Ecology

Question 1

Bioaccumulation

Answer 1

fat-soluble toxins (mercury, PCBs, DDT, toxins from dinoflagellates) are not excreted well and so they build up in the tissue. Top carnivores have the highest levels of all, as they essentially accumulate toxin from all the levels below them

Question 2

Nutrient Cycles

Answer 2

energy is the only thing put into an ecosystem, all other components are continually recycled

Question 3

Nitrogen Cycle

Answer 3

nitrogen is the major component of the atmosphere and is found in various biomolecules such as protein and nucleic acid

• bacteria
• cyanobacteria

Question 4

bacteria and nitrogen cycle

Answer 4

• bacteria convert nitrogenous (ammonification) waste products into ammonium.
• bacteria in soil or water convert (nitrification) the ammonium to nitrites (NO2 -)
• Other bacteria such as Nitrobacter covert it nitrates (NO3 -).

Nitrates can be used by plants

Question 5

other bacteria and nitrogen cycle

Answer 5

mostly cyanobacteria, but sulfur bacteria and some archaea can do nitrogen fixation (convert (N2) atmospheric nitrogen into NH or ammonium NH4 + that is usable by living organisms.

symbiotic relationship in the roots of certain plants (legumes) and provide the plants with nutrients

Question 6

symbiosis

Answer 6

two organisms living together
mutualism
commensalism
parasitism

Question 7

mutualism

Answer 7

both organisms benefit- bacteria that digest cellulose in the stomach of cows or human intestinal bacteria would be an example

Question 8

commensalism

Answer 8

one benefits and one is not affected-orchids growing on trees or remoras on sharks would be an example. Different bacteria and bacteria and yeast can also exist in this relationship

Question 9

parasitism

Answer 9

one benefits and the other is harmed- worms such as tapeworms are an example or malaria, the host is not killed but is certainly less viable

Question 10

Natural Selection

Answer 10

“survival of the fittest” - all organisms exist under the selection pressure. anything that decreases your chances of reproduction is a selection pressure. organisms that adapt to or survives the pressure will be most successful.