NEET Biology Human Physiology and Animal Kingdom MCQs Set 02

Answer: (a) regeneration

Explanation:
1. Planaria are flatworms (Platyhelminthes) with a remarkable power to regenerate lost parts, and a cut piece can grow into a whole worm.
2. Bioluminescence is shown by ctenophores and some others, and metamorphosis is shown by insects and amphibians.

Teacher's Note:
1. Regeneration is the ability to rebuild lost body parts.
2. It is the basis of asexual reproduction by fragmentation in some animals.

Answer: (d) enucleated RBCs

Explanation:
1. Birds and mammals both breathe with lungs, are homeothermous (warm-blooded) and have a four-chambered heart.
2. Mammalian red blood cells lose the nucleus (enucleated), but bird red cells are nucleated.

Teacher's Note:
1. Camels and llamas are the exception among mammals, as their RBCs are oval, but they are still enucleated.
2. Nucleated, oval RBCs are found in all other vertebrate classes.

Answer: (b) \(\textit{Canis}\)

Explanation:
1. \(\textit{Canis}\) (dog) is a mammal and fertilisation is internal.
2. Starfish, frog and \(\textit{Balanoglossus}\) shed gametes into water, so fertilisation is external.

Teacher's Note:
1. Reptiles, birds and mammals show internal fertilisation.
2. Most aquatic animals show external fertilisation.

Answer: (a) Mammalia : \(\textit{Camelus}\), \(\textit{Macaca}\), \(\textit{Rattus}\)

Explanation:
1. Camel (\(\textit{Camelus}\)), monkey (\(\textit{Macaca}\)) and rat (\(\textit{Rattus}\)) are all mammals.
2. \(\textit{Scypha}\) is a sponge, \(\textit{Pristis}\) (sawfish) is a cartilaginous fish, and \(\textit{Nereis}\) is an annelid, so (b), (c) and (d) are wrong.

Teacher's Note:
1. Always check each genus separately in a matching question.
2. Pila (apple snail) and Unio (freshwater mussel) are true molluscs.

Answer: (a) protection

Explanation:
1. Compound epithelium has two or more layers of cells (as in the skin and the lining of the buccal cavity, pharynx and ducts of salivary glands).
2. Its main function is protection against chemical and mechanical stresses. Secretion and absorption are the functions of simple epithelium.

Teacher's Note:
1. Cuboidal and columnar simple epithelia are specialised for secretion and absorption.
2. Stratified squamous epithelium is the commonest compound epithelium.

Answer: (b) dense regular connective tissue

Explanation:
1. In tendons and ligaments, fibroblasts and parallel bundles of collagen fibres are arranged in rows, so they are dense regular connective tissue.
2. Tendons join muscle to bone and ligaments join bone to bone.

Teacher's Note:
1. The skin dermis contains dense irregular connective tissue.
2. The fibres in dense regular tissue run in one direction, which gives strength in that direction.

Answer: (b) 5

Explanation:
1. The sense organs of a cockroach are the antennae, compound eyes, maxillary palps, labial palps and anal cerci. This is 5 structures.
2. Tentacles, osphradium, papillae, amphids and phasmids belong to other animals.

Teacher's Note:
1. The osphradium is found in molluscs, and amphids and phasmids in nematodes.
2. Anal cerci are the sensory structures in both sexes of the cockroach.

Answer: (d) The \(p_{\ce{CO2}}\) in deoxygenated blood is 95 mm Hg.

Explanation:
1. The \(p_{\ce{CO2}}\) in deoxygenated blood is 45 mm Hg (and 40 mm Hg in oxygenated blood and the alveoli).
2. The values of \(p_{\ce{O2}}\) in options (a), (b) and (c) are correct.

Teacher's Note:
1. Oxygen moves from the alveoli (104) to the blood, and carbon dioxide moves from the blood (45) to the alveoli (40).
2. The difference in the partial pressures decides the direction of diffusion.

Answer: (b) synthesis of prothrombin

Explanation:
1. The liver needs vitamin K to synthesise prothrombin and several other clotting factors (II, VII, IX and X).
2. Without vitamin K, prothrombin is not made and clotting is delayed.

Teacher's Note:
1. Vitamin K is produced by the intestinal bacteria and is fat soluble.
2. Calcium ions are also needed in several clotting steps.

Answer: (c) 0.5 seconds

Explanation:
1. The cardiac cycle lasts 0.8 s. Ventricular systole lasts about 0.3 s, from 'lubb' to 'dup'.
2. The rest of the cycle, about 0.5 s, is diastole, from 'dup' to the next 'lubb'.

Teacher's Note:
1. Lubb is the closing of the AV valves, and dup is the closing of the semilunar valves.
2. 0.3 plus 0.5 gives the 0.8 s of the cardiac cycle.

Answer: (c) six

Explanation:
1. Human urine contains urea (the major nitrogenous waste), uric acid, creatinine and a small amount of ammonium ions, along with water and electrolytes such as \(\ce{Na+}\).
2. All six substances are excreted.

Teacher's Note:
1. Normal urine is about 95 percent water.
2. Excess salts are removed in the urine to maintain osmotic balance.

Answer: (c) lactic acid

Explanation:
1. In prolonged activity, the oxygen supply is not enough, so muscle fibres respire anaerobically and pyruvic acid is converted into lactic acid.
2. Accumulation of lactic acid causes fatigue.

Teacher's Note:
1. Myoglobin stores oxygen in red muscle fibres.
2. Rest allows the lactic acid to be removed and oxygen debt to be repaid.

Answer: (b) vital capacity

Explanation:
1. The maximum volume of air a person can breathe in after a forced expiration, or breathe out after a forced inspiration, is the vital capacity.
2. It equals ERV + TV + IRV (about 3.5 to 4.5 litres).

Teacher's Note:
1. Total lung capacity is vital capacity plus residual volume.
2. Residual volume cannot be expelled even by forced expiration.

Answer: (a) colourless fluid containing lymphocytes

Explanation:
1. Lymph is a colourless fluid with specialised lymphocytes that respond to pathogens.
2. It has no red blood cells and no platelets, and it carries nutrients, hormones and absorbed fats.

Teacher's Note:
1. Lymph is formed from the tissue fluid that drains into the lymphatic capillaries.
2. Lymphocytes in the lymph are responsible for immune responses.

Answer: (c) fibrinogen

Explanation:
1. Filtration across the glomerular capillaries allows small molecules such as water, glucose, amino acids, urea and ammonia to pass.
2. Large plasma proteins such as fibrinogen cannot pass the filtration barrier.

Teacher's Note:
1. The glomerular filtrate is essentially plasma without proteins.
2. About 180 litres of filtrate are formed per day.

Answer: (b) cartilaginous joint

Explanation:
1. The two coxal bones of the pelvic girdle meet ventrally at the pubic symphysis, which has a pad of fibrocartilage. This is a cartilaginous joint.
2. The joint between the coxal bone and the femur is the ball and socket joint (hip joint).

Teacher's Note:
1. Cartilaginous joints, such as those between the vertebrae, allow only limited movement.
2. Do not confuse the joint within the pelvis with the hip joint.

Answer: (b) cholecystokinin

Explanation:
1. Cholecystokinin (CCK) acts on the pancreas to release pancreatic enzymes and on the gall bladder to release bile.
2. Secretin acts mainly on the exocrine pancreas to release water and bicarbonate ions. Gastrin acts on gastric glands, and GIP inhibits gastric secretion.

Teacher's Note:
1. CCK is secreted by the duodenum in response to fats and proteins.
2. Secretin was the first hormone to be discovered.

Answer: (a) 2

Explanation:
1. Cortisol, testosterone and estradiol are steroid hormones made from cholesterol.
2. Glucagon is a peptide hormone and epinephrine is an amino acid (tyrosine) derivative, so 2 hormones are not steroids.

Teacher's Note:
1. Steroid hormones are produced by the adrenal cortex and the gonads.
2. Peptide and amine hormones act on cell surface receptors.

Answer: (d) organ of Corti

Explanation:
1. The organ of Corti is located on the basilar membrane of the cochlea and has hair cells that act as the auditory receptors.
2. The macula and crista are in the vestibular apparatus, which maintains balance.

Teacher's Note:
1. Bending of the hair cells generates nerve impulses carried by the auditory nerve.
2. The macula and crista also have hair cells, but they detect balance and posture.

Answer: (b) Myelinated nerve fibres are not found in spinal and cranial nerves.

Explanation:
1. Myelinated nerve fibres are found in the spinal and cranial nerves, so statement (b) is false.
2. The other statements are true: neurons are excitable because of the polarised membrane, and unipolar neurons are found in the embryonic stage.

Teacher's Note:
1. Unmyelinated fibres are found mostly in the autonomic and somatic neural systems.
2. Myelinated fibres conduct impulses faster by saltatory conduction.

Answer: (c) 2

Explanation:
1. The corpora quadrigemina and the cerebral aqueduct are part of the midbrain.
2. The amygdala and hippocampus (limbic system) and the corpus callosum are in the forebrain. So 2 structures are not present in the forebrain.

Teacher's Note:
1. The forebrain consists of the cerebrum, thalamus and hypothalamus.
2. The midbrain has the four optic and auditory lobes called the corpora quadrigemina.