Transport Across Membranes To Learn

Question 1

Difference between cell surface membrane model and fluid mosaic model

Answer 1

No channel/carrier proteins whereas fluid mosaic does
Cholesterol present in fluid mosaic as well as glycolipids and glycoproteins

Question 2

Briefly outline the concept of simple diffusion

Answer 2

Diffusion on non-polar/small molecules down a concentration gradient

Question 3

Briefly outline the concept of facilitated diffusion.

Answer 3

Movement of large/polar molecules down the concentration gradient via a protein carrier/channel

Question 4

Briefly outline the concept of osmosis

Answer 4

Movement of water down a water potential gradient

Question 5

Briefly outline the concept of active transport

Answer 5

Active transport is the movement of substances against a concentration gradient via a protein carried using ATP

Question 6

Briefly outline the concept of co-transport

Answer 6

Co-transport of two different substances using a carrier protein

Question 7

Explain the role of ATP hydrolyse in the movement of substances

Answer 7

Converts ATP to ADP+Pi
This releases energy
The energy allows ions to be moved against a concentration gradient allowing transport

Question 8

Features of specialised cell for absorption

Answer 8

-microvilli to increase surface area
-large number of co-transport/carrier proteins for active transport
-large number of mitochondria for aerobic respiration

Question 9

How does the structure of the membrane allow transport

Answer 9

-levels of cholesterol affect fluidity/permeability
-phospholipid bilayer allows movement of non-polar/lipid-soluble substances
-phospholipid bilayer prevents movement of polar/lipid-insoluble molecules
-carrier proteins allow active transport
-channel/carrier proteins allow facilitated diffusion/co-transport
-number of channels/carriers determines which substances move