Competition, predators and prey, and partnerships
Grade 7 Science Worksheet - Building Confidence
Circle the best answer.
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Table (model data)
Plants per plot. Kind A alone: 40. Kind A with Kind B: 70. Kind B alone: 30. Kind B with Kind A: 55.
Ari counts two kinds of plants alone and together in garden plots. Which interaction do the counts show?
- Competition, because two kinds that share a plot affect each other's numbers
- Parasitism, because one kind gains by taking something from the other kind
- Mutualism, because both kinds have more plants when they grow together
- Commensalism, because one kind gains while the other kind stays the same
Table (model data)
Yearly growth of oak branches. Without mistletoe: 20 cm. With mistletoe: 12 cm. Mistletoe grows only on host trees such as oaks, about 6 clumps per branch.
Esme measures oak branches with and without mistletoe. Which interaction does the table show?
- Competition, because the oak and the mistletoe both lose when they share a branch
- Commensalism, because the mistletoe gains while the oak is not changed
- Parasitism, because the mistletoe gains from the oak while the oak grows less
- Mutualism, because the oak and the mistletoe both gain from living together
Table (model data)
Ferns grow on 18 oak branches out of 20, and on 4 bare rock ledges out of 20. Yearly oak branch growth: 21 cm with ferns, 21 cm without ferns.
Jun compares oak branches with and without ferns on them. Which interaction does the table show?
- Commensalism, because the ferns gain a place to grow while the oak's growth stays the same
- Mutualism, because the ferns and the oak both get something useful from living together on the branch
- Parasitism, because the ferns gain a place to grow and the oak is harmed by having them on its branches
- Competition, because the ferns and the oak use the same branches and both of them end up losing
Squash plants make more fruit when bees visit their flowers. A spray removes the bees from Kira's garden. What will most likely happen to the squash fruit?
- Fruit numbers will stay the same, because plants make fruit without help from other living things.
- Fruit numbers will rise, because the plants no longer share their nectar with the bees.
- Fruit numbers will rise, because the bees were competing with the plants for water.
- Fruit numbers will fall, because the plants lose the bees that carry pollen.
Orchids grow on the branches of a tree and take nothing from it. Luz removes the orchids. What will most likely happen to the tree's growth?
- The tree will grow faster, because the orchids were taking light and water from it.
- The tree will grow slower, because the tree needs the orchids to grow well.
- The tree will grow faster, because the orchids were hiding its leaves from the sun.
- Little change, because the orchids neither helped the tree nor harmed it.
Two kinds of plants share one bed and use the same light and water. Noah pulls out Kind B. What will most likely happen to Kind A?
- Kind A should grow less, since Kind A needs Kind B to grow well.
- Kind A should grow more, since it no longer shares light and water with Kind B.
- Kind A should grow less, since the bed will have fewer plants to hold the soil.
- Kind A should stay the same, since plants do not share light or water in a bed.
Bees counted. 30 flower patches: Species A 120, Species B 90. 15 flower patches: Species A 60, Species B 40. Pia compares two bee kinds before and after half the flower patches are cut. What do the counts best show?
- Species A limits Species B, since Species A has more bees than Species B in both rows.
- Flower patches limit both kinds, since both counts fell by about half when the patches were halved.
- Water limits both kinds, since bees need water to live in a meadow and the table has water too.
- Sunlight limits both kinds, since the table shows that sunlight changed when the patches were cut.
Table (model data)
Nesting pairs. 20 boxes: Kind X 12 pairs, Kind Y 8 pairs. 10 boxes: Kind X 6 pairs, Kind Y 4 pairs.
Ren counts nesting pairs of two songbird kinds that nest only in boxes. What do the counts best show?
- Weather limits both kinds, since cold weather lowers the number of boxes that the birds use.
- Food limits both kinds, since the table shows there was less food when the boxes were fewer.
- Nest boxes limit both kinds, since both counts fell by half when the boxes fell by half.
- Kind X limits Kind Y, since Kind X has more pairs than Kind Y in both rows of the table.
Table (model data)
Plants per plot. 200 mm of water: Grass 1 has 30, Grass 2 has 28. 400 mm: Grass 1 has 61, Grass 2 has 55. 800 mm: Grass 1 has 120, Grass 2 has 112.
Tala grows two grass kinds in plots given different amounts of water. What does the table best show?
- Both grass kinds grow more with more water, so water limits both kinds.
- Grass 1 grows less with more water, since its count rises faster than Grass 2.
- Water has no effect, since Grass 1 has more plants than Grass 2 in each plot.
- Light limits both grass kinds, since the table shows light changed with water.
Table (model data)
Fish in the tank. 4 hiding places: Kind F1 has 20, Kind F2 has 16. 8 hiding places: Kind F1 has 38, Kind F2 has 33.
Zee counts two fish kinds in a tank with different numbers of hiding places. Eight more hiding places are added to the 8. What is the best prediction?
- Kind F1 should rise and Kind F2 should fall, because F1 had more fish.
- Both kinds should fall, because more hiding places mean more room to compete in.
- Both kinds should increase, because hiding places limit both of them.
- Both kinds should stay the same, because 8 places were already enough for them.