Question 1

Which of the following best describes a multifactorial trait?

Accepted Answer

A trait controlled by multiple genes and environmental factors.

Question 2

A researcher is studying a trait controlled by 4 genes. According to the formula $$	ext{Number of phenotypic classes} = 2n + 1$$, how many phenotypic classes should she expect to observe?

Accepted Answer

$$9$$

Question 3

In a twin study, monozygotic twins show a much higher concordance for a trait than dizygotic twins. What does this suggest about the trait?

Accepted Answer

The trait is likely to be strongly influenced by genetic factors.

Question 4

Which of the following statements about heritability is correct?

Accepted Answer

Heritability is the correlation of offspring phenotype with parental phenotype.

Question 5

A patient with a mutation in the leptin gene is most likely to experience which of the following?

Accepted Answer

Increased hunger and weight gain due to impaired signaling to the brain.

Question 6

The thrifty gene hypothesis is used to explain which phenomenon?

Accepted Answer

The high prevalence of obesity in certain Pacific island populations due to selection for fat storage.

Question 7

Which of the following is NOT a function of melanin in human skin?

Accepted Answer

Increasing vitamin D production in low sunlight.

Question 8

A Manhattan plot is most useful for which of the following?

Accepted Answer

Displaying the results of a genome-wide association study to identify genes involved in a trait.

Question 9

A child is born with a genetic disorder caused by a mutation not present in either parent. This is best described as:

Accepted Answer

A de novo mutation.

Question 10

Which chromosomal abnormality is characterized by having three copies of a particular chromosome?

Accepted Answer

Trisomy

Question 11

A karyotype shows 47 chromosomes, including three copies of chromosome 21. What is the best description of this condition?

Accepted Answer

Trisomy 21

Question 12

Which prenatal screening method carries the highest risk of miscarriage but can be performed earlier in pregnancy?

Accepted Answer

Chorionic villus sampling

Question 13

Why does the risk of aneuploidy increase with maternal age?

Accepted Answer

Oocytes are arrested in metaphase of meiosis I for a long time, increasing the chance of non-disjunction.

Question 14

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

Accepted Answer

Labeling bacteriophage DNA with $$^{32}P$$ and protein with $$^{35}S$$ showed only $$^{32}P$$ entered bacteria.

Question 15

Which scientists are credited with discovering the double helix structure of DNA?

Accepted Answer

Watson, Crick, Wilkins, and Franklin

Question 16

During DNA replication, which strand is synthesized continuously toward the replication fork?

Accepted Answer

Leading strand

Question 17

Which of the following best describes the structure of a nucleosome?

Accepted Answer

DNA wrapped around histone proteins.

Question 18

Which process removes introns and joins exons in pre-mRNA?

Accepted Answer

RNA splicing

Question 19

A mutation changes the DNA sequence from ATG to ATA in the coding region of a gene. Using the genetic code, what is the most likely effect on the protein?

Accepted Answer

The start codon is lost, potentially preventing translation initiation.

Question 20

Which of the following statements about prions is correct?

Accepted Answer

Prions are infectious proteins that cause normal proteins to misfold.

Genetics Study Guide: Complex Traits, Cytogenetics, DNA, and Gene Expression

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