Populations, communities, ecosystems and biomes
Grade 7 Science Worksheet - Building Confidence
Circle the best answer.
Read this first
Table (model data)
Wildflower plants in 1 square meter and rain that year. Year 1: 40 plants, 700 mm. Year 2: 44 plants, 720 mm. Year 3: 15 plants, 250 mm. Year 4: 38 plants, 690 mm.
Ari counts wildflowers in a meadow each year and records the rain. What does the table best support?
- Wildflower numbers fell in year 3 because too many insects arrived that year, which the table shows.
- Wildflower numbers stay near 40 whatever the rain, so year 3 must be a counting mistake.
- Wildflower numbers fell in the year with the least rain, so water probably limited the population.
- Wildflower numbers rose each year, so rain has no effect on the number of plants.
Table (model data)
Tadpoles in one pond and water temperature. Summer 1: 120 tadpoles, 21 °C. Summer 2: 118 tadpoles, 23 °C. Summer 3: 40 tadpoles, 31 °C. Summer 4: 115 tadpoles, 22 °C.
Bo counts tadpoles in a pond each summer and records the water temperature. What does the table best support?
- Tadpole numbers fell in summer 3 because new fish moved in, which the table shows.
- Tadpoles need exactly 22 °C, so any other temperature drops the count a lot.
- Tadpole numbers fell when the water was much warmer, so heat may limit the tadpoles.
- Tadpole numbers grew when the water was much warmer, so heat helped the tadpoles most.
Esme plans four studies of one forest. Which study needs the whole ecosystem, not just a population or a community?
- How soil moisture and sunlight change how well the forest's plants and insects grow
- How the forest's beetle population changes in size from one year to the next year
- How the number of oak seedlings in the forest changes from one spring to the next year
- How the forest's birds, insects and plants affect each other's numbers over the years
Jun describes four groups in a pond. Which one is a community, not a population and not an ecosystem?
- The pond's water, mud, sunlight, plants, insects and fish together as one system
- One fish that lives in the pond and the spot where it rests during the day
- The plants, insects, fish and snails that live in the pond together
- The snails of one kind that live in the pond, counted together as one group
Table (model data)
Dissolved oxygen and fish seen in the pond. Day 1: 8 mg/L, 52 fish. Day 2: 8 mg/L, 50 fish. Day 3: 4 mg/L, 31 fish. Day 4: 5 mg/L, 33 fish.
Luz checks a pond for four days. Which conclusion does the table best support?
- Fewer fish were counted on the days with less oxygen, so oxygen may limit the fish.
- Oxygen and fish are not linked, because just four days of data were collected.
- Fewer fish in the pond caused the oxygen to drop, since oxygen was lowest on the days with fewer fish.
- The fish count stayed the same on each of the four days, because days 1 and 2 matched.
Table (model data)
Seeds sprouted out of 100 planted. 10 °C: 12 sprouted. 15 °C: 38 sprouted. 20 °C: 71 sprouted. 25 °C: 74 sprouted.
Milo plants 100 seeds in soil kept at four temperatures. What is the best conclusion from the table?
- Warmer soil sprouts more seeds each time, so 40 °C would sprout more than 25 °C.
- Colder soil sprouted more seeds, since 10 °C had the highest number of sprouts.
- Warmer soil sprouted more seeds up to about 20 °C, and after that it added little.
- Soil temperature does not matter, since 25 °C sprouted just 3 more seeds than 20 °C.
Table (model data)
Rain per year and plant cover. Plot A: 300 mm, 20% of the ground covered by plants. Plot B: 900 mm, 70% covered. Plot C: 1,500 mm, 95% covered.
Noah compares three plots. Which statement does the table support?
- Plot A had the most rain, because it had the lowest plant cover of the three plots.
- The three plots had about the same plant cover, because each of the three had some plants.
- More rain went with more plant cover across the three plots.
- Plant cover caused the rain, because the plot with the most plants got the most rain.
In a field, energy passes from sunlight to grass, to grasshoppers, to frogs. Which arrows show the path of energy, Ren?
- Grass → sunlight → grasshoppers → frogs
- Frogs → grasshoppers → grass → sunlight
- Sunlight → grass → grasshoppers → frogs
- Sunlight → frogs → grasshoppers → grass
Algae in a pond hold 10,000 energy units. About 10% passes to the next level up each time. How many units reach the second level of animals, Tala?
- 1,000 units: 10% of 10,000 passes up, and that is the whole amount for both animal levels
- 9,000 units: 10% of the energy is used up, so 90% moves to the next level
- 10 units: 10% of 10,000 is 1,000, then 100, then 10 for the second animals
- 100 units: 10% of 10,000 is 1,000 for the first animals, and 10% of that is 100
Energy units at each level of a meadow. Plants: 5,000. First animals: 500. Second animals: 50. Zee reads an energy table for a meadow. Which statement fits the numbers best?
- Each level has the same energy, because energy is not used up when it passes along.
- Each level has more energy than the one before, because animals are larger than plants.
- About 10% of the energy at one level reaches the next, so the top level has the least.
- The first animals hold the most energy, since they are in the middle of the table.