Biology Past Questions

Protein digestion occurs in the stomach and duodenum in which 3 main enzymes, pepsin secreted by the stomach, trypsin and chymotrypsin secreted by the pancreas, break down food proteins into polypeptides that are then broken down by various exopeptidases and dipeptidases into amino acids.

Carbohydrate digestion begins in the mouth with the mechanical action of chewing and the chemical action of salivary amylase. Carbohydrates are not chemically broken down in the stomach, but rather in the small intestine.

Lipids, or fat on the other hand, go undigested in your digestive tract until they reach your small intestine, where they meet bile. Bile contains bile salts, which act as an emulsifier of lipids. This breaks the large fat droplets into smaller droplets that are then easier for the fat-digesting enzyme pancreatic lipase to digest.

The conversion of excess amino acids into urea occurs in the liver.

In the human body, deamination takes place primarily in the liver. In situations of excess protein intake, deamination is used to break down amino acids for energy. The amino group is removed from the amino acid and converted to urea.

For pollination and fruit formation, the essential part(s) of the flower should be the pistil or gynoecium.

Pollination occurs in the stigma of a flower, which is the female reproductive part of the flower. After pollination, the seeds grow in the base of the pistil, which is called the ovule.

The Malpighian or Bowman's capsule is a cup-like sack at the beginning of the tubular component of a nephron in the mammalian kidney that performs the first step in the filtration of blood to form urine.

A potometer is a device used for measuring the rate of water uptake of a leafy plant shoot. The main reason for water uptake by a cut shoot is transpiration (evaporation in plants) and is effected by the transpiration stream.

In holophytic nutrition, an organism produces its own food through photosynthesis which is the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water.

Holozoic nutrition is a method of nutrition used by animals that involves the ingestion of liquid or solid organic material, digestion, absorption and assimilation of it to utilize it.

The most prominent roles of mitochondria are to produce the energy currency of the cell, ATP (adenosine triphosphate), through respiration, and to regulate cellular metabolism.

Anaerobic respiration is the process of producing cellular energy without oxygen. In anaerobic respiration, glucose is converted to carbon dioxide and alcohol.

The uriniferous tubule is the functional unit of the kidney, composed of a long convoluted portion (nephron) and an intrarenal collecting duct, through which renal filtrate from the renal corpuscle flows and is changed to urine by reabsorption and secretion.

If the bark and phloem tissue of a woody shoot are peeled off by ringing, the whole plant will eventually die because manufactured food does not reach the roots.