Biology Paper 2

The light-dependent reaction in such detail as to show that: chlorophyll absorbs light, leading to photoionisation of chlorophyll some of the energy from electrons released during photoionisation is conserved in the production of ATP and reduced NADP the production of ATP involves electron transfer associated with the transfer of electrons down the electron transfer chain and passage of protons across chloroplast membranes and is catalysed by ATP synthase embedded in these membranes (chemiosomot

Carbon dioxide reacts with ribulose bisphosphate (RuBP) to form two molecules of glycerate 3-phosphate (GP). This reaction is catalysed by the enzyme rubisco ATP and reduced NADP from the light-dependent reaction are used to reduce GP to triose phosphate some of the triose phosphate is used to regenerate RuBP in the Calvin cycle some of the triose phosphate is converted to useful organic substances. Idenifying environmental factors and agricultural practices to overcome this

Glycolysis is the first stage of anaerobic and aerobic respiration. It occurs in the cytoplasm and is an anaerobic process. Glycolysis involves the following stages: phosphorylation of glucose to glucose phosphate, using ATP production of triose phosphate oxidation of triose phosphate to pyruvate with a net gain of ATP and reduced NAD.

pyruvate is oxidised to acetate, producing reduced NAD in the process acetate combines with coenzyme A in the link reaction to produce acetylcoenzyme A

synthesis of ATP by oxidative phosphorylation is associated with the transfer of electrons down the electron transfer chain and passage of protons across inner mitochondrial membranes and is catalysed by ATP synthase embedded in these membranes (chemiosomotic theory) other respiratory substrates include the breakdown products of lipids and amino acids, which enter the Krebs cycle

If respiration is only anaerobic, pyruvate can be converted to ethanol or lactate using reduced NAD. The oxidised NAD produced in this way can be used in further glycolysis.

Nutrients are recycled within natural ecosystems, exemplified by the nitrogen cycle and the phosphorus cycle. Microorganisms play a vital role in recycling chemical elements such as phosphorus and nitrogen

Nutrients are recycled within natural ecosystems, exemplified by the nitrogen cycle and the phosphorus cycle. Microorganisms play a vital role in recycling chemical elements such as phosphorus and nitrogen

The use of natural and artificial fertilisers to replace the nitrates and phosphates lost by harvesting plants and removing livestock. environmental issue from fertilisers; leaching and eutrophication

Organisms increase their chance of survival by responding to changes in their environment. pecific growth factors move from growing regions to other tissues, where they regulate growth in response to directional stimuli. explanation of gravitropism and phototropism in flowering plants. Taxes and kineses

eceptors respond only to specific stimuli stimulation of a receptor leads to the establishment of a generator potential. The basic structure of a Pacinian corpuscle. human retina in sufficient detail to show how differences in sensitivity to light, sensitivity to colour and visual acuity are explained by differences in the optical pigments of rods and cones