Chapter Three: Movement of Particles

Question 1

Net Movement

Answer 1

An average or overall movement of particles

Question 2

Diffusion (4)

Answer 2

Is
-the net movement of particles from their region of higher concentration to a region of lower concentration.
-Down the concentration gradient.
-As a result of their random movement
-No energy is required as it is a passive transport.

Question 3

Concentration Gradient

Answer 3

An imaginary slope from a higher concentration to a lower concentration.

Question 4

How does temperature affect the movement of particles? (3)

Answer 4

-The higher the temperature the faster the particles move.
-This is because in higher the temperatures the more kinetic energy the particles have.
-And so the higher the temperature the faster the particle moves.

Question 5

Why does diffusion occur?

Answer 5

Diffusion occurs because of the random motion of particles. They spread quite evenly across the room.

Question 6

Kinetic Energy

Answer 6

The energy of moving objects

Question 7

Higher Concentration

Answer 7

When many molecules are close together, the area is said to have a higher concentration.

Question 8

Factors affecting Diffusion

Answer 8

Temperature, Concentration Gradient, Size of particles, Type of medium, Surface Area

Question 9

Temperature

Answer 9

Higher/ Steeper the temperature the faster the rate of diffusion

Question 10

Concentration Gradient

Answer 10

Higher/ Steeper the concentration gradient the faster rate of the diffusion.

Question 11

Size of Particles

Answer 11

The smaller the particles the faster the rate of diffusion.

Question 12

Surface Area

Answer 12

The rate of diffusion increases as the surface area decreases.

Question 13

Type of medium

Answer 13

The rate of diffusion is fastest in a gaseous medium, faster in liquids and slowest in solids.

Question 14

Example of Diffusion in Plants

Answer 14

During Photosynthesis CO2 molecules diffuse into the stoma while the O2 molecules diffuse out of the stomae. During Respiration O2 molecules diffuse into the stoma while CO2 molecules diffuse out of the stoma.

Question 15

Example of Diffusion in Animals

Answer 15

In animals, CO2 molecules diffuse into the alveolus from the blood vessel while the O2 molecules diffuse out of the alveolus into the blood vessel.

Question 16

Example of a Solution

Answer 16

In all living cells, the cytoplasm contains many different solutes such as glucose molecules and sodium ions. As they are free to move they can easily diffuse, distributing to all parts of the cytoplasm.

Question 17

Compound

Answer 17

A substance is formed by the chemical combination of 2 or more elements in fixed proportions.

Question 18

partially permeable membrane

Answer 18

a membrane (very thin layer) that lets some particles move through it but prevents others from passing through.

Question 19

osmosis

Answer 19

the net movement of water molecules from a region of higher concentration to a region of lower concentration (from hypotonic to hypertonic) down the gradient through a partially permeable membrane.

Question 20

osmosis in terms of water potential.

Answer 20

the net movement of water molecules from a region of a higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane.

Question 21

high water potential

Answer 21

an area where there are a lot of water molecules- a dilute solution.

Question 22

low water potential

Answer 22

an area where there are not many water molecules- concentrated

Question 23

water potential gradient

Answer 23

a difference in water potential between two areas.

Question 24

3 types of solutions

Answer 24

-Hypotonic
-Hypertonic
-Isotonic

Question 25

Hypertonic Solution

Answer 25

It causes a cell that is placed in it to shrink(due to osmosis*) as most of the water leaves the cell.

Question 26

Hypotonic Solution

Answer 26

It causes a cell that is placed in it to enlarge (swell up) due to osmosis* as most of the water enters the cells.

Question 27

Isotonic Solution

Answer 27

No change is observed as there is no movement of water.

Question 28

Importance of osmosis

Answer 28

-It is important to the cells because it is the way by which living organisms take up water.

Question 29

Animal cells in a hypotonic solution (3)

Answer 29

-Due to the cytoplasm being more concentrated than the surrounding water (due to containing proteins and other substances)
-the water moves from the region of higher conc to the region of lower conc, from outside the cell to inside the cell through the semi-permeable membrane
-until eventually the cell membrane stretches with too much strain that the cell bursts. (plasmolyses)

Question 30

Animal cells in a hypertonic solution (3)

Answer 30

-Due to the surrounding solution being more concentrated that the solution in the cell,
-the cell will lose water as the water molecules move from a region of higher conc to a region of lower conc through the semi-permeable membrane.
-the cytoplasm shrinks and so does the animal cell.

Question 31

Plant cells in a hypotonic solution (5)

Answer 31

-Due to the cytoplasm being more concentrated than the surrounding water (due to containing proteins and other substances)
-the water moves from the region of higher conc to the region of lower conc, from outside the cell to inside the cell through the semi-permeable membrane.
-The cytoplasm and the vacuole will swell. The cell membrane stretches.
-Due to the cell wall being fully permeable and stronger than the cell membrane, it prevents the cell from bursting by the wall resisting the pressure from the enlarging contents and pushing back against it.
-The cell is turgid.

Question 32

Plant cells in a hypertonic solution (4)

Answer 32

-Due to the surrounding solution being more concentrated that the solution in the cell,
-the cell will lose water as the water molecules move from a region of higher conc to a region of lower conc through the semi-permeable membrane.
-the cytoplasm and vacuole shrink but the cell wall is strong and stays in position., hence causing the cytoplasm and so the cell membrane to pull away from the cell wall.
-It is plasmolysed.

Question 33

Turgour Pressure

Answer 33

the pressure of the water pushing outwards on a plant cell wall.

Question 34

turgid

Answer 34

a description of a plant cell that is tight and firm

Question 35

flaccid

Answer 35

a description of a plant cell that is soft

Question 36

The danger of plasmolysis?

Answer 36

Plasmolysis can kill a plant cell because the cell membrane is damaged as it tears away from the cell wall.

Question 37

Active transport

Answer 37

The movement of molecules or ions through a cell membrane from a region of lower concentration to a region of higher concentration( against a concentration gradient) using energy from inspiration.

Question 38

Eg 1 of Active Transport (4)

Answer 38

-A plant takes up nitrate ions by active transportation very often the concentration of nitrates inside the root hair cell is much higher than the concentration in the soil
-In order to take up the nitrate ions the cell membrane of the root hair have special carrier molecules.
-These molecules grab nitrates change their shape and push the ions into the cell.
-This process needs energy in the form of ATP which they can get from aerobic respiration.

Question 39

Eg 2 of Active Transport (1)

Answer 39

-The absorption of glucose initially is by diffusion as the concentration inside increases, active transportation is applied in order to continue with the absorption carrier proteins are used for which energy is required which they get from Aerobic respiration.

Question 40

Measuring the rate of osmosis (5)

Answer 40

-Collect a piece of Visking Tubing,
-Moisten it and fill it with concentrated sugar solution.
-Place a long narrow glass tube as shown in the figure and tie it with a thread.
-Place the tubing inside the beaker of water.
-Mark the level of water inside the glass tube.

Question 41

carrier proteins (or protein carriers):

Answer 41

proteins molecules in cell membranes that can use energy to change shape and move ions or molecules into or out of a cell.