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?

   • Rising faster and faster with no end
   • Lower than 20, because the field is more crowded
   • Higher than 20, then it levels off again
   • Still 20, because the line was flat before
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 120, because the line is still rising
   • About 20, because the line starts over
   • About 80, because births stop at the top
   • About 100, the same as year 5
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 higher because it had more sugar
   • Jar A levels off higher because its sugar ran out first
   • Jar B levels off lower because sugar slows yeast
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
   • 20 more
   • 40 more
   • 60 more
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?

   • 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
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 sugar in the jar is running low
   • The jar has endless sugar, so it is still growing
   • The yeast have stopped making new cells
   • Yeast level off after five days, whatever the sugar
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
   • There is no limit, so it will rise again soon
   • 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
   • Open prairie was added next to the town
   • A very dry summer began
   • The town stopped having young
9. 9.

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

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