BioChem 2.9 Photosynthesis Flashcards
What is photosynthesis?
Photosynthesis is the production of carbon compound cells using LIGHT energy and simple inorganic substances (CO2 and water)
What is essential for living organisms to carry out life processes?
Require complex carbon compounds to build structure and perform functions
What is photosynthesis an example of?
energy conversion (light energy -> chemical energy stored in carbon compounds like carbohydrates, lipids, proteins)
How is the visible light ranged?
Has a range of wavelengths with violet (shortest) to red (longest)
Why is sunlight visible to us/plants?
Made up of all wavelengths of electromagnetic radiation our eyes can detect (other wavelengths invisible)
What are examples of short wavelengths?
Blue/Violet -> X-rays and ultraviolet radiation -> high energy
What are examples of long wavelengths?
Red/Orange -> infrared radiation and radio waves -> low energy
How is light absorbed by plants?
Chlorophyll absorbs red and blue light most effectively
What is the first stage of photosynthesis?
Absorption of sunlight through chemical substance/photosynthesizing pigment like chlorophyll
What are pigments?
Substances that absorb light (appear coloured).
White does not absorb any and has no colour and reflect light while black absorbs all and is black and emits nothing
Some pigments absorb only certain wavelengths of visible light eg. Gentian flower only absorbs all except blue
Why is our ecosystem mainly dominated by the colour green?
Because of the pigment chlorophyll, this is not very effective in absorbing green light which are therefore to be reflected
What are the products of photosynthesis?
Oxygen is produced in photosynthesis from photolysis
What colours are most effectively reflected by chlorophyll?
Green Light
Draw absorption spectrum of plant pigments
horizontal axis is labelled wavelengths (nm) and scale extends from 400 to 700 nm,
vertical axis is labelled %absorption with scale of 0 to 100,
chlorophyll a peaks at around 440 and 680,
chlorophyll b peaks at around 500 and 650,
carotenoids peaks at 470 and 510
Draw an action spectrum of a plan pigment
horizontal axis is labelled wavelengths (nm) and scale extends from 400 to 700 nm,
vertical axis measures amount of photosynthesis given as % of the max rate,
What are the effects of photosynthesis to the atmosphere?
rise in oxygen concentration, as methane and co2 in atmosphere decrease
What are the effects of photosynthesis on the ocean?
increased dissolved oxygen in the ocean causes oxidation of iron in water and precipitates onto the sea bed
What rock is formed due to the oxidation of dissolved iron in water?
banded iron formation (most important iron ore)
What is needed during photosynthesis?
Photosynthesis converts CO2 and H2O into Carbohydrates and O2 using light energy (endothermic)
Is a reaction where small molecules like CO2 and H2O combine to form larger compounds like glucose, exothermic or endothermic?
endothermic
Why does photosynthesis only occur in the light?
It provides energy that cannot disappear so that it can be converted into chemical energy
What are possible limiting factors on rate of photosynthesis?
temperature, light intensity, CO2 concentration
In a combination of limiting factors, can there be more than actually limiting photosynthesis rate?
No. There is only ONE LIMITING REACTANT. So the one furthest from optimum
If other factors are changed, but not the limiting factor does it have an effect on photosynthesis rate?
No, only the limiting factor has effect on the rate (until it is not longer the limiting factor)
