Biology Questions

Random mutations are the ultimate source of genetic variation. Mutations are likely to be rare and most mutations are neutral or deleterious, but in some instances, the new alleles can be favored by natural selection. Polyploidy is an example of chromosomal mutation.

Mutations are changes in the DNA. A single mutation can have a large effect.

1) mutation - an alteration in DNA sequence, various types

2) intragenic recombination - results in entirely new associations of genes not present in either parental genome.

Two forms of intragenic recombination:

a) crossing over
b) independent assortment
3) reticulation – acquisition of genetic material from unrelated or relatively unrelated sources (e.g., hybrid species, horizontal gene transfer).

The organs protected by the thoracic cage include the lungs and the heart.

Salivary glands of man are 3 pairs = 6. They are one pair of parotid glands, one pair of sub-maxillary or sub-mandibular glands and one pair of sub-lingual glands.

A vitamin is an organic molecule that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism.

There are 13 essential vitamins that our body need. They are categorized into 

1. Water soluble

2. Fat soluble

Water-soluble vitamins dissolve in water, which means these vitamins and nutrients dissolve quickly in the body. Unlike fat-soluble vitamins, water-soluble vitamins are carried to the body’s tissues, but the body cannot store them.

Water-soluble vitamins are Vitamin B1, B2, B3, B5, B12, B6, B7 & B9 and Vitamin C.

Fat-soluble vitamins are soluble in fats. They are absorbed by fat globules that travel through the small intestines and into the general blood circulation within the body. Unlike water-soluble vitamins, fat-soluble vitamins are stored in the body when they are not in use.

Fat-soluble vitamins are - Vitamin A, D, E and K.

Trypanasoma is a protozoan animal. It lives as a parasite in the blood and later invades the cerebrospinal fluid to cause the sleeping sickness. This parasite is transmitted by the Tsetse fly.

Synapsis is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them.

Synapsis takes place during prophase I of meiosis.

It is also called as Syndesis.