Body Fluids and Circulation MCQs for NEET — Zoology Questions with Answers

(a) Folic acid is erythrocyte maturing factor. Folic acid is a water-soluble vitamin that is important in red blood cell formation, protein metabolism, growth and cell division. Folic Acid has been shown to work together with vitamin B₆ and vitamin B₁₂ to reduce blood levels of homocysteine, an amino acid that builds and maintains tissues. Folic acid also works closely together with vitamin B₁₂ to regulate the formation of red blood cells and to help iron function properly in the body.

(b) : Normal blood sugar level in adult human varies from 80-100 mg/100 ml (fasting) to 100-120 mg/100 ml (after meal).

Normal blood urea is 20-40 mg/dl

Total blood volume is 4-5 litres

ESR in wintrobe method is 0-9 mm in male and

0-20 mm in female.

(a) : The gradually increasing contraction of ventricular muscles during systole first causes the
closure of bicuspid and tricuspid valves (AV valves), producing a low-pitched "lubb" sound. Later, it causes the opening of the semilunar valves of systemic and pulmonary aorta. At the end of ventricular systole, scmilunar valvcs shut, producing the sccond, louder heart sound, the "dup". Thus each heart beat is accompanied by a "lubb-dup" sound

(d)  Heparin prevents blood coagulation in the blood vessels. It is secreted by mast cells. It is an anticoagulant, blocking conversion of prothrombin to thrombin. Haemoglobin is the blood pigment necessary for oxygen transport. Plasma is the component of blood. Thrombin is the product of blood clotting.

(a) Thickening of arteries due to cholesterol deposition is arteriosclerosis. This is extremely widespread disease predisposes to myocardial infarction, cerebral thrombosis and other serious illness. It is characterized by infiltration of cholesterol and appearance of foam cells in certain lesions of arterial wall, distorting the vessels and making them rigid.

(d) Haemophilia B is due to deficiency of factor IX (Christmas factor). The patient may experience prolonged bleeding following any injury or wound, and in severe cases there is spontaneous bleeding into muscles and joints.

(b) The opening between the right atrium and right ventricle is guarded by a valve formed of three muscular flaps or cusps, the tricuspid valve.

(c) Ventricular diastole is the relaxation of ventricles that occurs due to the tissue. The tissue of heart results in contraction and relation due to their electrical activity. ​The contraction of the tissue of atria increases blood pressure that results in the opening of bicuspid and tricusid valves and blood rushes insdie the ventricles causing their relaxation (diastole).

(b) RBCs contain haemoglobin. It has four polypeptide chains and four haem groups attached to it or 4 atoms of iron in ferrous form (Fe²⁺), thus it can react with 4 molecules of oxygen to form oxyhaemoglobin.

(d) Anti-haemorrhagic vitamins are those substances which promote haemostasis or stop bleeding. Vitamin K is one of them.