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?

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

   All the open ground for burrows in the town was used by year 5. Zee predicts the year 6 count. Which prediction fits?

   • About 20, because the line starts over
   • About 100, the same as year 5
   • About 120, because the line is still rising
   • About 80, because births stop at the top
3. 3.

   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?

   • Lower than 80, because less light reaches the gap
   • Higher than 80, because the line was rising
   • Higher than 80, because shade helps seedlings sprout
   • About 80, because the gap is the same size
4. 4.

   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?

   • 80 more
   • 60 more
   • 40 more
   • 20 more
5. 5.

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

   • Town B, which gained 70 against 30
   • Town A, which had the steadier line
   • Town A, which began with the higher count
   • Neither, since both lines go up
6. 6.

   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?

   • Populations stop changing after four years
   • The seedlings get more light than they can use
   • No new seedlings sprout once the line is flat
   • The gap lets in a limited amount of light
7. 7.

   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 jar has endless sugar, so it is still growing
   • The sugar in the jar is running low
   • The yeast have stopped making new cells
8. 8.

   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 field is short of water
   • The shelter spots are all in use
   • There is no limit, so it will rise again soon
   • Rabbits stop being born at 40
9. 9.

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

   • A very dry summer began
   • Open prairie was added next to the town
   • The town stopped having young
   • Open ground next to the town was paved over
10. 10.

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

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