Biology bioenergetics

why is photosynthesis an endothermic reaction?

energy is transferred from the environment to the chloroplasts by light

how does light intensity, carbon dioxide levels and the amount of chlorophyll affect photosynthesis?

increase the rate of photosynthesis

how does temperature affect the rate of photosynthesis?

at low temperatures, the rate of photosynthesis will be low because the enzymes aren’t colliding with the substrates. at high temperatures, the enzymes will become denatured meaning they lose their shape and the substrate cannot bind to the enzyme’s active site

pondweed required practical

1. place a test tube rack with a boiling tube 10cm away from the light source using a ruler

2. fill the boiling tube with 100ml of sodium hydrogen carbonate solution

3. place the cut pondweed into the boiling tube and push pondweed down with glass rod

4. leave boiling tube to rest for 5 minutes

5. start stopwatch and count bubbles produced in a minute

6. repeat the count twice more and take a mean

7. repeat steps 1-6, moving the boiling tube 20,30 and 40cm away from the light source

8. plot a graph of rate of photosynthesis against light intensity

uses of glucose

• respiration

• converted to insoluble starch for storage

• used to produce fat for storage

• used to produce cellulose to strengthen cell wall

• used to produce amino acids for protein synthesis

differences between aerobic and anaerobic respiration

• aerobic has a lot of oxygen but anaerobic has none or little

• aerobic produces carbon dioxide and water but anaerobic produces lactic acid or ethanol and carbon dioxide

• aerobic releases more energy

why do organisms need energy

• chemical reactions to build larger molecules

• movement

• keeping warm

equation for anaerobic respiration in muscles

glucose → lactic acid

equation for anaerobic respiration in plant and yeast cells

glucose → ethanol + carbon dioxide

what is anaerobic respiration in yeast cells called?

fermentation

why is anaerobic respiration in yeast cells important to the economy?

makes bread and alcoholic drinks

why does breath volume, heart rate and breathing rate increase during exercise?

to supply the muscles with more oxygenated blood

what is oxygen debt?

the amount of extra oxygen the body needs after exercise to react with lactic acid and remove it from cells

what is metabolism?

sum of all the reactions in a cell or the body