Plants in a Changing Atmosphere

• what is a pollutant?

  a chemical that is in the wrong place at the wrong concentration and has the potential to cause damage to the environment
• what is an air pollutant?

  chemicals that are emitted into the atmosphere which adversely affect physical and biological systems
• what are the two types of air pollutant?

  particulate air pollutants and gaseous air pollutants
• what are the two types of gaseous air pollutants?

  primary pollutants and secondary pollutants
• what are primary pollutants?

  chemicals that are emitted directly into the atmosphere
• what are secondary pollutants?

  chemicals that are formed by the reactions in the atmosphere between primary pollutants and other agents
• name two examples of primary pollutants?

  nitrogen monoxide and sulphur dioxide
• name two examples of secondary pollutants?

  nitrogen dioxide and ozone
• name two natural emitters of gaseous pollutants?

  volcanoes and swamps
• name two anthropogenic emitters or gaseous pollutants?

  domestic sources and industrial sources
• what are the two primary effects of gaseous pollutants?

  inhibition of photosynthesis and inhibition of growth
• how do gaseous air pollutants inhibit photosynthesis?

  they disrupt the H+ gradient across the thylakoid membrane
• what are the secondary effects of gaseous air pollutants?

  increased acidity and loss of fertility in soil and ozone damage in crops
• what is global warming defined as?

  an average increase in Earth's temperature that in turn causes climate change
• what is the greenhouse effect defined as?

  the trapping of infrared radiation, produced when solar radiation is absorbed and then partially re-emitted by the earth's atmosphere
• what is a proportion of solar radiation received by earth re-emitted as?

  longer wavelengths
• what temperature would the earth be without the greenhouse effect?

  18 degrees C
• what are greenhouse gases?

  any gas that absorb infra-red radiation in the atmosphere
• what is climate change defined as?

  changes in climate resulting from global warming
• for each 1% decrease in stratospheric ozone there is a 2% increase in what?

  UV-B radiation reaching the biosphere
• what are the three types of ultraviolet radiation?

  UV-C, UV-B and UV-A
• what is the main effect of UV-B in humans?

  skin damage and UV-B induced skin cancers
• what are the targets for UV-B?

  nucleic acids in DNA and RNA, amino acids, proteins and signalling hormones
• what does UV-B damage to DNA in humans lead to?

  tumours
• why is there nor much evidence that UV-B induced DNA damage in plants is an issue?

  they are able to repair their DNA very quickly, unlike humans
• what are two of the morphological alterations that can occur in plants and are caused by UV-B?

  changes in stomal aperture and root and shoot branching
• how do plants acclimate to increase UV-B?

  by accumulating UV absorbing pigments
• where are the effects of UV likely to be the most pronounced?

  high latitude ecosystems
• what is the direct effect of increased CO2 concentrations on plants?

  increased photosynthesis
• what is the indirect effect of increased CO2 concentrations on plants?

  increased temperatures and increased drought
• why does increased CO2 concentrations lead to increased rates of photosynthesis?

  increased CO2 concentration gradient, increased CO2 uptake, increased CO2 concentration in the leaf and therefore an increased rate of photosynthesis