20.3. Pollution
A subsection of Biology, 0610, through 20. Human influences on ecosystems
Listing 10 of 168 questions
For Examiner's Use Sewage disposal involves the removal of human waste in pipes from houses to sewage treatment works. is a diagram that shows how sewage is treated. collection and pumping primary sedimentation screening grit removal aeration and digestion final sedimentation disinfection grit to landfill effluent solids to anaerobic digester oxygen solids to anaerobic digester chlorine recycled microorganisms river For Examiner's Use During stage 5 microorganisms break down organic matter consisting of cellulose, starch, protein and lipid . The microorganisms multiply during this stage and are recycled. Complete by writing in the boxes the names of the enzymes used to catalyse the reactions shown. The first box has been completed for you. cellulose cellobiose glucose cellulase starch maltose glucose protein amino acids lipid fatty acids and glycerol For Examiner's Use State why it is important that sewage is treated. At stage 5 in , oxygen and microorganisms are added. Explain why oxygen is bubbled through the tank at this stage. Suggest and explain the advantage of recycling microorganisms from stage 6 to stage 5 as shown in . 0610/32/O/N/11 For Examiner's Use Explain why chlorine is added at stage 7.
0610_w11_qp_32
THEORY
2011
Paper 3, Variant 2
View
When a mass of still air becomes trapped over a city, pollutants build up in the air next to the ground. Name two chemical pollutants that might build up over a busy city centre. Vehicles such as cars burn fossil fuels. Explain why vehicles may be banned from the city if pollution becomes severe. For Examiner's Use If air pollution is very severe, warnings may be given not to take young babies into the city centre and for any people with heart and respiratory problems to stay inside. Suggest two reasons for this advice.
0610_w13_qp_22
THEORY
2013
Paper 2, Variant 2
View
For Examiner's Use Molluscs are important animals in many aquatic and terrestrial ecosystems. shows four species of mollusc that live in the sea. common octopus Octopus vulgaris common whelk Buccinum undatum edible mussel Mytilus edulis stout razor clam Tagelus plebeius not to scale State two features shown by all mollusc species. State two features, visible in , in which the octopus differs from the other three molluscs. For Examiner's Use The edible mussel, Mytilus edulis, is attached to rocks that are exposed to the air at low tide. Use to suggest how an edible mussel is adapted to attach to rocks and survive when exposed to the air. The zebra mussel, Dreissena polymorpha, is a freshwater mussel that originates from rivers in southern Russia. The mussel was introduced into the Great Lakes of North America and has increased in huge numbers with serious effects on the food webs of the lakes. Explain why an introduced species, such as the zebra mussel, can have serious effects on the populations of the species that are already living in the area. For Examiner's Use The freshwater mussel, Pletholophus swinhoei, was used in a project to monitor water pollution by chemical waste in northern Vietnam. This was done by regularly counting the number of mussels in the river. Suggest the advantages of using freshwater mussels to monitor the pollution of water instead of carrying out chemical analysis of the water. Non-biodegradable plastics are a serious problem in many aquatic ecosystems. Explain the harm that non-biodegradable plastics may cause to organisms in aquatic ecosystems.
0610_w13_qp_32
THEORY
2013
Paper 3, Variant 2
View
Questions Discovered
168