Which of these is an effect of an algal bloom ? a. bacteria are introduced to break down hydrocarbons in an oil spill . b. materials containing metal are toxic to organisms that live in them . c. the mercury contained in fish builds up in animals that eat the fish . d. an increase growth in microorganisms results in oxygen depletion (apex)

The correct answer is option D

The growth of algal bloom is caused due to excessive runoff rich in the nutrients like nitrogen and phosphorous. This run off comes from the agricultural field.

These nutrients aids in the growth of the algae(microorganisms) in large number. This growth forms a layer on the water body and use the oxygen present in the water and makes the water oxygen deficient.

the correct answer is: b. pantala flavescens, because these organisms would have a high level of genetic variation due to sexual reproduction.  

because involves two organisms (parents) whose genetic material combines, sexual reproduction leads to genetic variation in new generations of offspring. the offspring is an unique organism, with new genome, more protected with the higher ability to adapted. this process is fundamental to evolution.

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.