GCSE - Topic 2 - Cell Transport - Year 9

Question 1

What is diffusion?

Answer 1

Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.

Question 2

What states does diffusion occur in?

Answer 2

Diffusion happens in both solutions and gases - that’s because the particles in these substances are free to move about randomly.

Question 3

How does the size of the concentration gradient affect the rate of diffusion?

Answer 3

The bigger the concentration gradient (the difference in concentration), the faster the diffusion rate.

Question 4

How does the temperature affect the rate of diffusion?

Answer 4

A higher temperature will give a faster diffusion rate because the particles have more energy, so move around faster.

Question 5

What does a cell membrane do?

Answer 5

They hold the cell together, as well as letting stuff in and out of the cell. Dissolved substances can move in and out of cells by diffusion.

Question 6

Which molecules can diffuse through a cell membrane?

Answer 6

Only very small molecules can diffuse through, though things like oxygen, glucose, amino acids and water are able to.

Question 7

Give an example of a big molecule that can’t fit through the membrane.

Answer 7

• Starch

- Proteins

Question 8

How does the surface area of the membrane affect the rate of diffusion?

Answer 8

The larger the surface area of the membrane, the faster the diffusion rate, because more particles can pass through at once.

Question 9

What is osmosis?

Answer 9

The net diffusion of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.

Question 10

What is a partially permeable membrane?

Answer 10

A partially permeable membrane is just one with very small holes in it. So small, in fact, only tiny molecules (like water) can pass through them, and bigger molecules (e.g. sucrose) can’t.

Question 11

How do the water molecules move during osmosis?

Answer 11

The water molecules pass both ways through the membrane during osmosis. This happens because water molecules move about randomly all the time.

Question 12

What does having more water molecules on one side than on the other mean?

Answer 12

Because there are more water molecules on one side than on the other, there’s a steady net flow of water into the region with fewer water molecules, i.e into the stronger sugar solution.

Question 13

Is osmosis a passive movement?

Answer 13

Osmosis is a passive movement of water molecules from an area of higher water concentration to an area of lower water concentration.

Question 14

Is the concentration of minerals higher in a root hair cell or the soil around them?

Answer 14

The conentration of minerals is usually higher in the root hair cells than in the soil around them.

Question 15

Do minerals move in or out of the root hairs?

Answer 15

Minerals should move out of the root hairs if they followed the rules of diffusion.

Question 16

What does active transport do?

Answer 16

It allows the plant to absorb minerals from a very dilute solution, against a concentration gradient. This is essential for its growth. Active transport needs ENERGY from respiration to make it work.

Question 17

What are factors that increase the rate of diffusion?

Answer 17

• More particles
• Bigger surface area to diffuse across
• Shorter distance to diffuse
• Temperature
• Mechanical movement (stirring or wind)

Question 18

Which diffuses faster, a liquid or a gas? Why?

Answer 18

Gas. Because they can move more easily as the particles are more spread out.

Question 19

A pant cell put in a dilute solution becomes ____.

Answer 19

Turgid.

Question 20

Plasmolysed is when the cytoplasm _____.

Answer 20

Shrinks.

Question 21

Osmosis will lead to the swelling of a raisin, but it will not burst because…

Answer 21

It is a plant.

Question 22

What type of transport protein is involved in active transport?

Answer 22

Carrier protein.

Question 23

What is active transport?

Answer 23

The movement of molecules from a low concentration to a high concentration area. The process requires energy and goes against the concentration gradient.

Question 24

Cells involved in active transport usually have a lot of ________ to provide the energy they need.

Answer 24

Mitochondria.

Question 25

What's an example of diffusion?

Answer 25

In the lung of a mammal, oxygen moves from the alveoli to the blood.

Question 26

What's an example of osmosis?

Answer 26

In the kidney of a mammal, water moves from the nephron to the blood.

Question 27

How do carrier proteins allow for facilitated diffusion?

Answer 27

They bind specifically to the molecule they assist.

Question 28

Is diffusion a passive process?

Answer 28

Yes.

Question 29

What's a passive process?

Answer 29

A passive process means that no energy is needed.

Question 30

During diffusion, do molecules move down or against the concentration gradient?

Answer 30

Down. They move from an area of high concentration to an area of low concentration.

Question 31

What does a partially permeable membrane do?

Answer 31

Allow small molecules to pass through by diffusion, for example, water, oxygen and carbon dioxide.

Question 32

Are flaccid (plasmolysed) cells or Turgid cells larger?

Answer 32

Turgid cells, they're filled with water.

Question 33

What's a turgid cell?

Answer 33

When water enters a plant cell by osmosis and pushes on the cell wall causing the cell to swell.

Question 34

What's a flaccid cell?

Answer 34

When water leaves a plant cell by osmosis, the cell contents shrink and the cell membrane pulls away from the cell.

Question 35

Which subcellular structures are in an animal cell?

Answer 35

``` Nucleus Cytoplasm Cell membrane Mitochondria Ribosomes ```

Question 36

Which subcellular structures are in a plant cell?

Answer 36

``` Rigid cell wall (made of cellulose) Permanent vacuole Chloroplasts Nucleus Cytoplasm Cell membrane Mitochondria Ribosomes ```

Question 37

Which subcellular structures are in a bacteria cell?

Answer 37

``` (May contain) One or more small rings of DNA called plasmids Single circular strand of DNA Cell wall Cell membrane Cytoplasm ```

Question 38

What does the nucleus do?

Answer 38

Contains genetic material that controls the activities of the cell.

Question 39

What does the cytoplasm do?

Answer 39

Gel-like substance where most of the chemical reactions happen. It contains enzymes that control these reactions.

Question 40

What does the cell membrane do?

Answer 40

Holds the cell together and controls what goes in and out.

Question 41

What do the mitochondria do?

Answer 41

These are where most of the reactions for aerobic respiration take place. Respiration transfers the energy that the cell needs to work.

Question 42

What do the ribosomes do?

Answer 42

These are where proteins are made, via protein synthesis.

Question 43

What does the rigid cell wall do?

Answer 43

It supports the cell and strengthens it. It's also made of cellulose.

Question 44

What do the chloroplasts do?

Answer 44

These are where protein synthesis occurs, which makes food for the plant. They contain a green substance called chlorophyll, which absorbs the light needed for photosynthesis.

Question 45

What are the specialisations of a sperm cell?

Answer 45

It has a long tail and a streamlined head to help it swim to the egg. There are a lot of mitochondria in the cell to provide the energy needed. It also carries enzymes in its head to digest through the egg cell membrane.

Question 46

What's the function of a nerve cell?

Answer 46

To carry electrical signals from one part of the body to another.

Question 47

What are the specialisations of a nerve cell?

Answer 47

These cells are long (to cover more distance) and have branched connections at their ends to connect to other nerve cells and form a network throughout the body.

Question 48

What's the function of muscle cells?

Answer 48

To contract quickly.

Question 49

What are the specialisations of a muscle cell?

Answer 49

They are long (so that they have space to contract) and contain lots of mitochondria to generate the energy needed for contraction.

Question 50

What's the function of a root hair cell?

Answer 50

To absorb water and minerals.

Question 51

What are the specialisations of a root hair cell?

Answer 51

Root hair cells are cells on the surface of the plant roots, which grow into long "hairs" that stick out into the soil. This gives the plant a big surface area for absorbing water and mineral ions.

Question 52

What's the function of phloem and xylem cells?

Answer 52

They form phloem and xylem tubes, which transport substances such as food and water around plants.

Question 53

What are the specialisations of phloem and xylem cells?

Answer 53

To form tubes, the cells are long and joined end to end. Xylem cells are hollow in the centre and phloem cells have very few subcellular structures, so that stuff can flow through them.

Question 54

Is active transport a passive process?

Answer 54

No, it's an active process. This means it requires energy.

Question 55

What's a hypotonic solution?

Answer 55

A solution that has more water molecules (higher concentration of water) than inside the cell.

Question 56

What's an isotonic solution?

Answer 56

A solution that has the same concentration as inside the cell.

Question 57

What's a hypertonic solution?

Answer 57

A solution that is more concentrated than inside the cell.

Question 58

What's an active process?

Answer 58

Something that requires energy.

Question 59

Is diffusion a specific process?

Answer 59

No.

Question 60

Is osmosis a specific process?

Answer 60

Yes.

Question 61

Is active transport a specific process?

Answer 61

Yes.