Question

Ground squirrels are found in many areas of the United States. They live in underground burrows and are often attacked by birds of prey, coyotes, and bobcats. Which of the following is a limiting factor for a ground squirrel population?
a population of tree squirrels
a population of hawks
genetic variability
breeding season
Which of these facts about wild boars is best supported by the evidence provided?
Wild boars were brought to the United States by humans.
Wild boars have quickly spread through the United States.
Wild boars have established successfully mostly in areas with warm climates.
Wild boars have a high reproductive rate and no natural predators.
White perch is a fish that is native to Atlantic coastal regions and is invasive to the Great Lakes. It feeds on native species and is thought to be the cause of the decline of the Great Lakes walleye fish populations. What was most likely its mode of introduction?
produce brought from the eastern states
trapped in a ship's ballast or a water tank
trapped in a cargo crate carrying nonperishable items
luggage brought in an overseas flight
What kind of display would be the best way to represent the data below?

Type of species
Critically endangered (%)
Endangered or vulnerable (%)
Plants
13
70
Invertebrates
0
35
Freshwater fish
9
37
Amphibians
7
30
Reptiles
5
28
Birds
0
12
Mammals
2
21
bar graph
pie chart
line graph
scatter plot
A trout population grew from 4 in 1992 to 16 in 1993 and then to 64 in 1994. If it continued to grow exponentially, approximately how many trout were there in 1995?
100
128
256
320

Answer 1

1) A population of hawks — predators are a limiting factor for ground squirrels (they reduce population size).

2) Wild boars were brought to the United States by humans — this is the best-supported factual claim (they are an introduced species).

3) Trapped in a ship's ballast or a water tank — ballast-water transport is the most likely introduction route for aquatic invasive fish.

4) Bar graph — categorical comparison of percentages across groups is best shown with a bar graph (clustered bars for the two status categories).

5) 256 — the population multiplies by 4 each year: 64 × 4 = 256.