Outline a mechanism used to transport products of digestion from the lumen of the ileum into the blood.

facilitated diffusion;

substance moves from high to low concentration/ down concentration gradient;

protein channels needed;

does not require ATP/energy / passive;

valid example; (eg amino acids / glucose / fructose / water soluble vitamins)

or

active transport;

substance moves from low to high concentration / against concentration gradient;

membrane pumps needed / Na/K pump, \({\text{C}}{{\text{a}}^{ +  + }}\);

ATP/energy required;

valid example; (eg amino acids / glucose / mineral irons / iron)

or

endocytosis/pinocytosis;

droplets of intestinal fluid surrounded by membrane;

forms vesicle;

vesicles are released inside villus cell;

valid example; (eg fat soluble vitamins)

Accept appropriate diagram.

There were good answers, but many answered "microvilli" and/or couldn't label the longitudinal muscles. Most gained all marks about the transport mechanisms, but many seemed to not have understood the question and discussed movement through the digestive tract. Outlining the role of membrane-bound enzymes was difficult, and the marks were gained mainly for examples only.