Quiz for EEI SAC Flashcards
why are there different types of plants
they are categorised into how they fix carbon into glucose
how do C3 plants carry out the Calvin Cycle
These plants carry out the original Calvin Cycle, using Rubisco, and are prone to photorespiration
what are optimal conditions for C3 plants
moist and cool conditions
how do C3 plants use RuBisco
use the Rubisco enzyme to fix inorganic carbon dioxide from the air and it enters the Calvin cycle joined to a carrier molecule (RuBP)
where does the Calvin Cycle take place in C3 plants
in the stroma of the leaf mesophyll cells
Photorespiration definition
a process in which plants take up oxygen rather than carbon dioxide in the light, resulting in photosynthesis being less efficient. (Rubisco takes up O2 instead of CO2)
what does rubisco normally do
brings carbon dioxide from the air into the Calvin cycle where the glucose is made, after making it into organic CO2
does photorespiration make glucose
nooooo
when does photorespiration occur
binds oxygen rather than carbon dioxide
why will Rubisco bind to oxygen instead of carbon dioxide
the active site can readily accommodate the oxygen molecules as well as the carbon dioxide molecules, so the two different molecules are in competition for the active site of Rubisco.
2 ways photorespiration arise in C3 plants (increase amount)
- temperature increases
- conditions dry out
how do C4 plants carry out the Calvin Cycle
carry out an adapted Calvin cycle, in which carbon fixation and glucose production occur in different cells
why does photorespiration increase as temperature increases
the ability of the Rubisco enzyme to distinguish between carbon dioxide and oxygen decreases and, as a result, Rubisco will increasingly bind oxygen.
why does photorespiration increase as conditions dry out
C3 plants close their stomata to prevent water loss. This closure blocks the entry of carbon dioxide needed as input to the Calvin cycle and limits the exit of oxygen produced
creating a high oxygen low CO2 environment inside the mesophyll cells
what are optimal conditions for C4 plants
These cells will thrive in warm and tropical regions
what anatomy changes are present in C4 plants (compared to C3 and CAM)
- bundle sheath cells have chloroplasts
- mesophyll cells that are arranged in a close association around the bundle sheath cells
where do the two processes occur in C4 plants
leaf mesophyll cells and bundle sheath cells
what happens in the first process in C4 plants (light dependent stage)
Carbon dioxide is converted into malic acid, in the mesophyll cells
PEP carboxylase catalyses the binding of carbon dioxide to an acceptor molecule (malic acid) (this is called carbon fixation)
what enzyme is used in the first step of C4 plants in photosynthesis
PEP carboxylase
why is PEP carboxylase used instead of RuBisco (C4)
It cannot bind to oxygen so photorespiration cannot happen
what happens in the second process of the C4 plants
Calvin cycle (glucose production) occurs in the bundle sheath cells
produce a steady supply of carbon dioxide from the breakdown of malic acid that raises the carbon dioxide concentration in their leaves. This allows the RuBisco in the bundle sheath cells to bind only to CO2
what are 3 key differences of c3 and c4 plants
- location of calvin cycle, mesophyll in c3, bundle sheath cells c4
- there are chloroplasts in bundle sheath cells in c4
- photorespiration doesn’t normally occur in c4
what is accuracy
Accuracy refers to how close an experimental measurement to a known value.
what is precision
Precision refers to how close multiple measurements of the same investigation are to each other.
what is repeatability
Repeatability is how close results of successive measurements are to each other in the exact same conditions.
what is reproducibility
Reproducibility is how close results are when the same variable is being measured (using the same method and investigation) but under different conditions
what is validity
The validity of data refers to the credibility of the research results from experiments or from observations.
what are random errors
Random errors are chance variations in measurements that affect the precision of measurements.
what are systematic errors
errors that affect the accuracy of a measurement and cannot be improved by repeating an experiment. They are usually due to equipment or system errors.
1 example of systematic errors
The markings on a ruler are slightly off so that every 1 cm on the ruler is actually 1.1 cm. Therefore, all measurements made using this ruler will be slightly lower than they actually are.
1 example of random errors
Measuring the zone of inhibition on an agar plate but not placing the ruler perfectly on the edge of an antibiotic disk each time.
