cell membrane and transport

Question 1

Describe how intrinsic protein would transport a molecule against a concentration gradient (2)

Answer 1

• active transport / carrier protein change shape
• require ATP

Question 2

Glucose is water soluble and vitamin A is lipid soluble how is each molecule transported across membrane (4)

Answer 2

• vitamin A - pass directly through phopholipid layer
• by diffusion
• glucose - cannot pas through phospholipid layer therefore uses transport protein
• via facilitated diffusion/active transport

Question 3

At 15 degrees celcius beetroot cells are place into ethanol why is there a leakage in pigment (2)

Answer 3

• ethanol emulsifies phospholipids
• creates pores in the membrane

Question 4

If the beetroot experiment wa repeated at 30 degrees celcius why does the time taken for ethanol to turn red decreases explain why (2)

Answer 4

• increased temperature increased kinetic energy of molecule
• increasing the rate of diffuion of dye across membrane

Question 5

State with explanation how the solubility in lipid affects the rate of diffuion through a membrane (2)

Answer 5

• a lipid solubility increases
• membrane contains a doubly layer of phospholipids
• lipid soluble substances can move through the membrane more eaily than water soluble substances

Question 6

Describe how molecular size affects the rate of diffusion Suggest an explanation for your answer (2)

Answer 6

• small molecules diffue faster]higher kinetic energy
• easier to pass between phospholipid molecules

Question 7

Name two factors which affect the rate of faciltated difusion of a substance through a membrane (2)

Answer 7

• concentration gradient
• more carrier proteins
• temperature

Question 8

Vitabin B1 is water oluble while vitamin K is fat soluble decribe the routes they take (4)

Answer 8

• vitamin B1- polar
• cannot pass through phospholipid layer
• non polar
• disolve in phospholipid membfrane
• so can pass directly through phospholipid

Question 9

Explain what the term is by active transport (2)

Answer 9

• movement against a concentration gradient
• require ATP

Question 10

What is the model given to the phospholipid bilayer and explain why (3)

Answer 10

• fluid mosaic model
• mosaic of protein molecules irregularly arranged
• lipid layer fluid

Question 11

State the function of channel proteins (1)

Answer 11

• allow passage of polar moelcules
• facilitated diffusion

Question 12

State two reason why transport across the membrane is vital to the cell (2)

Answer 12

• maintain water potential
• obtain nutrients
• obtain oxygen
• secrete molecules
• remove toxic substances

Question 13

State two functions of membrane proteins (2)

Answer 13

• transport / active transport/ facilitated diffusion
• enzyme system
• receptors

Question 14

Explain what is meant by the term lipid bilayer (1)

Answer 14

two layers of phospholipids

Question 15

Describe the process by which oxygen is aborbed by roots giving a reason (2)

Answer 15

• diffusion
• rate is proportional to concentration

Question 16

Explain why the rate of nitrate ions decreases then lowly plateus (1)

Answer 16

• increasing ion concentration increases chance that a molecules will collide with a carrier protein

Question 17

Name the process by which nitrate ions are taken up (1)

Answer 17

active transport

Question 18

Describe the events of an amoeba feeding on algae (2)

Answer 18

• phagocytosis
• cell membrane enguls to form a vesicle around the algae