Feathers shape the bird and give rigidity to the wings. a. contour b. crop c. down d. powder

Study the diagram of a cell. which structure is found only in plant cells and functions in the process of photosynthesis? w x y z

Anton created a chart listing different types of materials. which best complete the chart?

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.