2022 Topic 2 Revision

Select part of definitions that can define the term diffusion. (more than 1 correct answer)

• movement of water only through semi permeable membrane

• moves down concentration gradient, from higher to lower concentration

• movement of particles / molecules / ions

  e.g. oxygen / carbon dioxide / glucose

• moves against concentration gradient

Name the substance absorbed by plants using the process of osmosis.

• Gas

• Water

• Minerals

• Ions

Define osmosis and explain why osmosis is a special form of diffusion. Select the correct answers.

• For the process of diffusion, membrane is not required

• Osmosis is the movement of water molecules without the use of energy

• Is where water moves from high to low water water potential

• Is where water moves through a partially permeable membrane

What would happen to the red blood cell if placed in pure water? Select the correct explanations. (more than 1 correct answer)

• Red blood cell have higher water potential compared to pure water.

• Red blood cell have lower water potential compared to pure water.

• water enters

  by osmosis,

  cell expands and

  bursts since red blood cell has no cell wall

• water enters

  by osmosis,

  cell shrinks since

  red blood cell has no cell wall

Explain the importance of active transport in the human alimentary canal. Select the correct explanations. (more than 1 correct answer)

• Involves the absorption of digested substances against a concentration gradient

• glucose / amino acids / fatty acids / glycerol /

  minerals are absorbed by the villi

• Protein, carbohydrates and fats are absorbed by the villi

• Involves the absorption of large molecules against a concentration gradient

Explain what is meant by

active transport. Select the correct explanations. (more than 1 correct answer)

• Uses energy from respiration,

  moves through a membrane

• Involves the movement of molecules / ions,

  against concentration gradient from low to high concentration

• example includes

  e.g. nitrate ion absorbed into root hair cell

• example includes

  e.g. glucose

  absorbed into villi

Describe how mineral ions pass from the soil into the root hair cell. Select the correct explanations (more than 1 correct answer)

• Mineral ions are absorbed into the root hair cell against concentration gradient by active transport

• The mineral ions are dissolved in water before passing into the root hair cell

• Mineral ions pas through the cell wall,

  partially permeable cell membrane

  by active transport

• Using energy (for active transport)

  from (aerobic) respiration

Explain how the rate of ion uptake by active transport is affected by oxygen. Select more than 1 correct explanation.

• Oxygen is used in respiration, to release energy for active transport

• Respiration requires oxygen, Increase in oxygen will increase the rate of ion uptake

• As oxygen concentration increases, rate of ion uptake increases too,

  until the rate becomes constant

• Uptake of ion by active transport is a passive process

Explain plasmolysis in plant cells. Select more than 1 correct explanation.

• Water moves out of cell by osmosis, through a partially permeable cell membrane down concentration gradient

• Cell membrane gets pulled away from cell wall, cell is plasmolysed

• Water moves into the cell by osmosis (through) a

  partially permeable cell membrane

  down concentration gradient

• Cell expands in volume, cell membrane gets pushed against the cell wall, cell wall prevents cell from bursting