User interface language: English | Español

Date May 2018 Marks available 4 Reference code 18M.2.HL.TZ1.7
Level Higher level Paper Paper 2 Time zone Time zone 1
Command term Outline Question number 7 Adapted from N/A

Question

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

[4]
a.

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

[4]
b.

Explain how organic compounds are transported within plants.

[7]
c.

Markscheme

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.

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

 

b.

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

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Additional higher level » Topic 8: Metabolism, cell respiration and photosynthesis » 8.3 Photosynthesis
Show 33 related questions
Additional higher level » Topic 8: Metabolism, cell respiration and photosynthesis
Additional higher level

View options