Interactions and Ecosystems: Going Further

The same ecosystem ideas, applied to real Alberta data and food webs.

17 questions, free, marked as you go with a worked explanation on every one.

What this covers

The questions

  1. 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?
  2. 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?
  3. 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.
  4. 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?
  5. 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?
  6. Which of these are examples of a producer in an Alberta ecosystem? Select all that apply.
  7. 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?
  8. 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?
  9. Use the table. What happened to the fox population between 2022 and 2023, while the rabbit population it depends on was recovering?
  10. A forest fire burns through an area, and over the following years grasses, then shrubs, then young trees gradually reappear in that order. This gradual, ordered return of life to a disturbed area is called:
  11. A pond can only support about 40 frogs before food and space run out and the population stops growing. This maximum population an environment can sustain is called its:
  12. A deer population starts at 60 and the forest's carrying capacity is 150. If the population grows by 20 deer every year until it reaches carrying capacity, after how many full years will it first reach or exceed 150?
  13. A small fish cleans parasites off a larger fish's skin, and in return gets an easy meal. Both fish benefit from this relationship. This type of relationship is called:
  14. A barnacle attaches itself to a whale's skin, getting a free ride and access to new feeding grounds. The whale is unaffected either way. This type of relationship is called:
  15. Carbon moves from the atmosphere into plants through photosynthesis, into animals that eat those plants, and back to the atmosphere through respiration and decomposition. This continuous movement of carbon through an ecosystem is an example of:
  16. A wetland absorbs 70 percent of the sediment carried into it by a stream before the water reaches a lake downstream. If a stream carries 200 kg of sediment into the wetland, how many kilograms reach the lake?
  17. Two species of birds in the same forest both rely on the same limited supply of insects for food. This relationship, where two organisms rely on the same limited resource, is called:

Answer these free