Question 1

Which of the following best explains why unsaturated fatty acids are more likely to be liquid at room temperature compared to saturated fatty acids?

Accepted Answer

Unsaturated fatty acids have double bonds that introduce kinks, preventing tight packing of molecules.

Question 2

During DNA replication, which enzyme is responsible for synthesizing short RNA primers that provide a starting point for DNA polymerase?

Accepted Answer

Primase

Question 3

A mutation changes a codon from $	ext{GAG}$ (glutamic acid) to $	ext{GTG}$ (valine) in the hemoglobin gene, resulting in sickle cell anemia. What type of mutation is this?

Accepted Answer

Missense mutation

Question 4

Which of the following statements about the directionality of nucleic acids is correct?

Accepted Answer

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

Question 5

Which of the following best describes the role of the ribosome during translation?

Accepted Answer

It facilitates the matching of tRNA anticodons to mRNA codons and catalyzes peptide bond formation.

Question 6

A DNA molecule has 30% adenine. According to Chargaff's rules, what percentage of guanine would you expect?

Accepted Answer

$20\%$

Question 7

Which of the following molecules would diffuse most rapidly across a pure phospholipid bilayer?

Accepted Answer

$\mathrm{O}_2$

Question 8

During transcription, which strand of DNA serves as the template for RNA synthesis?

Accepted Answer

The strand that is complementary to the RNA sequence (template strand)

Question 9

Which of the following best describes the structure of a phospholipid and its behavior in water?

Accepted Answer

It has a polar head and nonpolar tails, making it amphipathic and able to form bilayers in water.

Question 10

A scientist is studying a mutation that introduces a premature stop codon in the coding region of a gene. What is the most likely consequence of this mutation?

Accepted Answer

The resulting protein will be truncated and likely nonfunctional.

Question 11

Which of the following best explains why DNA replication is described as 'semi-conservative'?

Accepted Answer

Each new DNA double helix consists of one old strand and one newly synthesized strand.

Question 12

Which of the following is a function of telomerase in eukaryotic cells?

Accepted Answer

It extends the ends of linear chromosomes to prevent loss of genetic information.

Question 13

Which of the following best describes the difference between a codon and an anticodon?

Accepted Answer

A codon is a three-nucleotide sequence on mRNA, while an anticodon is a complementary sequence on tRNA.

Question 14

Which of the following best explains why phospholipids form bilayers in water?

Accepted Answer

Their hydrophilic heads interact with water while hydrophobic tails avoid water, resulting in a bilayer.

Question 15

Which of the following statements about RNA polymerase is correct?

Accepted Answer

RNA polymerase can start synthesis without a primer, unlike DNA polymerase.

Question 16

A researcher is studying the permeability of a cell membrane to various molecules. Which of the following would cross the membrane most slowly?

Accepted Answer

Glucose

Question 17

Which of the following best describes the function of cholesterol in animal cell membranes?

Accepted Answer

It modulates membrane fluidity by preventing tight packing of phospholipids at low temperatures.

Question 18

During translation, what would be the anticodon on a tRNA that carries methionine if the mRNA codon is $5'	ext{-AUG-}3'$?

Accepted Answer

$3'	ext{-UAC-}5'$

Question 19

Which of the following best describes the difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose sugar and is more stable, while RNA contains ribose and is less stable.

Core Concepts in DNA, RNA, Replication, Genetic Code, and Membranes

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