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Practice Test 8 - Middle School Life Science

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

  1. Two proteins in one organism have different shapes. Why?
  2. In a class investigation, students raised pea plants in the same greenhouse with the same soil, water, and light for every generation. Parent plants: Plant A had purple flowers and Plant B had white flowers. In the offspring generation (20 plants), 14 had purple flowers and 6 had white flowers. In the next generation, students selected one purple-flowered offspring and one white-flowered offspring and crossed them (same greenhouse conditions). Their offspring included both purple and white flowers again. Which statement about inheritance is supported by the evidence across generations?
  3. Cells are the basis for determining whether something is living. A student looks at two model microscope images. Sample 1 (Thin slice of carrot): repeating box-like units with boundaries; many units show darker material inside. Sample 2 (Orange plastic bead): solid-looking material with swirls; no repeating box-like units with boundaries. Which claim is supported by the evidence shown in the models?
  4. Fossil layers show changes in life forms over time. Layers are ordered from older (bottom) to younger (top): - Layer 5 (oldest): leaf fossils - Layer 4: leaf + insect fossils - Layer 3: insect fossils only - Layer 2: insect + bird fossils - Layer 1 (youngest): bird fossils only Which inference about change is supported by the fossil layers as evidence?
  5. The diagram shows two organisms (A and B) with their body coverings zoomed in at the same scale. In both, the covering has repeating overlapping shapes. In A, the shapes are smooth; in B, the shapes have small ridges. Body structures can be compared across organisms using visible patterns. Which comparison of body structures is supported by evidence from the diagram?
  6. A student builds a before-and-after model showing that a gene change can affect a protein. Gene (before): [A B C D E] Gene (after): [A B X D E] Directional link: Gene → Protein Protein (before): folds into a shape that fits a target well (strong fit) Protein (after): folds into a slightly different shape (weaker fit) Which explanation best shows how the gene change affects the protein, using evidence from the model?
  7. The model below shows energy flow in an ocean ecosystem. The arrows show energy flow (not matter movement). Sunlight is the main energy source for most ecosystems. Which statement about energy flow is supported by the model?
  8. Which step in a plant model best shows water returning to nonliving parts?
  9. A population of rabbits has two inherited ear-length traits: long ears and short ears. The environment stayed the same (same temperature range and same predators) for 3 months. Researchers recorded how many rabbits survived. Data: Out of 60 long-eared rabbits, 39 survived. Out of 60 short-eared rabbits, 41 survived. Which statement is supported by the evidence about traits and survival?
  10. A population of flowering plants has two flower colors: red and white. Evolutionary change can be measured by shifts in trait frequency in a population across generations. In the same meadow, counts were recorded: Generation 1: 90 out of 120 red; 30 out of 120 white Generation 2: 84 out of 120 red; 36 out of 120 white Generation 3: 72 out of 120 red; 48 out of 120 white Generation 4: 60 out of 120 red; 60 out of 120 white Which statement about evolutionary change is supported by the evidence?
  11. A rabbit population has variation in running speed: fast or slow. A new predator arrives. After 6 generations, the percent of fast rabbits increases from 45% to 75%. A student says: "Fast rabbits increased because the fastest rabbit was the strongest and made the population fast." Which statement best evaluates the student's claim using evidence and population reasoning?
  12. A population of bacteria includes two trait variants: antibiotic-resistant (R) and non-resistant (N). An antibiotic was introduced and kept in the environment for 5 days. The population was sampled each day. Day 0: R 2%, N 98% Day 1: R 10%, N 90% Day 3: R 60%, N 40% Day 5: R 90%, N 10% What evidence links trait variation to the population change?
  13. Fossil records show patterns of diversity over time. A fossil sampler reports: - Oldest layer: 6 different shell types - Next layer: 2 different shell types - Next layer: 0 shell fossils found - Youngest layer: 3 different shell types Which claim about fossil diversity is incorrect based on the evidence and how fossils are preserved?
  14. A city park has a baseline population of squirrels that has been stable. Change: New park rules reduce litter and require trash cans to be squirrel-proof, decreasing access to human food scraps. Evidence: In the following weeks, observers record squirrels spending more time digging for nuts and less time near picnic areas. Which prediction about the squirrel population is supported by evidence about resources (before vs. after the rule change)? Population changes can be predicted from evidence, but predictions are not certainties.
  15. A simplified reproduction model shows two parent mice: Parent A has a long tail and dark fur; Parent B has a short tail and light fur. The offspring shown include multiple combinations of tail length and fur color, and the model states that sexual reproduction produces variation among offspring. Which statement about sexual reproduction is supported by evidence in the model?
  16. A population of insects has two wing types: long and short. Evolutionary change can be measured by shifts in trait frequency in a population across generations. In the same field, counts were recorded: Generation 1: 70 out of 100 long; 30 out of 100 short Generation 2: 50 out of 100 long; 50 out of 100 short Generation 3: 30 out of 100 long; 70 out of 100 short Which explanation best measures evolutionary change using the evidence?
  17. A simplified model of a lizard shows food molecules drawn as small circles inside its body. An arrow labeled energy released points outward to a symbol of motion/heat (zigzag lines). The food circles stay inside the lizard, while the energy symbol is shown leaving the body. Based on the model, which statement explains how organisms get energy from food?
  18. A model shows a gene before and after a mutation. Gene (before): GTT-ACG-CCA Gene (after): GTT-ACG-CCG Protein outcome in the model: The protein made after the mutation is unchanged. Evidence in the model: A student says, "If the gene changed, the organism's traits must change too." Which claim about mutations is incorrect based on the model and evidence?
  19. A class is studying an organism model that groups parts into systems. The model shows: - "Food Processing System": mouth + stomach - "Transport System": heart + blood vessels The note says: "Body systems are groups of interacting parts with related functions, and they can work together." Which statement about body systems is supported by the model?
  20. A river has a strip of plants along its banks called a riparian buffer. During rain, water flowing from nearby land passes through the buffer. Plant roots hold soil in place, and the buffer slows water so less soil washes into the river. This helps insects and fish by keeping gravel beds from being buried, and it helps people by keeping the water less muddy. Ecosystems provide services. Which prediction is supported if the riparian buffer is removed?

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