B2a

Question 1

What is the purpose of the cell membrane?

Answer 1

Control cell entry and exit

Question 2

What do ribosomes produce?

Answer 2

Proteins

Question 3

What does a cell wall do?

Answer 3

Made from cellulose,gives cell strength in organisms with no bones

Question 4

What does an animal cell contain? (5)

Answer 4

Nucleus, cytoplasm, mitochondria, ribosomes, cell membrane

Question 5

What does a plant cell contain? (8)

Answer 5

Cell wall, cell membrane, cytoplasm, nucleus, vacuole, chloroplasts, mitochondria, ribosomes

Question 6

What does a yeast cell contain? (7)

Answer 6

Cell wall, cell membrane, nucleus, cytoplasm, mitochondria, ribosomes, vacuole

Question 7

What does a bacteria cell contain? (5)

Answer 7

Cell wall, cell membrane, cytoplasm, ribosomes, plasmids (short section of DNA)

Question 8

What are specialised cells?

Answer 8

Cells with a particular function that are adapted to that function

Question 9

How are palisade cells adapted for photosynthesis?

Answer 9

Many chloroplasts - top of cell for light, tall - SA for CO2 absorption, thin - many packed in leaf

Question 10

How are guard cells adapted for photosynthesis?

Answer 10

Fill with water (turgid) - open stomata, empty (flaccid) - close stomata so no evaporation, close at night

Question 11

How are cells organised?

Answer 11

Similar cells, tissues. Tissues work together to make an organ. Organs group in organ systems

Question 12

What do organ systems do?

Answer 12

Exchange and transport materials

Question 13

What is diffusion?

Answer 13

The net movement of particles from an area of high concentration to an area of low concentration until an equilibrium is reached

Question 14

Why do cell membranes use diffusion?

Answer 14

To only allow small molecules into the cell that are needed for respiration

Question 15

What is the rate of diffusion affected by?

Answer 15

Temperature and concentration gradient

Question 16

What does the upper epidermal layer in a leaf do?

Answer 16

Allows light in for photosynthesis

Question 17

Why do leaves need air spaces?

Answer 17

To allow diffusion to occur

Question 18

What is the vascular bundle?

Answer 18

Xylem and phloem cells - xylem carries water, phloem carries nutrients

Question 19

Why are the stomata located on the bottom of a leaf?

Answer 19

To avoid water loss by evaporation

Question 20

What is the equation for photosynthesis?

Answer 20

Carbon dioxide + water

Glucose + oxygen

Question 21

Where does photosynthesis take place?

Answer 21

Chloroplasts

Question 22

What is glucose used for in plants?

Answer 22

Respiration, cellulose for cell walls, making proteins, lipids in seeds, starch

Question 23

What is starch?

Answer 23

A store of glucose used by plants when photosynthesis is not occuring

Question 24

What is the test for starch?

Answer 24

1) Hot water breaks down waxy layer
2) Ethanol extracts chlorophyll
3) Iodine turns blue if starch present (so photosynthesis is occurring)

Question 25

What are the three limiting factors of photosynthesis?

Answer 25

Light, CO2, temperature

Question 26

Describe the graph of rate of photosynthesis due to light and CO2

Answer 26

Steadily increases up to a certain point, when something else becomes the limiting factor

Question 27

Describe the effect of temperature on photosynthesis

Answer 27

Steadily increases but then starts to decrease at about 45 because enzymes are denatured

Question 28

How can farmers create an ideal plant growing environment?

Answer 28

``` Greenhouse - trap heat Artificial light Shades + ventilation Paraffin heaters - heat + CO2 Fertilisers ```

Question 29

Why do conditions need to just right for farmers?

Answer 29

To get a high yield without wasting money

Question 30

What can affect the distribution of organisms?

Answer 30

Temp, light, water, gases, nutrients

Question 31

What are nitrogen and magnesium used for in plants?

Answer 31

N - make proteins | Mg - make chlorophyll green, absorb light

Question 32

What are quadrats and how are they used?

Answer 32

1m^2 Placed at random point e.g. coordinate Count organisms Repeat, mean

Question 33

How can transects measure the distribution of organisms?

Answer 33

Mark out line | Count organisms touching line or place quadrat at regular interval

Question 34

How can results be reliable?

Answer 34

Reproducible - large sample size

Question 35

How can results be valid?

Answer 35

By controlling variables and using random samples