Middle School Science Quiz: Resources And Population Size
20 questions · exam conditions
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Resources And Population SizeQuestion 1 of 20

A wildlife biologist studied the same rabbit population in two fenced fields for 5 months. Both fields started with 30 rabbits. The fields were the same size and had the same weather. The only difference was the amount of grass available (a resource).

Data:

  • Field 1 (less grass) → 28 rabbits after 5 months
  • Field 2 (more grass) → 55 rabbits after 5 months

Which claim about population size is incorrect based on the evidence? (Resources can limit population size.)

The rabbit population size must be controlled only by genes, so grass availability cannot be a cause of the different population sizes.
With less grass available, fewer rabbits may survive or fewer babies may be born, which can limit population size.
The evidence suggests that when a key resource is more available, the rabbit population size can increase over time.
More grass could be a cause of a larger rabbit population because rabbits use grass as a resource for energy and growth.
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Middle School Science Quiz

Middle School Science Quiz: Resources And Population Size

Practice Resources And Population Size in Middle School Science with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Resources And Population Size, giving you a quick way to practice the rules, question types, and explanations that matter most for Middle School Science.

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.

All questions

Question 1

A wildlife biologist studied the same rabbit population in two fenced fields for 5 months. Both fields started with 30 rabbits. The fields were the same size and had the same weather. The only difference was the amount of grass available (a resource).

Data:

  • Field 1 (less grass) → 28 rabbits after 5 months
  • Field 2 (more grass) → 55 rabbits after 5 months

Which claim about population size is incorrect based on the evidence? (Resources can limit population size.)

  1. The rabbit population size must be controlled only by genes, so grass availability cannot be a cause of the different population sizes. (correct answer)
  2. With less grass available, fewer rabbits may survive or fewer babies may be born, which can limit population size.
  3. The evidence suggests that when a key resource is more available, the rabbit population size can increase over time.
  4. More grass could be a cause of a larger rabbit population because rabbits use grass as a resource for energy and growth.
Explanation: The core skill involves analyzing how resources limit population sizes in controlled studies. Resources affect population size by supporting or restricting survival and reproduction, such as grass availability influencing rabbit numbers. Evidence from field comparisons, like rabbits in areas with different grass levels, reveals cause-and-effect through patterns where more resources lead to population increases. To verify, examine if claims align with data showing resource-driven changes, identifying incorrect assertions like genetics solely controlling sizes. A misconception is that genes override environmental factors, but resources play a key role in population outcomes. Overall, populations can flourish with ample resources but face limitations when resources are scarce. Thus, population size hinges on resource availability interacting with other biological factors.

Question 2

A researcher studied the same population of snails in two identical aquarium tanks for 4 months. Both tanks started with 50 snails. The only planned difference was the amount of calcium available (calcium is a resource snails use to build shells).

Data after 4 months:

  • Low calcium → 44 snails
  • High calcium → 79 snails

Which statement is supported by the evidence about resources, population size, and cause? (Resources can limit population size.)

  1. Higher calcium availability was followed by a larger snail population, supporting that more of a needed resource can cause population size to increase over time. (correct answer)
  2. The snails in the high-calcium tank must have been a different species, because resources cannot affect population size.
  3. Since the population changed over months, resources cannot be the cause; causes must work instantly.
  4. The population size increased because shells looked shinier, and shinier shells mean more snails.
Explanation: The core skill is evaluating evidence for resource impacts on shelled organisms like snails. Resources affect population size by aiding critical functions, such as calcium enabling shell-building and reproduction in snails. Evidence from tank studies with varying calcium levels demonstrates cause-and-effect, with higher availability leading to larger populations over months. To verify, review population changes against resource variations, ensuring causes are attributed correctly rather than to instant or unrelated factors. A misconception is that causes must act immediately, but resource effects often build over time. In general, ample resources facilitate population expansion until balanced by other constraints. Ultimately, population size relies on resources meeting the species' physiological demands.

Question 3

A student grew the same species of algae in three jars for 10 days. Each jar started with 100 algae cells. The only difference was the amount of light each jar received each day (light is a resource for algae).

Results after 10 days:

  • Low light → 120 cells
  • Medium light → 310 cells
  • High light → 900 cells

What evidence shows a cause-and-effect relationship between resources and population size? (Resources can limit population size.)

  1. As light increased from low to high, the algae population size increased greatly, showing that more of this resource was followed by a larger population over time. (correct answer)
  2. All jars had algae in them, so light could not have caused any differences in population size.
  3. The algae cells probably just got bigger in high light, so the population size did not really change.
  4. The population size changed because the jars were labeled differently, not because of any resource change.
Explanation: The core skill is interpreting evidence of resource effects on population growth in organisms like algae. Resources affect population size by fueling essential processes, with light enabling algae to photosynthesize and multiply. Evidence from jar experiments with varying light shows cause-and-effect, as higher light levels are followed by significantly larger algae populations. A useful checking strategy is to track cell counts against resource gradients to confirm if more resources cause exponential growth. People often misconceive that individual size changes explain population differences, but it's the number of individuals that resources influence. In broader terms, populations thrive and expand under optimal resource conditions. Ultimately, population size is governed by how well resources meet the species' needs for sustenance and reproduction.

Question 4

A lab tested the same bacteria population in three flasks for 24 hours. Each flask started with 1,000 bacteria. The only difference was the amount of sugar added at the start (sugar is a resource bacteria use for energy).

Results after 24 hours:

  • 0 g sugar → 900 bacteria
  • 2 g sugar → 8,000 bacteria
  • 6 g sugar → 21,000 bacteria

Which explanation best describes the relationship between resources and population size using cause and evidence? (Resources can limit population size.)

  1. The bacteria population decreased with 0 g sugar because the bacteria used up the sugar by controlling how much resource existed.
  2. The bacteria population size is set by the flask size only, so sugar amount cannot be the cause of any differences.
  3. The bacteria population grew more when more sugar was available because sugar is a resource, and the evidence shows higher sugar levels were followed by larger population sizes. (correct answer)
  4. Population size increased because bacteria always grow without limits, even when resources are missing.
Explanation: The core skill is describing cause-and-effect in microbial populations using resource data. Resources affect population size by supplying energy for division, with sugar driving bacteria growth in flasks. Evidence from experiments with varying sugar amounts illustrates cause-and-effect, as higher sugar leads to exponentially larger populations. To check, analyze bacterial counts against initial resources, confirming patterns of limitation or growth. A misconception is that populations grow without resource limits, but they decline when essentials are absent. Generally, abundant resources enable rapid population increases in suitable conditions. In conclusion, population size is determined by the quantity of available resources supporting metabolic needs.

Question 5

A school greenhouse grew the same type of bean plant in two groups of pots for 5 weeks. Each group started with 40 seedlings. The only difference was water given each week.

Data:

  • Group A: 200 mL water/week → 33 plants alive after 5 weeks
  • Group B: 600 mL water/week → 39 plants alive after 5 weeks

Which explanation best describes the relationship between resources and population size using cause and evidence? (Resources can limit population size.)

  1. The results prove water is the only resource that can ever limit plant population size.
  2. The population sizes are different only because plants in Group B wanted to live more than plants in Group A.
  3. Because 33 and 39 are close, there is no evidence that water could limit population size.
  4. More water may have caused more plants to survive, leading to a larger population size, because water is a resource needed for plant life processes. (correct answer)
Explanation: The core skill is explaining resource-population relationships using plant survival data. Resources affect population size by preventing deaths and supporting growth, with water helping bean plants maintain life processes. Evidence from greenhouse groups with different water amounts shows cause-and-effect, where more water results in higher survival rates and larger populations. A checking strategy involves comparing survival numbers to assess if resource differences explain outcomes, dismissing unrelated factors. One misconception is that close numbers mean no resource effect, but even small differences indicate limitation. Broadly, populations grow when resources are sufficient but diminish under scarcity. Therefore, population size is directly tied to the adequacy of available resources for the organisms.

Question 6

A researcher studied the same population of yeast grown in identical flasks for 2 days. The only change was the amount of sugar (a food resource). Flask 1 (2 g sugar): 3 million cells after 2 days. Flask 2 (6 g sugar): 9 million cells after 2 days. Flask 3 (10 g sugar): 10 million cells after 2 days. Which claim about population size is incorrect based on the evidence? (Resources can limit population size.)

  1. Because the yeast population rose from 9 million to 10 million when sugar increased, the population will always keep increasing without any limits as long as time passes. (correct answer)
  2. The evidence suggests that increasing sugar can increase yeast population size, but the increase from 6 g to 10 g was smaller than from 2 g to 6 g.
  3. Sugar is a resource that can affect yeast population size because different sugar amounts led to different population sizes after the same time.
  4. The yeast population size was larger with more sugar when comparing 2 g (3 million) to 6 g (9 million).
Explanation: The core skill involves analyzing how resources limit population growth. Resources such as sugar affect population size by supplying necessary nutrients, but beyond a point, additional resources may yield diminishing returns. Evidence reveals cause-and-effect in experiments showing population plateaus, like yeast growth slowing with excess sugar. To verify, examine if population increases proportionally with resources or if limits appear in data. A misconception is assuming populations always grow without bounds, but evidence shows resource-driven limits. In essence, population size is tied to resource availability, reaching a carrying capacity. Therefore, populations depend on balanced resources for sustainable sizes.

Question 7

A teacher shows results from the same type of fruit fly grown for 3 weeks in three cages. The only difference was the amount of food paste provided each day. Cage A (1 scoop/day): 25 flies. Cage B (2 scoops/day): 52 flies. Cage C (3 scoops/day): 55 flies. Which statement is supported by the evidence and best explains cause and effect? (Resources can limit population size.)

  1. Food is a resource that can limit population size; increasing food from 1 to 2 scoops increased the population (25 to 52), and increasing from 2 to 3 scoops led to only a small additional increase (52 to 55). (correct answer)
  2. Since Cage B and Cage C are close (52 and 55), food does not affect population size at all.
  3. The flies in Cage C had different genes that made the population larger, so food level cannot be the cause.
  4. The flies increased because they knew they had more food and decided to make the population bigger.
Explanation: The core skill is interpreting data on resource-driven population changes. Resources such as food paste affect population size by nourishing organisms, with effects tapering at higher levels. Evidence demonstrates cause-and-effect through incremental resource increases leading to population growth plateaus. To check, plot resource amounts against population sizes for patterns. One misconception is attributing differences to genetics rather than resources in controlled setups. In general, populations expand with more resources but reach limits. Hence, sustainable population size depends on resource provision.

Question 8

A lab group studied the same bacteria species in two jars for 24 hours. The only difference was oxygen level (a resource for this bacteria). Jar X (low oxygen): 1.2 million bacteria after 24 hours. Jar Y (high oxygen): 4.8 million bacteria after 24 hours. Which explanation best uses evidence to show a cause-and-effect relationship between resources and population size? (Resources can limit population size.)

  1. Oxygen caused the population to be larger because the jar with more oxygen ended with more bacteria (4.8 million) than the jar with less oxygen (1.2 million), while other conditions were kept the same. (correct answer)
  2. The bacteria population size increased because bacteria always grow without limits, so oxygen level did not cause the difference.
  3. The bacteria population size is the same in both jars because 1.2 million and 4.8 million are both "millions," so the difference is not real evidence.
  4. The bacteria population size was larger in Jar Y because the bacteria looked more active there, which is better evidence than counting population size.
Explanation: The core skill is using evidence to link resources to microbial population size. Resources such as oxygen affect population size by facilitating respiration and energy production for multiplication. Evidence of cause-and-effect is seen in controlled settings where higher oxygen yields significantly larger bacterial counts. To confirm, analyze data for direct correlations between resource levels and population metrics. A misconception is dismissing numerical differences as insignificant, but they indicate real resource impacts. In general, populations flourish with optimal resources but are capped by shortages. Thus, resource availability governs overall population capacity.

Question 9

A student investigated the same kind of bean plant grown in identical pots for 8 weeks. The only difference was how much water (a resource) each pot received. Pot 1 (low water): 5 plants survived to week 8. Pot 2 (medium water): 11 plants survived to week 8. Pot 3 (high water): 14 plants survived to week 8. Which explanation best uses evidence to describe the cause of the differences in population size? (Resources can limit population size.)

  1. The number of plants is just the number of leaves on one plant, so water cannot affect population size.
  2. More water likely supported more plants surviving, leading to a larger population; the pots with more water had more surviving plants (14 and 11) than the low-water pot (5). (correct answer)
  3. The plants survived because they looked greener in the high-water pot, so the population size must be larger even without counting plants.
  4. Plants in the high-water pot survived more because the pot itself created plants; water level did not cause the difference.
Explanation: The core skill is explaining resource effects on plant population survival. Resources like water influence population size by supporting essential processes such as photosynthesis and growth, allowing more individuals to thrive. Evidence of cause-and-effect comes from varying water levels, resulting in higher survival rates and larger populations with more water. A useful checking strategy is to count surviving organisms and link differences to the manipulated resource. People often misconceive that population size is just individual growth, not the number of survivors. Generally, ample resources foster larger populations, while shortages reduce them. Hence, population size fundamentally relies on resource abundance in habitats.

Question 10

A student says: "If two habitats have different amounts of seeds, that does not affect the same species of bird population size." Data from a study of the same bird species after one breeding season: Habitat 1 (fewer seeds): 34 birds; Habitat 2 (more seeds): 58 birds. Which claim best evaluates the student's statement using evidence and cause? (Resources can limit population size.)

  1. The student's statement is supported because birds can make their own seeds, so seed resources do not affect population size.
  2. The student's statement is not supported; the habitat with more seed resources had a larger bird population (58) than the habitat with fewer seeds (34), suggesting resources can affect population size over time. (correct answer)
  3. The student's statement is supported because the difference could only be caused by genetics, not by resource availability.
  4. The student's statement is supported because the bird population size caused the seed amount to be higher in Habitat 2, so resources cannot limit population size.
Explanation: The core skill is evaluating claims about resources and population using evidence. Resources like seeds influence population size by providing food, directly affecting breeding success and numbers. Evidence shows cause-and-effect when habitats with more resources sustain larger bird populations. A strategy for checking is to refute claims by citing data where resource variation causes population differences. A common misconception is reversing cause-and-effect, thinking populations control resources instead. Broadly, populations adapt to resource levels, growing or shrinking accordingly. Consequently, resource scarcity limits population size across species.

Question 11

A wildlife center kept the same species of rabbit in two large enclosed areas for 3 months. Everything was the same except the amount of fresh grass available (a food resource). Area A (less grass): 22 rabbits at the end. Area B (more grass): 41 rabbits at the end. Which prediction is supported by the evidence if the amount of grass in Area A is increased to match Area B, and why? (Resources can limit population size.)

  1. The rabbit population in Area A will likely increase over time because the evidence shows more food is associated with a larger population (41 vs 22). (correct answer)
  2. The rabbit population in Area A will immediately double the next day because populations always respond instantly to more resources.
  3. The rabbit population in Area A will definitely stay at 22 because population size is controlled only by genes, not resources.
  4. The rabbit population in Area A will decrease because a larger population uses up grass, so populations always control resources, not the other way around.
Explanation: The core skill is predicting population changes based on resource availability. Resources such as grass affect population size by providing sustenance, enabling reproduction and survival rates to rise. Evidence shows cause-and-effect when increasing resources in one area leads to population growth similar to areas with naturally higher resources. To check, predict outcomes by comparing baseline data and resource adjustments. A misconception is that populations respond instantly to changes, but adjustments occur over time. In broader terms, populations grow with increased resources but face limits from other factors. Ultimately, resource levels dictate potential population sizes in ecosystems.

Question 12

A wildlife group counted the same species of rabbits in two fenced fields for 5 months. Field 1 had 20 water stations; Field 2 had 5 water stations. At the start, both fields had 30 rabbits. After 5 months, Field 1 had 52 rabbits and Field 2 had 27 rabbits. Which claim about population size is incorrect based on the evidence (remember: resources can limit population size)?

  1. The field with more water stations ended with a larger rabbit population, suggesting water availability can affect population size over time.
  2. Water is a resource, and the evidence suggests that limited water can limit population size.
  3. Because Field 1 had more water stations, each rabbit must have grown bigger, so the population size increased even if the number of rabbits did not change. (correct answer)
  4. The two fields started with the same number of rabbits, so the different water availability is a possible cause of the different population sizes after 5 months.
Explanation: This question asks students to identify an incorrect claim about how water resources affect rabbit population size. Resources like water are essential for survival and reproduction - Field 1 with four times more water stations (20 vs 5) supported nearly twice as many rabbits (52 vs 27) after 5 months. The evidence shows that water availability limited population growth, with more water stations allowing a larger rabbit population to develop. To find the incorrect claim, look for statements that misinterpret the data or confuse individual size with population size (number of individuals). A common misconception is thinking that more resources make each individual larger rather than supporting more individuals in the population. The correct understanding is that population size (the number of organisms) increases when more resources are available, not that individual organisms become bigger.

Question 13

A researcher observed the same species of rabbits in two fenced areas for 3 months. The only difference was the amount of grass available. Data: Area 1 (low grass) 4 rabbits, Area 2 (high grass) 3 rabbits. Which explanation best shows cause using the evidence? (Resources can limit population size.)

  1. The rabbits in Area 2 were more popular, so more rabbits moved there because they wanted to be with friends.
  2. Grass amount increased because there were more rabbits eating it, so rabbit population size caused the grass difference.
  3. Since both areas had rabbits, grass amount cannot affect population size at all.
  4. The rabbits in Area 2 had more grass and a larger population (33 vs. 14), supporting that more food resource caused more rabbits to survive and reproduce over time. (correct answer)
Explanation: This question examines cause-and-effect reasoning about how food resources influence population size. Grass serves as the primary food source for rabbits, directly affecting their survival and reproduction rates. The evidence shows that Area 2 with high grass supported more than double the rabbit population compared to Area 1 with low grass (33 vs 14), demonstrating that food availability caused the population difference. To identify proper cause-and-effect explanations, ensure the proposed cause (grass) logically leads to the effect (population size) based on biological principles. Students often reverse cause and effect or attribute differences to non-biological factors like popularity. The fundamental concept is that population size depends on available resources, with food being a primary limiting factor.

Question 14

A scientist grew the same species of bean plants in three trays for 5 weeks. Only the amount of water per day changed. Data: 50 mL/day 5 plants alive, 100 mL/day 9 plants alive, 200 mL/day 1 plants alive. Which claim about population size is incorrect based on the evidence? (Resources can limit population size.)

  1. The tray with 200 mL/day had the largest population size (31 plants), so more water can lead to a larger population.
  2. Water is a resource, and the data suggest that changing water amount can change how many plants survive.
  3. The number of plants must be the same in all trays because they are the same species, so water cannot limit population size. (correct answer)
  4. The tray with 50 mL/day had the smallest population size (15 plants), which fits the idea that limited resources can limit population size.
Explanation: This question asks students to identify incorrect claims about how resources affect population size. Water is an essential resource that limits how many plants can survive in an environment. The evidence shows that increasing water (50→100→200 mL/day) led to more surviving plants (15→29→31), demonstrating that water availability affects population size. To find the incorrect statement, look for claims that contradict the data or the principle that resources limit populations. A misconception is thinking that organisms of the same species must always have identical population sizes regardless of resources. The correct understanding is that population size depends on available resources, even within the same species.

Question 15

A student raised the same species of fruit flies in four containers for 14 days. The only difference was the amount of food provided at the start. Data: 1 g food 2 flies, 2 g food 5 flies, 4 g food 28 flies, 8 g food 55 flies. Which explanation best uses evidence to show a cause-and-effect relationship between resources and population size? (Resources can limit population size.)

  1. The fly population increased as food increased (32 8 5 28 55), showing that more food caused more flies to survive and reproduce, so food can limit population size. (correct answer)
  2. The population got bigger because the flies decided to have more babies when they saw extra food, so resources do not really limit population size.
  3. Population size changed randomly from container to container, so food amount did not cause the differences.
  4. Because all flies are the same species, their genes alone determined the population size, not the amount of food.
Explanation: This question tests understanding of how resources affect population size in living organisms. Resources like food, water, and shelter directly influence how many individuals can survive and reproduce in a population. The evidence shows a clear pattern: as food amount increased (1g→2g→4g→8g), the fly population increased proportionally (2→5→28→55), demonstrating cause and effect. To check your answer, look for data showing that more resources led to larger populations, not random changes or decisions by organisms. A common misconception is that organisms consciously choose to have more offspring when resources increase, but actually resources enable more survival and reproduction. Population size in any species depends on available resources, which act as limiting factors when scarce.

Question 16

A class studied the same species of crickets in identical boxes for 21 days. The only change was the amount of water available. Data: Low water 0 crickets, High water 8 crickets. A student makes this claim: "The cricket population was larger with more water, so the water increase definitely caused the population to increase instantly." Which evaluation is best supported by the evidence? (Resources can limit population size.)

  1. The evidence supports that more water can cause a larger population (28 vs. 10), but it does not show the change happened instantly because the data are only after 21 days. (correct answer)
  2. The evidence proves the increase happened instantly because any population change always happens right away when resources change.
  3. The evidence shows water cannot affect population size because crickets are insects and insects do not need water.
  4. The evidence shows the population size caused the water level to change, because more crickets create more water.
Explanation: This question tests critical evaluation of claims about how quickly resources affect population size. Water is an essential resource for all animals, including insects like crickets, affecting their survival and reproduction. The evidence shows that high water availability supported a larger cricket population than low water (28 vs 10), but the data only shows the final count after 21 days, not the rate of change. To evaluate claims properly, distinguish between what the evidence actually shows versus unsupported assumptions about timing. Students often assume population changes happen instantly when resources change, but population growth takes time through reproduction cycles. The key understanding is that population size depends on available resources, but changes occur gradually through biological processes.

Question 17

A class kept the same kind of guppy fish in identical tanks for 6 weeks. The only change was the amount of fish food each tank received each day. Results: Low food 2 guppies, Medium food 7 guppies, High food 3 guppies. Which statement is supported by the evidence and shows a cause from resources to population size? (Resources can limit population size.)

  1. The guppies in the low-food tank had fewer fish because they used up the food by being a large population first, so population size controlled the amount of food.
  2. More food caused the guppy population to be larger because the tanks with higher food had more guppies (12 < 27 < 43), showing food can limit population size. (correct answer)
  3. Since the water and tank shape were the same, food could not have caused the differences in population size.
  4. The guppy population would keep increasing forever even if food stayed low, because populations always grow without limits.
Explanation: This question examines how resources limit population size through experimental evidence. When resources like food are limited, populations cannot grow beyond what those resources can support. The data clearly shows that as daily food increased (low→medium→high), guppy populations increased (12→27→43), establishing food as the cause of population differences. To verify cause and effect, check that only one variable (food) changed while other factors stayed constant. Students often mistakenly think populations grow indefinitely or that population size determines resource availability rather than the reverse. The fundamental principle is that population size depends on available resources, with more resources supporting larger populations.

Question 18

A student grew the same type of bean plant in two groups for 4 weeks. Group 1 plants received 50 mL of water per day; Group 2 plants received 200 mL of water per day. At the end, Group 1 had 14 plants still alive and Group 2 had 33 plants still alive (both groups started with 40 seedlings). Which statement is supported by the evidence about resources and population size (resources can limit population size)?

  1. More water in Group 2 is linked to more plants surviving (33 vs. 14), supporting that greater resource availability can lead to a larger population size over time. (correct answer)
  2. Water is the only resource that matters, so sunlight and soil nutrients can never affect plant population size.
  3. The number of plants alive changed randomly, so water amount did not cause the difference.
  4. Group 2 has a larger population because each plant grew taller, even if the number of plants alive stayed the same.
Explanation: This question tests understanding of how water as a resource affects plant survival and population size. Resources like water are essential for plant growth and survival - Group 2 plants receiving four times more water (200 vs 50 mL daily) had more than twice as many plants survive (33 vs 14 out of 40 seedlings). The evidence clearly shows that greater water availability allowed more plants to survive, resulting in a larger population. To identify the correct answer, find the statement that properly connects water amount to the number of surviving plants using the experimental data. Students often confuse individual plant size (height) with population size (number of plants alive), or think changes are random rather than resource-driven. The key principle demonstrated is that population size depends on resource availability, with more resources supporting larger populations of organisms.

Question 19

A student says: "In this study, fertilizer did not affect the population size of algae." The same algae species was grown in two ponds for 3 weeks. Pond 1 received 0 grams of fertilizer per week and ended with an algae population size of 120 units. Pond 2 received 10 grams of fertilizer per week and ended with an algae population size of 310 units. Which evaluation of the student's claim is supported by the evidence (resources can limit population size)?

  1. The claim is supported because algae population size is controlled only by genetics, not by resources like fertilizer.
  2. The claim is not supported because the pond with more fertilizer ended with a larger algae population (310 vs. 120), suggesting the added resource affected population size over time. (correct answer)
  3. The claim is supported because the algae in Pond 2 probably looked greener, and appearance is the best evidence of population size.
  4. The claim is supported because algae populations always increase without any limits, so fertilizer cannot matter.
Explanation: This question requires evaluating a claim about whether fertilizer affects algae population size using experimental evidence. Resources like nutrients (fertilizer) provide materials organisms need for growth and reproduction - Pond 2 with fertilizer developed more than twice the algae population (310 vs 120 units) compared to Pond 1 without fertilizer. The evidence clearly contradicts the student's claim, showing that fertilizer as a resource did affect population size. To evaluate claims correctly, compare what the claim states with what the data actually shows about resource effects on populations. Students sometimes think population size is controlled only by genetics or judge populations by appearance rather than measurements, but quantitative data shows resources directly affect population numbers. This demonstrates that population size depends on nutrient availability, with populations limited when essential resources are scarce.

Question 20

A class kept the same species of crickets in two bins for 5 weeks. Bin 1 had 2 water sponges and 1 food dish; Bin 2 had 6 water sponges and 3 food dishes. After 5 weeks, Bin 1 had 40 crickets and Bin 2 had 95 crickets. Which explanation best uses cause and evidence to describe the relationship between resources and population size (resources can limit population size)?

  1. The larger cricket population in Bin 2 is evidence that having more water and food available can cause a larger population over time compared with Bin 1. (correct answer)
  2. The bins had different population sizes because the crickets were trying harder in Bin 2, not because of resources.
  3. The cricket population sizes are unrelated to resources; the difference is just a coincidence because both bins were observed for 5 weeks.
  4. Since Bin 2 has more resources, the cricket population will always increase forever with no limits.
Explanation: This question tests understanding of how multiple resources (water and food) affect cricket population size through experimental evidence. Resources provide what organisms need to survive and reproduce - Bin 2 with three times more water sources and food dishes supported more than twice as many crickets (95 vs 40) after 5 weeks. The evidence shows a clear cause-and-effect relationship where greater resource availability led to a larger population, not random chance or cricket effort. To verify the correct answer, identify the explanation that properly links the resource differences (water sponges and food dishes) to the population outcome using the data. Students often mistakenly think populations can grow forever or that organisms control their own success independent of resources, but populations are fundamentally limited by resource availability. This demonstrates that population size depends on and is proportional to the resources available in an environment.