© 2015 The Regents of the University of California. Image credit: Shutterstock; Getty Images.

Background Information: Green Group

A. Model what molecules could be in Julia’s cells just after she ran.

When you exercise, the cells of your body need to

be constantly supplied with glucose and oxygen. If

these molecules do not get into your cells, you will feel

tired. Glucose comes from food; glucose is broken

down from larger starch molecules. Oxygen comes

from air and is already small enough to travel into

the circulatory system and into the cells. The cells of

Julia’s body also need amino acids, which also come

from food; larger protein molecules are broken down

in the digestive system into amino acid molecules,

which can travel through the circulatory system and

into the cells.

B. Model what molecules could be in John’s cells since he didn’t eat breakfast.

When you don’t eat breakfast, you can feel very tired because your cells are not getting the molecules from

food that they need to function. Glucose and amino acids are molecules that come from food; glucose is broken

down from larger starch molecules, and amino acids are broken down from larger protein molecules.

C. Model what would happen in Levi’s body and cells just after he ate a meal of fish for dinner.

Fish is mostly protein. Protein molecules are large

molecules that are found in many foods like meats,

nuts, and beans. In the digestive system, protein gets

broken down into smaller molecules, amino acids,

which are small enough to get into the circulatory

system and then into the cells. Because fish doesn’t

have any starch, Levi would not have starch in his

digestive system, and he wouldn’t be getting glucose

(the smaller molecule that starch breaks down into)

into his circulatory system and cells. Because Levi is

breathing, he would be taking oxygen into his lungs,

and the oxygen molecules are already small enough to

travel into the circulatory system and cells.

© 2015 The Regents of the University of California. Image credit: Shutterstock.

D. Model what Lily’s cells would look like after she ate rice, potatoes, and no protein.

Rice and potatoes are made of starch, and starch is

broken down into glucose in your digestive system.

That glucose is then delivered to your cells. Protein

is a large molecule that is broken down into amino

acids in your digestive system. Amino acids are

then delivered to the cells by the circulatory system.

Because Lily is breathing, she would be taking oxygen

into her lungs, and the oxygen molecules are already

small enough to travel into the circulatory system and

cells.