Biology (Zoology and Botany)

(d) Vagus

The vagus nerve (cranial nerve X) is the longest and most widely distributed cranial nerve. It runs down through the neck and thorax into the abdomen, supplying the heart, lungs and most abdominal viscera, so it is the only cranial nerve that supplies the body beyond the head and neck.

(c) 12 pairs

Rabbit, like other mammals, reptiles and birds (the amniotes), has 12 pairs of cranial nerves, from olfactory (I) to hypoglossal (XII). Lower vertebrates such as the frog have only 10 pairs.

(c) nematodes

Nematodes (roundworms, e.g. Ascaris) have a pseudocoelom, a body cavity that is not completely lined by mesoderm. Annelids have a true coelom, platyhelminthes are acoelomate, and cnidarians have no body cavity other than the gastrovascular cavity.

(a) mitochondria

Of the organelles listed, mitochondria are the largest (about 0.5-10 $\mu$m in length). The nucleolus lies inside the nucleus, the centriole is about 0.2 $\mu$m, and lysosomes are about 0.1-1 $\mu$m. (The nucleus is the largest organelle overall, but it is not an option.)

(a) Mangifera indica

Mango belongs to the family Anacardiaceae. Morus alba is mulberry, and Aegle marmelos is bael.

(c) it can replicate

A genetic material must be able to store information and make exact copies of itself so that traits pass from cell to cell and generation to generation. DNA does this by semi-conservative replication.

(a) 1RNA

Influenza virus has an RNA genome (single-stranded, negative-sense, in 8 segments) and no DNA. Of the options, the single RNA genome is the correct choice.

(b) Cytoplasm

Glycolysis, the breakdown of glucose to two molecules of pyruvate, takes place in the cytosol and needs no oxygen. The later steps (Krebs cycle, electron transport) occur in the mitochondria.

(a) ribosome

Ribosomes read mRNA and assemble amino acids into polypeptides (translation), so they are called the protein factories of the cell.

(b) Ancylostoma

Ancylostoma (hookworm) lives in the small intestine and is an intestinal nematode. Trypanosoma and Plasmodium live in blood, and Schistosoma (blood fluke) lives in the blood vessels.

(a) trypanosome

African sleeping sickness is caused by Trypanosoma brucei gambiense and T. b. rhodesiense, transmitted by the tsetse fly (Glossina).

(c) hypotonic

Plasmolysis is shrinkage of the protoplasm away from the cell wall when water leaves the cell by exosmosis. It occurs when the external solution is hypertonic, that is, the cell sap is hypotonic relative to the surroundings. In an isotonic medium there is no net movement of water, so (c) is the best option.

(a) Salivary amylase

Carnivores eat little starch, and their saliva lacks amylase. Protein and fat digestion proceed with pepsin, trypsin and lipase.

(b) Eight

The frog has nine vertebrae and a urostyle. The first to seventh are procoelous, the eighth is amphicoelous (concave at both ends), and the ninth is biconvex.

(d) Mnemotaxis

Mnemotaxis is orientation using memory of landmarks. A honey bee returns to flowers it has visited by remembering their location and surrounding landmarks.

(c) Inflorescences

The edible white curd of cauliflower (Brassica oleracea var. botrytis) is a mass of undeveloped, fleshy flower clusters, that is, an inflorescence.

(a) Urinary bladder

Transitional epithelium lines the urinary bladder, ureters and part of the urethra. Its cells change shape, flattening when the organ stretches and becoming cuboidal when it is empty.