B8 - Photosynthesis Flashcards
how do plants make their food
by photosynthesis
how do plants absorb light energy
through chlorophyll in chloroplasts
What type of reaction is photosynthesis
endothermic
What is the word equation for photosynthesis
water + carbon dioxide (+ light) -> glucose + oxygen
What is the symbol equation for photosynthesis
6H2O + 6CO2 (+ light) -> 6O2 + C6 H12 O6
How is the glucose produced in photosynthesis used
some is used by plants for respiration, some is converted into insoluble starch and stored, some is converted to cellulose for strength
how can you show that a plant is photosynthesising
by seeing the oxygen gas given off, which relights a glowing splint
how are leaves adapted for photosynthesis (6)
- 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
how do algae get resources to photosynthsise
absorb carbon dioxide dissolved in the water, and produce oxygen that gets dissolved in the water
What are 4 factors that limit the amount of photosynthesis a plant can do
- light
- temperature
- carbon dioxide concentration
- chlorophyll levels
how does light intensity affect photosynthesis
the more light received, the more photosynthesis
how does temperature affect photosynthesis
the higher the temperature, the faster the rate of photosynthesis, until the enzymes denature
how does carbon dioxide concentration affect photosynthesis
- how does this fluctuate throughout the day
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
Why are greenhouses good for photosynthesis
increase light intensity, CO2 concentration and temperature which allows for more photosynthesis
why are some plants not able to produce enough chloroplasts
not enough mineral ions
what is the inverse square law for light intensity
light intensity = 1 / distance^2
why is glucose stored as starch in plant cells
it is insoluble in water so it does not affect the balance of water inside and outside the cell
where is starch stored in plants
- in the cells of leaves as an energy store
- in special storage areas for winter
how can starch be tested for in leaves
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)
how do plants make amino acids using photosynthesis
combining glucose with nitrate ions
why are bogs hard places for plants to live
few mineral ions
why are carnivorous plants adapted to live in mineral poor soil
they digest insects that contain most of the nutrients they need
Why are lipids produced by plants
- how
used as energy or to strengthen cell walls
- combining glucose from photosynthesis and energy from respiration
why are greenhouses used
can control and increase the temperature, CO2 concentration and light intensity allowing crops to be grown quicker
what is hydroponics
not using soil for plants, but instead giving water with a perfect balance of nutrients
what are the benefits of growing crops in labs (4)
- complete control of external factors
- completely done by computer systems
- fast turnover so high profits
-no need to plough or prepare land
what are the drawbacks of growing crops in labs (2)
- very expensive
- must be carefully monitored
