium levels. Thus, both hormones act antagonistically to maintain calcium balance.
Correct answer: Calcitonin7093. Underactivity of parathyroid gland leads to:
- A. Diabetes
- B. Dwarfism
- C. Kidney stones
- D. Muscular tetany
Explanation: Hypoparathyroidism causes decreased PTH secretion → low blood calcium → increased excitability of nerves and muscles → painful spasms (tetany).
Correct answer: Muscular tetany7094. Most of the pancreas acts as:
- A. Endoctine
- B. Exocrine
- C. Merocrine
- D. Autocrine
Explanation: About 98% of pancreas is exocrine, consisting of acini that secrete digestive enzymes (amylase, lipase, trypsin) into the small intestine.
Correct answer: Exocrine7095. Which of the following statement is incorrect regarding insulin?
- A. Inhibits glycogen hydrolysis
- B. Increases glycolysis
- C. Converts glucose to protein
- D. Increases lipolysis
Explanation: Insulin promotes glucose uptake, glycogen formation, glycolysis, protein synthesis, and fat storage. It inhibits lipolysis instead of increasing it.
Correct answer: Increases lipolysis7096. All are functions of glucagon except:
- A. Glycogenesis
- B. Gluconeogenesis
- C. Lipolysis
- D. Protein synthesis
Explanation: Glucagon raises blood glucose by stimulating glycogen breakdown, gluconeogenesis, and lipolysis. It does not promote protein synthesis.
Correct answer: Protein synthesis7097. Which hormone is released during stress to increase glucose levels?
- A. Aldosterone
- B. Cortisol
- C. ADH
- D. Calcitonin
Explanation: Cortisol, a glucocorticoid, mobilizes glucose during stress by gluconeogenesis.
Correct answer: Cortisol7098. Which hormone increases reabsorption of sodium in kidneys?
- A. ADH
- B. Cortisol
- C. Aldosterone
- D. Calcitonin
Explanation: Aldosterone enhances sodium reabsorption and potassium excretion in renal tubules.
Correct answer: Aldosterone7099. Which hormone stimulate milk secretion after childbirth?
- A. Oxytocin
- B. Prolactin
- C. Estrogen
- D. Progesterone
Explanation: Prolactin stimulates mammary glands for milk production, while oxytocin aids milk ejection.
Correct answer: Prolactin7100. Which hormone regulates circadian rhythms?
- A. Cortisol
- B. Melatonin
- C. Serotonin
- D. Thyroxine
Explanation: Melatonin, secreted by the pineal gland, controls sleep-wake cycles.
Correct answer: Melatonin