Topic 4 - Bioenergetics Flashcards
(41 cards)
What is the word equation for Photosynthesis?
carbon dioxide + water —–light——> glucose + oxygen
What is the balanced symbol equation for Photosynthesis?
6Co(2) + 6H(2)O —> C(6)H(12)O(6) + 6O(2)
What kind of reaction is photosynthesis?
An endothermic reaction in which energy is transferred from the environment to the chloroplasts by light.
In what 7 ways are leaves adapted to carry out Photosynthesis?
- The Palisade layer is packed with chloroplasts for photosynthesis.
- The leaf has a transparent upper epidermis to let light through to the palisade layer.
- The leaf has a broad shape to increase Surface area to catch more light.
- The leaf is thin to allow rapid diffusion for gaseous exchange.
- The leaf has air spaces in the spongy layer to allow for gaseous exchange.
- The leaf has lots of stomata to allow for gaseous exchange.
- The leaf has guard cells to control if the Stomata are open or closed.
What factors affect the rate of photosynthesis? (4)
- temperature
- light intensity
- carbon dioxide concentration
- amount of chlorophyll/ chloroplasts
What affect does higher light intensity have on photosynthesis?
The higher the light intensity, the faster the rate of photosynthesis - provided that there is lots of carbon dioxide and the temperature is warm enough.
What affect does higher carbon dioxide concentration have on photosynthesis?
The higher the carbon dioxide level, the faster the rate of photosynthesis - provided there is plenty of light + a suitable temperature.
What affect does higher temperature have on photosynthesis to a certain point? What happens after this certain point?
As temperature rises, the rate of photosynthesis increases - provided there is plenty of carbon dioxide and light.
However, at a certain point the higher temperature causes the enzymes to denature and photosynthesis slows down, before eventually stopping.
What affect does more chloroplasts have on photosynthesis?
The more chloroplasts a plant has, the faster the rate of photosynthesis.
What can the amount of chlorophyll be affected by? (3)
- diseases - e.g. tobacco mosaic virus
- lack of nutrients - magnesium etc.
- loss of leaves - fewer leaves = fewer chloroplasts
Why is water usually not considered a limiting factor of photosynthesis?
If water availability is low, plants close their stomata to stop transpiration, meaning that photosynthesis is limited by carbon dioxide.
Do the limiting factors of photosynthesis interact?
These factors interact and any one of them may be the factor that limits photosynthesis.
What does it mean for a factor to be limiting?
If a factor is limiting, it stops the reaction, in this case photosynthesis, from happening any faster.
As distance increases, light intensity increases. How are these related?
Inversely proportional.
What is the equation for light intensity, and what is it measured in?
light intensity = 1/distance²
- measured in arbitrary units (au)
How have greenhouse economics developed to enhance conditions to gain the maximum rate of photosynthesis while still maintaining profit? (7)
- Shades removed from ceiling to allow maximum light
- Artificial light for winter/darker hours
- Ventilation helps prevent plants getting too hot
- Heater burns paraffin, produces heat and C0(2) as a by product
- Watering system to make sure plants stay well watered
- Keeping plants in greenhouses makes it easier to remove pests and diseases, and add fertilisers
- Greenhouse traps the suns heat so temperature doesn’t limit photosynthesis
How does a farmer gain profit from greenhouse economics?
If conditions are kept just right for photosynthesis (too much = a waste of money, and too little won’t work), the plants will grow much faster and a decent crop can be harvested much more often - can then be sold.
What is the purpose of Required Practical 6?
To investigate the effect of light intensity on the rate of photosynthesis using an aquatic organism such as pondweed.
What will you do required practical 6?
Measure the volume of oxygen produced by the pondweed as the light intensity changes as the light source is moved.
What is the 9 step method for the practical? - with pondweed
- Put your 10 cm piece of pond weed (cut edge at top) into a beaker of water.
- Cover the pondweed with an inverted filter funnel - raised off the bottom of the beaker with plasticine.
- Fill the measuring cylinder with water and gently position over the funnel in the beaker.
- Use the ruler to position the beaker of pondweed 1 metre away from the light source.
- Start the stop watch and:
a) count and record the number of bubbles released in three minutes
b) record the volume of gas produced and collected in the measuring cylinder in the same three minutes. - Record your results in a table.
- Move the light source so that the pondweed beaker is 80 cm away.
- Refill the measuring cylinder with water and gently position as before.
Then repeat steps 5 and 6. - Repeat for distances of 60, 40 and 20 cm.
What conclusions can be made from the pondweed practical?
The further away the light source, the less oxygen produced, meaning the rate of photosynthesis is slower.
What can the glucose produced in photosynthesis be used for in a plant? (7)
- used for respiration to release energy for cells
- converted into insoluble starch for storage as it won’t affect osmosis in cells
- used to produce fats or oils for energy storage in seeds
- used to produce cellulose, which strengthens the cell wall
- used to produce amino acids for protein synthesis
- used to produce protein by combining with nitrate ions that have been absorbed from the soil
- converted into sucrose for transport around the plant
What tests can you do to prove the uses of glucose are true?
- test for starch
- test for glucose
- test for protein
What kind of reaction is cellular respiration?
An exothermic reaction which is continuously occurring in living cells - releases energy.
The energy transferred supplies all the energy needed for living processes.
