Paper 1 Cell 4

Question 1

Define a strong solution

Answer 1

A low concentration of water

Question 2

What’s a hypotonic solution?

Answer 2

Distilled water

Question 3

In an animal cell, if the surrounding solution is too dilute what would happened?

Answer 3

• the solution is hypotonic to the cell
• water will enter the cell and cause it to burst
• because there’s less water in the cell so due to osmosis the water from the surroundings goes into the cell

Question 4

What’s a hypertonic solution?

Answer 4

A strong solution

Hyper lots of sugar

Question 5

If the solution is more concentrated then the animal cell what would happen?

Answer 5

If the solution is too concentrated, we say it’s hypertonic to the cell
Water will leave the cells, causing them to shrivel up

Question 6

If the surrounding solution is the same concentration as the animal cell, what will happen to the animal cell?

Answer 6

• if the solution is the same concentration as the cell, it’s called isotonic
• under these conditions, there’s no net movement of water so the cells will remain the same size

Question 7

What’s an isotonic solution?

Answer 7

When the concentration outside the cell is equal to concentration in the cell, so there’s no net movement
(It’s what kidneys try to do)

Question 8

What happens to plant cells, if water enters the cell?

Answer 8

• if water enters a plant cell, the vacuole swells and pushes the cytoplasm against the cell wall
• But the wall pushes preventing the cell from bursting
• the ce,k becomes swollen and ‘turgid’ which is important in maintaining the rigid shape of the plant

Question 9

What happens when a plant is dehydrated?

Answer 9

The solution outside the cell become too concentrated, so water leaves the cell and loses its rigid form which is called plasmolysed
This causes the plant to wilt

Question 10

Why and how does active transport work?

Answer 10

• to control reactions in cells, it’s often necessary to build a higher concentration of molecules on 1 side of a membrane than another
• active transport uses energy for the membrane proteins to pump molecules against their concentration gradient

Question 11

Explain why active transports happens in plant root hair cells?

Answer 11

-plant root hair cells use active transport to carry the low concentration of mineral salts from the soil into the cells

Question 12

Explain why active transports happens in the small intestine?

Answer 12

• after eating, the high concentration of molecules in the gut allows them to pass through to blood by diffusion at first
• as the concentration decreases, active transport by the cells lining the intestine move the remaining molecules across against their concentration gradients

Question 13

What do cells contain to carry out active transports?

Answer 13

• cells that carry out active transport have lots of mitochondria to carry out reparation
• they also require a large supply of oxygen to enable aerobic respiration to provide all of the energy needed to do active transport

Question 14

Define active transport

Answer 14

• the process in which dissolved molecules move across a cell membrane from a lower concentration to a higher concentration
• particles move across the concentration gradient, therefore require an input of energy from the cell

Question 15

Define breathing

Define respiration

Answer 15

• breathing-Moving air in and out of the lungs

- respiration-the release of energy from glucose

Question 16

Where is osmosis used in living things (2 examples)

Answer 16

• it’s used in plant cells it inflates the cell and makes it rigid
• absorbing water in the large intestine (through its wall)

Question 17

name the action of water vapour being lost from a leaf?

Answer 17

Transpiration

Question 18

Name 2 food molecules absorbed by epithelial cells by active transport?

Answer 18

Amino acids

Glucose

Question 19

What are epithelial cells?

Answer 19

They form the lining of your small intestine

but also parts of the body

Question 20

Give a substance plants absorb by active transport

Answer 20

Mineral ions

Question 21

What word is used to describe plant cells surrounded by a hypotonic solution?

Answer 21

Turgid

Question 22

What word is used to describe plant cells placed in a hypertonic solution?

Answer 22

Plasmolysed

Question 23

What type of solutions are High energy drinks used in sports?

Answer 23

Isotonic

Question 24

How are fish gills adapted for exchanging materials?

Answer 24

• water enters the mouth, oxygen diffuses from the water into the blood in the gills & CO2 diffuses from the blood into the water
• the gills have gill filaments, which have tiny lamellae which increase the surface area for the exchange of gases
• lamellae have lots of blood capillaries (speed up diffusion) & have a thin layer of cells to minimise the distance gases have to diffuse
• blood and water flow in opposite directions in the lamellae which keeps a large concentration gradient between water and blood
• the concentration of oxygen in the water is always higher then that in the blood so as much oxygen as possible diffuses from the water into the blood

Question 25

Give 2 examples if substances transported in and out of cells by diffusion?

Answer 25

• oxygen and carbon dioxide (gas exchange)

- waste product urea from cells into the blood plasma for excretion in the kidney

Question 26

What’s the advantage if single-celled organism having a large surface area to volume ratio?

Answer 26

It allows sufficient transport of molecules into and out of the cell to meet the demands of the organism

Question 27

Explain how exchange surfaces are adapted to maximise effectiveness?

Answer 27

• they have a thin membrane, so substances only have a short distance to diffuse
• a large surface area so lots of substances can diffuse at once
• exchange surfaces in animals have lots of blood vessels, so it gets stuff in and out of the blood efficiently and quickly
• gas exchange surfaces in animals (alveoli) are ventilated