F4 B3

Question 1

What does a phospholipid molecule consists of?

Answer 1

• polar head (hydrophilic)

- polar tail (hydrophobic)

Question 2

What is the functions of cholesterols in the phospholipid bilayer?

Answer 2

• make it stronger
• more flexible
• less permeable to water-soluble substances (ions)

Question 3

What is selectively permeable membrane?

Answer 3

• only allows free movement of certain molecules across it

- prevent or limit the movement of other substances

Question 4

What is passive transport?

Answer 4

• does not require energy
• move down the concentration gradient ( from an area of high concentration to an area of low concentration )
• simple diffusion, osmosis, facilitated diffusion

Question 5

What is active transport?

Answer 5

• requires energy
• move against a concentration gradient
• requires specific carrier protein with specific sites
• can change shapes

Question 6

What is the meaning of isotonic solution?

Answer 6

• both solutions have same concentration of solutions

Question 7

What is hypotonic solution?

Answer 7

• has low solute concentration but high water potential

Question 8

What is hypertonic solution?

Answer 8

• has high solutes concentration but low water potential

Question 9

What is the effects of hypotonic solution to animal cells?

Answer 9

• water diffuse into cell by osmosis
• plasma membrane too thin to withstand high osmotic pressure
• bursting = haemolysis

Question 10

What is the effect of hypertonic solution to animal cells?

Answer 10

• water will move out
• cell shrink
• undergo crenation

Question 11

What happen if animal cell is placed in isotopic solution?

Answer 11

• water diffuse in and out by osmosis at same rate
• no net movement of water
• maintain shape

Question 12

What is the effect of hypotonic solution to plant cell?

Answer 12

• water diffuse in by osmosis
• vacuoles expand
• push cytoplasm & plasma membrane against wall ( turgid state )
• do not burst ( wall rigid & strong )

Question 13

What happen if plant cell in hypertonic solution?

Answer 13

• water diffuse out of vacuoles by osmosis
• vacuoles shrink
• plasma membrane pulled away from cell wall (plasmolysis)
• leaves and stems bend downwards and wilt
• regain turgidity if returned to hypotonic solution immediately. (deplasmolysis)

Question 14

What is the effect of isoto/nic solution to plants cells

Answer 14

• water potential is the same
• movement in and out of cell is same
• become flaccid