Bioenergetics Flashcards
Paper 1 - B4
What is the word equation for photosynthesis?
carbon dioxide + water –light–> glucose + oxygen
What is the symbol equation for photosynthesis?
6CO2 + 6H2O –> C6H12O6 + 6O2
What type of reaction is photosynthesis and why?
Endothermic because energy is transferred from the environment to the chloroplasts by light
State the four factors that affect the rate of photosynthesis
Temperature, light intensity, carbon dioxide concentration and amount of chlorophyll
Why does a change in temperature affect the rate of photosynthesis?
Because photosynthesis involves enzymes which work better at higher temperatures but denature at extremes of temperature
Why would the line on a graph of rate of photosynthesis against light intensity level off?
Because at high light intensities, something else is limiting the rate, such as carbon dioxide concentration
How could we use the inverse square law to work out the light intensity in the pondweed investigation?
Calculate 1/distance^2 so when the distance doubles, the light intensity is divided by 4.
Why do plant growers need to consider limiting factors when deciding how much to spend on enhancing conditions in a greenhouse?
Increasing a limiting factor (e.g. light intensity) can increase the rate of photosynthesis, but only up to a point. Increasing it further wouldn’t make a difference and can also be expensive.
What are the ways in which the plants use the glucose produced in photosynthesis?
Respiration; converted to starch; fats and oils; cellulose to strengthen cell wall; amino acids for protein synthesis
Why is glucose converted to starch for storage by plants and not just left as glucose?
Starch is insoluble. This means it will not move out of the cell and will not affect osmosis
Plants can convert glucose from photosynthesis into amino acids for protein synthesis. What ions are added from the soil to do this?
Nitrate ions
What type of reaction is cellular respiration and why?
Exothermic because energy is released
What is the purpose of respiration?
To transfer energy for living processes
Which type of respiration requires oxygen?
Aerobic respiration
Which type of respiration does not require oxygen?
Anaerobic respiration
Which type of respiration releases less energy per molecule of glucose?
Anaerobic respiration
What is produced in anaerobic respiration but not in aerobic respiration?
Lactic acid
Give 3 reasons why energy from respiration is needed in the body
For chemical reactions to build larger molecules; for movement; for keeping warm
Write the word equation for aerobic respiration
glucose + oxygen –> carbon dioxide + water
What is the symbol equation for respiration?
C6H12O6 + 6O2 –> 6CO2 + 6H2O
Write the word equation for anaerobic respiration in muscles
glucose –> lactic acid
Write the word equation for anaerobic respiration in plant and yeast cells
glucose –> ethanol + carbon dioxide
Why is less energy transferred in anaerobic respiration than in aerobic respiration
Oxidation (breakdown) of glucose is incomplete, so not all the energy is released
What is the name of anaerobic respiration in yeast cells?
Fermentation