A grass starts with [tex]$30,000 kJ$[/tex] of energy. How much energy would a cheetah acquire after the grass?

A. 30 kJ
B. 300 kJ
C. [tex]$3,000 kJ$[/tex]
D. [tex]$30,000 kJ$[/tex]

The cheetah would acquire 300 k J of energy after consuming the herbivore that ate the grass. This is based on the 10% rule of energy transfer in ecosystems. Therefore, the correct choice is B .300 k J .
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Answered by Anonymous | 2025-07-04

The grass starts with 30 , 000 k J of energy.
Apply the 10% rule to find the energy transferred to the herbivore: 30 , 000 k J × 0.1 = 3 , 000 k J .
Apply the 10% rule again to find the energy transferred to the cheetah: 3 , 000 k J × 0.1 = 300 k J .
The cheetah acquires 300 k J ​ of energy.

Explanation

Understanding the Problem Let's analyze the problem. We are given that grass has 30 , 000 k J of energy. We need to find out how much energy a cheetah would acquire after the grass. This involves understanding how energy transfers between different levels in an ecosystem.

Applying the 10% Rule The key concept here is the 10% rule, which states that only about 10% of the energy from one trophic level is transferred to the next trophic level. This is because organisms use most of the energy they consume for their own life processes, such as respiration, movement, and reproduction.

Energy Transfer to Herbivore First, we need to determine how much energy is transferred from the grass to the herbivore that eats the grass. According to the 10% rule, the herbivore gets 10% of the grass's energy. So, the energy transferred to the herbivore is: 30 , 000 k J × 0.1 = 3 , 000 k J

Energy Transfer to Cheetah Next, we need to determine how much energy is transferred from the herbivore to the cheetah, which is a carnivore. Again, according to the 10% rule, the cheetah gets 10% of the herbivore's energy. So, the energy transferred to the cheetah is: 3 , 000 k J × 0.1 = 300 k J

Final Answer Therefore, the cheetah acquires 300 k J of energy after the grass.


Examples
The 10% rule is a fundamental concept in ecology. For example, if a field of grass has 10,000 kJ of energy, a cow eating the grass will only get about 1,000 kJ of energy. If a human then eats the cow, they will only get about 100 kJ of energy. This illustrates why there are fewer top predators in an ecosystem compared to herbivores or plants. Understanding energy transfer helps us manage resources and understand food web dynamics.

Answered by GinnyAnswer | 2025-07-04