All Free Biology MCQs with Answers

1541. Smooth muscles, cardiac muscles and glands are regulated by:

• A. Central nervous system
• B. Parasympathetic nervous system
• C. Sympathetic nervous syetem
• D. Autonomous nervous system

Explanation: Smooth muscle, cardiac muscle and glands are controlled involuntarily by the autonomic nervous system. Students may choose the parasympathetic or sympathetic division because both are parts of it, but neither division alone regulates all three types in every situation.

1542. Stress indicating hormones are____________?

• A. Cortisol
• B. Adrenaline
• C. ACTH
• D. All of these

Explanation: Cortisol, adrenaline and ACTH all participate in the body's stress response: ACTH stimulates cortisol release, while adrenaline produces rapid fight-or-flight effects. Students may choose cortisol alone because it is the best-known stress hormone, overlooking the coordinated roles of ACTH and adrenaline.

1543. Which of the following are insulin dependent Glut receptors?

• A. Glut 1&3
• B. Glut 2
• C. Glut 1
• D. Glut 4

Explanation: GLUT4 is insulin-dependent and moves to the cell membrane in response to insulin, especially in skeletal muscle and adipose tissue. GLUT1, GLUT2 and GLUT3 are generally insulin-independent transporters, so students may select GLUT2 because it is important in pancreatic beta cells and glucose sensing.

1544. More water is reabsorbed in blood due to _________ ?

• A. More anti-diuretic hormone
• B. Lesser anti-diuretic hormone
• C. Active functioning of pancreas
• D. Inactivity of pituitary gland

Explanation: Antidiuretic hormone, or ADH, increases water reabsorption by making the collecting ducts more permeable to water, so more water returns to the blood. Students may choose lesser ADH because they associate it with reduced urine formation, but lesser ADH actually causes more water to remain in urine.

1545. Protein which acts as hormone is__________?

• A. Casein
• B. Trypsin
• C. Oxytocin
• D. Keratin

Explanation: Oxytocin is a peptide hormone released from the posterior pituitary that promotes uterine contractions and milk ejection. Students may choose trypsin because it is a biologically active protein, but trypsin is a digestive enzyme rather than a hormone.

1546. The hormone that helps in Parthenocarpy?

• A. Abscisic acid
• B. Cytokinin
• C. Ethylene
• D. Gibberellin

Explanation: Gibberellins can induce parthenocarpy, the development of fruit without fertilisation, often producing seedless fruits. Students may choose cytokinin because it promotes cell division and growth, but gibberellin is the hormone class commonly associated with inducing parthenocarpic fruit development.

1547. Epinasty is controlled by_____________?

• A. Gibberellins
• B. Abscisins
• C. Auxins
• D. Cytokinins

Explanation: Epinasty, such as downward bending of a leaf, commonly results from unequal auxin distribution that causes greater growth on one side of the organ. Students may choose abscisic acid because it is associated with stress responses and stomatal closure, but auxin is the hormone classically linked with differential growth and epinasty.

1548. Roots of a plant show______________?

• A. Positive phototropism and negative geotropism
• B. Negative phototropism and positive geotropism
• C. Negative tactic movement and positive tropic movement
• D. Positive geotropism of stem and roots

Explanation: Roots grow away from light, showing negative phototropism, and grow in the direction of gravity, showing positive geotropism. Students may choose a by reversing both responses, but roots generally seek darkness and grow downward while shoots show the opposite pattern.

1549. Insufficient secretion of iodothyroxine in adults causes____________?

• A. Myxedema
• B. Cretinism
• C. Goiter
• D. Exopthalmic goiter

Explanation: Low secretion of thyroid hormones in an adult causes myxedema, producing reduced metabolic activity and symptoms such as lethargy and weight gain. Cretinism is the corresponding thyroid-hormone deficiency during childhood, while goiter is enlargement of the thyroid and may have several causes.

1550. Insulin and glucagons are __________ in nature.

• A. Protein
• B. Amino acid derivative
• C. Polypeptide
• D. Steroid

Explanation: Insulin and glucagon are peptide hormones made of amino-acid chains, so they are classified broadly as proteins. Insulin contains 51 amino acids and glucagon contains 29 amino acids. The likely alternative is polypeptide, but that term describes their chain structure and is a narrower description than the expected broad class protein.