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
Define respiration
Respiration is the process of transferring energy from glucose, which occurs in every cell
What is the equation for aerobic respiration?
oxygen + glucose –> carbon dioxide and water
6O₂ + C₆H₁₂O₆ –> 6CO₂ + 6H₂O
What is the equation for anaerobic respiration (animals)?
glucose –> lactic acid
Define anaerobic
without oxygen
Which transfers the most energy- aerobic or anaerobic respiration?
Aerobic
What is the equation for anaerobic respiration (plants + yeast)?
glucose –> ethanol + carbon dioxide
What is another name for anaerobic respiration in plant and yeast cells?
Fermentation
What are some changes in the body when you exercise?
- breathe faster and deeper
- get hotter
- sweat
- heart rate increases
Why does breathing rate increase when we exercise?
to supply muscle cells with oxygen for aerobic respiration and to remove CO₂ (from lactic acid)
Define oxygen debt
An oxygen debt is the amount of extra oxygen your body needs to react with the build up of lactic acid to remove it from the cells - oxygen reacts to lactic acid to form CO₂ and water
What do you use for “describe how your …. changes during exercise”
OGRE
- more oxygen
- more glucose
- more respiration
- more energy
Define metabloism
the sum of all the reactions in the cell/body - it depends in age, gender, genes, muscle etc.
How is cramp caused?
it is caused by a build up of lactic acid from anaerobic respiration
How does the body get rid of lactic acid?
Lactic acid can be converted back into glucose or mixed with oxygen to make carbon dioxide and water which is breathed out
