the rate of photosynthesis Flashcards
name 4 factors that affect photosynthesis
light intensity
carbon dioxide concentration
temperature
amount of chlorophyll
define limiting factor
-when a process depends on two or more factors, the rate of that process is limited by the factor which is shortest in supply
-an environmental factor which can restrict rate of photosynthesis
draw the graphs for light intensity, co2 and temperature, when they each are the limiting factor
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what does light provide for photosynthesis to take place?
energy
describe the effect of the rate of photosynthesis as the light levels increase
The rate of photosynthesis increases steadily, as light levels increase. This is because, the higher the light levels, the more energy is produce. This happens up to a certain point where the rate won’t increase as either the temperature or the carbon dioxide level is the limiting factor and needs to be increased.
why will a lack of carbon dioxide decrease the rate of photosynthesis?
Carbon dioxide is one of the reactants in photosynthesis so it is a necessary factor. Therefore, if there is a lack of it, less photosynthesis is performed as the plant doesn’t have enough of the required reactants, so the rate decreases.
what does the graph show when the line flattens out (CO2)?
While the amount of CO2 is till increasing, the rate no longer increases. This shows that CO2 is no longer the limiting factor, and it is either light or temperature.
why does temperature affect the rate of photosynthesis?
-Enzymes are required for photosynthesis, and temperature affects them. -Enzymes work slower at a lower temperature, so if the temperature is the limiting factor, it tends to be because it is too low.
-Increasing the temp increases the rate as the kinetic energy of particles increases.
-However, if the plant gets too hot (about 45°C), the enzymes needed will get damaged and denature.
-This is because the bonds holding the enzymes together break, so the substrate won’t fit anymore.
what can the amount of chlorophyll be affected by and how does chlorophyll affect the rate of photosynthesis?
The amount of chlorophyll in a plant can be affected by disease or environmental stress, such as a lack of nutrients. This can cause chloroplasts to become damaged, therefore not making enough chlorophyll. This means that the rate of photosynthesis is reduced because they can’t absorb as much light.
how does carbon dioxide concentration affect the rate of photosynthesis?
-increasing carbon dioxide concentration increases the rate as it is required to make glucose
-until another factor is limiting
what word is used when a graph levels off?
plateaued
describe and explain how the rate varies with temperature
-rate initially increases the temperature
-as particles have more energy so move faster and collide more frequently
-highest rate is at optimum temperature for enzymes
-at higher temp the rate decreases as bonds holding the enzyme together begin to break so enzyme changes shape
-rate falls to zero as enzyme denatures
