Practice Test 34 - 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 population of mice includes heritable variation in fur thickness. A cold climate persists for hundreds of generations. Mice with thicker fur stay warmer, survive winters more often, and have more offspring. Which statement best describes why thick fur is considered an adaptation in this environment?
2. A trait is considered an adaptation when it increases an organism's fitness (survival and reproduction) in a specific environment and becomes common in a population over time. Which example best matches this definition?
3. In a population of beetles, color is controlled by a gene with two alleles: $G$ (green) and $g$ (brown). A pesticide is applied. Individuals with genotypes $GG$ and $Gg$ have a 90% chance of surviving to reproduce, while $gg$ individuals have a 20% chance of surviving. Without doing any Hardy-Weinberg calculations, which allele is expected to increase in frequency in the next generation, and why?
4. A mountain ecosystem contains several plant species adapted to cool temperatures. Warming climate conditions are shifting suitable habitat uphill, shrinking available area and threatening local extinctions. Which strategy most directly addresses the long-term driver of biodiversity loss in this scenario (even if results take time)?
5. A gene's mRNA is normally read in codons as: AUG-CCG-GAA-UCU... A mutation deletes one nucleotide early in the sequence (a deletion of 1 base). Which outcome is most likely for the resulting protein?
6. A simplified DNA diagram shows two long backbones on the outside with repeated sugar and phosphate units. What is the best description of the sugar-phosphate backbone in DNA?
7. A teacher draws two arrows to show the relationship between the processes: Photosynthesis $\rightarrow$ (glucose and $O_2$) $\rightarrow$ Cellular respiration Cellular respiration $\rightarrow$ ($CO_2$ and $H_2O$) $\rightarrow$ Photosynthesis Which statement best summarizes the complementary nature of these arrows?
8. Two populations are shown on the same graph (x-axis = time; y-axis = population size). Curve A rises slowly at first and then becomes steeper and steeper without leveling off. Curve B rises quickly but then slows and levels off near a constant value. Which statement correctly matches each curve to a growth pattern?
9. A herd of deer feeds in an open field while a few individuals periodically lift their heads and scan for wolves. Compared with a deer feeding alone, what is a key advantage of feeding in a herd?
10. A student observes many elongated muscle cells contracting together in a bundle to help move a body part. This bundle is made mostly of the same type of cell working together. What level of biological organization is being described?
11. A student walks outside on a cold day and begins to shiver. Their skin also looks paler than usual. Which model best represents system integration in this temperature-response scenario?
12. Claim: Cooperation improves success at defending territory from rivals. Evidence: - Observational study of 18 territories of the same species: - Territories defended by pairs successfully repelled intruders in 14/18 encounters. - Territories defended by single individuals successfully repelled intruders in 6/18 encounters. - Additional note: paired defenders tended to occupy territories with more hiding places. Which evaluation is most accurate?
13. A teacher summarizes phenotype as: phenotype = genotype + environment. Which observation best supports this statement?
14. Claim: Without decomposers, nutrients become locked in dead material and plant growth will decrease over time. Two identical terrariums were set up for 2 months: - Terrarium 1: normal soil with decomposers - Terrarium 2: sterilized soil (few/no decomposers) Results: 1) Terrarium 2 accumulated dead leaves; Terrarium 1 did not. 2) Soil nutrient test strips showed lower nitrate in Terrarium 2 than Terrarium 1. 3) Plants in Terrarium 2 produced fewer new leaves than plants in Terrarium 1. 4) Both terrariums had the same light and water. Which evidence set is most sufficient to support the claim?
15. A student is chewing and swallowing a sandwich. Which option best describes how the nervous and digestive systems interact during this process?
16. Two siblings (not identical twins) have the same parents but look different. Which set of processes best explains why siblings can have different combinations of traits?
17. Two stream sites were monitored after a toxic chemical release in Year 0. Site A is 2 km downstream from the spill. Site B is an undisturbed reference stream nearby. Macroinvertebrate species richness (number of different macroinvertebrate species found in samples) was measured. Results: - Site A: Pre-spill 24; Year 0: 6; Year 1: 12; Year 4: 19 - Site B: Pre-spill 25; Year 0: 25; Year 1: 24; Year 4: 26 What is the best interpretation of recovery at Site A by Year 4?
18. A student compares transcription and translation. Which statement correctly describes translation (not transcription)?
19. Environmental factors can increase mutation rates. A student compares two mutation types in a coding region: - Substitution: one base replaced (e.g., ATGCCC → ATGCTC) - Insertion: one base added (e.g., ATGCCC → ATGCCCC) Which statement best distinguishes their likely effects on the protein?
20. In a lake, dead algae and dead fish sink to the bottom and are broken down by bacteria and fungi. Which option best explains how producers, consumers, and decomposers together support matter cycling?

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