Practice Test 6 - Middle School Life Science

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

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1. A diagram compares a fossil fish-like body outline and a modern fish-like body outline. Both have a tail fin and paired side fins in similar positions, but the fossil has a longer tail fin. Anatomy can be compared across time using evidence from structures. Which statement about fossil and modern anatomy is correct based on the evidence?
2. A river has an invasive plant spreading along its banks, reducing habitat for native insects and birds. Managers are evaluating two solutions using multiple criteria. Solution 1: Hand-pull invasive plants in 5 km of riverbank each summer. Solution 2: Apply a targeted herbicide in spring to the same 5 km. Evidence: - Scientific criteria: Hand-pulling removed about 60% of invasive plants each year but disturbed soil, leading to 20% more erosion in some sections; native plant cover increased by 8% after 2 years. Targeted herbicide removed about 90% of invasive plants; native plant cover increased by 15% after 2 years; however, surveys found a temporary 12% decrease in aquatic insect larvae in treated areas for 3 weeks. - Economic/social constraints: Hand-pulling costs $55,000/year in labor and is supported by volunteer groups; herbicide costs $28,000/year but some residents oppose chemical use near water. Which evaluation is best supported by the evidence and criteria?
3. Food webs show interconnected feeding relationships in an ecosystem. In the food web model below, arrows show the direction of energy transfer (from the organism being eaten to the organism that gets the energy). Producers are the plants. Model (arrows show energy transfer): - Oak tree (producer) → Caterpillar - Oak tree (producer) → Squirrel - Berry bush (producer) → Squirrel - Caterpillar → Robin - Caterpillar → Lizard - Robin → Hawk - Lizard → Hawk - Squirrel → Fox Which claim about feeding relationships is incorrect based on the food web model?
4. Embryology provides evidence for relatedness by comparing embryos at comparable stages for shared structures. At the same stage, these observations were made: - Species A1: pharyngeal arches present; tail present; 2 limb buds - Species A2: pharyngeal arches present; tail present; 2 limb buds - Species B1: pharyngeal arches present; tail present; 4 limb buds - Species B2: pharyngeal arches absent; tail present; 4 limb buds Claim: "Species A1 and A2 are most closely related to each other." Which claim is best supported by the embryological evidence?
5. A farmer practices selective breeding in a corn field with the same soil, water, and sunlight each year. The farmer saves seeds only from the plants with the biggest ears. Data collected from the field: - Before selective breeding (Generation 0): 30% of plants had "large ears," 70% had "small ears." - After 6 generations of selective breeding: 78% of plants had "large ears," 22% had "small ears." Which explanation best shows how humans changed the trait distribution using the before-and-after data?
6. Two ecosystem models are shown. Ecosystem A (forest floor): mushrooms break down dead leaves; earthworms eat decaying leaves; robins eat earthworms. Ecosystem B (city compost bin): bacteria break down food scraps; pill bugs eat decaying scraps; chickens eat pill bugs. Students say interaction patterns can be compared across ecosystems. Which evidence supports the comparison that both ecosystems include a similar decomposition-related interaction pattern?
7. Behaviors or physical traits can affect reproductive success. Two groups of flowering plants of the same species grew in the same garden with the same watering and sunlight. Group T had tall stems; Group S had short stems. Pollinators were counted visiting flowers over the same 5-day period. Which evidence statement is supported by the table?
8. Ecosystems provide services that support humans and other organisms. In a mangrove forest along a tropical coast, tangled roots slow water currents and trap sediment. This creates calmer water where young fish can hide and grow. A nearby seagrass bed stays clearer because less sediment reaches it. Which statement about ecosystem services is supported by the mangrove scenario?
9. A population of fish shows variation in coloration: striped and solid. A new predator is introduced that more easily catches solid-colored fish in this habitat. The table shows the number of offspring produced by surviving adults. Striped adults: average 30 offspring per adult Solid adults: average 12 offspring per adult Which statement about trait distribution is supported by the evidence over multiple generations? (Natural selection affects populations, not individuals.)
10. Use the cell model shown. Arrows show coordination: cell membrane → cytoplasm (materials move in/out), cytoplasm → vacuole (storage), and vacuole → cytoplasm (materials released when needed). The model states that overall cell function depends on coordination and that no single part works alone. Which prediction about coordination is supported if the vacuole becomes much smaller than usual?
11. A whole-organism model of a person sleeping shows and labels the respiratory system (lungs), circulatory system (heart), nervous system (brain), and muscular system (chest muscles). Arrows show air moving into lungs, blood moving from the heart, and nerve signals coordinating breathing muscles. The model states: "Body systems form an integrated system." What evidence in the model best shows integration (not just separate activity) among systems?
12. Which claim about ecosystem energy is incorrect?
13. A scientist has embryo models shown in a diagram for Species U, V, and W at Stage 1 (early). Species U and V both show a tail bud and two neck grooves. Species W shows a tail bud but no neck grooves. Embryological similarities can suggest relationships among species. Which prediction about relatedness is supported by the embryo evidence?
14. A rock column has 5 fossil layers, ordered oldest to youngest: Layer 1, Layer 2, Layer 3, Layer 4, Layer 5. Fossils found: Layer 1: trilobite, fern. Layer 2: trilobite, fern, ammonite. Layer 3: fern, ammonite. Layer 4: fern. Layer 5: fern, mammal tooth. Fossils provide evidence of extinction and appearance because they show when organisms are present in some layers but not others. Which evidence from these layers best supports that the trilobite became extinct in this area after Layer 2?
15. A coastal city wants to maintain biodiversity in nearby salt marshes while reducing flooding. Two proposed solutions are being compared using evidence. Solution 1: Build a concrete seawall. How it works: blocks storm surge from reaching neighborhoods. Evidence from a similar coast: marsh area decreased by 30% over 10 years because the marsh could not move inland as sea level rose; bird nesting sites declined. Constraints/tradeoffs: expensive to repair; reduces tidal exchange in some areas; protects homes immediately. Solution 2: Restore a wide "living shoreline" (oyster reef + native marsh plants). How it works: reefs and plants slow waves and trap sediment, helping marshes build elevation. Evidence from a pilot site: marsh plant cover increased by 18% in 3 years; fish species counts increased; flooding reduction was moderate, not as immediate as a seawall. Constraints/tradeoffs: needs space; takes time to establish; may require limits on boat traffic during restoration. Solutions can be compared using evidence about biodiversity and constraints. Which comparison of solutions is supported by the evidence?
16. A student draws a model to explain photosynthesis and plant growth. Their model shows an arrow labeled sunlight (matter) entering the leaf and an arrow labeled oxygen (matter) entering the leaf. The student also labels new plant tissue inside the plant but does not show any matter entering from air as carbon dioxide or from soil as water. The student concludes: "Photosynthesis adds matter to living things." Which change would best correct the model using evidence-based reasoning about matter entering organisms?
17. Use the model to trace matter through multiple processes (digestion and respiration). Which prediction about matter movement is supported if oxygen intake stops (no oxygen enters the lungs)?
18. Fossil layers show changes in life forms over time. A stratigraphic model (from older to younger) is: - Layer 1: only pollen grains - Layer 2: pollen grains + small mammal teeth - Layer 3: small mammal teeth + bird bones - Layer 4: only bird bones Which set of 2–3 statements is supported by the evidence in the fossil layers?
19. A dairy farm uses artificial insemination to ensure that only a few bulls with high milk-yield offspring become fathers of many calves. Over 8 generations, the average milk produced per cow per day increases from 18 L to 27 L. Humans can influence trait inheritance using technology. Which technology is being used to influence trait inheritance in this scenario?
20. Food webs show interconnected feeding relationships in an ecosystem. In the model below, arrows show the direction of energy transfer. A student redraws the model and accidentally reverses every arrow so that arrows point from consumers to what they eat. What is the main problem with the student's new model?

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