B8 - Photosynthesis

Question 1

how do plants make their food

Answer 1

by photosynthesis

Question 2

how do plants absorb light energy

Answer 2

through chlorophyll in chloroplasts

Question 3

What type of reaction is photosynthesis

Answer 3

endothermic

Question 4

What is the word equation for photosynthesis

Answer 4

water + carbon dioxide (+ light) -> glucose + oxygen

Question 5

What is the symbol equation for photosynthesis

Answer 5

6H2O + 6CO2 (+ light) -> 6O2 + C6 H12 O6

Question 6

How is the glucose produced in photosynthesis used

Answer 6

some is used by plants for respiration, some is converted into insoluble starch and stored, some is converted to cellulose for strength

Question 7

how can you show that a plant is photosynthesising

Answer 7

by seeing the oxygen gas given off, which relights a glowing splint

Question 8

how are leaves adapted for photosynthesis (6)

Answer 8

• broad, giving a large surface area
• thin so short diffusion distances
• contain chlorophyll that absorbs light
• veins bring plenty of water through the xylem
• air spaces allow carbon dioxide and oxygen to diffuse
• guard cells open and close stomata to regulate gas exchange

Question 9

how do algae get resources to photosynthsise

Answer 9

absorb carbon dioxide dissolved in the water, and produce oxygen that gets dissolved in the water

Question 10

What are 4 factors that limit the amount of photosynthesis a plant can do

Answer 10

• light
• temperature
• carbon dioxide concentration
• chlorophyll levels

Question 11

how does light intensity affect photosynthesis

Answer 11

the more light received, the more photosynthesis

Question 12

how does temperature affect photosynthesis

Answer 12

the higher the temperature, the faster the rate of photosynthesis, until the enzymes denature

Question 13

how does carbon dioxide concentration affect photosynthesis
- how does this fluctuate throughout the day

Answer 13

the higher the concentration of CO2, the higher the rate of photosynthesis

• tends to be more in the night / early day when it is released by respiration, and before it is taken in for photosynthesis

Question 14

Why are greenhouses good for photosynthesis

Answer 14

increase light intensity, CO2 concentration and temperature which allows for more photosynthesis

Question 15

why are some plants not able to produce enough chloroplasts

Answer 15

not enough mineral ions

Question 16

what is the inverse square law for light intensity

Answer 16

light intensity = 1 / distance^2

Question 17

why is glucose stored as starch in plant cells

Answer 17

it is insoluble in water so it does not affect the balance of water inside and outside the cell

Question 18

where is starch stored in plants

Answer 18

• in the cells of leaves as an energy store
• in special storage areas for winter

Question 19

how can starch be tested for in leaves

Answer 19

boil leaf in ethanol to remove waxy cuticles and colour
- rinse in hot water to soften
- add iodine solution to test for starch (blue-black)

Question 20

how do plants make amino acids using photosynthesis

Answer 20

combining glucose with nitrate ions

Question 21

why are bogs hard places for plants to live

Answer 21

few mineral ions

Question 22

why are carnivorous plants adapted to live in mineral poor soil

Answer 22

they digest insects that contain most of the nutrients they need

Question 23

Why are lipids produced by plants
- how

Answer 23

used as energy or to strengthen cell walls
- combining glucose from photosynthesis and energy from respiration

Question 24

why are greenhouses used

Answer 24

can control and increase the temperature, CO2 concentration and light intensity allowing crops to be grown quicker

Question 25

what is hydroponics

Answer 25

not using soil for plants, but instead giving water with a perfect balance of nutrients

Question 26

what are the benefits of growing crops in labs (4)

Answer 26

• complete control of external factors
• completely done by computer systems
• fast turnover so high profits
  -no need to plough or prepare land

Question 27

what are the drawbacks of growing crops in labs (2)

Answer 27

• very expensive
• must be carefully monitored