B4 - Bioenergetics34 Flashcards
What is the symbol equation for photosynthesis
6CO2 + 6H20 – C6H12O6 + 6O2
What is symbol equation for glucose
C6H12O6
Name the different ways plants use glucose
( 6 marks)
CRIPS
[C] Cell walls made of cellulose - glucose converted into cellulose for making strong plant cell walls
[R] Respiration - transfers energy from glucose which enables the plants to convert the rest of the glucose into various other useful substances
[I] In seeds - Glucose is turned into lipids for storing in seeds
[P] Proteins - Glucose combined with nitrate ions - amino acids, then turned into protein
[S] Starch - glucose is turned into starch and stored in roots, stem and leaves
Why is glucose stored as starch rather than glucose itself
Starch is insoluble - makes it better for storing than glucose
Name the limiting factors of photosynthesis
Light
CO2 concentration
Light intensity
Amount of chlorophyll
Name the environmental conditions that is linked with the limiting factors
Light - when it is night
Winter - temperature
Warm and bright enough - CO2 usually limiting
How can the amount of chlorophyll be affected ( 2 marks)
By a disease i.e. TMV or environmental stress such as lack of nutrients causes chloroplasts to become damaged or not make enough chlorophyll
Rate of photosynthesis reduced because they cannot absorb as much light
Describe how light intensity affects rate of photosynthesis ( 3 marks)
As light intensity increases, rate of photosynthesis increased up until a point
After this point, light intensity is no longer the limiting factor because CO2 concentration or temperature will be the limiting factor
In a lab how do you change the light intensity
moving a lamp closer to or further away from your plant
Describe how CO2 concentration affects rate of photosynthesis ( 3 marks)
Amount of CO2 will only increase the rate of photosynthesis up to a point
Beyond this point, as CO2 increases - rate of photosynthesis will not increase - CO2 no longer the limiting factor
Describe how temperature affects rate of photosynthesis (4 marks)
If temperature is the limiting factor, it’s because it is too low - enzymes needed for photosynthesis work more slowly at low temperatures
When plant gets too hot - the enzymes it needs for photosynthesis and its other reaction will be damaged
This is around 45 degrees
Describe how a student can investigate oxygen production to show the rate of photosynthesis
( 6 marks)
Place source of white light 30 cm away from the pondweed
Leave pondweed to photosynthesise for 30 seconds
As it photosynthesizes, the oxygen released will collect in a capillary tube
At the end of the experiment, use a syringe to draw the gas bubble in the tube up alongside a ruler and measure the length of the gas bubble this is proportional to the volume of O2 produced
Control the temperature and the time the pondweed is left to photosynthesise for it to be a fair experiment
Repeat experiment twice with light source at the same distance and calculate the mean volume of O2 produced
Whole experiment is repeated with the light source at different distances from the pondweed
Equation for the rate of photosynthesis
1/distance squared
How can a farmer artificially create the ideal conditions for farming ( 6 marks)
Grow in a greenhouse - greenhouses help to trap the Sun’s heat, temperature is not limiting
In winter, use a heater to keep the temperature at the ideal level
In summer, use shades and ventilation to cool temperature
Supply plants with artificial light after the Sun goes down
Increase levels of carbon dioxide in the greenhouse - by using a paraffin heater to heat the greenhouse - as paraffin burns, it makes carbon dioxide
What is metabolism
Sum of all chemical reactions in an organism
