Biology Paper 4 November 2004

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1. AGreen
2. BDark orange
3. CLight orange
4. DOrange

1. ALight yellow
2. BLight orange
3. CDark orange
4. DGreen

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1. AA higher substrate concentration lowers the activation energy needed for hydrolysis.
2. BA higher substrate concentration increases the optimum temperature of the enzyme.
3. CA higher substrate concentration reduces the amount of enzyme needed to complete the reaction.
4. DA higher substrate concentration increases the rate of enzyme-substrate complex formation, so the enzyme converts more substrate to product in the same time.

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1. AThe temperature of the water bath
2. BThe colour of the test tube rack used
3. CThe order in which tubes A, B and C were labelled
4. DThe brand of glassware used to hold the tubes

1. AThe pH of the reaction mixture
2. BThe time of day the experiment was performed
3. CThe name written on the test tube label
4. DThe shape of the test tube rack

1. AThe volume of the water bath itself
2. BThe distance between the test tubes in the rack
3. CThe concentration of solution P (the enzyme/amylase) added
4. DThe colour of solution P before use

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1. AP is an enzyme (a protein), and boiling denatured it so it could no longer hydrolyse starch to reducing sugar.
2. BP is a simple inorganic catalyst that boiling made more active.
3. CP is the reducing sugar itself, and boiling destroyed it before the test.
4. DP is distilled water with no catalytic activity, boiled or not.

1. AThe pH stays roughly constant, then rises (for NaOH) or falls (for HCl) more steeply once more drops are added.
2. BThe pH rises steadily and steeply from the very first drop, at a constant rate throughout.
3. CThe pH oscillates randomly with no consistent pattern as drops are added.
4. DThe pH is unaffected by either NaOH or HCl at any point in the titration.

1. AAlbumin physically absorbs the added acid or alkali onto its surface without any chemical reaction taking place.
2. BAlbumin evaporates any acid or alkali added to the solution.
3. CAlbumin is chemically inert and simply dilutes whatever is added to the solution.
4. DAlbumin is amphoteric: its ionic/ionisable groups can donate protons to an added base or accept protons from an added acid, buffering the change.

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1. AReducing the volume of albumin solution used in each tube.
2. BUsing a pH meter to record pH directly instead of matching indicator colour by eye against a chart.
3. CUsing fewer, larger drops so the titration finishes faster.
4. DRemoving the universal indicator so colour cannot bias the reading.

1. ARepeating the whole experiment with a different protein instead of albumin.
2. BUsing a burette (or similar titration apparatus) to add and measure the actual volume added, instead of counting drops.
3. CUsing bigger test tubes so more albumin solution can be tested at once.
4. DRecording the room temperature instead of the pH.

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1. AIt has true roots that anchor it firmly into the substrate.
2. BIt has leaves with a waxy cuticle to reduce water loss.
3. CIt has a vascular system of xylem and phloem running through a true stem.
4. DIt is an assemblage of similar cells forming a simple filament, with no true roots, stems or leaves.

1. AEosinophil
2. BMonocyte
3. CNeutrophil
4. DLymphocyte

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1. ASwitch to the lowest available magnification before doing anything else.
2. BSuperimpose (align) the eyepiece graticule scale over the stage micrometer scale.
3. CRemove the eyepiece graticule entirely and measure the cell with an external ruler only.
4. DIncrease the light intensity until the cell is no longer visible.

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