What makes a population grow or shrink

Grade 7 Science Worksheet

Circle the best answer.

1. 1.

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

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

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

   • 60 more
   • 80 more
   • 40 more
   • 20 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 B, which gained 70 against 30
   • Town A, which had the steadier line
   • Neither, since both lines go up
   • Town A, which began with the higher count
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?

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

   • The yeast have stopped making new cells
   • The jar has endless sugar, so it is still growing
   • Yeast level off after five days, whatever the sugar
   • The sugar in the jar is running low
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
   • The field is short of water
   • Rabbits stop being born at 40
   • There is no limit, so it will rise again soon
8. 8.

   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
   • The town stopped having young
   • Open prairie was added next to the town
   • Open ground next to the town was paved over
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?

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