B4 Bioenergetics Flashcards
what does chlorophyll do?
absorb light
is photosynthesis exothermic or endothermic?
endothermic
what is the word equation for photosynthesis?
carbon dioxide + water -> glucose + oxygen
what is the balanced symbol equation for photosynthesis?
6CO2 + 6H20 -> C6H12O6 + 6O2
do plants carry out respiration?
yes
what is cellulose used for?
making strong plant cell walls
how is glucose used to make amino acids?
glucose is combined with nitrate ions (absorbed from the soil) to make amino acids, which are then made into proteins
where is starch stored in plants?
roots, stems and leaves
what is the rate of photosynthesis affected by?
intensity of light, concentration of CO2, temperature and amount of chlorophyll
what can the amount of chlorophyll in a plant be affected by?
disease (e.g. TMV) or environmental stress (e.g. lack of nutrients)
what does a plateau on a graph measuring the rate of photosynthesis against a limiting factor mean?
something else has become the limiting factor
why does a graph measuring the rate of photosynthesis against temperature drop off after a certain point?
the enzymes are damaged (denatured)
what is the inverse square law?
the light intensity is inversely proportional to the square of the distance
light intensity is proportional to 1/distance squared
if you halve the distance of a light source away from a sample, how much will the light intensity increase by?
4 times
if you third the distance of a light source away from a sample, how much will the light intensity increase by?
9 times
what does a.u. stand for?
arbitrary units
what is respiration?
the process of transferring energy from glucose, which goes on in every cell
is respiration an exothermic or endothermic reaction?
exothermic
what are three examples of how organisms use the energy transferred by respiration?
- to build up larger molecules from smaller ones
- in animals it’s used to allow muscles to contract
- in mammals and birds the energy is used to keep their body temperature steady in colder surroundings
what is metabolism
all the chemical reactions in an organism
what are the two types of respiration?
aerobic and anaerobic
which type of respiration is the more efficient way to transfer energy from glucose?
aerobic respiration
what are the word and balanced symbol equations for aerobic respiration?
glucose + oxygen -> carbon dioxide + water
C6H12O6 + 6O2 -> 6CO2 + 6H20
what is the symbol for glucose?
C6H12O6
what is the word equation for anaerobic respiration in muscle cells?
glucose -> lactic acid
which transfers more energy, aerobic or anaerobic respiration?
aerobic
what is the word equation for anaerobic respiration in plant and yeast cells?
glucose -> ethanol + carbon dioxide
what is anaerobic respiration in yeast cells called?
fermentation
what does oxygen react with lactic acid to form?
CO2 and water
which plant can be used to measure the effect of light intensity on the rate of photosynthesis?
Canadian pondweed
describe the way the equipment is set up for a practical to investigate the effect of light intensity on the rate of photosynthesis
cut a piece of Canadian pondweed and place it in a test-tube filled with water. Place a bung connected to a capillary tube filled with water on the test tube, and attach the end of the capillary tube to a syringe. Then set up a light source a set distance away from the test tube, placing a ruler next to it so you are able to vary the distance from the plant.
describe an experiment to measure the effect of light intensity on the rate of photosynthesis.
- an LED light (so that the pondweed isnt affected by the heat from the lamp) is placed at a specific distance from the pondweed. You then leave the pondweed to sit for a minute to acclimatise to the new environment.
- the pondweed is left to photosynthesise for a set amount of time. As it photosynthesises, the oxygen released will collect in the capillary tube
- at the end of the experiment, the syringe is used to draw the gas bubble in the tube up alongside a ruler and the length of the gas bubble is measured. This is proportional to the volume of O2 produced
- for this experiment, any variables that could effect the results should be controlled, e.g. the temperature and time the pondweed is left to photosynthesise
- the experiment is repeated twice with the light source at the same distance and the mean volume of O2 produced is calculate
- then the whole experiment is repeated with the light source at different distances from the pondweed
describe how the experiment to investigate how light intensity affects the rate of photosynthesis (the pondweed experiment) could be modified to measure the effect of temperature or CO2 on photosynthesis.
the test tube of pondweed could be put into a water bath at a set temperature, or a measured amount of sodium hydrogencarbonate could be dissolved in the water (which gives off CO2). The experiment can then be repeated with different temperatures of water / concentrations of sodium hydrogen carbonate
