Lesson 1 - Transport in cells

Question 1

state the 2 functions of the cell membrane

Answer 1

• the transport of materials in & out of the cell
• the transport of materials within the cell

Question 2

state the function of glycoproteins

Answer 2

may act as antigens, and are important for cell recognition or as receptors for hormones or neurotransmitters, setting up a chain of reactions within the cell

Question 3

state the function of peripheral proteins

Answer 3

may be enzymes, can be involved in regulating transport

Question 4

state the function of integral proteins

Answer 4

the main transport system of the membrane, either forming hydrophilic channels or other transport mechanisms

Question 5

meaning active transport

Answer 5

the net movement of molecules against a concentration gradient, from an area of low concentration to an area of high concentration. It is an active process using ATP

Question 6

name 3 mechanisms of passive transport

Answer 6

diffusion, facilitated diffusion, osmosis

Question 7

name 3 mechanisms of active transport

Answer 7

endocytosis, exocytosis, active transport

Question 8

explain why transport systems are needed in cells

Answer 8

the transport systems are necessary for the cells obtaining nutrients, oxygen, water, and secreting carbon dioxide, excess water and other products.

Question 9

why do small warm blooded mammals need to eat constantly

Answer 9

because they lose heat very quickly, due to their large SA:V ratio

Question 10

how and why do desert plants minimise their surface area

Answer 10

if their leaves would be flat, they would lose water very quickly. Thus, they minimise their SA:V ratio to conserve water

Question 11

why can large multicellular organisms not rely on diffusion alone

Answer 11

• low SA:V ratio
• long diffusion distances
• higher demand for oxygen e.g. maintaining body temperature