4. Which of the following statements about physical digestion and chemical digestion is correct?
A. Bile involves both physical and chemical digestion.
B. In the mouth cavity, carbohydrates undergo physical digestion only.
C. In both types of digestion, food substances are broken down into simpler molecules.
D. Physical digestion can enhance the efficiency of chemical digestion.

D

Explanation:

Example the action of teeth on food in the mouth increase surface area for salivary amylase to start digestion of starch

amber has allowed scientists to study dna that has been preserved over millions of years.

•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation: