- enzyme pepsin: chemically digests the proteins in the food, breaking down into amino acids
- hydrochloric acid (strong acid): provides an acid environment for pepsin and kills bacteria (food); without this acid, the stomach could not function properly.
Answer: b. to form RNA molecules form DNA
Half-life = time in which half of material is lost
1/4 = 1/2 x 1/2 so 2 half lives have gone by if only 1/4 of it is left.
age of rock = 2 x half life = 2x1.3 = 2.6 billion years.
