Question

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In DNA the structure and size of the four nitrogen bases allows only one kind of base to pair with one other kind. This is called the pre-pairing rule. Which of the following shows how bases pair in complementary strands of DNA?
A. A-A and T-T
B. A-C and T-G
C. A-G and T-C
D. A-T and C-G

____ is a source of genetic variation that involves the swapping of sections of chromosomes during meiosis.
A. Transcription
B. Crossing over
C. Translation
D. Fertilization

Answer 1

1st. D
A and G are double ringed while C and T are single ringed structures. A double ring pairs with a single ring. A with T and G with C.

2nd. Its crossing over which is responsible for genetic variations.

Answer 2

Thank you so much

Answer 3

Pleasure!