if the grass contains 100,000 kcal of energy, how much energy will a fox obtain from eating a bird? 10,000…

if the grass contains 100,000 kcal of energy, how much energy will a fox obtain from eating a bird? 10,000 kcal 1,000 kcal 100 kcal 10 kcal

if the grass contains 100,000 kcal of energy, how much energy will a fox obtain from eating a bird? 10,000 kcal 1,000 kcal 100 kcal 10 kcal

Answer

Explanation:

Step1: Recall energy transfer rule

In a food chain, only about 10% of energy is transferred from one trophic level to the next. Grass is a producer (trophic level 1), grasshopper is primary consumer (trophic level 2), bird is secondary consumer (trophic level 3), fox (if eating bird) would be tertiary consumer? Wait, no, the question is fox eating a bird. Wait, first, grass (producer) has 100,000 kcal. Primary consumer (grasshopper) gets 10% of that: (100000\times0.1 = 10000) kcal. Secondary consumer (bird) gets 10% of primary consumer's energy: (10000\times0.1 = 1000) kcal? Wait no, wait the bird is secondary consumer. Wait, then fox eating the bird: the bird is secondary consumer, so the energy in bird is 10% of primary, which is 10% of producer. Wait, let's re - track:

Producer (grass): 100,000 kcal.

Primary consumer (grasshopper): 10% of 100,000 = (100000\times\frac{10}{100}=10000) kcal.

Secondary consumer (bird): 10% of primary consumer's energy = (10000\times\frac{10}{100} = 1000) kcal? Wait no, wait the fox is eating the bird. Wait, but maybe the fox is a tertiary consumer? Wait, no, the question is how much energy the fox gets from eating the bird. The bird's energy is what's available to the fox. Wait, the bird is a secondary consumer. So the energy in the bird is 10% of the primary consumer, which is 10% of the producer. Wait, let's do it step by step:

Trophic level 1 (Producer - grass): 100,000 kcal.

Trophic level 2 (Primary consumer - grasshopper): (100000\times0.1=10000) kcal.

Trophic level 3 (Secondary consumer - bird): (10000\times0.1 = 1000) kcal? Wait, no, that can't be. Wait, maybe I messed up. Wait, the 10% rule: each trophic level gets 10% of the energy from the level below. So grass (level 1) has 100,000. Level 2 (primary) gets 10%: 10,000. Level 3 (secondary, bird) gets 10% of level 2: 1,000. Then level 4 (tertiary, fox eating bird) would get 10% of level 3? But the question is fox eating the bird. Wait, the bird is level 3 (secondary consumer). So the energy in the bird is 1,000 kcal? No, wait no, wait the grass is 100,000. Primary consumer (grasshopper) gets 10%: 10,000. Secondary consumer (bird) gets 10% of 10,000: 1,000. Then if a fox eats the bird, the fox is a tertiary consumer, so it gets 10% of the bird's energy? Wait, but the options are 10,000; 1,000; 100; 10. Wait, maybe I mis - identified the trophic levels. Wait, maybe the bird is a secondary consumer, so the energy in the bird is 10% of primary, which is 10% of producer. Wait, let's recalculate:

Producer (grass): 100,000 kcal.

Primary consumer (grasshopper): (100000\times0.1 = 10000) kcal (10% of producer).

Secondary consumer (bird): (10000\times0.1=1000) kcal? No, that's not matching the options. Wait, maybe the bird is a secondary consumer, so the energy available to the bird is 10% of primary, but then the fox eating the bird: the fox is a tertiary consumer, so it gets 10% of the bird's energy. Wait, but the options include 100. Wait, maybe I made a mistake. Wait, let's check the trophic levels again. Grass (producer) → grasshopper (primary) → bird (secondary) → fox (tertiary). So energy transfer:

Grass (100,000) → grasshopper: (100000\times0.1 = 10000)

Grasshopper → bird: (10000\times0.1 = 1000)

Bird → fox: (1000\times0.1=100)

Ah! So the fox eating the bird (which has 1000 kcal) will get 10% of that, which is 100 kcal.

Step2: Calculate energy for fox

The bird (secondary consumer) has energy equal to 10% of primary consumer, which is 10% of producer. Let's re - express:

Energy at producer (grass): (E_1 = 100000) kcal.

Energy at primary consumer (grasshopper): (E_2=E_1\times0.1 = 100000\times0.1 = 10000) kcal.

Energy at secondary consumer (bird): (E_3 = E_2\times0.1=10000\times0.1 = 1000) kcal? Wait no, wait no, earlier mistake. Wait, no, the bird is secondary consumer, so when the fox eats the bird, the fox is a tertiary consumer? Wait, no, maybe the fox is a secondary consumer? No, the bird is secondary, fox eating bird would be tertiary. Wait, but according to the calculation above, if bird has 1000 kcal, then fox gets 10% of that, which is 100 kcal. That matches one of the options.

Answer:

100 kcal (corresponding to the option "100 kcal")