Question 1

Which of the following best describes the difference between negative feedback and positive feedback in biological systems?

Accepted Answer

Negative feedback maintains homeostasis by counteracting changes, while positive feedback reinforces the direction of change.

Question 2

A scientist observes that a certain plant species only grows in areas with high nitrogen content in the soil. She hypothesizes that nitrogen is essential for the plant's growth. Which of the following best describes the type of reasoning she is using?

Accepted Answer

Inductive reasoning

Question 3

Which of the following statements about the three domains of life is correct?

Accepted Answer

Archaea and Eukarya share a more recent common ancestor with each other than with Bacteria.

Question 4

During which phase of mitosis do sister chromatids separate and move toward opposite poles of the cell?

Accepted Answer

Anaphase

Question 5

A researcher is studying a cell that has 24 chromosomes during G1 phase. After meiosis II, how many chromosomes will each gamete contain?

Accepted Answer

$$12$$

Question 6

Which of the following mechanisms does NOT contribute to genetic variation in sexually reproducing organisms?

Accepted Answer

Replication of DNA during S phase

Question 7

In Mendel’s experiments, crossing true-breeding purple-flowered plants with true-breeding white-flowered plants resulted in all purple-flowered offspring in the F1 generation. What is the most likely explanation for this observation?

Accepted Answer

The purple allele is dominant over the white allele.

Question 8

A woman who is a carrier for a recessive X-linked disorder and a man who does not have the disorder have a son. What is the probability that their son will have the disorder?

Accepted Answer

$$0.5$$

Question 9

Which chromosomal abnormality is characterized by the presence of an extra chromosome 21 and is associated with intellectual disability and characteristic facial features?

Accepted Answer

Down Syndrome

Question 10

Which experiment provided the first strong evidence that DNA, and not protein, is the genetic material in cells?

Accepted Answer

Hershey and Chase’s bacteriophage experiment

Question 11

During DNA replication, which enzyme is responsible for unwinding the DNA double helix?

Accepted Answer

Helicase

Question 12

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

DNA polymerase can only add nucleotides to the 3' end, so the lagging strand is synthesized discontinuously.

Question 13

A point mutation changes a codon from $$UAC ($$tyrosine) to $$UAA. $$What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 14

Which of the following statements about the genetic code is TRUE?

Accepted Answer

The genetic code is nearly universal among all organisms.

Question 15

Which process occurs in the nucleus of eukaryotic cells but not in prokaryotic cells?

Accepted Answer

RNA splicing

Question 16

A woman with type AB blood and a man with type O blood have a child. What are the possible blood types of their child?

Accepted Answer

Type A or Type B

Question 17

Which of the following best describes pleiotropy?

Accepted Answer

One gene affects multiple traits.

Question 18

Which of the following is a real-world example of polygenic inheritance?

Accepted Answer

Human skin color

Question 19

Why are extranuclear genes in mitochondria and chloroplasts typically inherited from the mother?

Accepted Answer

Eggs contain most of the cytoplasm, including mitochondria and chloroplasts.

Question 20

A cell is observed to have a single X chromosome and no second sex chromosome (XO). Which syndrome does this individual most likely have?

Accepted Answer

Turner Syndrome

Core Principles of Biology: Evolution, Cell Division, Genetics, and Gene Expression

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