Topic 4 - Bioenergetics Flashcards
What is the word equation for photosynthesis?
carbon dioxide + water –> glucose + oxygen
What is the balanced symbol equation for photosynthesis?
6CO₂ + 6H₂O –> C₆H₁₂O₆ + 6O₂
Briefly describe the 5 ways plants use glucose
- cellulose - for making strong plant cell walls
- respiration - transfers energy from glucose to use in other parts of the plant
- oils and fats - turned into lipids for storing in seeds
- proteins - combined with nitrate ions to make amino acids which are then made into proteins
- starch - turned into starch and stored in roots, stems and leaves for when photosynthesis isn’t happening
Why is starch a good way to store glucose?
Starch is insoluble so it doesn’t draw up water and swell up like glucose would (due to osmosis)
What are the 4 limiting factors of the rate of photosynthesis?
- temperature, CO₂ concentration, light intensity, amount of chlorophyll
Describe the graph for light intensity
- rate of photosynthesis increases steadily with light intensity until a certain point
- beyond that, the light won’t make any difference and the rate won’t increase anymore (won’t decrease either) - CO₂ or temp needs to increase
Describe the graph for CO₂ concentration
- rate of photosynthesis increases steadily with CO₂ until a certain point
- beyond that, the light won’t make any difference and the rate won’t increase anymore (won’t decrease either) - light or temp needs to increase until a certain point
Describe the graph for temperature
- rate of photosynthesis increases steadily with temperature until about 40 degrees
- if the plant gets too hot (45 degrees ish), the enzymes denature so photosynthesis won’t happen
How is a leaf adapted for photosynthesis?
- chlorophyll captures sunlight
- thin so only a short distance for diffusion
- waxy layer stops water loss
- big surface area to absorb light
- air spaces so gases can diffuse
What are some features to speed up growth in greenhouses?
- more CO₂
- more bees (to pollenate)
- more light
- biological pest control
- higher temp
Define a limiting factor
A limiting factor is one which increases the rate of photosynthesis when its value is increased
What does the inverse square law mean?
light intensity = 1/d²
if you half distance, light increases by 4
Describe the pondweed experiment, investigating the effect of light intensity on the rate of photosynthesis
- fill a beaker with water and pondweed and place lamp 10cm away from beaker
- count bubbles for 1 min, move 10 cm further and repeat until 70cm away
- repeat the experiment and discard anomalies
- temperature, background light and time should be the same always
Define anomalous results
results that do not fit in the pattern shown by the rest of the data - don’t include these in averages
Define osmosis
Osmosis is the movement of water from an area of high water concentration to an area of low water concentration through a partially permeable membrane
