AP Biology Quiz: Biodiversity

What this quiz covers

This quiz focuses on Biodiversity, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Biology.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. Plot 2 has greater richness because a single species dominates the community
2. Plot 1 has greater evenness, increasing its diversity compared with Plot 2 (correct answer)
3. Plot 2 has greater diversity because it contains a higher proportion of the most common species
4. Plot 1 has lower diversity because it lacks a dominant species to stabilize the community
5. The plots have equal diversity because they have the same number of species

Explanation: Biodiversity analysis is the skill of assessing species richness and evenness to understand differences in community diversity across habitats. Here, both plots have the same richness of 12 tree species, but Plot 1 has higher evenness with each species at about 8% of individuals, unlike Plot 2 where one species dominates at 70%. This greater evenness in Plot 1 increases its overall diversity by ensuring no single species overwhelmingly dominates the community. The evidence from abundance distributions highlights how evenness contributes to diversity when richness is equal. A tempting distractor is choice A, which claims Plot 2 has greater richness due to a dominant species, but this misconceives that dominance increases richness, when in fact richness is simply the species count and dominance reduces evenness. In biodiversity questions, remember to evaluate evenness alongside richness, as equal species counts do not guarantee equal diversity if abundances are uneven.

Question 2

1. Deep water has higher diversity because it contains the same number of species as shallow water
2. Shallow water has higher diversity because species are more evenly represented there (correct answer)
3. Deep water has higher richness because most individuals belong to two species
4. Both depths have equal diversity because richness is identical and abundance is irrelevant
5. Shallow water has lower diversity because no species dominates the community

Explanation: Biodiversity analysis is the skill of assessing species richness and evenness to compare diversity across environmental gradients like lake depths. Both depths have equal richness of 16 zooplankton species, but shallow water has higher evenness with even abundances compared to deep water's two species at 90%. This leads to shallow water having higher diversity, supported by the abundance distributions under identical sampling methods. The evidence emphasizes evenness's impact when richness is the same. A tempting distractor is choice C, claiming deep water has higher richness due to most individuals in two species, but this misconceives that dominance increases richness, when richness is the species count independent of abundance. For biodiversity questions, prioritize evenness in equal-richness scenarios, ensuring sampling consistency for accurate comparisons.

Question 3

1. Site 2 has higher biodiversity because it has the same richness and more total cover.
2. Site 1 has higher biodiversity because evenness is greater with the same richness. (correct answer)
3. Both sites have equal biodiversity because species richness is identical.
4. Site 2 has higher biodiversity because dominance indicates successful adaptation.
5. Biodiversity cannot be compared because both sites are grasslands.

Explanation: This question requires analyzing biodiversity by comparing communities with identical species richness but different evenness patterns. Site 1 has higher biodiversity because, with the same number of species (15), it shows relatively even cover across species compared to Site 2 where one grass species dominates with 80% cover. When species richness is equal, evenness becomes the determining factor for biodiversity—more even distribution of individuals among species indicates higher biodiversity. The misconception in choice C is that species richness alone determines biodiversity, ignoring the critical role of evenness in community structure. To assess biodiversity comprehensively, examine both richness and evenness, understanding that when richness is equal, the community with more even species distribution has higher biodiversity.

Question 4

1. Site M is more biodiverse because it has more individuals overall.
2. Site N is more biodiverse because evenness is higher despite lower abundance. (correct answer)
3. Both sites are equally biodiverse because richness is identical.
4. Site M is more biodiverse because dominance indicates better adaptation.
5. Biodiversity cannot be compared because the sites are different sizes.

Explanation: This question requires analyzing biodiversity when total abundance differs dramatically between sites. Site N is more biodiverse because, despite having the same species richness (5 species each), it shows much higher evenness with each species comprising 15-25% of individuals, compared to Site M where one species makes up 92%. The extreme dominance in Site M indicates very low evenness, which reduces biodiversity regardless of higher total abundance. The misconception in choice A is that total number of individuals relates to biodiversity, when biodiversity actually depends on species richness and evenness, not total abundance. When comparing communities, focus on richness and evenness patterns rather than total counts, as biodiversity measures community structure, not population size.

Question 5

1. The center has higher biodiversity because two species are very abundant.
2. The edge has higher biodiversity because evenness is greater with equal richness. (correct answer)
3. Both areas have equal biodiversity because richness is the same.
4. The center has lower biodiversity because amphibians avoid the edge.
5. The edge has lower biodiversity because dominance increases stability.

Explanation: This question tests biodiversity analysis within a single wetland comparing edge and center habitats. The edge has higher biodiversity because, with equal species richness (13 species each), it shows moderate evenness compared to the center where two species account for 85% of individuals. When species richness is identical, the community with more even distribution of individuals among species (higher evenness) has greater biodiversity. The misconception in choice C is assuming equal richness means equal biodiversity, overlooking how dominance patterns reduce diversity even with the same number of species. To assess biodiversity within habitats, examine both richness and evenness, recognizing that spatial variation in dominance patterns can create biodiversity gradients even when species richness remains constant.

Question 6

1. Community S has higher biodiversity because fewer species reduces competition.
2. Community R has higher biodiversity because species richness is greater. (correct answer)
3. Both communities have equal biodiversity because evenness is similar.
4. Community S has higher biodiversity because storms select for fewer species.
5. Biodiversity cannot be compared because both are kelp forests.

Explanation: This question assesses biodiversity comparison after disturbance when evenness is similar. Community R has higher biodiversity because it contains 11 invertebrate species compared to Community S's 7 species, representing greater species richness. Since both communities show similar evenness (no strong dominance), species richness becomes the sole differentiating factor for biodiversity. The storm's impact reduced species richness in Community S without creating dominance patterns in either community. The misconception in choice A is that fewer species somehow increases biodiversity by reducing competition, when species richness is a fundamental component of biodiversity. When comparing post-disturbance communities with similar evenness, the community with more species has higher biodiversity, as disturbances often act as filters reducing species richness.

Question 7

1. The reef has higher biodiversity because it has greater species richness. (correct answer)
2. The seagrass meadow has higher biodiversity because it has greater evenness.
3. Both ecosystems have equal biodiversity because total abundance is similar.
4. The reef has lower biodiversity because dominant species are more evolved.
5. The seagrass meadow has lower biodiversity because it has fewer species.

Explanation: This question requires comparing biodiversity between different marine ecosystems with varying richness and evenness. The coral reef has higher biodiversity because it contains 22 species compared to the seagrass meadow's 16 species, representing significantly greater species richness. Although the reef has lower evenness (3 species account for 75% of individuals), the substantial difference in species richness (22 vs 16) outweighs the evenness advantage of the seagrass meadow. The misconception in choice B is overvaluing evenness when there's a significant difference in species richness between communities. When comparing biodiversity across ecosystems, recognize that a notable difference in species richness typically determines overall biodiversity, even when evenness patterns differ.

Question 8

1. Downstream biodiversity is higher because one taxon is very abundant.
2. Downstream biodiversity is lower because richness and evenness are both reduced. (correct answer)
3. Downstream biodiversity is unchanged because both sites contain macroinvertebrates.
4. Downstream biodiversity is higher because fewer taxa increases community stability.
5. Biodiversity cannot be compared because taxa are not the same as species.

Explanation: This question assesses the skill of analyzing biodiversity by comparing species richness and evenness in different ecosystems. Downstream biodiversity is lower because both richness drops to 6 taxa from 14 upstream and evenness decreases with one taxon at 75% dominance, compared to no taxon exceeding 20% upstream. The same sampling effort reveals how pollution likely reduces community complexity downstream. This is supported by the data showing fewer taxa and increased dominance, indicating disrupted structure. A tempting distractor is choice A, which claims higher diversity from abundance, falling for the misconception that dominance enhances rather than reduces biodiversity. A transferable strategy for biodiversity questions is to always evaluate both species richness and evenness, especially when richness is identical, to determine overall diversity.

Question 9

1. Downstream biodiversity is higher because one species is very abundant.
2. Upstream biodiversity is higher due to greater richness and greater evenness. (correct answer)
3. Biodiversity is equal because both segments are in the same stream.
4. Downstream biodiversity is higher because fewer species reduces competition.
5. Upstream biodiversity is lower because no single species dominates the community.

Explanation: This question tests biodiversity analysis in the context of environmental disturbance (wastewater outfall). The upstream segment has higher biodiversity due to both greater species richness (18 vs 10 species) and greater evenness (6 species each contributing 10-15% vs one species making up 70% downstream). The wastewater outfall has reduced both components of biodiversity downstream, creating a community dominated by pollution-tolerant species. The misconception in choice A is that high abundance of one species indicates high biodiversity, when actually dominance by a single species indicates low evenness and reduced biodiversity. When analyzing biodiversity patterns, consider how environmental stressors often reduce both species richness and evenness, creating communities dominated by tolerant species.

Question 10

1. Pond X has higher biodiversity because it contains more species, despite low evenness. (correct answer)
2. Pond Y has higher biodiversity because species abundances are more evenly distributed.
3. Both ponds have equal biodiversity because total abundance is similar.
4. Pond X has lower biodiversity because its dominant species are better adapted.
5. Pond Y has lower biodiversity because it contains fewer species than Pond X.

Explanation: This question tests your ability to analyze biodiversity by considering both species richness (number of species) and evenness (distribution of individuals among species). Pond X has higher biodiversity because it contains 12 species compared to Pond Y's 8 species, giving it greater species richness. While Pond X has low evenness (4 species make up 90% of individuals), species richness is the primary determinant of biodiversity when the difference is substantial (12 vs 8 species). The misconception in choice B is that evenness alone determines biodiversity, but biodiversity encompasses both richness and evenness, with richness often being the stronger factor. When comparing biodiversity between communities, always evaluate both species richness and evenness, recognizing that a community with significantly more species typically has higher biodiversity even if evenness is lower.

Question 11

1. Plot A has greater diversity because it has higher evenness among the same richness. (correct answer)
2. Plot B has greater diversity because dominance by one species increases diversity.
3. The plots have equal diversity because richness is identical in both plots.
4. Plot B has greater diversity because rare species contribute little to diversity.
5. Plot A has greater diversity because it contains more total stems than Plot B.

Explanation: This question assesses the skill of analyzing biodiversity by comparing species richness and evenness in different ecosystems. Plot A has greater diversity because it shares the same richness of 12 species with Plot B but features higher evenness, with each species contributing 8–10% of stems, unlike Plot B's dominance by one species at 70%. This even distribution in Plot A supports a more diverse community, as evidenced by the identical plot sizes and sampling methods. The stimulus shows that rarity in Plot B reduces the effective contribution of most species to biodiversity. A tempting distractor is choice C, which assumes equal diversity based only on identical richness, ignoring the misconception that evenness significantly influences diversity indices. A transferable strategy for biodiversity questions is to always evaluate both species richness and evenness, especially when richness is identical, to determine overall diversity.

Question 12

1. Pool 2 has higher biodiversity because it contains more barnacles overall.
2. Pool 1 has higher biodiversity because species abundances are more evenly distributed. (correct answer)
3. Both pools have equal biodiversity because they contain the same number of species.
4. Pool 2 has higher biodiversity because it has a larger total number of individuals.
5. Biodiversity cannot be compared because both pools were sampled in different microhabitats.

Explanation: This question assesses the skill of analyzing biodiversity by comparing species richness and evenness in different ecosystems. Pool 1 has higher biodiversity because, despite both pools having the same species richness of four, the even distribution of 60 individuals across each species in Pool 1 contrasts with Pool 2's dominance by barnacles at 220 individuals. This evenness in Pool 1 allows for a more balanced community structure, which is a key component of biodiversity metrics like the Shannon index. The evidence from the equal area and similar total individuals highlights how abundance distribution affects overall diversity. A tempting distractor is choice C, which equates biodiversity solely to species richness, overlooking the misconception that evenness also plays a critical role. A transferable strategy for biodiversity questions is to always evaluate both species richness and evenness, especially when richness is identical, to determine overall diversity.

Question 13

1. Wash B has higher biodiversity because it has a larger population of one species.
2. Wash A has higher biodiversity because it has greater evenness with equal richness. (correct answer)
3. Both washes have equal biodiversity because richness is identical.
4. Wash B has higher biodiversity because dominance increases community complexity.
5. Biodiversity cannot be compared because annual plants vary in size.

Explanation: This question assesses the skill of analyzing biodiversity by comparing species richness and evenness in different ecosystems. Wash A has higher biodiversity because it shares equal richness of 7 species with Wash B but exhibits greater evenness, with each species having 12–18 individuals versus B's one species at 90%. The same rainfall event and similar total individuals highlight how balanced abundances boost diversity. This is evidenced by A's lack of dominance, promoting a more stable community. A tempting distractor is choice C, assuming equal diversity from richness alone, overlooking the misconception that evenness is crucial. A transferable strategy for biodiversity questions is to always evaluate both species richness and evenness, especially when richness is identical, to determine overall diversity.

Question 14

1. Reef B is more diverse because the most common species are more abundant.
2. Reef A is more diverse because it has greater evenness at the same richness. (correct answer)
3. The reefs are equally diverse because they have the same number of species.
4. Reef B is more diverse because it likely has more total fish individuals.
5. Diversity cannot be inferred without measuring genetic variation within species.

Explanation: This question assesses the skill of analyzing biodiversity by comparing species richness and evenness in different ecosystems. Reef A is more diverse because, with the same richness of 25 species as Reef B, it has greater evenness, as the top five species comprise only 40% of individuals versus 85% in B. The identical sampling effort and season underscore how this distribution fosters higher diversity. Evidence from the equal areas shows reduced dominance in A supports a balanced community. A tempting distractor is choice C, equating diversity to richness alone, ignoring the misconception that uneven abundance lowers overall biodiversity. A transferable strategy for biodiversity questions is to always evaluate both species richness and evenness, especially when richness is identical, to determine overall diversity.

Question 15

1. Site R, because higher richness always indicates higher biodiversity regardless of evenness.
2. Site S, because much higher evenness can result in higher overall diversity despite lower richness. (correct answer)
3. Site R, because dominance by one species increases community diversity.
4. Both, because equal total individuals means equal biodiversity.
5. Neither, because arthropod biodiversity requires measuring biomass instead of abundance.

Explanation: This question tests understanding of how extreme differences in evenness can override richness advantages in biodiversity assessment. Site S likely has higher biodiversity because its much higher evenness can result in greater overall diversity despite having fewer species. Site R has 14 species but extreme dominance with 88% being a single ant species, creating very low evenness. Site S has 10 species with the most common at only 20%, indicating relatively high evenness with no extreme dominance. The dramatic difference in evenness (88% vs 20% for top species) suggests Site S's community structure is more diverse overall. A common misconception (choice A) is that higher richness always means higher biodiversity, but extreme dominance can negate richness advantages. When comparing biodiversity, recognize that very low evenness (extreme dominance) can reduce overall diversity below that of communities with fewer but more evenly distributed species.

Question 16

1. Plot X is more diverse because species are more evenly represented in the community. (correct answer)
2. Plot Y is more diverse because one species has a much higher abundance than others.
3. The plots have equal diversity because they have the same species richness.
4. Plot Y is more diverse because total population size is matched across plots.
5. The plots have equal diversity because both are forest ecosystems with birds present.

Explanation: This question requires analyzing biodiversity differences when species richness is equal but evenness differs between communities. Plot X has higher biodiversity because its 12 bird species are more evenly distributed with only 1-3 pairs per species, indicating high evenness. In contrast, Plot Y shows very low evenness with one species comprising 70% of all pairs while the other 11 species share only 30%. When richness is equal, the community with higher evenness has higher overall biodiversity. The data demonstrates that Plot X's even distribution creates a more diverse community structure than Plot Y's dominance pattern. A common misconception (choice C) is that equal species richness means equal biodiversity, ignoring the critical role of evenness in biodiversity assessment. To compare biodiversity when richness is equal, focus on evenness by examining whether species abundances are similar or if one species dominates the community.

Question 17

1. The seagrass bed is more diverse because it has fewer species but greater dominance.
2. The reef is more diverse because it has higher species richness, even with lower evenness. (correct answer)
3. Both are equally diverse because the total number of fish counted is identical.
4. The seagrass bed is more diverse because it has lower species richness but equal abundance.
5. Biodiversity cannot be compared because the habitats are different ecosystem types.

Explanation: This question requires analyzing biodiversity in marine communities with different richness and evenness patterns. The reef has higher biodiversity because its greater species richness (30 species) outweighs its lower evenness, even though 60% of individuals are one damselfish species. The seagrass bed has only 18 species but shows higher evenness with individuals spread more evenly among species. Despite the reef's dominance pattern, having 12 more species creates substantially higher richness that results in greater overall biodiversity. The data demonstrates that significant richness differences can overcome evenness disadvantages in biodiversity comparisons. A common misconception (choice C) is that equal total fish counts mean equal biodiversity, ignoring how those individuals are distributed among different species. When assessing biodiversity across habitats, weigh the magnitude of richness differences against evenness patterns; large richness advantages often indicate higher biodiversity even with some species dominance.

Question 18

1. Site 2 has higher biodiversity because it has two dominant species.
2. Site 1 has higher biodiversity because it has greater evenness at the community level. (correct answer)
3. The sites have equal biodiversity because species richness is identical.
4. Site 2 has higher biodiversity because it has the same total number of individuals.
5. The sites have equal biodiversity because both include algae and invertebrates.

Explanation: This question requires analyzing biodiversity when species richness is identical but evenness differs dramatically between sites. Site 1 has higher biodiversity because its 15 species (9 invertebrates + 6 algae) occur in moderate numbers, indicating high evenness across the community. Site 2 has the same 15 species but shows extremely low evenness, with 90% of individuals belonging to just one barnacle and one alga species. The data clearly shows Site 1's even distribution creates higher overall biodiversity than Site 2's dominance pattern. When richness is equal, evenness becomes the determining factor for biodiversity comparisons. A common misconception (choice C) is that identical species richness means equal biodiversity, failing to consider how species abundances affect diversity. To assess biodiversity comprehensively, always examine both richness and evenness, recognizing that communities with similar species numbers can have very different diversity levels based on dominance patterns.

Question 19

1. Wetland A has higher species evenness and higher overall diversity than Wetland B (correct answer)
2. Wetland B has higher diversity because it contains a greater total number of individuals
3. Wetland A has lower richness because individuals are evenly distributed among species
4. Wetland B has higher richness because one species is numerically dominant
5. The two wetlands have the same diversity because both contain 100 total individuals

Explanation: Biodiversity analysis is the skill of evaluating species richness, the number of species present, and evenness, the relative distribution of individuals among those species, to assess overall ecosystem diversity. In this scenario, Wetland A demonstrates higher species richness with 10 bird species compared to Wetland B's 2 species. Additionally, Wetland A shows greater evenness, as each species has 10 individuals, while Wetland B has low evenness with one species dominating at 95 individuals. These factors combined support that Wetland A has higher overall diversity, especially given the similar environmental conditions like water depth and vegetation. A tempting distractor is choice B, which suggests Wetland B has higher diversity due to a greater total number of individuals, but this reflects the misconception that diversity is solely based on total abundance rather than the interplay of richness and evenness. For biodiversity questions, always compare both richness and evenness, recognizing that dominance by one species can significantly lower diversity even if total individuals are the same.

Question 20

1. Pool B has higher diversity because rare species increase the total count of species
2. Pool A has higher diversity because it has greater evenness at the same richness (correct answer)
3. Both pools have equal diversity because they have the same number of algal species
4. Pool B has higher richness because one species is dominant in the community
5. Pool A has lower diversity because equal abundances reduce the number of species present

Explanation: Biodiversity analysis is the skill of evaluating species richness and evenness to compare diversity in microhabitats like tide pools. Both pools have equal richness of 5 algal species, but Pool A has greater evenness with equal abundances of 20 each, unlike Pool B's dominance with 96 in one and 1 in others. This leads to Pool A having higher diversity, as shown by the balanced distribution versus B's extreme unevenness at the same total of 100 individuals. The specific abundance numbers provide clear evidence for evenness's role. A tempting distractor is choice A, suggesting Pool B has higher diversity due to rare species increasing richness, but this misconceives that rare species boost diversity when they actually lower evenness without adding to richness. In biodiversity questions, emphasize evenness in equal-richness cases, using precise abundance data to calculate relative impacts.