Forests cover one-third of Earth’s landmass. These ecosystems all provide vital ecological and economic services. Why might it be more difficult to convince the human population of the value of a forest’s ecological services as opposed to the value of its economic services? A. Ecological services cannot be monetarily estimated.

B. Ecological services are not easily observed by the average human.

C. Ecological services detail the cost of use on the environment.

D. Ecological services are only a focus of less developed economies.

we solve the problem using the hardy-wineberg equation.

let us start with the homozygous recessive proportion of individuals with sickle cell anaemia,

we have the proportion as q² = 0.25.

∴ q = 0.5 (frequency of hbs in population)

further,

solving for the frequency of normal cell by using the fact that,

p + q = 1

∴ p = 1 - 0.5 = 1 - 0.5 = 0.5

now we can calculate 2pq in p² + 2pq + q², which is the frequency for heterozygous carriers of sickle cell anaemia,

∴ 2pq = 2 x 0.5 x 0.5 = 0.5

and the homozygous normal cell individuals proportion is given by the expression,

∴ p² = 0.5² = 0.25

hence, the carriers for sickle cell anaemia are in proportion, 0.5, or 50%.