Ecology 2 (HL)

Question 1

Give an example of a ‘parasitic’ pyramid of numbers.

Answer 1

Question 2

Give an example of an inverted pyramid of numbers.

Answer 2

Question 3

Define competition, and differentiate between contest and scramble competition.

Answer 3

1. Competition is when organisms actively struggle for a scarce resource.
2. Contest competition occurs when there’s an active physical struggle between two individual organisms.
3. Scramble competition occurs when all competing organisms get some of the resource.

Question 4

What is ‘predation’? Differentiate between a predator and the prey.

Answer 4

1. Predation is the catching, killing and eating of another organism.
2. A predator is an organism that catches, kills and eats another organism.
3. The prey is the organism eaten by the predator.

Question 5

What is ‘parasitism’? Differentiate between exoparasites and endoparasites.

Answer 5

1. Parasitism is when one organism obtains its food from, and to the disadvantage of, another organism of a different species. The two organisms live in close association.
2. Exoparasites live on the outside of their host.
3. Endoparasites live on the inside of their host.

Question 6

What is the difference between symbiosis and mutualism?

Answer 6

1. Symbiosis occurs when two organisms of different species have to live in close association and where at least one benefits.
2. Mutualism occurs when this ‘symbiotical relationship’ benefits both organisms (e.g. w/ nitrogen-fixing bacteria living in the nodules of legumes).

Question 7

Name three factors that affect predator-prey relationships.

Answer 7

1. Availability of food.
2. Concealment (mostly of prey).
3. Movement/relocation of predators.