Question 1 of 10
Which class of biomolecule is built from nucleotide monomers?
ACarbohydrates
BProteins
CLipids
DNucleic acids (DNA and RNA)
Explanation
Nucleic acids (DNA, RNA) are polymers of nucleotide monomers — each nucleotide is a phosphate + sugar + nitrogenous base. Distractors: Proteins are polymers of *amino acids*. Carbohydrates are polymers of *monosaccharides* (e.g., glucose). Lipids are not true polymers — they assemble from fatty acids and glycerol but don't repeat a single monomer.
Question 2 of 10
Which graph correctly shows exponential growth?
AA
BB
CBoth
DNeither
Explanation
📌 Exponential growth = J-shaped curve (slow start, rapid increase)
Linear growth = straight line (constant rate)
Graph A shows exponential growth.
Linear growth = straight line (constant rate)
Graph A shows exponential growth.
Question 3 of 10
All three domains of life (Bacteria, Archaea, and Eukarya) share which structural feature?
ARibosomes for protein synthesis
BChloroplasts for photosynthesis
CA membrane-bound nucleus
DMulticellular organization
Explanation
All cellular life — Bacteria, Archaea, and Eukarya — uses ribosomes to build proteins. Distractors: a membrane-bound nucleus is found only in Eukarya (Bacteria and Archaea are prokaryotic). Multicellularity appears only in some Eukarya — most life is unicellular. Chloroplasts are organelles found only in plants and algae (a subset of Eukarya).
Question 4 of 10
During which phase of the cell cycle does DNA replication occur? 
AM phase
BG2 phase
CS phase
DG1 phase
Explanation
📌 DNA replication occurs during S phase (Synthesis) of interphase.
Interphase: G1 → S → G2, then Mitosis.
Interphase: G1 → S → G2, then Mitosis.
Question 5 of 10
Epigenetics studies how:
Acells divide
BDNA sequence changes
Cgene expression changes without altering DNA sequence
Dorganisms evolve
Explanation
📌 Epigenetics = changes in gene expression WITHOUT changing DNA sequence.
Mechanisms: DNA methylation, histone modification.
Affected by environment, diet, stress.
Mechanisms: DNA methylation, histone modification.
Affected by environment, diet, stress.
Question 6 of 10
Why does the left ventricle have a thicker muscular wall than the right ventricle?
AIt must pump blood at higher pressure to reach the entire body
BIt is in direct contact with the lungs
CIt receives more deoxygenated blood from the body
DIt contains valves that the right ventricle lacks
Explanation
The left ventricle pumps oxygenated blood through the *systemic circuit* — every tissue in the body — which requires high pressure. The right ventricle only needs to push blood a short distance to the lungs (pulmonary circuit), so its wall is thinner. Distractors: the left ventricle pumps *oxygenated* blood, not deoxygenated. Both ventricles have valves (AV and semilunar). The right ventricle, not the left, is closer to the lungs.
Question 7 of 10
Which pair of processes drives the most direct exchange of CO₂ between living organisms and the atmosphere?
ATranspiration (releases CO₂) and condensation (absorbs CO₂)
BPhotosynthesis (releases CO₂) and cellular respiration (absorbs CO₂)
CPhotosynthesis (absorbs CO₂) and cellular respiration (releases CO₂)
DNitrogen fixation (absorbs CO₂) and decomposition (releases O₂)
Explanation
Photosynthesis consumes atmospheric CO₂ to build glucose (CO₂ → sugar), while cellular respiration breaks glucose back down to CO₂ and water. Together they form the short-term carbon cycle between the biosphere and atmosphere. Distractor B reverses the direction. Transpiration moves water vapor, not CO₂. Nitrogen fixation moves nitrogen, not carbon.
Question 8 of 10
The Hardy-Weinberg principle states that allele frequencies remain constant when:
Athe population is very small
Bnatural selection is strong
Cthere is no evolution occurring
Dmutations are common
Explanation
📌 Conditions: no mutation, no migration, random mating, large population, no natural selection.
Any violation → evolution occurs.
Any violation → evolution occurs.
Question 9 of 10
In a DNA nucleotide, which component carries the genetic code through its specific sequence?
ADeoxyribose sugar
BHydrogen bond
CNitrogenous base
DPhosphate group
Explanation
The nitrogenous base (adenine, thymine, guanine, or cytosine) is the part of a DNA nucleotide that varies — its sequence along the strand IS the genetic code. The phosphate and deoxyribose sugar are identical in every nucleotide and form the structural 'backbone' of the DNA strand; they don't store information. Hydrogen bonds hold the two strands together at the bases but are not part of a single nucleotide.
Question 10 of 10
In the food web below, what would happen if all the frogs were removed? 
ANothing changes
BAll organisms die
CSnake population increases
DInsect population increases and snake population decreases
Explanation
📌 If frogs are removed:
• Insects (grasshoppers) they ate would INCREASE (no predator)
• Snakes that ate frogs would DECREASE (less food)
• This demonstrates how removing one species affects the entire food web.
• Insects (grasshoppers) they ate would INCREASE (no predator)
• Snakes that ate frogs would DECREASE (less food)
• This demonstrates how removing one species affects the entire food web.