Question 1

Which of the following best describes the role of the anticodon on a tRNA molecule during translation?

Accepted Answer

It base-pairs with a complementary codon on the mRNA to ensure the correct amino acid is added.

Question 2

A patient is prescribed an antibiotic that specifically targets bacterial ribosomes. Which of the following best explains why this antibiotic does not harm the patient’s own cells?

Accepted Answer

Bacterial ribosomes are structurally different from eukaryotic ribosomes, allowing selective targeting.

Question 3

During translation, what is the correct order in which a tRNA moves through the ribosomal binding sites?

Accepted Answer

A → P → E

Question 4

Which of the following events occurs during the termination phase of translation?

Accepted Answer

A release factor binds to the stop codon in the A site, triggering hydrolysis of the polypeptide from the tRNA.

Question 5

A mutation changes a DNA sequence from CTC to CAC in the beta-globin gene. What is the consequence of this mutation at the protein level, and which disease does it cause?

Accepted Answer

It substitutes valine for glutamic acid, causing sickle cell anemia.

Question 6

Which of the following modifications is NOT part of eukaryotic pre-mRNA processing?

Accepted Answer

Removal of exons by the spliceosome

Question 7

Which of the following best explains why water is an excellent solvent for ionic compounds?

Accepted Answer

Water’s polarity allows it to surround and separate ions, dissolving them.

Question 8

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

Accepted Answer

Both Bacteria and Archaea are prokaryotic and lack membrane-bound organelles.

Question 9

A red blood cell is placed in a hypotonic solution. What is the most likely outcome, and why?

Accepted Answer

The cell will burst (lyse) because water enters the cell.

Question 10

Which of the following equations correctly represents cellular respiration?

Accepted Answer

$$C_6H_{12}O_6$ + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP$$

Question 11

Which process is responsible for the breakdown of polymers into monomers, and what molecule is required for this reaction?

Accepted Answer

Hydrolysis; water is added.

Question 12

Which of the following best describes the function of enzymes in biological systems?

Accepted Answer

They lower the activation energy, speeding up reactions without being consumed.

Question 13

A scientist uses CRISPR-Cas9 to correct a point mutation in hematopoietic stem cells from a sickle cell patient. What is the main ethical concern if this technology is applied to human germline cells?

Accepted Answer

It may result in the creation of 'designer babies' with heritable genetic changes.

Question 14

Which of the following is a correct sequence of events during the cell cycle in a eukaryotic cell?

Accepted Answer

G₁ → S → G₂ → M

Question 15

Which of the following statements about photosynthesis is correct?

Accepted Answer

Light-dependent reactions split water, releasing O₂ and generating ATP and NADPH.

Question 16

Which of the following best explains why saturated fats are solid at room temperature while unsaturated fats are liquid?

Accepted Answer

Saturated fats have no double bonds, allowing tight packing; unsaturated fats have double bonds causing kinks.

Question 17

Which of the following is a direct result of the second law of thermodynamics in biological systems?

Accepted Answer

Energy transformations increase the entropy (disorder) of the universe.

Question 18

Which of the following best describes the difference between meiosis I and meiosis II?

Accepted Answer

Meiosis I separates homologous chromosomes, reducing ploidy; meiosis II separates sister chromatids.

Question 19

Which of the following is a property of hydrogen bonds that is crucial for the structure of DNA?

Accepted Answer

They stabilize the base pairing between complementary strands.

Question 20

A solution has a pH of 4. Which of the following statements is true about this solution?

Accepted Answer

It is acidic and has a high concentration of H⁺ ions.

Central Dogma, Gene Expression, and Cellular Biology: Comprehensive Study Notes

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