Question

Questions

1. Remove one organism from your food web. Which organism did you choose?

NOTE: The sun is not an organism and can not be removed from the food web!!!

Let's remove grass.

• What other organisms are affected by its removal?

Grass eating animals would be affected like rabbits and grasshopper

• Are there other food sources that these organisms could begin to eat in order to replace the
  removed food source?

Rabbits can switch over to carrots but grass is the main food of grasshoppers. Their number will obviously reduce if the grass is removed from the food web.

2. Describe two predator-prey combinations from your food web.

A lion is the predator and deer is the prey. A Bear is the predator and a fish is the prey. Both these evolve according to their respective needs such as prey develops strategies to hide like camouflage, it develops speed, a good sense of smell etc. Likewise, a predator in order to survive also develops strategies like developing immunity against the poisonous substances produced by a prey. Some common strategies working for both the prey and predator is a sense of speed, hearing, smell and sight.

3. List one example of a parasite from your food web.

• How is a parasite like the predators you described in #2?

• How is a parasite different from a predator?

4. Describe one example of competition from your food web.

• What affect does competition for food resources have on each population involved?

• Describe how the competition interactions would change if one of the involved organisms suddenly switched to a different food source.

5. Since food webs report who eats who, they do not illustrate commensalism and mutualism.

Use an outside resource (i.e. internet) to describe a real life example of each.

Questions on the food pyramid

1. Explain why a pyramid is the best shape to represent how energy flows through an ecosystem.

2. Explain why producers are the base of the pyramid.

3. As an omnivore, from which trophic level would you be able to obtain the greatest amount of the sun’s energy?

4. Does the size of individual organisms increase or decrease as they move up the energy pyramid? Explain why this happens.

5. What two important groups of organisms are not depicted in Figure 13.4 that can be found on 2nd through 5th trophic levels?

Answer 1

3) One example of a paarsite from food web is : nematodes like Hook worms.

Predators feed on the lower trophic level and have their entire nutrition depended on the lower organism. Similarly a parasite lives off the host cell and derives it's nutrition from it.

A parasite generally lives within the body of the host cell and stays there even after deriving the nutrition. The predators are generally large animals. Parasites do not always kill the entire host but predators kill the organism on which they feed on.

4) One example of competition in a food web is when two predators have a similar source of nutrition. Like suppose in a food web, both the hawk and the fox feeds on the common limited source snake. This would lead to an interspecific competition for the same limited nutrient that would lead to an existential crisis of either of the predators

If one of the hawk or the fox switches to a different food source like if the fox shifts to rabbits as their source of food, there will be no more competition and there will a stable relationship in the food webs.

5) Commensalism is a type of phenomenon where two organisms benefit each other without any harm. Mutualism is similar to that of commensalism in a way where two individuals benefit each other in a combined way. One example of commensalism is the cattle ergets that feeds off the insects or ticks off the cattle thereby providing nutrition and the cattle in turn is benefitted by getting rid of the ticks . This can be a mutualistic relationship in one way.

Food pyramid:-

1) Energy through an ecosystem flows in the 10% law. The energy is passed on to every trophic level about 10% of the previous energy. By the time it reaches the top consumer, the energy is very less as similar as the tip of the pyramid which is smaller at the top but larger at the base where the producers gain more energy.

2) Producers are the main producers of the food and energy for the entire ecosystem and have the most energy from the sun. Hence they are at the base.

3) The producer level will have the greatest energy from the sun

4) The size of the individual increases as we move up the trophic level. This is the biomass action.