What makes a population grow or shrink

Grade 7 Science Worksheet

Circle the best answer.

1. 1.

   The rabbit count was flat at 20 while shelter was short. Brush piles add shelter spots in year 4. Bo predicts year 5. Which prediction fits?

   • Lower than 20, because the field is more crowded
   • Rising faster and faster with no end
   • Higher than 20, then it levels off again
   • Still 20, because the line was flat before
2. 2.

   Light reaching a forest gap lets oak seedlings grow. In year 4, branches spread over the gap and shade it. Kira predicts year 5. Which prediction fits?

   • About 80, because the gap is the same size
   • Higher than 80, because shade helps seedlings sprout
   • Lower than 80, because less light reaches the gap
   • Higher than 80, because the line was rising
3. 3.

   Field A has 2 brush piles and Field B has 6. Milo compares the lines. In year 5, how many more rabbits are in Field B than in Field A?

   • 40 more
   • 20 more
   • 60 more
   • 80 more
4. 4.

   Noah compares two prairie dog towns that both have open ground around them. Which town grew faster from year 1 to year 4?

   • Town A, which had the steadier line
   • Neither, since both lines go up
   • Town A, which began with the higher count
   • Town B, which gained 70 against 30
5. 5.

   Pia reads about oak seedlings in a small gap among tall trees. The line levels off at 60. Which cause best explains the level-off?

   • The gap lets in a limited amount of light
   • Populations stop changing after four years
   • No new seedlings sprout once the line is flat
   • The seedlings get more light than they can use
6. 6.

   Ari's yeast line levels off at 80 on day 5. Nothing else in the jar changed. Which cause best explains the level-off?

   • Yeast level off after five days, whatever the sugar
   • The sugar in the jar is running low
   • The jar has endless sugar, so it is still growing
   • The yeast have stopped making new cells
7. 7.

   A field has plenty of plants and water but only 4 brush piles. Esme sees the rabbit line level off at 40. Which cause best explains it?

   • The shelter spots are all in use
   • There is no limit, so it will rise again soon
   • The field is short of water
   • Rabbits stop being born at 40
8. 8.

   Jun sees a letter mark event X at year 3 on the prairie dog graph. Which event fits the line after X?

   • Open ground next to the town was paved over
   • The town stopped having young
   • Open prairie was added next to the town
   • A very dry summer began
9. 9.

   Ren sees a letter mark event X on day 4 on the yeast graph. Which event fits the line after X?

   • The yeast stopped making new cells
   • Some of the sugar water was poured out
   • The jar was left on the shelf unchanged
   • More sugar was stirred into the jar
10. 10.

    Tala sees a letter mark event X at year 4 on the oak seedling graph. Which event fits the line after X?

    • The gap was widened for more light
    • A very dry year began
    • Seedlings stopped sprouting
    • Tall branches spread out over the gap