To perform a testcross, scientists cross an organism with an unknown genotype with a homozygous recessive organism.
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Answer:
mouth ⇒ oesophagus (gullet, food pipe) ⇒ stomach ⇒ duodenum ⇒ ileum ⇒ colon ⇒ rectum ⇒ anus
Explanation:
The things that birds have attached to their bodies called their wings, a left one and a right one, cause them to have the ability to fly.
The answer to your question is <span>B. Natural selection acted on the variation that was present in the population.
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