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

Clotting of blood is indeed a characteristic of human blood, making A true. Each erythrocyte possesses hemoglobin (Hb), which is also true. However, the presence of Hb in erythrocytes does not explain why blood clots. Therefore, both A and R are true, but R is not a correct explanation of A.

Refer NCERT, Heading 8.3, para-1, page-127

Fatty acids and glycerol are first incorporated into small droplets called micelles which move into the intestinal mucosa. They are re-formed into very small protein coated fat globules called the chylomicrons which are transported into the lymph vessels (lacteals) in the villi. These lymph vessels ultimately release the absorbed substances into the blood stream. (page- 265)

Amylase is secreted in pancreatic juice. Gastric juice contains hydrochloric acid and enzymes like rennin, pepsin, etc. (page-262)

Trypsinogen is activated by an enzyme, enterokinase, secreted by the intestinal mucosa into active trypsin, which in turn activates the other enzymes in the pancreatic juice (page-262).

The bile duct and the pancreatic duct open together into the duodenum as the common hepato-pancreatic duct which is guarded by a sphincter called the sphincter of Oddi. (page- 261).

Parietal or oxyntic cells present in mucosa of stomach secrete HCl and intrinsic factor (factor essential for absorption of vitamin B12). If these cells become partially non-functional, then HCl would not be secreted in adequate amounts, thus it would not allow the conversion of pepsinogen to pepsin which converts proteins into proteoses and peptones. (page-262).

Mucosa forms small finger-like foldings called villi in the small intestine. The cells lining the villi produce numerous microscopic projections called microvilli giving a brush border appearance. These modifications increase the surface area enormously. Villi are supplied with a network of capillaries and a large lymph vessel called the lacteal. (page- 260).

Absorption of fats: Fatty acids and glycerol being insoluble, cannot be absorbed into the blood after digestion and thus needs to be modified. They are first incorporated into small droplets called micelles which move into the intestinal mucosa. They are re-formed into very small protein coated fat globules called the chylomicrons which are transported into the lymph vessels (lacteals) in the villi. These lymph vessels ultimately release the absorbed substances into the blood stream.

Carbohydrates and proteins: Amino acids and glucose do not need any modification because they can be directly absorbed by active, passive and facilitated diffusion. (page-265).

see the dental formula for adult