How Muscles Move Bones

Question 1

When you reach up to grab a basketball from a low shelf, which statement correctly explains how your biceps and triceps move your forearm?

Accepted Answer

Your biceps shortens to bend the elbow as you lift the ball, and then your triceps shortens to straighten the elbow as you lower the ball back down.

Answer

Both the biceps and the triceps shorten at the same time to bend the elbow.

Answer

Your triceps shortens to bend the elbow, and your biceps shortens to straighten the elbow.

Answer

Only the biceps works; the triceps stays relaxed the whole time.

Question 2

You are sitting quietly reading a book. While you read, three different muscles are working: the heart pumps blood, the muscles in your stomach push food along, and the biceps in your upper arm lift the book. Which two of these muscles work without you having to think about them?

Accepted Answer

The heart and the muscles in your stomach that push food along

Answer

The biceps in your upper arm and the heart

Answer

The biceps in your upper arm and the muscles in your stomach that push food along

Answer

The heart and the biceps in your upper arm

Question 3

Sam wants to pick up a small toy from the floor. First he bends his elbow to grab the toy, then he straightens his arm to put the toy on a table. Which description shows what the biceps and triceps are doing during the two movements?

Accepted Answer

When Sam bends his elbow, his biceps contracts and his triceps relaxes; when he straightens his elbow, his triceps contracts and his biceps relaxes.

Answer

When Sam bends his elbow, both his biceps and triceps contract; when he straightens his elbow, both muscles relax.

Answer

When Sam bends his elbow, his triceps contracts and his biceps relaxes; when he straightens his elbow, his biceps contracts and his triceps relaxes.

Answer

His biceps contracts in both the bend and the straighten, while his triceps stays relaxed the whole time.

Try three questions

When you reach up to grab a basketball from a low shelf, which statement correctly explains how your biceps and triceps move your forearm?

You are sitting quietly reading a book. While you read, three different muscles are working: the heart pumps blood, the muscles in your stomach push food along, and the biceps in your upper arm lift the book. Which two of these muscles work without you having to think about them?

Sam wants to pick up a small toy from the floor. First he bends his elbow to grab the toy, then he straightens his arm to put the toy on a table. Which description shows what the biceps and triceps are doing during the two movements?

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