B4

Question 0

What is the role of the palisade layer

Answer 0

Photosynthesis is carried out here. They are near the top of the leaf so that they can absorb the most sunlight. They are chloroplast abundant.

Question 1

What pigments are available for photosynthesis and why is there more than one pigment involved?

Answer 1

Pigments available :
Chlorophyll a
Chlorophyll b
Carotene
Xanthophyll 
Different pigments absorb different wavelengths of light, having different pigments means you can get the most of the suns energy absorbing as much as possible.

Question 2

What is the role of the guard cells

Answer 2

Leaves have guard cells surrounding the stoma. They control when they open and closes. Allows guard cells to control gas exchange. Photosynthesis and produces glucose.

Question 3

What is the balanced symbol equation

Answer 3

6co2+6H2O - 6O2+C6H12O6

Question 4

What would happen to an animal cell if it were placed in a hypertonic solution

Answer 4

It would cause the cell to shrivel because it will be loosing water this cause crenation. Animals need to keep the amount of water in each cell constant.

Question 5

What would happen to a plant cell if it were placed into a hypertonic solution.

Answer 5

It can wilt (droop) this is because everything from the cell wall has shrunk and pulled away from it. They are said to be called plasmolysed.

Question 6

What does hypertonic mean

Answer 6

It means lots of glucose (sugar) in a solution

Question 7

What are the key differences between diffusion and osmosis

Answer 7

Osmosis happens across a permeable wall, diffusion doesn’t

Osmosis takes place only in water
Diffusion takes place in water and gas.

Question 8

What is a selective permeable membrane

Answer 8

It is a wall in osmosis which has wholes only small enough for water to pass through

Question 9

How does transpiration keep a plant turgid

Answer 9

Because there’s more water inside the plant than outside it, water escapes through stomata. So if there’s lots of water available the stoma will remain open.

Question 10

How does transpiration cool a plant down

Answer 10

The constant stream of water from the ground to keep the plant cool.

Question 11

What factors affect the rate of transpiration

Answer 11

An increase in light intensity
An increase in temperature
An increase in air movement
A decrease in air humidity

Question 12

Name three devices used to collect small animals

Answer 12

Pooter = small insects 
Pitfall = animals 
Net = air/water

Question 13

What method and calculation would you use to determine the abundance of animals in an area

Answer 13

Capture-recapture
Population size = 
no.in first sample X no.in 2 sample
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
No. In second sample previously marked

Question 14

Describe in detail the process of photosynthesis

Answer 14

Photosynthesis uses energy from the sun to change CO2 and H2O into glucose and O2. It takes place in chloroplasts in plant cells - they contain pigments like chlorophyll which absorb light energy.

Question 15

What are the products of photosynthesis used for

Answer 15

Glucose: respiration 
Lipids - storing in seeds 
Making proteins 
Making cell walls 
Stored as starch

Question 16

How does temperature affect the rate of photosynthesis

Answer 16

Photosynthesis works best warm but not hot. As temp rises so does rate of photosynthesis. But if too high the enzymes become denatured making the rate decrease (45 degrees).

Question 17

What is the job of the xylem

Answer 17

They carry water and minerals from the roots up to the shoot to the leaves in the transpiration stream.

Question 18

What is the job of the phloem.

Answer 18

They transport food substances (mainly sugar) both up and down the stem to growing and storage tissues.

Question 19

What is the movement of food substances in phloem tubes called.

Answer 19

Translocation

Question 20

How are cacti adapted for surviving in arid (dry) conditions.

Answer 20

Stems that can store water.
Widespread root systems that can collect water from a large spines instead of leaves, minimise the surface area so reduce water loss by transpiration.

Question 21

Why do plants need nitrates and magnesium

Answer 21

Nitrates - for making amino acids and proteins needed for cell growth.

Magnesium - in small amounts, required for making chlorophyll which is needed for photosynthesis

Question 22

What happens if plants don’t get the nitrate or magnesium.

Answer 22

Plants without either will have yellow leaves and if nitrate isn’t available growth will be poor

Question 23

What is active transport

Answer 23

Uses energy from respiration to help plant pull minerals into the root hair against the concentration gradient (from low to high)

Question 24

Why is active transport unique compared to osmosis or diffusion.

Answer 24

It goes against the concentration gradient, low to high

Question 25

What is a detritivore and give an example

Answer 25

They feed on dead and decaying material | An example would be earthworms, maggots and woodlice

Question 26

How do saprotrophic bacteria (saprophytes) feed

Answer 26

By extracellular digestion Feed by secreting digestive enzymes onto material outside of cells, enzymes break down material which are then absorbed by them.

Question 27

Name two decomposes

Answer 27

Fungi and bacteria

Question 28

Describe 3 ways of preserving food

Answer 28

Canning - food in airtight can, keeps decomposers out Cooling - food in fridge, slows down decomposers reproduction rate Freezing - food in freezer, decomposers can't reproduce at all at such low temps

Question 29

Name 2 advantages of organic and non organic farming

Answer 29

Organic - fewer chemicals used Better for the environment, less chance of polluting rivers Non organic - producing as much food as possible Reduces energy loss in food chains

Question 30

2 disadvantages for organic and non organic farming

Answer 30

Organic - takes up more space You can't grow as much food Non organic - pesticides disturb food chains Careless use of fertilisers can pollute rivers

Question 31

What are the conditions needed for bacteria to carry out decay process effectively

Answer 31

Temperature- a hot temp=decay faster, it speeds up respiration in microorganisms Amount of water makes things decay faster - when they're moist because microorganisms need water Amount of O2 - decay=faster with O2 available

Question 32

What would happen if bacteria were deprived O2 during the decay process

Answer 32

The rate of decay would decrease | Microorganisms reproduce slower

Question 33

What is osmosis

Answer 33

The net movement of water molecules across a partially permeable membrane from a higher water concentration to a lower (dilute to concentrated)

Question 34

If there is more water on side b than a why do the water molecules go to side a - osmosis

Answer 34

Because they are trying to create a water equilibrium.

Question 35

What is diffusion

Answer 35

Net movement of particles from a high to low concentration