C1.3 - photosynthesis process (4a) Flashcards
what is photosythesis?
an endothermic reaction in which energy is transferred from the environment to chloroplasts by light
what is the equation for photosynthesis?
carbon dioxide + water – light –> oxygen + glucose
6CO2 + 6H2O –> O2 + C6H12O6
what is the photosynthesis process?
the production of carbon compounds in chloroplasts within cells, using light energy
what group or organisms carries out photosynthesis?
plants, algae and cyanobacteria carry out photosynthesis
where do plants obtain carbon dioxide from?
- absorbed from the air
- from water (for aquatic plants)
what transfer of energy occurs during photosynthesis?
light energy –> chemical energy
why is energy transformation needed from photosynthesis?
supplies most of the chemical energy needed for life processes in ecosystems
what is an example of an energy transformation during photosynthesis?
where is this energy stored?
e.g) glucose is respired to release ATP to support metabolic reactions in living organisms
- this chemical energy is stored in covalent bonds
how is glucose used by plants?
glucose forms carbohydrates or other carbon compounds
how are nitrates used by plants?
nitrates are used to produce nitrogen-containing compounds such as amino acids, nucleotides and ATP
how are phosphates used by plants?
phosphates are used to produce phosphate-containing compounds such as phospholipids, nucleotides and ATP
what is the process of photosynthesis?
- the splitting of water and the production of oxygen requires light:
- this process is called photolysis
- oxygen is the by product of photosynthesis and is released into the atmosphere - hydrogen ions are released, which reduce carbon dioxide
- carbon dioxide is ‘fixed’ when it is converted to glucose
- the glucose is converted to a wide range of organic compounds
what happens when a pigment molecule absorbs light?
- when a pigment molecule absorbs light some of its electrons become excited
- the excited electrons can be used to make chemical bonds, thus transforming the light energy to chemical energy
- thus there is transformation of light energy to chemical energy
what does the exciting an electron require?
exciting an electron requires a specific amount of energy to raise it to a higher energy level
- the amount of energy differs depending on the pigment molecule, and so different wavelengths of light are required to provide each of these
what is an absorption spectra?
the absorption spectrum shows the wavelengths of light that are absorbed by each pigment
- different pigments absorb different wavelengths of light and have different peaks, allowing for a wider action spectrum
what is an action spectrum?
an action spectrum is a graph that shows the rate of photosynthesis at different wavelengths of light
what are similarities between action and absorption spectra?
- they both have a similar shaped graph for chlorophyll
- both have wavelength or colour of light in the x-axis
how can we determine rates of photosynthesis for varying wavelengths?
recording the rate of oxygen production or carbon dioxide intake allows direct measurement of photosynthesis rate
what must be corrected for these methods?
the rate of cell respiration must be corrected, and this is possible as the plant has a fairly consistent rate of cell respiration as long as this is corrected for cell respiration
what type of spectrum would be produced?
if the independent variable is wavelength of light, plotting the rate of photosynthesis against this produces an action spectrum
what wavelengths of light are absorbed the most and least by chlorophyll?
most - red and blue
least - green (it is reflected)
