Osmosis And Plant Transport

Question 1

Osmosis definition

Answer 1

Osmosis is the diffusion of water molecules from a dilute solution to a more concentrated solution, across a selectively permeable membrane

Question 2

Selectively permeable membrane

Answer 2

A selectively permeable membrane has holes in it that permit water molecules through but are too small to allow larger molecules through.

Question 3

Visking tube

Answer 3

Osmosis can be demonstrated by using visking tubing filled with a solution and placed in a beaker of pure water.

Question 4

Dilute solutions

Answer 4

Dilute solutions have a high concentration of water molecules

Question 5

Concentrated solution

Answer 5

Concentrated solutions have a low concentration of water molecules

Question 6

What happens to water molecules during osmosis

Answer 6

Initially, there is a larger number of water molecules in the more dilute solution than the concentrated solution. Some of the water molecules randomly diffuse across the selectively permeable membrane into the more concentrated solution. Eventually the molecules end up more evenly distributed.

Question 7

Plant cells placed in high concentrated solution

Answer 7

Water has left the cell by osmosis because the solution surrounding the cell is more concentrated than the cytoplasm inside the cell.

The cytoplasm has pulled away from the cell wall

The cell is plasmolyse

Question 8

Plant cell placed in medium concentration

Answer 8

The cells cytoplasm is the same concentration as the solution surrounding the cell.

There is no net movement of water

Question 9

Plant cell placed in low concentration

Answer 9

We’re has entered the cell by osmosis. ThI cytoplasm is more concentrated than the very dilute solution surrounding the cell.

The cytoplasm is pushing against the cell wall

The cell is turgid

Question 10

Lysis

Answer 10

In dilute solutions, osmosis can cause animal cells, such as red blood cells, to swell up and burst.

Question 11

Crenation

Answer 11

In concentrated solutions, water loss causes the cell to shrink.

Question 12

Animal cells placed in high concentration

Answer 12

Water has left the cell by osmosis because the concentration of the solution outside the cell is more than the concentration in the cell.

The cell becomes crenated as the cytoplasm pulls away from the cell membrane

Question 13

Animal cell placed in medium concentration

Answer 13

The cell cytoplasm is at the same concentration as the solution surrounding the cell.

There is no net movement is water

Question 14

Animal cells placed in Low concentration

Answer 14

Water has entered the cell by osmosis, pushing the cytoplasm against the cell membrane. Because the cell has no cell wall it bursts as it becomes turgid

The cell is destroyed

Question 15

Why use a ruler when measuring potato cylinder

Answer 15

It has smaller divisions so you can measure in millimetres

Question 16

Two factors to control during potato cylinder investigation

Answer 16

> The volumes of liquids in each beaker

>The same potato and size

Question 17

How would you know if water have moved out of potato

Answer 17

Mass decrease or length decrease

Question 18

Why is necessary to calculate percentage mass change

Answer 18

To compare the results

Question 19

How can you improve the potato cylinder experiment

Answer 19

> Measuring to more than one decimal place

>Repeat experiment more than once

Question 20

What fills the spaces between the membrane and cell wall.

Answer 20

Sugar solution

Question 21

Why is water important

Answer 21

> Support
Transport
Photosynthesis
Transpiration

Question 22

Support

Answer 22

We know that when plant cells absorb water they become turgid

Question 23

Transport

Answer 23

Water is a solvent, many substances dissolve into water. This allow easy transport from one part of the plant to another

Question 24

Photosynthesis

Answer 24

Water is an reactant in this process

Question 25

Transpiration

Answer 25

A process that results from the evaporation of water from the surface of the leaf. Important as it keeps the steer moving through the plant

Question 26

Transpiration

Answer 26

Transpiration is the evaporation of water from mesophyll cells followed by diffusion through air spaces and the stomata

Question 27

Stage 1: transpiration

Answer 27

Water diffuses front the soil into the roots. Roots are covered in tiny projections called root hair cells. These structures increases the surface are of the roots

Question 28

Stage 2:transpiration

Answer 28

Water travels up the stem of the xylem. It diffuses from an are of higher concentration the an area of lower water concentration

Question 29

Stage 3: transpiration

Answer 29

Water travels through veins into the leaves. It then diffuses out of the veins into cells and air spaces. From theses spaces, water evaporates through the stomata, into the air

Question 30

Stage 4: transpiration

Answer 30

The loss of water through transpiration in the leaves set up a concentration gradient, continuously pulling water form the soil into all parts of the plant

Question 31

Factors affection the rate of transpiration

Answer 31

> Humidity (amount of moisture in the air)
Temperature
Wind speed (air movement)q

Question 32

Humidity

Answer 32

Humid environments, such as rainforests, have high levels of water vapour in the air. This decreases the rate of transpiration because the air is already saturated with water. Transpiration will decrease when humidity increase

Question 33

Temperature

Answer 33

High temperatures heat the leaves and cause water to evaporate more quickly. Warm air is also able to absorb more water vapour than cool air. This means a temperature increase will increase the rate of transpiration

Question 34

Wind speed

Answer 34

When it’s windy, air saturated with water vapour is quickly moved away from the plant and replaced by drier air. The water concentration in the air will stay lower than in the plant, and this increase transpiration

Question 35

Surface area

Answer 35

A greater surface area means that there are more stomata and therefore more water can be lost

Therefore the greater the surface area the greater the rate of transpiration

Question 36

How the rate of transpiration can be measured

Answer 36

> Bubble/water uptake potometer

>Weight potometer

Question 37

Two precautions taken when using water uptake potometer

Answer 37

> cut the shoot under water to prevent air entering the xylem

>the whole system needs to be air tight. There should be no air bubbles other than the one on the scale

Question 38

How to stimulate environmental conditions

Answer 38

Wind speed: fan
Humidity: place a bag over the plant
Temperature: heater

Question 39

The leaf and transpiration

Answer 39

Leaves represent main site of transpiration

Water escapes via the stomata. No most plants the number of stomata is directly linked to how quickly water is lost.

Question 40

Leaf and transpiration experiment

Answer 40

Weigh at the start- record initial mass in grams
Hang up
Leave for 24hours
Reweigh
Calculate percentage change in mass

Question 41

Purpose of reservoir in water uptake potometer

Answer 41

To reset the bubble