Biology Quiz 7

Barr body is the inactive X-chromosome in the somatic cells of mammalian females. Human females have two X chromosomes, while males have one X and one Y. In all of the female somatic cells, which don't take part in sexual reproduction, one of the X chromosomes is active, and the other is inactivated in a process called lyonization, becoming the Barr body.

Men and women have an equal number of bones which is 206. A baby's body has about 300 bones at birth. These eventually fuse (grow together) to form the 206 bones that adults have.

All eukaryotic cells have a surrounding plasma membrane (cell membrane). The plasma membrane is made up of a phospholipid bilayer with embedded proteins that separate the internal contents of the cell from its surrounding environment.

The ability of the eye to see in the dark is due to the production of a purple pigment known as Rhodopsin. Rhodopsin, also known as visual purple, is the photopigment used by the rods and is the key to night vision. It is a pigment-containing sensory protein that converts light into an electrical signal.

A typical heart has four chambers (two upper and two lower). The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the more muscular right and left ventricles, pump blood out of the heart. The heart valves are gates at the chamber openings.

Mycobacterium Bovis, a bacterial species of the M. tuberculosis complex, is a pathogen that primarily infects cattle. However, humans also can become infected, most commonly through the consumption of unpasteurized milk products from infected cows.

When one gene pair hides the effect of the other unit. The phenomenon is referred to as epistasis. Epistasis is the interaction between two non-linked genes which causes one gene to mask the expression of the other in the phenotype.

The human-infective stage of malaria is sporozoites from the salivary gland of an infected mosquito. The sporozoites grow and multiply in the liver to become merozoites.

Pulmonary Vein brings clean blood from the lungs into the heart. Its function is to transport oxygenated blood from the lung alveoli into the left atria.

The adult human brain weighs about 1200–1400 gm which is about 2% of the total body weight. The weight of an average human brain is about 1.36 kg.