Chapter 8 - Osmosis

Question 1

What is the term to describe cell membranes ?

Answer 1

selectively permeable

Question 2

What is the definition of Osmosis ?

Answer 2

Osmosis can be defined as the diffusion (movement) of water from a dilute solution to a more concentrated solution through a selectively permeable membrane.

Question 3

What is lysis ?

Answer 3

Lysis occurs when water moves into the cell and the volume increases too much and the cell bursts

Question 4

How does a plant cell become turgid?

Answer 4

When water enters the cell the vacuole increases in size and pushes the cell membrane against the cell wall.

Question 5

What are the benefits of a plant cell being turgid ?

Answer 5

• gives plant support

- prevents too much water from entering

Question 6

When does wilting in a plant occur ?

Answer 6

Wilting occurs when there is not enough water in the cells and they become flaccid.

Question 7

What is the condition called when a plant loses too much water by osmosis ?

Answer 7

plasmolysis

Question 8

What happens during plasmolysis ?

Answer 8

so much water leaves the cell that the cell’s contents shrinks pulling the cell membrane away from the wall. plasmolysed cells are unlikely to survive.

Question 9

What is transpiration ?

Answer 9

Transpiration is defined as evaporation from mesophyll cells followed by diffusion through air spaces and stomata

Question 10

Why is the continuous movement of water through a plant so important ?

Answer 10

• The supply of water to the leaves acts as raw material for photosynthesis
• the movement of water transports water through the roots and to other parts of the plant
• provides support through turgor
• provides water for the process of transpiration itself

Question 11

What is a bubble potometer used for ?

Answer 11

it is used to measure the water uptake from a leafy shoot

Question 12

What does the distance the bubble moved in the potometer show ?

Answer 12

The distance the bubble moved is the rate of water uptake

Question 13

What does the syringe in a potometer allow the user to do ?

Answer 13

It allows the user to rest the bubble position, so multiple results can be recorded

Question 14

Why is it important that the potometer is properly sealed ?

Answer 14

Air bubbles in the potometer can affect the uptake of water in a plant

Question 15

What non-environmental factor can affect the rate of water uptake of a leaf ?

Answer 15

• surface area of the leaf (more stomata present)

Question 16

What factors will increase the rate of water uptake ?

Answer 16

• wind speed

- increased temperature

Question 17

What factors will slow down the levels of water uptake ?

Answer 17

• increased humidity

lowers the concentration gradient

Question 18

What is an alternative way of measuring transpiration rate ?

Answer 18

weigh how much water a plant loses over time