Identify the term by its definition:
1. Localization of genes using microscopy.
2. Using genetic crosses to determine relative recombination distances.
3. Using DNA cloning to determine nucleotide sequence distance

1. Cytogenetic mapping.

2. Linkage mapping.

3. Physical mapping.

Explanation:

1. Cytogenetic mapping - Gene localization using microscope.

A cytogenetic mapping is defined as the visual appearance of genes when seen by using microscope. The genes are stained and seeing under microscope that shows visually distinct regions, called dark and light bands and provide unique appearance to the genes.

2. Linkage mapping - recombination distance s measured using genetic crosses.

Linkage mapping is done using linkage analysis by observing the genes linked to the offspring. It do not show physical distances but only shows genetic distances and how the two genes inherited together.

3. Physical mapping - Determine nucleotide sequence distance using DNA cloning.

Physical mapping is a technique by which physical distance between DNA base pairs can be evaluated with the help of DNA makers and also determine DNA base pairs sequences with high accuracy.