Short notes on Edexcel A2 Biology - Part 3

5.3 Global warming

Role of (herbivorous/omnivores) animal in recyling carbon

• reference to {carbon / organic / eq} compounds in plant material ;
• idea that digestion provides respiratory substrates ;
• carbon dioxide released (from respiration) ;
• (this carbon dioxide is) available for photosynthesis ;
• reference to woodlice {eaten / decompose} ;

Role of microorganisms in recycling carbon

• reference to {decomposition / decay / putrefaction } (by microorganisms) ;
• reference to respiration ;
• releases carbon dioxide for photosynthesis / eq ;
• methane released in anaerobic (conditions);
• (methane) available as fuel / eq ;

Biofuels may help to reduce global warming

• reference to biofuels being (possibly)carbon neutral ;
• idea that {plants / crops} are used for biofuels;
• idea that carbon dioxide used for photosynthesis (by plants / in production of biofuels) ;
• idea of using biofuels to replace fossil fuels ;

Disadvantage of using biofuels to reduce global warming

• land has to be cleared to grow plants for biofuels / eq ;
• burning produces carbon dioxide / the plants growing there would have been {photosynthesising / using carbon dioxide} / machinery uses fossil fuels / loss of habitat ;
• decomposition of dead plant material (after clearing) / eq ;
• produces carbon dioxide / eq ;
• idea that the land could have been used for food production ;
• less food produced / eq ;
• ref to use of fertilisers ;
• idea of eutrophication OR use oil-based products

Production of biofuels may not be carbon neutral

• idea that biofuel production may (overall) results in more carbon dioxide in the atmosphere ; OR idea that carbon neutral means that the carbon dioxide produced equals the carbon dioxide used ;
• idea of forests as carbon {sinks / eq} ;
• idea that {clearing land / deforestation} results in (net) increase in carbon dioxide (in atmosphere) ;
• (less plants means) less carbon dioxide {removed / used / eq} by photosynthesis ;
• {burning / eq} trees produces carbon dioxide ;
• idea that (increased) decomposition produces carbon dioxide;
• idea of using {(fossil) fuels / petrol / diesel} by {lorries / machinery / eq}produces carbon dioxide ;
• {burning /eq} of biofuels produces carbon dioxide ;

Combustion of biofuels may lead to global warming

• reference to production of {greenhouse gases / named greenhouse gas} ;
• idea that these gases {build up/ remain / form a layer} in (upper) atmosphere;
• which {absorb / trap / eq} {heat energy / infra-red / IR / eq} ;
• reflected from earth’s surface ;
• idea that increased levels of these gases increase the greenhouse effect ;
• idea that (mean) temperature of earth’s {surface / atmosphere} is increasing ;

Forest fires may lead to global warming

• reference to {fires / burning / eq} produces carbon dioxide ;
• which is a greenhouse gas ;
• idea that these gases {build up / remain / form a layer / increase} in (upper) atmosphere;
• which {absorb / trap / eq} {heat energy / infra red / IR / eq} ;
• reflected from earth’s surface ;
• idea that increased levels of these gases increase the greenhouse effect ;
• idea that (mean) temperature of earth’s {surface / atmosphere} is increasing ;
• idea that less carbon dioxide {removed / used / eq} by photosynthesis ;

Greenhouse effect by methane and carbon dioxide

• (carbon dioxide and / or methane) are greenhouse gases / eq ;
• which {absorb / trap / eq} {heat / infra red / IR / long wave} (radiation) / eq ;
• {reflected / (re)radiated} from the Earth’s surface / eq ;
• prevent {heat / infra red / IR / long wave / eq} (radiation) escaping ;
• idea of temperatures maintained higher (than they would be) ;

Reduction in use of fossil fuels may not prevent further global warming

• carbon dioxide produced {by using / in production of / eq} fossil fuels / eq ;
• no (direct) evidence that increased carbon dioxide leads to global warming / eq ;
• reference to carbon dioxide released from {other processes / named process} ;
• idea of removal of {carbon sinks / named example / eq} (also) leads to increase in carbon dioxide ;
• stated example of any other greenhouse gas released from another source e.g. CFC, water vapour, methane ;
• description of source e.g. ruminant animals, paddy fields, melting ice, clearance of peat land ;
• idea of natural {cycles / events / phenomena / eq} may be involved (in global warming) e.g. solar, volcanoes ;
• idea of evidence from past is being used ;
• idea of {(past evidence) is not in indicator of future events / limitations of (climatic) models} ;
• idea that scientists may be biased ;
• description of bias e.g. employed by {company / country} with vested interest, self promotion ;
• specific example of problem with / disadvantage of} alternative source of energy ;

Why body temperature effects rate of development of animals

• reference to increase in {metabolic rate / enzyme activity / eq} as temperature rises ;
• reference to increase in {kinetic / eq} energy of molecules (as temperature rises) / eq ;
• reference to increase in {enzyme- substrate complexes / energy of collisions / eq} (as temperature rises) ;
• idea of {inactivation at lower temperatures/ denaturation at higher temperatures} of enzymes ;
• idea that temperature affects {differentiation / growth /division / eq} ;

Affect of global warming on distribution

• idea that global warming will increase the temperature (at the latitudes) ;
• idea that temperatures (at these latitudes) may become too high for any of the species ;
• idea that new temperature may be above the maximum to complete development or above the upper lethal limit ;
• idea that species move { to cooler regions / eq} ;
• ref to change in {food source / predators / competition / eq}