Transport of substances across membranes (B1.6 - B1.10)

Question 1

Function of nucleus

Answer 1

Contains DNA

Question 2

Function of the cytoplasm

Answer 2

This is where chemical reactions take place

Question 3

Function of the cell membrane

Answer 3

Controls what enters and leaves the cells

Question 4

Function of the mitochondria

Answer 4

This is the site of respiration

Question 5

Function of cell wall

Answer 5

It gives the plant strength and support

Question 6

Why are ribosomes needed in a cell?

Answer 6

Ribosomes are the site where proteins are made.

Question 7

Function of chloroplasts in plant cells

Answer 7

Chloroplasts contain chlorophyll which traps sunlight energy which is needed for photosynthesis.

Question 8

Define diffusion

Answer 8

Diffusion is the net random movement of particles from an area of HIGH concentration to an area of LOW concentration.

Question 9

Define Osmosis

Answer 9

Osmosis is the net random movement of WATER from an area of high concentration to an area of low concentration, across an PARTIALLY PERMEABLE MEMBRANE

Question 10

What happens to an animal cell when it is placed in a more DILUTE solution?

Answer 10

The cell gains water by osmosis, swells up and may burst.

Question 11

What happens to an animal cell when it is placed in a more CONCENTRATED solution?

Answer 11

The cell loses water by osmosis and shrivels up.

Question 12

Define active transport

Answer 12

The movement of substances from an are of LOW concentration to an area of HIGH concentration ( against concentration gradient ) across a partially permeable membrane which requires energy.

Question 13

What happens to a plant cell when it is placed in a more DILUTE solution?

Answer 13

The cell gains water by osmosis but does not burst. This cell is now turgid.

Question 14

Why does a plant cell not burst when it is placed in a more dilute solution?

Answer 14

The plant cell has a cell wall.

Question 15

What happens to an plant cell when it is placed in a more CONCENTRATED solution?

Answer 15

The cell loses water by osmosis. The cell membrane pulls away from the cell wall ( shrivels up ). This is is called plasmolysis.

Question 16

Give an example of molecules that move by active transport.

Answer 16

Mineral ions in the soil are in low concentration

Question 17

How do you calculate % change in mass?

Answer 17

(Final mass - initial mass) ÷ (initial mass) x 100

Question 18

How are root hair cells adapted for their function?

Answer 18

Have a large surface area due to root hairs, meaning more water can be absorbed by osmosis.

Question 19

What is the function of root hair cells in a plant?

Answer 19

They are specialised to absorb water by osmosis and mineral ions by active transport from the soil.