Hat's a stalactite? a. large mound of dirt created by erosion b. poisonous mass found in caves that is formed by polluted water c. dripstone produced by a buildup of minerals precipitated from groundwater d. mound-shaped stone shaped by weathering

(amoeba sisters video recap: pedigrees and need

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.

Which cell organelle is the site for photosynthesis? a. chloroplast b. endoplasmic reticulum c. golgi apparatus d. lysosome