The correct answer is: Artificial selection (selective breeding).
Artificial Selection is a form of selection, totally influenced by human, in which traits that should be passed onto offspring are chosen by human. Selective breeding was used long before the genetics was discoverd. Farmers used individuals with beneficial traits, larger in size, with bigger fruit etc.
Hunting is also one type of selective breeding, since the hunters choose the animal and remove it from the population (gene pool), leaving the “weaker” to pass on to the next generation.
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Full Question:</u></h2>
In the family tree below, people with the recessive trait of attached earlobes are shaded gray.
What must be true about the person labeled "A"?
A. It is a male with at least one dominant allele.
B. It is a male with two dominant alleles.
C. It is a female with at least one dominant allele.
D. It is a female with two dominant alleles.
<h2><u>Answer:</u></h2>
Its a male with atleast one dominant allele.
Option A.
<h3><u>Explanation:</u></h3>
The gene for the attached earlobe is recessive while the gene for the free earlobes is dominant. In the phylogenetic tree, we can see that both the father and mother aren't having attached earlobes. So both of them are having atleast one dominant allele which makes them have free earlobe.
In the F1 offsprings, one of the female and a male is having free earlobes. So both of them have atleast one dominant allele. The 2nd female is having an attached earlobe. So both the recessive allele have come form one parent each. So both of them are heterozygous.
Thus, the male marked as A atleast have one dominant allele. He can be a homozygous dominant, but the probability is 25%.
Answer:
Cool dense water sinks to the ocean floor.
Warm water replaces cool surface water.
Wind blowing parallel to the shore causes upwelling of cool water.