Interactions and Ecosystems: Going Further
The same ecosystem ideas, applied to real Alberta data and food webs.
8 questions, free, marked as you go with a worked explanation on every one.
What this covers
- ecosystems and interactions
The questions
- A wetland near Airdrie has cattails, red-winged blackbirds, dragonflies and pond snails. A road is built and salt from winter de-icing runs into the wetland each spring. The snails disappear first. What does that tell you about the snails?
- In a grassland food web, grass is eaten by grasshoppers, grasshoppers by mice, and mice by hawks. A drought kills much of the grass. Which effect on the hawks is best supported by the food web?
- A lake is showing signs of eutrophication: thick algae, then dead fish. Which of these would you expect to find if that diagnosis is right? Select all that apply.
- A field study estimates that 12000 kJ of energy is stored in the plants in one plot. Ecologists use the rule that about 10 percent of the energy at one level reaches the next. About how many kilojoules reach the second-level consumers, two steps up from the plants?
- Two students argue about a study showing that an introduced fish species is thriving in a lake while three native species declined. One says the introduction caused the decline. The other says something else may have changed the lake at the same time. What would settle it best?
- Which of these are examples of a producer in an Alberta ecosystem? Select all that apply.
- A researcher catches 40 fish in a lake, marks them, and releases them. A week later she catches 50 fish and 8 of them are marked. Using the rule that the fraction marked in the second catch matches the fraction marked in the lake, what is the estimated population of the lake?
- A biologist writes: "The pond had 340 mg/L of dissolved solids in May and 890 mg/L in August." Which statement is an inference rather than an observation?