Quick Ecology Question

[BiomajorPreDent]

Hi, I am trying to figure out the reasoning behind the answer choice for this q, I am hoping someone here can explain it to me.

According to the top-down (trophic cascade) model of community control, which trophic level would you decrease if you wanted to increase the vegetation level in a community?

A. Nutrients
B. Vegetation
C. Secondary consumers (carnivores)
D. Tertiary consumers
E. Omnivores

The ideal choice, primary consumers, isnt here, so I picked what I thought was the next best thing, E. My reasoning was that since Omnivores eat both plants and animals, if you reduced them, you would increase the amount of vegetation.

The book says that its D, tertiary consumers. (no explanation)

Tertiary consumers eat other animals..including primary consumers, so if you got rid of the 3ary consumers, the primary consumers would increase..thus decreasing vegetation..right?

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[navneetdh]

Hi, I am trying to figure out the reasoning behind the answer choice for this q, I am hoping someone here can explain it to me.

According to the top-down (trophic cascade) model of community control, which trophic level would you decrease if you wanted to increase the vegetation level in a community?

A. Nutrients
B. Vegetation
C. Secondary consumers (carnivores)
D. Tertiary consumers
E. Omnivores

The ideal choice, primary consumers, isnt here, so I picked what I thought was the next best thing, E. My reasoning was that since Omnivores eat both plants and animals, if you reduced them, you would increase the amount of vegetation.

The book says that its D, tertiary consumers. (no explanation)

Tertiary consumers eat other animals..including primary consumers, so if you got rid of the 3ary consumers, the primary consumers would increase..thus decreasing vegetation..right?

Yeah I agree with you that E. isnt a good answer. The first thing we are taught in these classes is the effects one level can have on others. Tertiary consumer would decrease would mean that their prey will increase. WHich is primary and secondary consumers. SO primary consumers are going to eat up all the grass/vegetation. I don't understand this either.

 

[vlct0ria]

Hi, I am trying to figure out the reasoning behind the answer choice for this q, I am hoping someone here can explain it to me.

According to the top-down (trophic cascade) model of community control, which trophic level would you decrease if you wanted to increase the vegetation level in a community?

A. Nutrients
B. Vegetation
C. Secondary consumers (carnivores)
D. Tertiary consumers
E. Omnivores

The ideal choice, primary consumers, isnt here, so I picked what I thought was the next best thing, E. My reasoning was that since Omnivores eat both plants and animals, if you reduced them, you would increase the amount of vegetation.

The book says that its D, tertiary consumers. (no explanation)

Tertiary consumers eat other animals..including primary consumers, so if you got rid of the 3ary consumers, the primary consumers would increase..thus decreasing vegetation..right?

I think its because if you decrease tertiary consumers (secondary carnivores), then the secondary consumers (primary carnivores) they eat would be allowed to thrive...if the secondary consumers are thriving, then the primary consumers they eat are diminishing. The vegetation normally eaten by those now diminishing primary consumers is allowed to increase. Makes sense to me!

I think because they're talking about a top-down trophic cascade, they are assuming each trophic level only eats members of the trophic level directly below it, so I believe they are asking you to assume tertiary eats only secondary, secondary eats primary, primary eats vegetation.

 

[276640]

I believe Victoria's reasoning is correct. That's what I was thinking too.

 

[BiomajorPreDent]

Yeah, thanks alot. It makes sense now.