Question

ii. based on the diagram on the front, answer the following questions:

1. why are the arrows always drawn from the prey towards the predators? what are they showing the flow of?
2. the four plants and algae at the bottom of your food web are the only organisms that do not have any arrows pointing at them. what is their source of energy? these are often referred to as producers. what exactly do they produce?
3. primary consumers are organisms that directly feed on producers. what organisms on your food web would be classified as primary consumers? what characteristics do they have in common?
4. secondary consumers are organisms that directly feed on primary consumers. what organisms on your food web would be classified as secondary consumers? what characteristics do they have in common?
5. tertiary or top consumers are organisms at the top of the food web. they may feed off either primary or secondary consumers. what organisms would fit into this classification? what characteristics do they have in common?
6. if you were to take a walk through a part of yellowstone national park, which level of the food web would you expect to see the most of? which level of the food web would you expect to see the least of? explain why for both.
7. according to the “ten percent law”, only about 10% of the energy consumed makes it from one trophic level to the next. based on your diagram, if you started with 1000 calories of willow leaves, how many calories would make it to each of these other animals?

a. deer mouse: ____________
b. red fox: ____________
c. gray wolf: ____________

1. based on your answers to the previous question, why are there so many more producers in any given ecosystem than any other organism? why are top predators so rare to witness in the wild?

Explanation:

Question 7a: Deer mouse

Step1: Identify the trophic level transfer.

Willow leaves (producer) to deer mouse (primary consumer). The ten - percent law states that only 10% of energy is transferred between trophic levels. So we calculate 10% of 1000 calories.
The formula for calculating the energy transferred is $Energy_{transferred}=Energy_{initial}\times\frac{10}{100}$
Substituting $Energy_{initial} = 1000$ calories, we get $Energy_{transferred}=1000\times\frac{10}{100}$

Step2: Calculate the energy.

$1000\times\frac{10}{100}=100$ calories.

Step1: Determine the trophic levels.

Red fox is a secondary consumer. First, energy from willow leaves (1000 cal) to primary consumer (e.g., deer mouse, 100 cal as calculated above), then from primary consumer to secondary consumer (red fox). Using the ten - percent law again, we calculate 10% of the energy available at the primary consumer level.
The formula is $Energy_{transferred}=Energy_{at\ primary\ level}\times\frac{10}{100}$
We know $Energy_{at\ primary\ level}=100$ calories (from 7a).

Step2: Calculate the energy.

$100\times\frac{10}{100} = 10$ calories.

Step1: Determine the trophic levels.

Gray wolf is a tertiary consumer. First, energy from willow leaves (1000 cal) to primary consumer (100 cal), then to secondary consumer (10 cal), then to tertiary consumer (gray wolf). Using the ten - percent law, we calculate 10% of the energy available at the secondary consumer level.
The formula is $Energy_{transferred}=Energy_{at\ secondary\ level}\times\frac{10}{100}$
We know $Energy_{at\ secondary\ level}=10$ calories (from 7b).

Step2: Calculate the energy.

$10\times\frac{10}{100}=1$ calorie.

Answer:

100 calories

Question 7b: Red fox