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

   Luz grew yeast in two jars of sugar water. Jar A had 1 spoon of sugar and Jar B had 2 spoons. Which statement fits the graph?

   • Both jars level off at the same amount
   • Jar B levels off lower because sugar slows yeast
   • Jar A levels off higher because its sugar ran out first
   • Jar B levels off higher because it had more sugar
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?

   • 20 more
   • 40 more
   • 80 more
   • 60 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
   • Neither, since both lines go up
   • Town A, which had the steadier line
   • Town A, which began with the higher count
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 gap lets in a limited amount of light
   • The seedlings get more light than they can use
   • No new seedlings sprout once the line is flat
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?

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

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

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

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

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