BIO Q, need help understanding....

[illbirz]

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The ecological efficiency is only 5% from one trophic level to the next. For every 250 J of energy required by the secondary consumers, what is the minimum amount of energy the primary producers will have to generate?

answer is 250/(0.05)^2 = 100,000 J


can any1 help? cause the achiever sure aint.

 

[jntruong2003]

haha. i did it another way.

i just used the answer choices and found 5% of 100,000, which is 5000. 5% of 5,000 is then 250 J of energy Sometimes it is much better to just randomly choose answer choices than figuring out the proper equation to use.

 

[raiden117]

So, I think the reason why the answer is 250/(.5^2) rather than 250/(.5) is because there are two levels that separate secondary consumers from primary producers, with the intermediate level being primary consumers. For each level, you have to divide by .05 (the equivalent of multiplying by 20) to find the total amount of energy in each level. Therefore, the answer should be 250(20)(20 = 100,000 J. Hope this helped

 

[illbirz]

awwww hu! Well thank you both for replying soo quickly and showing me 2 ways of solving this problem and helping me understand the Question and method of solving. But now im wondering what if they had given me a second degree consumer that lived in an environment with efficiency of 25% for each level, could i use the same formula to find the bare minimum energy required for it? or the question would have to give me a total energy produced by the primary producer in order for me to solve for it?

 

[jntruong2003]

you can use the same formula to find the bare minimum energy required. in your question, you provided the effiency of 25%, but you either need the total amount of mnimum energy or the amount of energy provided by the secondary consumer to fully answer the question.

 

[illbirz]

thnx....now back to AP cliff notes cuz time is of the essence and judgment day is approaching quickly.

 

[jntruong2003]

haha, funny.

thats exactly what i'm doing now....AP cliff notes...D-day on the 22nd. boohoo.

 

[illbirz]

Oh i decided to take mine on the ONE day that comes around every 4 years. YUP u guessed it, Feb 29th. Goodluck and keep me, well "us" posted.

 

[lilietta2000]

😕

So, I think the reason why the answer is 250/(.5^2) rather than 250/(.5) is because there are two levels that separate secondary consumers from primary producers, with the intermediate level being primary consumers. For each level, you have to divide by .05 (the equivalent of multiplying by 20) to find the total amount of energy in each level. Therefore, the answer should be 250(20)(20 = 100,000 J. Hope this helped

I don't understand where you got the 20..😕

 

[therealsquat]

,

 

[lilietta2000]

5% = 0.05 ----> dividing by 0.05 is the same as multiplying by 20

thus, dividing by 0.05^2 is the same as multiplying by 20 twice, or 20^2


hope that helps

Ohhhhhhhh 🙂) Thanx