Billy and Johnny are brothers, but they do not look alike. Which one of the following pairs of factors contributed to this genetic variation?

A- Non-disjunction and mitosis.
B- Cytokinesis and cloning.
C- Crossing over and independent assortment.
D- Asexual reproduction and binary fission.

C- Crossing Over

Explanation:

Crossing over is essentially the gene shuffling and swapping around of genetic information.

A- is false because mitosis describes the building of nonsexual cells. So in terms of genetics, meiosis is the one you're looking for in this scenario.

B- Brothers are not clones.

D- Your parents had to have sex to produce a child. This is not Asexual.

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igneous rock formed from below the surface would have more crystals because

answer: because magma cools more slowly than lava

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.