NEET Biology Human Physiology and Animal Kingdom MCQs Set 01

Answer: (a) a - left ventricle; b - goes directly to aorta

Explanation:
1. In systemic circulation oxygenated blood is pumped from the left ventricle into the aorta.
2. The aorta distributes it to the body tissues; deoxygenated blood returns through the vena cavae to the right atrium.
3. Blood going from the right ventricle to the lungs is the pulmonary circulation.

Teacher's Note:
1. Systemic: left ventricle to aorta to body to right atrium.
2. Pulmonary: right ventricle to pulmonary artery to lungs to left atrium.

Answer: (d) vasopressin and aldosterone

Explanation:
1. Vasopressin (ADH) increases water reabsorption in the distal convoluted tubule and collecting duct.
2. Aldosterone promotes reabsorption of \( \ce{Na+} \) and water and excretion of \( \ce{K+} \), maintaining electrolyte balance and body fluid volume.
3. So the pair is vasopressin and aldosterone.

Teacher's Note:
1. ADH and aldosterone regulate water and ion balance respectively.
2. ANF (atrial natriuretic factor) opposes the renin-angiotensin mechanism.

Answer: (b) \( \ce{K+} \) and negatively charged proteins

Explanation:
1. In a resting neuron the axoplasm has high \( \ce{K+} \) and negatively charged proteins and low \( \ce{Na+} \).
2. The fluid outside has high \( \ce{Na+} \) and low \( \ce{K+} \); this gives the resting potential, with the inside negative.

Teacher's Note:
1. The sodium-potassium pump throws out 3 \( \ce{Na+} \) and brings in 2 \( \ce{K+} \).
2. Organic anions cannot leave the axon.

Answer: (c) ii \( \to \) i \( \to \) iv \( \to \) iii

Explanation:
1. The bladder first fills and is stretched (ii).
2. Stretch receptors signal the CNS (i).
3. The CNS sends motor messages that contract the bladder and relax the sphincter (iv).
4. Urine is released: micturition (iii). Order: ii, i, iv, iii.

Teacher's Note:
1. Micturition is a reflex that can be controlled voluntarily by the cerebral cortex.
2. The sphincter relaxes only after the CNS signal.

Answer: (b) fovea

Explanation:
1. The fovea is a thin, central part of the macula lutea of the retina where only cones are densely packed.
2. This gives the greatest visual acuity (resolution) and colour vision.
3. The blind spot has no photoreceptors.

Teacher's Note:
1. Blind spot: no rods or cones. Fovea: only cones, highest acuity.
2. The visual cortex is in the brain, not the retina.

Answer: (b) osteoporosis

Explanation:
1. Estrogen helps keep bone mass by slowing bone resorption.
2. In post-menopausal women estrogen falls, bone mass decreases and the bones become brittle: osteoporosis.

Teacher's Note:
1. Gout is caused by uric acid crystals; rheumatoid arthritis is autoimmune.
2. Calcium and vitamin D help prevent osteoporosis.

Answer: (d) Three

Explanation:
1. (i) True: type II pneumocytes secrete surfactant.
2. (ii) False: lymph is a colourless fluid with lymphocytes.
3. (iii) True: the glomerulus ultrafilters the blood. (iv) True: visceral muscles are smooth. Three statements are true.

Teacher's Note:
1. Lymph lacks red blood cells, hence it is colourless.
2. Smooth muscle is involuntary and non-striated.

Answer: (c) eye of insects

Explanation:
1. Insects (such as cockroach) have compound eyes made of many structural and functional units called ommatidia.
2. Each ommatidium has its own lens and photoreceptor cells, giving mosaic vision.

Teacher's Note:
1. Compound eyes occur in arthropods such as insects and crustaceans.
2. A cockroach eye has about 2000 ommatidia.

Answer: (d) areolar connective tissue - beneath skin

Explanation:
1. Areolar tissue is a loose connective tissue with a network of collagen and elastic fibres and cells such as fibroblasts, macrophages and mast cells.
2. It is found beneath the skin and serves as a support framework for epithelium; it is also present between organs.
3. Dense regular tissue forms tendons and ligaments, dense irregular tissue forms skin dermis, and adipose tissue stores fat.

Teacher's Note:
1. Areolar tissue is the most widely distributed connective tissue.
2. Dense regular connective tissue is found in tendons and ligaments (not in the heart).

Answer: (c) a-iii, b-i, c-iv, d-ii

Explanation:
1. Sycon is a sponge with flagellated collar cells (choanocytes): a-iii.
2. Nereis is a polychaete annelid with lateral parapodia: b-i.
3. Asterias (starfish) is an echinoderm with a water vascular system: c-iv. Aurelia has polyp and medusa forms: d-ii.

Teacher's Note:
1. Parapodia help in swimming in polychaetes.
2. Echinoderms have tube feet linked to the water vascular system.

Answer: (b) solid and ventral nerve cord

Explanation:
1. Both are non-chordates and have a solid, double, ventral nerve cord with ganglia (unlike the dorsal hollow nerve cord of chordates).
2. Earthworm excretes through nephridia and cockroach through Malpighian tubules; the cockroach has a chitinous exoskeleton, whereas the earthworm has only a thin cuticle.

Teacher's Note:
1. Chordate nerve cord is dorsal, hollow and single; non-chordate nerve cord is ventral, solid and double.
2. Match the excretory organ with the animal.