Biology 9700 · AS & A Level · Transport of oxygen and carbon dioxide
Transport of oxygen and carbon dioxide — practice question
Table 2.1 lists eight ions of biological significance: ammonium ($\text{NH}_4^{+}$), hydrogen ($\text{H}^{+}$), hydrogen carbonate ($\text{HCO}_3^{-}$), iron ($\text{Fe}^{2+}$), magnesium ($\text{Mg}^{2+}$), nitrate ($\text{NO}_3^{-}$), phosphate ($\text{PO}_4^{3-}$), sulfate ($\text{SO}_4^{2-}$). For each statement below, select the ion that fits it. In every case, write one letter from Table 2.1. Any letter from A to H may be used once, repeatedly, or not used at all.
(a(i))[1]
A constituent of polynucleotides.
(a(ii))[1]
Ion formed through enzyme action inside red blood cells.
(a(iii))[1]
Ion used in the production of all amino acids in chloroplasts.
(a(iv))[1]
Ion that moves through carrier proteins together with sucrose into companion cells in phloem tissue.
(a(v))[1]
Component of haem group in haemoglobin that attaches oxygen.
(b)[4]
Explain how the enzyme nitrogenase works during the fixation of nitrogen.
(c)[5]
Using Table 2.2 as reference, suggest how the cell surface membranes of root cells account for ion concentrations in the roots relative to the surrounding solution.
Worked solution & mark scheme
This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: “G” …