Question 1

Which of the following best describes Chargaff’s Rule regarding the composition of DNA?

Accepted Answer

The amount of adenine equals the amount of thymine, and the amount of cytosine equals the amount of guanine.

Question 2

A scientist is studying a DNA molecule and finds that 30% of its bases are cytosine. According to Chargaff’s Rule, what percentage of the bases are adenine?

Accepted Answer

$$20\%$$

Question 3

Which experiment provided direct evidence that DNA, not protein, is the genetic material by using radioactive labeling of bacteriophages?

Accepted Answer

Hershey-Chase Experiment

Question 4

During DNA replication, which enzyme is responsible for adding nucleotides to the growing DNA strand?

Accepted Answer

DNA polymerase

Question 5

A mutation changes a codon from $$	ext{UAC} to$$ $$	ext{UAA}. $$What type of mutation is this, and what is its likely effect on the protein?

Accepted Answer

Nonsense mutation; results in a premature stop codon

Question 6

Which of the following statements about the directionality of DNA is correct?

Accepted Answer

DNA strands are antiparallel, with one running $$5' \rightarrow 3'$$ and the other $$3' \rightarrow 5'.$$

Question 7

Which process involves the conversion of mRNA into a polypeptide chain, and where does it occur in eukaryotic cells?

Accepted Answer

Translation; cytoplasm

Question 8

A population of beetles is exposed to a pesticide. After several generations, most beetles are resistant. Which component of natural selection does this scenario best illustrate?

Accepted Answer

Differential survival and reproduction

Question 9

Which of the following would disrupt Hardy-Weinberg equilibrium in a population?

Accepted Answer

Gene flow due to migration

Question 10

If $$p is $$the frequency of the dominant allele and $$q is $$the frequency of the recessive allele in a population, which equation represents the expected genotype frequencies under Hardy-Weinberg equilibrium?

Accepted Answer

$$p^2 + 2pq$$ + $$q^2 = 1$

Question 11

A small population of cheetahs experiences a drastic reduction in numbers due to a natural disaster. The resulting population has reduced genetic diversity. What is this an example of?

Accepted Answer

Bottleneck effect

Question 12

Which of the following is NOT a requirement for a population to be considered a biological species under the Biological Species Concept?

Accepted Answer

Occupying the same geographic area

Question 13

Which of the following is an example of a mutualistic relationship?

Accepted Answer

Bees pollinating flowers while collecting nectar

Question 14

Which process removes carbon dioxide from the atmosphere and incorporates it into organic molecules?

Accepted Answer

Photosynthesis

Question 15

Which of the following best describes an r-selected species?

Accepted Answer

Short lifespan, many offspring, little parental care

Question 16

A non-native plant species is introduced to a new ecosystem and rapidly spreads, outcompeting native plants. What is the most likely consequence for the ecosystem?

Accepted Answer

Decreased biodiversity

Question 17

Which of the following is a direct result of the greenhouse effect?

Accepted Answer

Increase in average global temperatures

Question 18

Which of the following best explains why habitat fragmentation can threaten species survival?

Accepted Answer

It reduces available resources and isolates populations.

Question 19

Which of the following statements about gene expression is correct?

Accepted Answer

Gene expression can be regulated by epigenetic modifications such as DNA methylation.

Question 20

A population of frogs has the following genotype frequencies: $$AA = 0.36$$, $$Aa = 0.48$$, $$aa = 0.16. $$What are the allele frequencies of $$A$$ and $$a$$?

Accepted Answer

$$A = 0.6$$, $$a = 0.4$$

Comprehensive Study Notes: DNA Structure & Gene Expression, Evolution, and Ecology

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