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).

A neuron or nerve cell is a cell that carries electrical impulses. Neurons are the basic units of the nervous system and its most important part is the brain. Every neuron is made of a cell body (also called a soma), dendrites and an axon. Dendrites and axons are nerve fibres.

The gap between two communicating neurons is termed Synaptic cleft.

A tertiary consumer is an animal that obtains its nutrition by eating primary consumers and secondary consumers.

Usually tertiary consumers are carnivorous predators, although they may also be omnivores, which are animals that feed on both meat and plant material.

Tertiary consumers often occupy the top trophic level, and so are predated by no other animals; in this case they are called "apex predators". However, when they die their bodies will be consumed by scavengers and decomposers.

Cellular repiration takes place in the mitochodria.

There are 3 phases of cellular respiration. They are:

1. Glycolysis (Fermentation),

2. Krebs Cycle, and

3. Electron Transport.

Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport takes place in the mitochondria.

In a nucleosome, the DNA is wrapped around histone octamer.