Why do some organisms use both types of reproduction? {sexual and asexual reproduction}

What kind of seafood would you expect to have the highest levels of mercury and why? kelp, because they use the sun to photosynthesize on the bottom trophic level. oysters, because they filter feed on plankton on a lower trophic level. small fish, because they eat plankton on a higher trophic level. sharks, because they feed on organisms on a higher trophic level.

What will happen to a population of predators if there is a sudden, temporary increase in the number of prey? a. the population of predators will be uniform with no change. b. the population of predators will increase first and then decrease slowly. c. the population of predators will increase continuously.

Could someone me with number one you