Transport across Cell Membranes

Question 1

Microvilli

Answer 1

on the epithelial cells of the illium

finger-like projections

from the surface of Cell Membrane

increase the surface area

0.6µm long

Question 2

D/FD/AT/O

4 types of cellular transport

Answer 2

Diffusion - the movement of particles from a high concⁿ to a lower concⁿ e.g. O₂ & CO₂

FD - moving particles across a membrane down a concⁿ gradient using a carrier protein e.g. some glucose

AT - pumps particles against the concⁿ gradient using a carrier protein and energy e.g. sodium

Osmosis - the movement of water through SP Memb following the concⁿ gradient

Question 3

Co-transport

Answer 3

1. remove Na⁺ from epithelial cell by active transport
2. increases concⁿ of Na⁺ in the lumen of intestine
3. therefore, Na⁺ diffuses into the epithelial cell from the lumen of the ileum down the concⁿ gradient via facilitated diffusion using a carrier protein
4. glucose or aa transported through the carrier protein together with the Na⁺
5. the glucose or aa then pass into the blood via another carrier