Practice Test 2 - Middle School Life Science

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

A student draws this model and says: sunlight is the main energy source for most ecosystems. The arrows represent energy flow (not matter movement). Model: Sunlight → oak tree (producer) → caterpillar (consumer) → bird (consumer). Which claim about energy transfer is incorrect based on the model?
A simplified model shows a gene segment before and after a mutation: Before gene: A B C D E After gene: A B X D E Protein outcome shown by the model: the protein's shape changes. Evidence in the model about organism effects: - In Environment 1, organisms with the changed protein survive better. - In Environment 2, organisms with the changed protein survive worse. Based on the model, which outcome of the mutation is supported by the evidence?
A student draws a simplified cell model. The model is meant to show the cell as a system of interacting parts (not exact scale). Model description: Mitochondrion has an arrow to cell activities labeled "energy." Cell membrane has arrows showing "nutrients in" and "waste out." Which statement best identifies an error in the model if the goal is to represent interactions among parts?
In a lake, an invasive fish (Fish I) eats the same insects as a native fish (Fish N), creating competition for food. A survey measured average body condition (higher = better survival chances) and number of eggs per female. Data (same lake zone, same month): - Where Fish I is common: Fish N body condition = 0.82; Fish N eggs/female = 1,200 - Where Fish I is rare: Fish N body condition = 1.05; Fish N eggs/female = 1,900 Which explanation best links the interaction to survival and reproduction outcomes using evidence? (Interactions can affect survival and reproduction.)
Two simplified models show reproduction. Reproduction type affects genetic outcomes. Model 1 (Asexual): Parent count: [1] Parent: ○(pattern A) Offspring: ○(pattern A) ○(pattern A) ○(pattern A) (very similar) Model 2 (Sexual): Parent count: [2] Parent A: ○(pattern A) Parent B: ○(pattern B) Offspring: ○(pattern A-like) ○(mixed) ○(pattern B-like) (variation) Which prediction about offspring similarity is supported by the models?
A student steps outside and feels warm sunlight on their skin. Use the pathway model Stimulus → Receptor → Brain processing → Response or stored information. What evidence shows the sequence in the model? Stimulus: warmth from sunlight.
Use the model to trace matter and energy separately. In this model, solid arrows show matter movement, and dashed arrows show energy flow. The model includes a producer (algae) and a consumer (small fish). The model shows that matter and energy follow different paths, so they must be traced separately. Model (text description): - Sun - Algae (producer) - Small fish (consumer) - Larger fish (consumer) - Decomposers Arrows: - Solid: Algae → Small fish (matter in food) - Solid: Small fish → Larger fish (matter in food) - Solid: Larger fish → Decomposers (matter in waste/remains) - Solid: Decomposers → Water nutrients → Algae (matter reused) - Dashed: Sun → Algae (energy captured) - Dashed: Algae → Small fish (energy transferred) - Dashed: Small fish → Larger fish (energy transferred) - Dashed: Larger fish → heat to water (energy leaves) Which statement about the model is supported?
A river ecosystem was monitored for trout population each year: Year 1 = 300, Year 2 = 295, Year 3 = 290, Year 4 = 150. Two explanations are offered: Explanation 1: A new dam built before Year 4 blocked trout migration and reduced reproduction. Explanation 2: A heat wave in summer of Year 3 warmed the river and caused trout deaths. Evidence: Construction records show the dam was completed just before Year 4. Temperature records show the heat wave occurred in Year 3, but there was no large population drop recorded until Year 4. Explanations must be evaluated using evidence (fit and completeness). Which explanation is best supported by the evidence?
Fossil layers in a cliff are ordered from older (bottom) to younger (top). The fossil layers show changes in life forms over time. The layers contain: Bottom layer: only shell fossils; Middle layer: shells + coral fossils; Top layer: mostly coral fossils, fewer shells. Which statement about the fossil layers is correct based on the evidence?
A forest area was treated with an insecticide to reduce mosquitoes. Population counts (per square kilometer) were measured before and after treatment: - Mosquitoes: 10,000 before, 2,000 after - Dragonflies (mosquito predators): 300 before, 120 after - Frogs (eat insects): 200 before, 140 after - Songbirds (eat insects): 80 before, 65 after Which argument best explains the population shift using the evidence? Your argument must link the ecosystem change to the population responses using the data.
Fossil layers show changes in life forms over time. A cliff shows 4 layers from older (bottom) to younger (top): - Layer D (oldest): ammonite fossils - Layer C: ammonites + small reptile bones - Layer B: small reptile bones - Layer A (youngest): small reptile bones + flowering plant pollen What evidence from the fossil layers best shows change over time?
A tundra ecosystem was observed for 5 years. Data show lemming population rose from 60 to 140 by Year 3, then fell to 50 by Year 5. Over the same years, snowy owl population rose from 6 to 12 by Year 4, then fell to 7 by Year 5. Two explanations are offered: Explanation 1: Owl population changes are linked to lemming population changes because owls rely on lemmings as a food source. Explanation 2: Lemming population changes are caused mainly by owls, and the owl changes are unrelated. Using the shared population evidence, which statement correctly evaluates the explanations?
A drought occurred in a grassland between Year 2 and Year 3. Disturbances can change population dynamics. Use the population data over time to choose the statement supported by evidence. Population counts (individuals): - Year 1: 120 - Year 2: 130 - Year 3 (during drought): 70 - Year 4: 90 - Year 5: 110 Which statement about the disturbance and population change is supported by the evidence?
A bright flashlight is pointed toward a student's eyes. In the model: stimulus (bright light) → eye receptor detects light → signal travels to the brain → brain processes the signal to form a perception of brightness. Which claim about the brain is incorrect based on the model?
Refer to the ecosystem model. Which statement about matter movement is supported by evidence in the model and shows that matter cycles through ecosystems? Model: Plant → Grasshopper → Frog; dead organisms/waste → Decomposers; decomposers → Soil nutrients; soil nutrients → Plant; Plant ↔ Air (matter taken in and released).
Consider this simplified model of matter movement during photosynthesis: arrows show carbon dioxide (matter) entering the leaf from the air and water (matter) entering the plant through roots. A separate arrow shows sunlight (energy) entering the leaf. Inside the plant, a label says matter becomes part of sugars that are used to build stems, leaves, and roots. Which statement about matter entry is supported by evidence from the model?
A simplified inheritance model shows two parent horses. Parent Horse 1 has a dark mane and white socks (white fur on lower legs). Parent Horse 2 has a light mane and no white socks. Arrows from both parents to each foal are labeled "genetic information passed to offspring." Two foals are shown: Foal A—dark mane, no white socks; Foal B—light mane, white socks. Which statement about inheritance is supported by evidence from the model?
Use the energy-flow model. Remember: energy flows through ecosystems rather than cycling. Which statement about energy flow is supported by the model?
A simplified model says: Gene instructions → Protein produced → Trait/function. It also states, "Genes provide instructions for proteins." Which prediction about protein production is supported by the model if a cell has a gene with missing instructions?
A wildlife camera recorded wolves during spring, when pups are typically born. In one pack, adults were frequently observed bringing food back to a den site. In a nearby pack, this behavior was observed less often. Later, the number of pups surviving to 8 weeks was higher in the pack with more food deliveries to the den. Behaviors can affect reproductive outcomes. Which prediction is supported if the food-delivery behavior decreases in a pack during the same season?

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