Biology Test Biology Ecology and Evolution 4

Question 1

What is 'biological magnification' (biomagnification) in an ecosystem?

Accepted Answer

The accumulation of toxins at higher trophic levels

Answer

Biomagnification occurs when pollutants like DDT or mercury concentrate at increasingly higher levels as they move up the food chain.

Question 2

Which concept explains why two species with identical ecological niches cannot coexist in the same habitat?

Accepted Answer

Competitive exclusion principle

Answer

The competitive exclusion principle states that two species competing for the same limiting resource cannot stably coexist; one will outcompete the other.

Question 3

What type of natural selection favors individuals at both extremes of a trait distribution over those in the middle?

Accepted Answer

Disruptive selection

Answer

Disruptive (diversifying) selection increases the frequency of extreme phenotypes and can eventually lead to the divergence of a population into two distinct groups.

Question 4

How does mutualism differ from commensalism in terms of ecological benefit?

Accepted Answer

Mutualism benefits both species; commensalism benefits only one

Answer

In mutualism both species gain a fitness benefit (e.g., clownfish and anemones), while in commensalism only one species benefits and the other is unaffected.

Question 5

In population ecology, what does the logistic growth model add to the exponential growth model?

Accepted Answer

Carrying capacity (K)

Answer

The logistic model incorporates carrying capacity (K), limiting population growth as resources become scarce and population size approaches the environmental maximum.

Biology Practice Test

Biology Practice Test

Biology Test Biology Ecology and Evolution 4