Short notes on Edexcel A2 Biology - Part 2

5.2 How ecosystem works

NPP

• (rate of) {production of / energy incorporated into / eq} {biomass / organic material / eq} ;
• reference to {losses in respiration / GPP – respiration / eq} ;
• in {producers / plants};

Why NPP may increase due to increase in temperature

• idea that the rate of {(bio)chemical / metabolic / photosynthetic / named} reactions increases ;
• idea of increase in {movement / kinetic energy} of {enzyme / substrate / molecules / particles} / eq ;
• idea of (increase in reaction rate) because of more enzyme substrate interaction ;

Importance of NPP to farmer to use a land for cattles

• cattle {are primary consumers / herbivores / eat grass / eat plants / eq} ;
• (therefore) gain energy (available as NPP) ;
• idea of grazing capacity of the grassland ;
• idea of affect on yield of {meat / milk / eq} ;
• idea of changing to a more {efficient / NPP yielding} crop ;

Factors which may influence NPP

• grazing / {consumers / herbivores / named herbivore} / eq ;
• trampling / eq ;
• shading by {plants / named plant} / eq ;
• competition from other plants / eq ;
• disease / eq ;

Succession

• idea of (a sequence of) changes in {a community / organisms / species / plants} ;
• over a period of time / eq ;

Climax community

• idea of final {stage / sere / community} ;
• feature of community described e.g. self-sustaining , stable, one dominant species, a few codominant species ;

Importance of conserving endangered plants

• idea of conservation of {genetic diversity / genetic variation / biodiversity} ;
• idea of extinction ;
• idea of aesthetic reasons ;
• idea that these plants may be useful e.g. as medicines ;
• idea that other animals depend on these plants as a {source of food / habitat} ;

Nich

• idea of the {role / purpose / interaction / eq} of {organism / sea anemone / species / eq} ;
• reference to trophic level(s) ;

Succession

• reference to lichens and mosses as pioneer community ;
• able to grow in {little / no} soil / eq ;
• (that) breaks up (rock) fragments / forms {thin / shallow / eq} soil;
• reference to {plants / eq} with {small / short / eq} roots ;
• (able to) grow in {thin / shallow / eq} soil / eq ;
• idea that changes in soil structure enable {trees / shrubs} to grow / eq ;
• general points to be included:
  • reference to soil able to {hold / retain / contain / eq} {water / minerals} ;
  • as plants {lose leaves / die / decay / eq} ;
  • reference to {organic matter / humus / eq} {increases / released / eq} ;
  • reference to competition effects ;

Climax community

• includes (both) animals and plants / has many species / has high biodiversity / eq ;
• reference to {interaction / eq} between species / eq ;
• idea of balanced equilibrium of species ;
• reference to {dominant / codominant} (plant or animal) species ;
• reference to stable if no {change to environment / human influence} ;