Question 1

Which of the following best explains why ice floats on water, and why this property is crucial for aquatic life in cold climates?

Accepted Answer

Hydrogen bonds in ice are more ordered and stable, making ice less dense than liquid water, so it floats and insulates the water below.

Question 2

A scientist is studying a molecule with the formula $$C_{6}H$$_{12}$$O_{6}$. Which class of macromolecule does this molecule belong to, and what is its monomeric form?

Accepted Answer

It is a carbohydrate; its monomer is a monosaccharide.

Question 3

Which of the following bonds is the strongest in biological systems and is responsible for holding together the atoms within a water molecule?

Accepted Answer

Covalent bond

Question 4

A mutation causes a single amino acid substitution in the primary structure of hemoglobin. Which level(s) of protein structure could be affected by this change?

Accepted Answer

Primary, secondary, tertiary, and possibly quaternary structures

Question 5

Which experiment provided direct evidence that DNA, not protein, is the genetic material in viruses that infect bacteria?

Accepted Answer

Hershey-Chase experiment using radioactive phosphorus and sulfur

Question 6

Which of the following statements about saturated and unsaturated fats is correct?

Accepted Answer

Saturated fats have no double bonds and are typically found in animal products like butter and lard.

Question 7

Which property of water allows a gecko to climb smooth surfaces due to weak, distance-dependent interactions?

Accepted Answer

Van der Waals interactions

Question 8

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

Accepted Answer

Helicase

Question 9

A DNA strand has the sequence 5'-GGCATTA-3'. What is the complementary DNA sequence?

Accepted Answer

3'-CCGTAAT-5'

Question 10

Which of the following best describes the semiconservative model of DNA replication?

Accepted Answer

Each daughter DNA molecule consists of one parental strand and one newly synthesized strand.

Question 11

Which functional group is found in all amino acids and is responsible for their acidic properties?

Accepted Answer

Carboxyl group ($$-COOH)$$

Question 12

Which of the following is a correct pairing of a macromolecule and its monomer?

Accepted Answer

Carbohydrate – monosaccharide

Question 13

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

Accepted Answer

Hydrolysis; water

Question 14

Which of the following best explains why water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water is polar and can form hydrogen bonds with solutes.

Question 15

Which of the following is a real-world consequence of a mutation in the gene encoding hemoglobin?

Accepted Answer

The mutation causes sickle-cell disease, resulting in misshapen red blood cells that can clog blood vessels.

Question 16

Which of the following statements about DNA structure is correct?

Accepted Answer

The sugar-phosphate backbone is on the outside, and nitrogenous bases are on the inside.

Question 17

Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

DNA ligase

Question 18

Which of the following best describes the role of phospholipids in biological membranes?

Accepted Answer

They form a bilayer with hydrophobic tails facing inward and hydrophilic heads facing outward, creating a selective barrier.

Question 19

Which of the following is a property of water that helps regulate temperature in living organisms and environments?

Accepted Answer

High specific heat capacity

Question 20

Which of the following best explains why enzymes are essential for life?

Accepted Answer

They speed up chemical reactions by lowering activation energy, allowing metabolic processes to occur at life-sustaining rates.

Foundations of Biology: Chemistry of Life, Macromolecules, and Molecular Genetics

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