photosynthesis spec questions Flashcards
Define the terms autotropic
living thing that can make its own food from simple chemical substances such as carbon dioxide and light
define the term heterotrophic
an organism that eats other plants or animals for energy and nutrients
What is the equation for photosynthesis?
carbon dioxide + water —> oxygen + glucose
6CO2 + 6H20 —–> C6H1206 + 602
what is the equation for respiration
glucose + oxygen —> carbon dioxide + water
Explain energy transfers in photosynthesis
light energy is absorbed by photosynthetic pigements found in chloroplasts. The light energy excites electrons in photosystems which then pass down an electron transport chain. This releases the energy for chemiosmosis which combines ADP and Pi to make ATP
explain chemiosmosis
The pumping of protons into the thylakoid membrane setting up a proton gradient, resulting in H+ ions diffusing through the channel of ATP synthase which combines ATP and Pi to make ATP
what kind of pigment is chlorophyll a and what is its function
chlorophyll a is a primary pigment , absorbs light energy at colours of blue/red/orange at wavelengths of 450 and 670
name the accessory pigments
chlorophyll b, carotenoids xantophyll
what is the absorbtion spectra
used to determine the wavelengths absorbed by specific pigments, showing the percentage of light absorbed at each wavelength
what is the action spectra
Action spectrum helps to show the relationship between the rate of photosynthesis for a given wavelength
what technique can be used to separate pigments
chromotography
What are the 2 stages of photosynthesis?
light dependant and light independant
( calvin cycle )
Where does the light dependant reaction take place?
thylakoid membrane
What 2 things are need for the light dependant reaction
light
water
What are the 3 products of the light independent reaction?
glucose
NADP+
ADP + Pi
What is photolysis
splitting of a water molecule using light to produce hydrogen ion, oxygen and electrons
How is NADP reduced?
Reduced NADP is produced when hydrogen ions combine with the carrier molecule NADP using electrons from the photolysis of water
What is photophosphorylation
the process by which light energy is used to produce ATP, the energy currency of cells.
What happens in cyclic phosphorylation
only involves PS1 and is where Light energy excites electrons, and energy is used to create an H+ gradient in the same way, with ATP synthase transporting H+ out of the stroma. Less ATP is made via cyclic photophosphorylation, but importantly the electrons aren’t given to NADP the electrons are recycled
Where does the light independent reaction take place?
stroma
What 2 products of the light dependent reaction are needed for the light independent reaction?
reduced NADP and ATP
What are the 3 processes involved in the light independent reaction?
fixation, reduction and regeneration
Name the enzyme involved in the Calvin cycle.
RuBisCO
What are the products of the Calvin cycle
TP - used to create a hexose sugar
What are the limiting factors of photosynthesis?
temperature
CO2 concentration
light intensity
How does temperature affect the rate of photosynthesis?
as the light independant stage is controlled by enzymes temperature can increase the rate of photosynthesis however past the optimum temperature enzymes can become denatured and rate of photosynthesis will be very slow
How are C4 plants adapted?
such as maize and sorghum are adapted to work at high temperatures. The enzymes involved in photosynthesis have a higher optimum temperature, so are not damaged by the high temperatures.
How are CAM plants adapted?
adapt to arid conditions for photosynthesis by opening their stomata at night to minimise water loss.
How can an understanding of the effect of limiting factors on the rate of photosynthesis can be used to increase crop yields?
in order to maximise photosynthesis farmers can ensure that temperature CO2 and light intensity are at their optimum levels. Eg farmers can install CO2 machines, thermastatically control greenhouses, provide lights at night ect.
