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Practice Test 7 - Middle School Life Science

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

  1. A diagram shows the leg structures of three organisms (1, 2, and 3) in the same side-view orientation with a scale bar. Each leg has three main segments in a row. In organism 2, the middle segment is much longer than the other two. Body structures can be compared across organisms using segment number, order, and relative lengths. Which statement about similarity is correct?
  2. A farm region wants to maintain biodiversity of pollinators and birds while still producing crops. Two solutions are proposed. Solution A (Hedgerows and flower strips): plant native flowering strips and shrubs along field edges to provide nectar and nesting habitat. Constraints/tradeoffs: uses some land area; requires maintenance to control weeds; benefits may take 1–2 seasons. Solution B (Increase pesticide use): apply more insecticide to reduce crop pests. Constraints/tradeoffs: may increase short-term yield; can reduce insect populations that pollinators and birds rely on; risk of pesticide drift to nearby habitats. Evidence from local trials: fields with hedgerows had higher wild bee species counts and more insect-eating bird sightings; fields with increased pesticide had lower bee counts and fewer bird sightings. Which comparison of solutions is supported by evidence for maintaining biodiversity, considering constraints?
  3. A student compares two inherited varieties of rabbits raised in the same barn (same diet, cage size, temperature, and care). Variety G rabbits averaged 2.8 kg at 6 months. Variety H rabbits averaged 2.1 kg at 6 months. The student concludes: "The barn environment caused Variety G to be heavier." Which evaluation of the student's claim is best supported by the evidence?
  4. Use the diagrams to compare body structures across organisms. The highlighted parts are intended to be comparable. Which evidence best shows a difference between the structures? (Orientation note: both are side views facing left; the dashed line marks the same reference position in both drawings.)
  5. A model shows arrows pointing into a plant labeled carbon dioxide (from air) and water (from soil). A separate arrow labeled sunlight energy points to the leaves. Inside the plant is a label: new plant material (more cells). Which claim about plant mass is incorrect based on evidence from the model?
  6. A clinic uses preimplantation genetic testing (PGT) during IVF to select embryos that do not have a specific inherited disorder. In one group of families, the number of children born with the disorder decreased from 1 in 4 to 0 in 10 births after PGT was used. However, the clinic reported that the process required hormone treatments and multiple medical visits, and some IVF cycles did not result in a pregnancy. Technologies have impacts and tradeoffs. Which evaluation best reflects the impacts of PGT based on the evidence?
  7. Use the model to trace matter and energy separately. In this model, solid arrows show matter movement and dashed arrows show energy flow. Matter and energy must be traced separately because they follow different paths. Comparison question: Which choice correctly compares what happens to matter and energy after the hawk eats the snake? Model (labels): - Producer: prairie grass - Consumers: mouse, snake, hawk - Solid arrows (matter): prairie grass → mouse → snake → hawk; hawk → decomposers; decomposers → soil nutrients → prairie grass - Dashed arrows (energy): sunlight → prairie grass; prairie grass → mouse → snake → hawk; hawk → heat to environment
  8. Fossil layers in a canyon wall are ordered from older (bottom) to younger (top). The fossil layers show changes in life forms over time. The layers contain: Oldest: only algae-like fossils; Next: algae-like fossils + small shell fossils; Next: mostly shell fossils; Youngest: shell fossils + fish fossils. Which prediction about a deeper (older) layer below the oldest layer is most supported by the pattern in the fossil layers?
  9. A student uses this model and says: sunlight is the main energy source for most ecosystems. The arrows show energy flow, and the organisms themselves (matter) do not travel along the arrows. Model: Sunlight → maple tree (producer) → deer (consumer) → wolf (consumer). Which statement about energy flow is supported by the model?
  10. A student is shown embryo images for three mammals (Species 1–3) and one insect (Species 4) at the same developmental stage. The mammal embryos share a similar overall body plan and similar limb buds. The insect embryo has a very different body plan. Claim: "Embryology provides evidence for relatedness, so Species 1–3 are more closely related to each other than any of them is to Species 4." Which statement is the best-supported conclusion from the embryo evidence?
  11. A simplified model shows energy flow: Sunlight → algae (producer) → small fish → heron. The arrows represent energy flow. Matter (like the algae's material) can move from one organism to another when one eats another, but energy does not cycle back to sunlight. Sunlight is the main energy source for most ecosystems. Which statement about energy flow is supported by the model?
  12. A population of insects has two inherited traits for body size: large and small. The environment stayed constant (same pesticide exposure level and same food supply) for 2 weeks. Researchers recorded survival. Data: Out of 150 large insects, 45 survived. Out of 150 small insects, 75 survived. Which statement about survival is supported by the evidence?
  13. Use the organism model: A frog is shown with two labeled systems—Respiratory System (lungs/skin) and Circulatory System (heart/blood vessels). Arrows show oxygen moving from the Respiratory System to the Circulatory System, and arrows show carbon dioxide moving from the Circulatory System back to the Respiratory System. The model notes: "The frog's movement and survival depend on system interaction." Which statement about system interaction is supported by the model and explains how these systems interact to support organism function?
  14. Ecosystem A: A plant produces seeds that fall near the parent plant; many seedlings grow crowded. Ecosystem B: A plant produces seeds that stick to animal fur and get carried far away; seedlings are more spread out. Interaction patterns can be compared across ecosystems. Which prediction about interaction change is supported by evidence if animals that carry seeds become rare in Ecosystem B?
  15. A model shows a plant stem thickening after being bent. In the before panel, small molecules are shown inside the stem near the bend. Arrows show these small molecules being assembled into larger, stronger structures in the stem. In the after panel, the stem is thicker and the bend area is reinforced. The model states: "Rearranged molecules support growth and repair." Which prediction is supported by the model if the plant cannot get enough small molecules to use inside the stem?
  16. Starting condition (before): A colony of bacteria in a lab dish grows steadily because nutrients are added each day. Change in resources (after): The nutrient solution is accidentally diluted, so fewer nutrients are available. Evidence: After several hours, the dish becomes cloudy more slowly than before. Time: before vs after is described. Population changes can be predicted from evidence. Which statement best predicts the outcome for the bacterial population based on resources and evidence?
  17. A lab group compares two simplified reproduction models. Model X (Asexual): Parent count: [1] Parent: ◆(purple) Offspring: ◆(purple) ◆(purple) ◆(purple) (very similar) Model Y (Sexual): Parent count: [2] Parent 1: ◆(purple) Parent 2: ◆(orange) Offspring: ◆(purple-orange mix) ◆(more purple) ◆(more orange) (variation) What evidence from both models shows differences in variation between asexual and sexual reproduction?
  18. A student reads: "Humans can influence trait inheritance using technology." In one project, scientists edited a gene in mosquitoes so that more offspring have non-functional wings. Over 3 generations in the lab, the percentage of mosquitoes with non-functional wings rose from 0% to 40%. Which statement is supported by the evidence and best matches the idea of human influence?
  19. A town is evaluating ways to reduce plastic waste harming sea turtles. Solutions are evaluated using multiple criteria (scientific, economic, and social) and the evidence below. Solution 1: Install trash-capture nets at two stormwater outflows. Solution 2: Run a school and community education campaign about reducing single-use plastics. Evidence: - Scientific criteria: Trash-capture nets reduced plastic entering the bay by 65% at similar outflows, but they also trapped some leaves and required weekly cleaning; turtle strandings linked to plastic decreased by 20% in 1 year in a similar town. Education campaigns increased recycling rates by 10% but reduced plastic entering waterways by only 15% in similar towns; turtle strandings decreased by 5%. - Economic/social constraints: Nets cost $90,000 upfront and $20,000/year maintenance; education costs $18,000/year and is widely supported. Which statement correctly evaluates the solutions using the evidence and criteria?
  20. Use the model to trace matter through multiple processes (digestion and respiration). A student says: "Respiration is only breathing in and out, so matter does not move to body cells." Which claim is unsupported by the model?

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