Questions and Answers

Describe the principles of cell signalling using the example of the control of blood glucose concentration by glucagon, limited to: • binding of hormone to cell surface receptor causing conformational change • activation of G-protein leading to stimulation of adenylyl cyclase • formation of the second messenger, cyclic AMP (cAMP) • activation of protein kinase A by cAMP leading to initiation of an enzyme cascade • amplification of the signal through the enzyme cascade as a result of activation of more and more enzymes by phosphorylation • cellular response in which the final enzyme in the pathway is activated, catalysing the breakdown of glycogen

Relate the detailed structure of the Bowman’s capsule and proximal convoluted tubule to their functions in the formation of urine

Describe the roles of the hypothalamus, posterior pituitary gland, antidiuretic hormone (ADH), aquaporins and collecting ducts in osmoregulation

State that urea is produced in the liver from the deamination of excess amino acids

Describe and carry out investigations using whole plants, including aquatic plants, to determine the effects of light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis

Describe and carry out investigations using redox indicators, including DCPIP and methylene blue, and a suspension of chloroplasts to determine the effects of light intensity and light wavelength on the rate of photosynthesis

Explain the effects of changes in light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis

Explain that during photophosphorylation: • energetic electrons release energy as they pass through the electron transport chain (details of carriers are not expected) • the released energy is used to transfer protons across the thylakoid membrane • protons return to the stroma from the thylakoid space by facilitated diffusion through ATP synthase, providing energy for ATP synthesis (details of ATP synthase are not expected)

Explain that in non-cyclic photophosphorylation: • photosystem I (PSI) and photosystem II (PSII) are both involved • photoactivation of chlorophyll occurs • the oxygen-evolving complex catalyses the photolysis of water • ATP and reduced NADP are synthesised

Explain that in cyclic photophosphorylation: • only photosystem I (PSI) is involved • photoactivation of chlorophyll occurs • ATP is synthesised