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Practice Test 12 - Middle School Life Science

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

  1. Ecosystem model (described): Two ecosystems are modeled. Model 1 (garden): soil matter → tomato plant; air matter → tomato plant; tomato plant matter → caterpillar; caterpillar matter → bird; dead matter → decomposers; decomposer matter → soil. Model 2 (ocean shore): water matter → seaweed; air matter → seaweed; seaweed matter → crab; crab matter → gull; dead matter → decomposers; decomposer matter → sand/sediment. Both models state: Matter cycles through ecosystems. Comparison: Which statement is supported by evidence from both models?
  2. Use this garden energy-flow model: Sunlight → Tomato plant (producer) → Caterpillar (consumer) → Lizard (consumer). Decomposers (worms/fungi/bacteria) receive energy from dead tomato plants, dead caterpillars, dead lizards, and wastes (arrows from each to decomposers). The model states: energy flows through ecosystems rather than cycling. If the tomato plants decrease greatly for several weeks, which prediction about energy availability is supported by the model?
  3. A diagram compares embryo images at the same early stage for Species X and Species Y. Both show highlighted pharyngeal pouches and a tail. A student concludes: "Species X is more evolved than Species Y because its embryo looks slightly more complex." Embryological similarities can suggest common ancestry. Which evaluation of the student's claim is best supported by the embryo images?
  4. Use the photosynthesis model shown and what you know about matter and energy. Photosynthesis involves inputs and outputs of matter. Which item in the model is energy (not matter), even though it enters the leaf?
  5. A farmer recorded comb shape in chickens raised on the same farm with the same feed. Generation 1 parents: both parents had a "single" comb. Their 10 offspring had comb shapes: 7 single, 3 rose. From those offspring, two chickens with rose combs were paired (same farm). Their 8 offspring had comb shapes: 6 rose, 2 single. Variation can be inherited. Which explanation best fits the inherited variation pattern shown by the evidence across generations?
  6. Cells are the basis for determining whether something is living. A simplified microscope model shows two samples side by side: Sample A (yeast mixture) and Sample B (sugar solution). In the model, Sample A shows many separate round units with clear boundaries. Sample B looks evenly shaded with no separate bounded units. Which prediction about a living sample is supported by the model evidence?
  7. A student walks into a bakery and smells fresh bread (stimulus). Use the pathway model: Stimulus → Sensory receptor detects stimulus → Brain processes signal → Response or stored information. What evidence shows the sequence is important for how sensory input can lead to responses or stored information?
  8. A teacher provides a model with a clear arrow from gene to protein and states: gene changes can affect proteins. Model: - Before: Gene 9 = W X Y Z A → Protein 9 has a flat surface that stacks well with other Protein 9 units - After: Gene 9 = W X Y Z B → Protein 9 surface becomes curved and stacks poorly Which explanation best uses evidence from the model to connect gene change to protein function?
  9. A city park is trying to increase habitat for native birds. Evidence shows: the park currently has 70% mowed lawn, 20% trees, and 10% shrubs; bird surveys found more native birds in areas with shrubs and native plants; converting 10 hectares of lawn to native shrubs and wildflowers increases insect abundance (bird food) by about 40%; adding bird feeders increases bird sightings but mostly of a few common species; planting more trees provides nesting sites but takes years to mature. Conservation choices: Option 1: Convert part of the lawn to native shrubs and wildflowers. Option 2: Install more bird feeders. Option 3: Plant 200 young trees. Criteria: scientific effectiveness (supporting diverse native birds), economic cost, and social feasibility (park users). Constraints: the park must keep at least 50% of the area open lawn for sports; the budget allows either lawn conversion or tree planting, not both; feeders require ongoing maintenance. Which conservation choice is best justified by the evidence and constraints?
  10. Fossil records can show patterns of diversity through time, but they do not include every organism that lived. A core sample has four layers from oldest to youngest with these fossil types: - Layer 4 (oldest): 2 types - Layer 3: 5 types - Layer 2: 5 types - Layer 1 (youngest): 5 types A student predicts what might be found if a new layer formed above Layer 1 and conditions stayed similar to the time Layers 3–1 formed. Which prediction about the diversity in the new youngest layer is best supported by the trend in the fossil evidence?
  11. Use the photosynthesis model and what you know about matter and energy. Photosynthesis involves inputs and outputs of matter. Of the things shown entering the leaf, which substance is an input of matter (not energy)?
  12. A fossil site contains three layers (oldest at the bottom). Layer 1: only marine fossils (coral, seashells). Layer 2: marine fossils plus fish fossils. Layer 3 (youngest): mostly fish fossils and a few marine shells. Which statement is best supported by the fossil evidence about how life has changed over long periods of time at this location?
  13. A simplified plant model shows these labeled arrows: carbon dioxide (matter) enters the leaf from the air, water (matter) enters through roots, and sunlight (energy) enters the leaf. Inside the plant, a label says incoming matter becomes sugars that are used to make new leaf and stem tissue. Which claim about plant mass is incorrect, based on evidence from the model?
  14. A model shows dust particles (stimulus) landing on receptors in the lining of the nose (receptor). A "signal" icon appears at the receptors. The person sneezes (response). Which statement about detection is supported by the model, using evidence?
  15. Model (arrows show energy flow, not matter movement): Sunlight → grass (producer) → rabbit → fox. Matter (atoms) moves differently because organisms become part of each other when eaten, but energy flows one way through the model. Sunlight is the main energy source for most ecosystems. Which organism in the model gets energy directly from sunlight?
  16. Two populations of the same lizard species live on the same rocky hillside. The visible trait difference is toe pad size. Students tracked reproductive success by counting the number of hatchlings produced per 10 females. Which statement is supported by the evidence? Data (same hillside): - Large toe pads: 10 females produced 34 hatchlings - Small toe pads: 10 females produced 20 hatchlings
  17. A desert model shows: Sunlight → Cactus (producer) → Jackrabbit (consumer) → Coyote (consumer). Decomposers (bacteria/fungi) receive energy from dead cactus, dead animals, and wastes (arrows from each to decomposers). The model states: energy flows through ecosystems rather than cycling. Which statement about energy flow is supported by the model?
  18. Two groups of the same kind of houseplant differ in an inherited trait: Variety P (inherited to grow longer stems) and Variety Q (inherited to grow shorter stems). They are grown for 3 weeks in two environments: Watering A = daily watering, Watering B = watering once per week. Average stem length is shown. Genes: Variety P vs Variety Q Environment: daily vs weekly watering Which statement is supported by the evidence?
  19. A pond model tracked algae and zooplankton (tiny animals that eat algae) for 4 weeks under the same light and temperature. Data: Week 1 algae density = 60 units, zooplankton = 10; Week 4 algae density = 25 units, zooplankton = 35. Interactions can affect survival and reproduction. Which statement about survival and reproduction is supported by the evidence from the data?
  20. A city park tracked squirrel population estimates: Year 1 = 90, Year 2 = 92, Year 3 = 88, Year 4 = 40. Two explanations are offered: Explanation 1: Park managers removed many nut-producing trees in late Year 3, reducing food. Explanation 2: A loud music festival in early Year 4 scared squirrels away permanently. Evidence: Park maintenance records confirm many nut trees were removed in late Year 3. The festival lasted 2 days in early Year 4, and squirrel counts taken 2 weeks after the festival were still low. Explanations must be evaluated using evidence (fit and completeness). Which explanation is best supported by the evidence?

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