Outline how greenhouse gases interact with radiation and contribute to global warming.

Outline how plants make use of the different wavelengths of light.

Explain how organic compounds are transported within plants.

a. carbon dioxide is a greenhouse gas 

b. methane/nitrogen oxide/water vapour is a greenhouse gas 

c. sunlight/light/(solar) radiation passes through the atmosphere (to reach the Earth’s surface) 

d. CO₂ in atmosphere/greenhouse gases absorb/trap/reflect back some radiation/heat (emitted by the Earth’s surface) 

e. CO₂ in atmosphere/greenhouse gases allow short wave radiation to pass (through atmosphere) but absorb long wave/infra-red 

f. solar radiation/sunlight is (mostly) short wave 

g. radiation/heat emitted by the Earth is long wave/infra-red

Allow answers presented in a clearly annotated diagram.

a. light used in photosynthesis/light-dependent reactions/photolysis/photosystems/photophosphorylation/excitation of electrons/switch to flowering 

b. chlorophyll absorbs red AND blue light (more) 

c. chlorophyll/leaf/plant reflects/does not absorb/does not use green light 

d. absorption spectrum of chlorophyll has peaks in the red and blue/sketch graph to show this 

e. action spectrum shows which wavelengths plants use in photosynthesis/sketch graph of action spectrum showing peaks in the blue and red 

f. accessory/other (named) photosynthetic pigments absorb different wavelengths/colours 

g. violet is the shortest wavelength and red the longest 

h. red light and far red/infra-red absorbed to measure length of light/dark periods

a. transported in/translocated in/loaded into phloem

b. in sieve tubes 

c. by mass flow 

d. from sources to sinks 

e. from leaves/other example of source to roots/other example of sink 

f. loading (of sugars/organic compounds) by active transport 

g. cause high concentration of solutes (in phloem/sieve tubes) 

h. water uptake (in phloem/sieve tubes) by osmosis/water diffuses into phloem 

i. rise in (hydrostatic) pressure at source (in phloem) 

j. creates a (hydrostatic) pressure gradient/higher pressure in source than sink 

k. flow can be in either direction/bidirectional