Unit Test: Ecosystems, Living Systems, and Cells

Benchmark Test · Grade 5 · Science

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Adaptive Selected Response

• Q1. What is the basic unit of all living things?

  • An organ
  • A tissue
  • A cell
  • A molecule

  Answer: A cell

  Explanation: The cell is the smallest and most basic unit of life. All living organisms are made of one or more cells.

• Q2. Which cell structure controls what enters and leaves the cell?

  • The cell wall
  • The nucleus
  • The cell membrane
  • The mitochondria

  Answer: The cell membrane

  Explanation: The cell membrane is a selectively permeable barrier that regulates the movement of substances into and out of the cell.

• Q3. A student looks at two cells under a microscope. One cell has a cell wall and chloroplasts. The other cell does not. What conclusion can the student BEST draw? [FIGURE: Side-by-side labeled diagram of two cells under a microscope: Cell A (plant cell) showing a rectangular shape with visible cell wall, large central vacuole, and green chloroplasts; Cell B (animal cell) showing an irregular round shape with no cell wall, no chloroplasts, and smaller vacuoles. Both cells show a nucleus and cell membrane.]

  • Cell A is an animal cell and Cell B is a plant cell.
  • Cell A is a plant cell and Cell B is an animal cell.
  • Both cells are plant cells at different stages of growth.
  • Both cells are animal cells with different functions.

  Answer: Cell A is a plant cell and Cell B is an animal cell.

  Explanation: Cell walls and chloroplasts are structures found only in plant cells. Cell A has both, making it a plant cell. Cell B lacks these structures, making it an animal cell.

• Q4. Which organelle is responsible for producing energy for the cell?

  • Vacuole
  • Mitochondria
  • Ribosome
  • Chloroplast

  Answer: Mitochondria

  Explanation: Mitochondria convert glucose and oxygen into energy (ATP) through cellular respiration. They are often called the 'powerhouse of the cell.'

• Q5. A food web in a pond ecosystem is shown below. [FIGURE: Diagram of a pond food web with labeled arrows showing energy flow. Algae → Water flea → Small fish → Large fish → Osprey. Also: Algae → Tadpole → Snake → Osprey. Arrows point from prey to predator.] What would MOST LIKELY happen to the small fish population if all the water fleas disappeared?

  • The small fish population would increase.
  • The small fish population would stay the same.
  • The small fish population would decrease.
  • The small fish population would move to a new ecosystem.

  Answer: The small fish population would decrease.

  Explanation: Water fleas are a food source for small fish. If water fleas disappear, small fish lose a key food source, so their population would decrease.

• Q6. In a forest ecosystem, which organism is a producer?

  • A deer that eats grass and shrubs
  • A mushroom that breaks down dead logs
  • An oak tree that makes its own food from sunlight
  • A hawk that hunts small mammals

  Answer: An oak tree that makes its own food from sunlight

  Explanation: Producers are organisms that make their own food through photosynthesis. Oak trees use sunlight, water, and carbon dioxide to produce glucose.

• Q7. The table below shows the population data for four organisms in a meadow ecosystem over three years. | Organism | Year 1 Population | Year 2 Population | Year 3 Population | |----------|-------------------|-------------------|-------------------| | Grass | 10,000 | 8,500 | 7,200 | | Rabbits | 500 | 420 | 350 | | Foxes | 80 | 65 | 50 | | Hawks | 30 | 25 | 20 | Based on the data, which statement BEST describes the trend in this ecosystem?

  • Only the predator populations are declining over time.
  • All populations are increasing at the same rate.
  • All populations are declining, suggesting the ecosystem may be under stress.
  • Producers are increasing while consumers are decreasing.

  Answer: All populations are declining, suggesting the ecosystem may be under stress.

  Explanation: All four populations — grass (producer), rabbits and foxes (consumers), and hawks (top predator) — show consistent decline over three years, indicating a systemic stress on the ecosystem such as habitat loss or drought.

• Q8. Which process do plants use to make their own food using sunlight?

  • Cellular respiration
  • Decomposition
  • Photosynthesis
  • Fermentation

  Answer: Photosynthesis

  Explanation: Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to produce glucose and oxygen.

• Q9. A student sets up an experiment with two identical plants. Plant A is placed in sunlight and given water. Plant B is placed in a dark closet and given water. After two weeks, Plant B is wilted and yellow. [FIGURE: Side-by-side illustration of two identical potted plants after two weeks. Plant A (in sunlight) is tall, green, and healthy. Plant B (in a dark closet) is wilted, pale yellow, and shorter. Both pots are labeled with equal amounts of water given.] Why did Plant B turn yellow and wilt?

  • Plant B received too much water without sunlight.
  • Plant B could not perform photosynthesis without light to make food.
  • Plant B grew too fast in the dark and used up all its nutrients.
  • Plant B's cell walls broke down because of the cold temperature in the closet.

  Answer: Plant B could not perform photosynthesis without light to make food.

  Explanation: Plants need light to perform photosynthesis and produce glucose for energy and growth. Without light, Plant B could not make food, causing it to weaken, turn yellow (lose chlorophyll), and wilt.

• Q10. Which of the following BEST describes the role of decomposers in an ecosystem?

  • They convert sunlight into chemical energy for other organisms.
  • They hunt and eat other animals to control population size.
  • They break down dead organisms and return nutrients to the soil.
  • They compete with producers for water and minerals in the soil.

  Answer: They break down dead organisms and return nutrients to the soil.

  Explanation: Decomposers such as bacteria and fungi break down dead organic material, recycling nutrients back into the soil where producers can use them again.

• Q11. A scientist studied how energy moves through a food chain. The diagram below shows the amount of energy available at each level. [FIGURE: Energy pyramid diagram with four levels. Bottom level (Producers/Grass) labeled 10,000 units. Second level (Grasshoppers) labeled 1,000 units. Third level (Frogs) labeled 100 units. Top level (Hawks) labeled 10 units. Each level is progressively smaller and shaded darker going up.] About what percentage of energy is passed from one level to the next level up in the pyramid?

  • 100%
  • 50%
  • 10%
  • 1%

  Answer: 10%

  Explanation: The 10% rule states that only about 10% of energy is transferred from one trophic level to the next. The rest is lost as heat or used for life processes.

• Q12. Which of the following is an example of a biotic factor in an ecosystem?

  • The temperature of a pond
  • The amount of rainfall in a forest
  • The bacteria living in the soil
  • The type of rock found on a hillside

  Answer: The bacteria living in the soil

  Explanation: Biotic factors are the living components of an ecosystem. Bacteria are living organisms, making them biotic. Temperature, rainfall, and rock type are abiotic (non-living) factors.

• Q13. A student examines a cell and notices it has a large central vacuole, a cell wall, and chloroplasts. Which type of cell is this?

  • A human muscle cell
  • A bacterial cell
  • A plant cell
  • An animal skin cell

  Answer: A plant cell

  Explanation: Large central vacuoles, cell walls, and chloroplasts are structures found only in plant cells. These structures help plants store water, maintain shape, and perform photosynthesis.

• Q14. The graph below shows the population of wolves and elk in a national park over 20 years after wolves were reintroduced. [FIGURE: Dual-line graph titled 'Wolf and Elk Populations in Yellowstone National Park (Years 1–20).' X-axis: Year (1–20). Y-axis: Population (0–20,000). Blue line (Elk) starts high at ~18,000 in Year 1, decreases to ~8,000 by Year 20. Red line (Wolves) starts low at ~50 in Year 1, increases to ~300 by Year 20. Lines move in opposite directions, crossing around Year 8.] What relationship do the wolf and elk population trends BEST show?

  • As the wolf population increases, the elk population also increases.
  • As the wolf population increases, the elk population decreases.
  • The elk population controls the size of the wolf population.
  • The two populations change independently of each other.

  Answer: As the wolf population increases, the elk population decreases.

  Explanation: Wolves are predators of elk. As the wolf population grows, more elk are eaten, causing the elk population to decline. This is a classic predator-prey relationship.

• Q15. Which of the following BEST explains why there are fewer organisms at the top of an energy pyramid than at the bottom?

  • Top-level predators need less food than organisms at lower levels.
  • Energy is lost at each level, so less energy is available to support large populations at higher levels.
  • Top-level predators reproduce more slowly, so their populations are naturally smaller.
  • Organisms at the bottom of the pyramid compete with top-level predators for food.

  Answer: Energy is lost at each level, so less energy is available to support large populations at higher levels.

  Explanation: Only about 10% of energy is transferred between trophic levels. This means far less energy is available to support organisms at higher levels, resulting in fewer individuals.

• Q16. A group of students measured the dissolved oxygen levels in two ponds. Pond A had many aquatic plants. Pond B had very few plants. Their results are shown below. | Pond | Number of Aquatic Plants | Dissolved Oxygen (mg/L) | |------|--------------------------|-------------------------| | A | High (abundant) | 9.2 | | B | Low (few) | 4.1 | What is the MOST LIKELY reason Pond A has higher dissolved oxygen levels?

  • Pond A is located at a higher elevation than Pond B.
  • Pond A's plants release oxygen during photosynthesis.
  • Pond A has warmer water that holds more oxygen.
  • Pond A has more fish that produce oxygen through respiration.

  Answer: Pond A's plants release oxygen during photosynthesis.

  Explanation: Aquatic plants perform photosynthesis and release oxygen as a byproduct. Pond A has more plants, so more oxygen is released into the water, increasing dissolved oxygen levels.

• Q17. How are the cells in a multicellular organism organized to carry out life functions?

  • All cells in an organism are identical and perform the same job.
  • Cells are grouped into tissues, which form organs, which form organ systems.
  • Each cell works alone and does not interact with other cells.
  • Cells are randomly arranged with no specific structure or function.

  Answer: Cells are grouped into tissues, which form organs, which form organ systems.

  Explanation: In multicellular organisms, cells with similar functions group together to form tissues. Tissues form organs, and organs work together as organ systems to carry out complex life functions.

• Q18. A student is comparing how matter cycles through an ecosystem. Which statement BEST describes the role of decomposers in the carbon cycle?

  • Decomposers absorb carbon dioxide from the air to build their own food.
  • Decomposers release carbon back into the environment by breaking down dead organisms.
  • Decomposers store carbon in their bodies permanently, removing it from the cycle.
  • Decomposers convert carbon into oxygen that other organisms can breathe.

  Answer: Decomposers release carbon back into the environment by breaking down dead organisms.

  Explanation: When decomposers break down dead organisms, they release carbon dioxide back into the atmosphere and carbon compounds back into the soil, completing the carbon cycle.

• Q19. A scientist observes that a species of frog has disappeared from a wetland ecosystem. She also notices that the mosquito population has dramatically increased and the heron population has declined. Which statement BEST explains these observations?

  • The herons left the wetland because the water became too cold for them.
  • The loss of frogs disrupted the food web, reducing heron food and allowing mosquitoes to multiply.
  • Mosquitoes and herons are not connected to frogs in the food web.
  • The increase in mosquitoes caused the frogs to disappear from the wetland.

  Answer: The loss of frogs disrupted the food web, reducing heron food and allowing mosquitoes to multiply.

  Explanation: Frogs eat mosquitoes (keeping their population in check) and are eaten by herons (providing herons with food). When frogs disappear, mosquitoes increase unchecked and herons lose a food source, causing their population to decline.

• Q20. A class is designing a model ecosystem in a closed terrarium. They include soil, rocks, water, plants, small insects, and a decomposer layer of leaf litter with microbes. The terrarium receives sunlight through a glass top. [FIGURE: Labeled cross-section diagram of a sealed glass terrarium ecosystem. Layers from bottom to top: gravel drainage layer, soil layer with microbes and leaf litter (labeled 'decomposers'), small plants (labeled 'producers'), two small insects (labeled 'consumers'). Arrows show: sunlight entering from above, water cycling as condensation on the glass walls, and nutrient arrows between decomposer layer and soil.] If the students seal the terrarium completely and observe it for one month, which statement BEST predicts what will happen to the matter inside the terrarium?

  • All the matter will be used up by the organisms and the terrarium will become empty.
  • Matter will cycle continuously among the organisms, soil, water, and air inside the terrarium.
  • New matter will enter the terrarium from outside through the glass to support the organisms.
  • The organisms will produce more matter than was originally placed in the terrarium.

  Answer: Matter will cycle continuously among the organisms, soil, water, and air inside the terrarium.

  Explanation: Matter is neither created nor destroyed in an ecosystem — it cycles. In a closed terrarium, matter cycles among producers, consumers, decomposers, soil, water, and air continuously, even though no new matter enters from outside.

Grade

• Grade 5

State

• Other / Multi-State

Subject

• Science

Framework

• NWEA MAP

Standards

• NGSS 5-LS1-1
• NGSS 5-LS2-1
• NGSS 5-PS3-1
• NGSS 5-LS1-2

Difficulty

• On Grade Level

Total Points

• 20

Total Questions

• 20

Estimated Time Minutes

• 40

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