Competition, predators and prey, and partnerships

Grade 7 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   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.

2. 1.

   Ari counts two kinds of plants alone and together in garden plots. Which interaction do the counts show?

   • Parasitism, because one kind gains by taking something from the other kind
   • Commensalism, because one kind gains while the other kind stays the same
   • Competition, because two kinds that share a plot affect each other's numbers
   • Mutualism, because both kinds have more plants when they grow together

3. Table (model data)

   Plants per plot. Kind C alone: 50. Kind C with Kind D: 28. Kind D alone: 60. Kind D with Kind C: 31.

4. 2.

   Bo counts two kinds of plants alone and together in garden plots. Which interaction do the counts show?

   • Competition, because both kinds have fewer plants when they share a plot
   • Commensalism, because one kind is not changed by the other kind
   • Parasitism, because one kind gets smaller while the other kind grows larger
   • Mutualism, because both kinds are affected by the other kind in the plot

5. 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.

6. 3.

   Esme measures oak branches with and without mistletoe. Which interaction does the table show?

   • Commensalism, because the mistletoe gains while the oak is not changed
   • Mutualism, because the oak and the mistletoe both gain from living together
   • Competition, because the oak and the mistletoe both lose when they share a branch
   • Parasitism, because the mistletoe gains from the oak while the oak grows less
7. 4.

   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 rise, because the plants no longer share their nectar with the bees.
   • Fruit numbers will fall, because the plants lose the bees that carry pollen.
   • Fruit numbers will rise, because the bees were competing with the plants for water.
   • Fruit numbers will stay the same, because plants make fruit without help from other living things.
8. 5.

   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.
   • Little change, because the orchids neither helped the tree nor harmed 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.
9. 6.

   Mistletoe takes water and minerals from the oak it grows on. Milo removes the mistletoe from one oak. What will most likely happen to that oak's growth?

   • Its growth should rise, because the mistletoe was taking water and minerals from it.
   • Its growth should stay the same, because a plant living on an oak cannot affect the oak.
   • Its growth should fall, because the oak needs the mistletoe to grow well and stay healthy.
   • Its growth should fall, because the oak will lose the shade that the mistletoe was giving it.
10. 7.

    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 stay the same, since plants do not share light or water in a bed.
    • Kind A should grow less, since the bed will have fewer plants to hold the soil.
    • Kind A should grow more, since it no longer shares light and water with Kind B.
11. 8.

    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?

    • Sunlight limits both kinds, since the table shows that sunlight changed when the patches were cut.
    • Water limits both kinds, since bees need water to live in a meadow and the table has water too.
    • 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.

12. 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.

13. 9.

    Ren counts nesting pairs of two songbird kinds that nest only in boxes. What do the counts best show?

    • Nest boxes limit both kinds, since both counts fell by half when the boxes fell by half.
    • Food limits both kinds, since the table shows there was less food when the boxes were fewer.
    • Kind X limits Kind Y, since Kind X has more pairs than Kind Y in both rows of the table.
    • Weather limits both kinds, since cold weather lowers the number of boxes that the birds use.

14. 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.

15. 10.

    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?

    • Both kinds should stay the same, because 8 places were already enough for them.
    • 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.
    • Kind F1 should rise and Kind F2 should fall, because F1 had more fish.