Practice Test 22 - High School Biology

20 questions. Answer them in any order, then submit to see your score and every explanation.

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1. A student says: "In DNA, adenine (A) pairs with cytosine (C)." Which statement correctly fixes the student's mistake?
2. Crossing over (recombination) increases genetic diversity during meiosis. Which statement best describes crossing over?
3. A bacterial population contains 10% antibiotic-resistant cells and 90% susceptible cells. When an antibiotic is applied, 95% of susceptible cells die, while only 5% of resistant cells die. After treatment, what happens to the frequency of resistance in the surviving population?
4. A conservation group compares a single-species pine plantation to a nearby mixed forest with many tree and understory plant species. After a windstorm, many pines fall in the plantation, and few young trees survive because the understory is sparse. In the mixed forest, some trees fall, but many other species remain standing and seedlings from multiple species grow in the new gaps. Which statement best explains how biodiversity affects recovery and population stability after disturbance?
5. A mutation occurs in a gene, but it is located in a non-coding region (a stretch of DNA that is not translated into protein). Which outcome is most likely regarding the protein made from this gene?
6. A simplified mRNA segment is: AUG–UUU–GGC–UAA. In translation, what does the ribosome do with this information?​
7. Two islands each have lizards with a gene that affects camouflage: allele $C$ (better camouflage) and $c$ (worse camouflage). On Island 1, survival is 95% for $C$-carrying lizards and 90% for $cc$ lizards. On Island 2, survival is 95% for $C$-carrying lizards and 10% for $cc$ lizards. Which island will experience faster evolution (faster change in allele frequencies) due to natural selection, and why?
8. During aerobic cellular respiration, a person eats food and breathes air. Where do the cell's two key inputs come from?
9. Consider the food chain: Algae → Tadpole → Frog → Snake. Which statement correctly identifies the trophic levels and energy source differences?
10. A student touches a hot pan and quickly pulls their hand away. How do the nervous and muscular systems interact to produce this fast movement?
11. A classroom model shows DNA as a twisted ladder (double helix). The sides of the ladder are repeating sugar-phosphate units, and the rungs are pairs of bases in the center. Which statement correctly describes how the bases pair in DNA?
12. A grassland habitat provides enough food for 900 antelope, enough water for 1,200 antelope, and enough shelter (safe resting sites) for only 650 antelope. Assuming one limiting resource sets carrying capacity, what is the carrying capacity (K) for antelope in this habitat?
13. A student builds a DNA strand using repeating building blocks called nucleotides. Which set lists the three parts found in a DNA nucleotide?
14. A simplified energy pyramid is shown below. Producers: 10,000 units Primary consumers: 1,000 units Secondary consumers: 100 units Tertiary consumers: 10 units Which conclusion is most consistent with this pyramid?
15. Claim: Decomposition returns nutrients to the soil. A student places equal masses of dried leaves in two mesh bags: - Bag 1 is placed on moist soil outdoors. - Bag 2 is placed on dry sand indoors. After 8 weeks: 1) Bag 1 loses 60% of its mass; Bag 2 loses 5%. 2) Soil under Bag 1 shows higher phosphate (PO$_4^{3-}$) than nearby soil without a bag. 3) The leaves in Bag 1 appear darker and more crumbly. 4) The outdoor site received more rain than the indoor site. Which evidence is most directly relevant to the claim (not just conditions that might explain it)?
16. A school of fish is attacked by a larger predator. The fish swim in a tight, synchronized group, making it hard for the predator to focus on one individual. Which benefit of group living does this best illustrate?
17. A snail population has a shell-color gene with two alleles: $G$ (green shell) and $g$ (brown shell). Allele frequencies are measured over 25 generations. Generation 0: $f(G)=0.80$, $f(g)=0.20$ Generation 5: $f(G)=0.68$, $f(g)=0.32$ Generation 10: $f(G)=0.55$, $f(g)=0.45$ Generation 15: $f(G)=0.42$, $f(g)=0.58$ Generation 25: $f(G)=0.30$, $f(g)=0.70$ Which statement best describes the evolutionary change?
18. A plant makes glucose during photosynthesis using CO2 from the air and H2O from the soil. Later, the plant builds proteins. Which statement best traces where the atoms in the plant's proteins come from and what happens to them during synthesis?
19. In a diagram of DNA, the sugar-phosphate backbone is shown on the outside of the double helix. Where are the nitrogenous bases (A, T, G, C) located in this structure?
20. Which event happens during interphase (before mitosis begins)?​

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