CSET CSET Subtest II Life Sciences 4

Question 1

Which mechanism drives natural selection according to Darwin's theory of evolution?

Accepted Answer

Differential reproductive success based on heritable traits

Answer

Natural selection acts when individuals with heritable advantageous traits survive and reproduce more than others.

Question 2

A cell in G2 phase of the cell cycle has a DNA content of 8 picograms. What was the DNA content at the start of S phase?

Accepted Answer

4 picograms

Answer

S phase replicates DNA, so before replication (G1 end/S start) the cell had 4 pg; after S phase it has 8 pg.

Question 3

Which type of ecological succession occurs on bare rock with no prior soil?

Accepted Answer

Primary succession

Answer

Primary succession begins on lifeless substrate like bare rock, starting with pioneer species such as lichens.

Question 4

The Hardy-Weinberg principle states that allele frequencies in a population remain constant if which condition is met?

Accepted Answer

Natural selection, mutation, migration, and genetic drift are absent

Answer

Hardy-Weinberg equilibrium requires no mutation, random mating, no selection, no gene flow, and large population size.

Question 5

Which molecule acts as the final electron acceptor in aerobic cellular respiration?

Accepted Answer

Oxygen

Answer

Oxygen accepts electrons at the end of the electron transport chain, combining with hydrogen ions to form water.

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