Biology · May / June 2021 · Paper 42 · Question 4

habitat destruction / named example ;

removing (too many) of a plant species ;

(named) pollutants (of plants) ;

additional named pollutant (of plant) ;

introduced species / disrupted food chains ;

disease ;

AVP ; e.g. extinction of other species / fewer, pollinators / (named) pesticides killing pollinators / reduced genetic diversity / stated impact of GM crops / war

any four from:

more carbon dioxide (is being released / in the atmosphere) ; (carbon dioxide is produced by) burning / use of, fossil fuels ; deforestation (leads to more carbon dioxide in atmosphere) ; more methane (is being released / in the atmosphere) ;

(methane is produced by) farming ;

(methane produced by) landfill ;

increased / increasing human population ;

enhanced greenhouse effect ;

(greenhouse / named) gases trap, heat / (infra-red) radiation ; AVP ;

any three from:

ensure (genetic) variation / AW ;

represent many environments where the plant grows / able to survive (in a changing environment) / AW ;

more chance of cross-fertilisation ;

not enough seeds in any one population ;

increases chances of successful germination ;

AVP ;

mutations (of DNA) / genetic change / change (base sequence of) DNA ;

any two from:

low (kinetic) energy ;

for enzymes ;

low rate of (effective) collisions / AW ;

slow diffusion (of oxygen) ;

any three from:

water ;

oxygen ;

suitable / optimum, temperature ;

AVP ;

obtain (named) resources from, larger / deeper, area ;

so that they have enough roots to survive (the reintroduction process) ; ref. to large(r) surface area ;

more root hair (cells) ;

for (more) water and (named) minerals / ions / salts, uptake ; anchorage / described ;

so that not pulled out (when animals grazing / wind etc) ;

reduced soil erosion ;

AVP ; e.g. named use of, water / mineral ion

lag ;