B1 Movement In and Out of Cells

Question 1

Diffusion

Answer 1

The net movement of molecules from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement.

Question 2

Osmosis

Answer 2

The diffusion of water molecules from a region of their higher concentration (dilute solution) to a region of their lower concentration (concentrated solution), through a partially permeable membrane.

Question 3

Gas diffusion in alveoli

Answer 3

Oxygen diffuses from high concentration in the alveoli to the low concentration in the capillary (RBC).
Carbon dioxide diffuses from high concentration in the capillary to the low concentration in the alveoli.

Question 4

Gas diffusion in cells

Answer 4

Oxygen diffuses from the blood in the capillary (high concentration) into the tissue fluid and cells.
Carbon dioxide diffuses from the cells and tissue fluid (high concentration) to the blood.

Question 5

Solute diffusion

Answer 5

Mineral ions will dissolve in water and diffuse into the roots of plants (through active transport).
Kidneys will diffuse waste out of the blood and diffuse required nutrients and minerals back into the blood.

Question 6

Water uptake (plants)

Answer 6

Water will diffuse through the process of osmosis from an area of high water potential (diluted) to an area of low water potential (concentrated).
Water absorbed by the roots, diffuses into the xylem and up the stem. Water then exits the xylem in the veins of the leaf.
The water may be used for photosynthesis or evaporate in the leaf. The water can exit the leaf through the stomata (transpiration).

Question 7

Turgor pressure

Answer 7

High concentration in the vacuole will cause water to fill the vacuole and cell, creating pressure in the cell. This is supported by the cell wall.
Water flowing out of the cell will cause the cell to become flaccid.