Adaptations Topic

How Animals Adapt in the Desert?

This science revision note aims to help your child

– to identify the correct concept to explain this situation.

– proper scientific keywords to explain the concepts clearly.

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In the desert, a snake uses its whole body to slither across the hot sand, while a lizard runs across the sand. At any point in time, the lizard only has two legs that are in contact with the sand.

On a hot day in the desert, which of the animals (snake or lizard) can move a longer distance across the sand before they need to find shelter?

STEP 1

Which aspect of the surroundings do the animals have to adapt to?

In the desert, the snake and lizard have to adapt to the heat, by reducing the amount of heat gained from the hot sand.

STEP 2

Consider how the snake and lizard move across the sand. Which factor affecting the rate of heat gain is different between the two?

The snake uses its whole body to move across the sand. The lizard has two legs in contact with the sand.

Hmmm… Did you identify the correct concept?

–>The factor affecting the rate of heat gain that is different between the two is the surface area in contact with the hot sand.

–> As the lizard steps on the sand using only two legs at a time, the surface area of the lizard’s body in contact with the sand is less than that of the snake, which uses its entire body.

STEP 3

How does this factor affect the rate of heat gain?

The lower the surface area in contact with the hot sand, the slower the rate of heat gain from the sand to the body.

As the lizard has a slower rate of heat gain, it can travel longer than the snake before the lizard gets too hot and needs to find shelter.

FINALLY, put your answer together

Question: On a hot day in the desert, which of the animals (snake or lizard) can move a longer distance across the sand before they need to find shelter?

Answer:

The lizard will be able to travel a longer distance compared to the snake.

As the lizard steps on the sand using only two legs at a time, the surface area of the lizard’s body in contact with the hot sand is less than that of the snake, which uses its entire body.

As the lizard has a slower rate of heat gain from the sand to its body compared to the snake, the lizard can travel longer distances across the desert than the snake before finding shelter.

Note: Link the rate of heat gain back to the question.

Common mistakes

Wrong answer: The lizard will be able to travel a longer distance at a time compared to the snake because the lizard is smaller, so will gain heat from the sand slower.

Teachers’ comments:

Firstly, the student does not know the size of each animal, so you cannot assume that the lizard is smaller.

Secondly, even if the lizard is smaller, this answer is still incomplete. This is because simply stating the difference in size is not sufficient to explain the difference in the rate of heat gain. You need to specify the factor that affects the rate of heat gain – the surface area in contact with the hot sand.

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