Biology Questions

Uracil is not found in DNA but found in RNA.

Prokaryotic cells lack a nucleus and do not have an extensive system of interior membranes. They are encased in a cell wall and many contain external structures such as a capsule, flagellum, or pili. Prokaryotes – have a relatively uniform interior that is not subdivided by internal membranes.

A pulse can be detected most easily in Arteries as they are under much greater pressure than veins because they are carrying blood away from the heart which is the pumping machine to force blood to move to all of the body.

Every time the hear contracts, it can be felt in an artery where a surge of blood has just been forced.

A capillary is too small to feel a pulse and a lacteal is part of the lymphatic system found in the small intestine.

A nitrogenous base, or nitrogen-containing base, is an organic molecule with a nitrogen atom that has the chemical properties of a base. The main biological function of a nitrogenous base is to bond nucleic acids together. A nitrogenous base owes its basic properties to the lone pair of electrons of a nitrogen atom.

In DNA, four bases have been found. They are

1. Adenine (A),

2. Guanine (G),

3. Cytosine (C) and

4. Thymine (T).

The first three of these bases are found in RNA also but the fourth which is Uracil (U) is absent in it.

RNA contains cytosine and uracil as pyrimidine bases while DNA has cytosine and thymine.

High frequency sound attacks the tympanic memberane and makes it defective. 120 decibles is too high a pitch to be heard and therefore it impairs the hearing ability.

Genetic drift or allelic drift is the change in the relative frequency in which a gene variant (allele) occurs in a population due to random sampling and chance.

When is genetic drift a major factor in evolution is

* When there is low gene flow.

* When there is no selective pressure.

* When there is a bottleneck.