Answer:
Option-D, a segment of DNA
Explanation:
A gene represents the particular segment of DNA which contains the instruction for the trait of an organism. The nucleotide sequence present in the segment provides the instruction in the form of codons.
The gene is present in the form of its alternative form called alleles which are located on the chromosomes at locus. The alleles represent the variants of the gene and therefore controls the two variety of a single trait.
Thus, Option-D is correct.
Natural selection can only occur because of a variety in a population. Natural selection refers to environmental factors that affect a population and causes some of the population to have more surviving offspring than others. An example is a giraffe with a longer neck will be more likely to survive and reproduce (as it can gather more food from taller trees)
Answer:
guard cells
Explanation:
they control the opening and closing of the stomata
When the upper water layers warm in the summer months, they become separated from deep water by a transition zone known as a thermocline. In a thermocline, the temperature decreases rapidly with small increases in depth. This phenomenon linking temperature change with depth is called temperature stratification.
