Download 8Ae6 Eat to live - School

8Ae6 Eat to live
Proteins contain the elements carbon, hydrogen, oxygen and nitrogen. The proteins that we eat
are digested into amino acids. Cells inside our bodies use these amino acids to produce new
proteins that we need. Muscle cells contain a lot of protein.
Fats contain the elements carbon, hydrogen and oxygen. The fats that we eat are digested into
fatty acids and another substance called glycerol The body uses these to make different types of
fat. Cell membranes contain a lot of fat.
Carbohydrates also contain carbon, hydrogen and oxygen but in different proportions to fats.
Carbohydrates are digested into small sugars. Glucose is the main sugar that is produced and
this is used in respiration. If more carbohydrates are eaten than can be respired, the extra is
turned into fat and stored.
The word equation for respiration is:
glucose + oxygen +
water + carbon dioxide (+ energy)
It can be shown that food is used in respiration by using radioactive markers. One type of
carbon is slightly radioactive. Rats fed on glucose containing this sort of carbon are found to
breathe out radioactive carbon dioxide!
1
2
3
4
5
a
What are proteins digested into?
b
Name one place in the body where new proteins are made.
a
What are fats digested into?
b
Name one place where fats are important.
a
What are the reactants in respiration?
b
How do each of these reactants reach the cells?
a
What are the products of respiration?
b
Explain how carbon dioxide is excreted from the body.
Proteins are not usually used for respiration. Explain how a scientist would show that
proteins are not used in respiration.
[ knowledge, literacy ]