The energy an animal must expend to move uphill is proportional to its body weight, whereas the animal's energy outpu...

Victoria June 19, 2021

Hi @Ryan_B,

First off, don't be so hard on yourself! The language is often designed to trip you up. You'll get the speed down with practice.

This is a strengthen with necessary premise question. We are looking for the answer choice that, if negated, no longer allows us to draw our conclusion properly.

To start, what is the stimulus telling us?

If an animal wants to move uphill, then the amount of energy they must use to do so is proportional to its body weight. The amount of energy that an animal has available to move uphill is proportional to its surface area.

In other words, the heavier you are, the more energy you must use to get uphill. The more surface area you have, the more energy you will have available. Therefore, weight and surface area must be related in some way because the former tells us how much energy we need and the latter tells us how much energy we have,

Let's think of two examples. Let's say we have two squirrels: Nuts and Bolts.

In our first example, Nuts and Bolts have the exact same surface area. This means that they have the same amount of energy. However, Nuts weighs twice as much as Bolts. Therefore, Nuts requires more energy to move uphill than Bolts.

What does this mean? It would take Nuts more time to get up the hill than Bolts because they have the same amount of energy, but Nuts requires more energy to get up the hill due to his added weight. Therefore, he would need to move slower or stop to rest more frequently.

In our second example, Nuts and Bolts have the exact same weight. This means that moving up a hill will require the same amount of energy for each squirrel. However, Bolts has twice the surface area that Nuts does. Therefore, Bolts has more energy available than Nuts.

What does this mean? It would take Bolts less time to get up the hill than Nuts because they require the same amount of energy to complete the task, but Bolts has more energy available to him than Nuts.

Overall, what does this tell us? If you have more weight, then you will move slower. If you have more surface area, then you will move faster.

Answer choice (C) tells us that the ratio of surface area to body weight is smaller in large animals than it is in small animals.

In other words, the amount of energy available (surface area) is closer to the amount of energy required (body weight) for a large animal to move uphill. For small animals, the amount of energy available (surface area) is far greater than the amount of energy required (body weight).

This explains why smaller animals are able to move uphill more quickly than larger animals.

If we negated this answer choice, then it would tell us that larger animals are able to move uphill more quickly than smaller animals, contradicting the stimulus.

Hope this helps! Keep up the great work and please let us know if you have any further questions.

denleybishop November 30, 2022

Yes, sir I agree Vicky you are right. There is a reason they make it impossible! God Bless Ryan. My father always said, "you can not get anything without putting work in to it!" God's Strength is enough! I was stuck between those two also!

July 9, 2024

I find that talking to myself out loud, paraphrasing, explaining things to myself, and drawing pictures, helps. It definitely helped here. Explain it to yourself like you're 3 years old, possibly with crayons. It helps. lol :))