GCSE Bio U4L7 The Small Intestine

What is the name of the structures that are responsible for the absorption of digested minerals into the blood stream?

In which organ are villi found?

What is the singular form of the word 'villi'?

What is the function of villi?

• To digest food molecules

• To absorb food molecules

• To emulsify food molecules

• To move food molecules

Where does the absorption of food molecules occur?

• The small intestine

• The large intestine

• The stomach

• The liver

The surface cells of each villus have microvilli. What is the purpose of microvilli?

• They increase the surface area of the villus

• They increase the concentration gradient between the small intestine and the blood

• They decrease the distance that digested food molecules must travel

• They allow the absorption of fatty acids

The wall of each villus is only one cell thick. What is the purpose of this?

• It increases the surface area of the villus

• It increases the concentration gradient between the small intestine and the blood

• It decreases the distance that digested food molecules must travel

• It allows the absorption of fatty acids

True or false: The villus has thin cell walls

• True

• False

Answer explanation

The cells don't have walls. The walls are thin, and the walls are one cell thick, but there are no cell walls.

Which feature of villi maximises the concentration gradient between the small intestine and the blood stream?

• Microvilli

• Thin walls

• Good blood supply

• Lacteal

Answer explanation

The movement of blood removes molecules that have already diffused, so there is always a lower concentration of molecules in the blood compared to the small intestine.

What is the purpose of the lacteal?

• Increase the surface area of the villus

• Increase the concentration gradient between the small intestine and the blood

• Decrease the distance that digested food molecules must travel

• Allow the absorption of fatty acids