Ecology Test Review Answer Key

J C G L B M E D K I A H F N

Grass  Deer  Wolves What would happen to the population of deer if hunters killed off the wolves in the area? Explain. The population of deer would increase because there would be fewer wolves hunting them as their food source.

Grass  Deer  Wolves What would happen to the population of grass if hunters killed off the wolves in the area? Explain. The population of grass would decrease because there would be more deer to eat the grass.

Grass  Deer  Wolves What would happen to the population of wolves if drought killed off the grass? Explain. The population of wolves would decrease because the dead grass would cause the population of deer to decrease due to starvation, and the deer are the food source for the wolves.

Grass  Deer  Wolves Deer Wolves Deer, Wolves Deer Grass Wolves

Are deer herbivores, carnivores or omnivores?

To what trophic level do wolves belong? 3rd level (secondary consumer)

What are the two producers in this food web? Grass and pond algae

To what trophic level do worms belong? 2nd (primary consumer)

How much energy was passed from the deer to the wolf? 10% of the energy from the deer would be passed on to the wolf.

Write one of the complete food chains shown in the web above. Grass  Rabbits  Wolves  Decomposers

Would there be more deer or wolves in the ecosystem? Explain. There would be more deer in the ecosystem because they occupy a lower trophic level. The deer have more energy available to them through the grass than the wolves do, so the ecosystem can support more deer than wolves.

Would there be more stored toxins in the fish or the worms? Explain. There would me more toxins in the fish than in the worms. This would be due to biological magnification. The toxins would be stored in the tissues of the organisms, and consumed by their predators. Consequently, the amount of toxins would build as you move up the food chain.

What is the difference between the flow of nutrients and the flow of energy? Nutrients are made of matter, and that stays constant. Matter is neither created nor destroyed, it just changes forms. So nutrients are continuously recycled in ecosystems. Energy flows in only one direction. It cannot be recycled because most of it is used by organisms or lost as heat. Ecosystems need a constant supply of new energy, usually coming from the sun.

Construct an energy pyramid for a food chain with 3 trophic levels Construct an energy pyramid for a food chain with 3 trophic levels. The producers in this food chain take in 5000 kcal of energy. 50 kcal 500 kcal 5000 kcal

8 Photosynthesis Cellular respiration combustion Precipitation Evaporation transpiration Nitrogen fixation amino acids proteins

Which process represents photosynthesis? 9 Which process represents photosynthesis? 2

Which process represents cellular respiration? 9 Which process represents cellular respiration? 1

What is the form of carbon found in the atmosphere? 9 What is the form of carbon found in the atmosphere? Carbon dioxide

What form of carbon is transmitted between organisms? 9 What form of carbon is transmitted between organisms? Glucose

Which process(es) do animals carry out? 9 Which process(es) do animals carry out? Cellular respiration

Which process(es) do plants carry out? 9 Which process(es) do plants carry out? Cellular respiration and photosynthesis

Which process above returns carbon dioxide to the atmosphere? 9 Which process above returns carbon dioxide to the atmosphere? Cellular respiration

9 In addition to this process, what human activity creates carbon dioxide? Burning of organic materials like wood and fossil fuels

Explain how the processes of photosynthesis and cellular respiration move carbon through an ecosystem. Photosynthesis pulls carbon out of the atmosphere and put it, or fixes it, into the form of glucose. The glucose is then used by the plant or consumed by other organisms that eat the plant in order to get energy through the process of cellular respiration. As cellular respiration happens, carbon dioxide is created as a waste product, and then returned back into the atmosphere where the carbon can again be absorbed by plants through photosynthesis.

What role do plants play in the water cycle? Plants absorb water from the ground through their roots. They use some of the water in the process of photosynthesis, and they release the rest of the water into the atmosphere through the process of transpiration.

What role do bacteria play in the nitrogen cycle? Bacteria absorb nitrogen from the atmosphere and fix it into forms that are usable by plants, like nitrates and nitrites.