Answer:
see below
Explanation:
their roots respond positively, growing down, into the soil, and their stems respond negatively, growing upward, to reach the sunlight.
Answer: Certain traits increase in frequency in a population because when recombination occurs during sexual reproduction, genes are usually shuffled so that each parent gives its offspring a random assortment of its genetic variation, so the frequency of a gene may increase in a population through this genetic variation. One quote from a source I read states, "When recombination occurs during sexual reproduction, genes are usually shuffled so that each parent gives its offspring a random assortment of its genetic variation. However, genes that are close together on the same chromosome are often assorted together. Therefore, the frequency of a gene may increase in a population through genetic hitchhiking if its proximal genes confer a benefit."(lumen) This quotes explains why certain traits increase in frequency in a population.
Work Cited: https://courses.lumenlearning.com/boundless-biology/chapter/population-evolution/