paper 1 past exam questions

• which of the following is not an example of cell signalling?

  • the hormone insulin being removed from the blood by the glomerulus
• haematopoetic stem cells found in the bone marrow, which of the following describe haemopoetic stem cells?

  • they are multipotent but not pluripotent
• pluripotent

  can form any cell type in the body
• multipotent


  can only form a limited selection of related cells
• • auxin is synthesised in cells at the tip of the shoot
  • auxin causes cells to elongate on one side
  • scientists originally thought auxin was destroyed by light
  • this was disproved by the fact that plants growing in the dark and plants growing in unilateral light had similar auxin levels
• the plant was found to have high levels of abscisic acid (ABA) in its tissues, which explains this observation

  • ABA stimulates stomatal closing
• which hormones are involved in the control of leaf drop

  auxin and ethene
• damage to the hypothalamus results in lower water potential of the blood, which explains this observation

  • fewer water channels are inserted into the cell surface membranes of the collecting duct
• explain why gibberellin is classed as a plant hormone

  • gibberellin is a chemical messenger
  • produced in one part of the plant but has effects in another part
• suggest why anabolic steroids are effective when applied to the surface of the skin

  • skin has a large surface area for absorption
  • steroids are lipid-soluble so it can cross the phospholipid bilayer
• what is meant by a conjugated protein

  • has a prosthetic group
  • has a covalent/ionic/hydrogen bonds
• cortisol


  regulation of metabolism
• suggest why reduced heart rate is sometimes seen in people who are very aerobically fit

  • increased stroke volume
  • increased thickness of heart muscle
  • increased volume of ventricle
• two examples of commercial uses of auxin

  • weed killers
  • promote fruit ripening
• in the krebs cycle, ADP being phosphorylated is called

  substrate level phosphorylation
• U= ATP synthase

  Q= electron carrier

  P= intermembrane space

  S= matrix

  R= krebs cycle

  T= ATP synthesis

  
• What properties of the mitochondrial inner membrane allow chemiosmosis to occur?

  • impermeable to H+ ions
  • large surface area
• Most ATP is produced in mitochondria by chemiosmosis. Outline how ATP is produced in mitochondria by chemiosmosis.

  • H+ ions move down a concentration gradient
  • through ATP synthase
  • from intermembrane space to matrix
• Which statement about lipids is correct?

  Phospholipids containing unsaturated fatty acids can increase the fluidity of cell membranes.
• Increasing the pH of an enzyme solution from 7.4 to 8.0 causes the rate of the reaction to fall by 90%. When the pH of the solution returns to 7.4 the rate of reaction returns to its original value.

  Increasing the pH from 7.4 to 8.0 breaks hydrogen bonds but returning the pH to 7.4 allows them to re-form.
• Which of the options describes movement of water through a plant?

  The Casparian strip forces water to enter the cytoplasm before it can enter the xylem
• Which of the statements about the absorption spectra shown in the diagram is not correct?

  Chlorophyll a absorbs red light but not blue light and chlorophyll b absorbs blue light but not red light.
• The Pacinian corpuscle is a type of sensory receptor that detects pressure. Which of the options describes the action of a Pacinian corpuscle?

  A strong stimulus at a Pacinian corpuscle produces a generator potential that exceeds a threshold value.
• The students were asked to decide whether the permeability of the membrane is significantly greater with 50% ethanol compared to 40% ethanol. Which statistical test should they use?

  t-test
• suggest an advantage on the increase of cardiac output

  • deliver more blood to the placenta
  • to meet the need for a higher metabolic rate
• ‘As cardiac output increased blood pressure dropped so there must have been a decrease in vascular resistance.’ Evaluate this conclusion.

  • decreased vascular resistance could explain drop in pressure
  • during weeks 9-24 as cardiac output increases, blood pressure decreases
  • no data available at 0 weeks
• Explain how the different affinities of maternal and fetal haemoglobin enable transfer of oxygen from the maternal circulation to the fetus

  • fetal haemoglobin has a higher affinity for oxygen
  • oxygen dissociates from adult haemoglobin in placenta
  • oxygen diffuses from maternal to fetal blood
• give 3 functions of the cytoskeleton

  • movement of cells
  • strengthening/supporting cells
  • for spindle in mitosis and meiosis
• Suggest how a mutation in cytoskeleton genes could cause a disease of the nervous system

  • change in cytoskeleton protein
  • no movement of vesicles
  • could change diameter of axon
• Outline the processes in the loop of Henle that cause the solute concentration to increase.

  • water cannot leave the ascending limb
  • Na+ / Cl– , diffuse , out of lower part of ascending limb
  • diffusion of , Na+ / Cl– , into descending limb
• Suggest the consequences of an increase in the thermogenic set point in the hypothalamus

  • increase in set point will result in fever
  • raised body temps help to kill pathogens
• State two functions of the cell surface membrane that are illustrated by the action of PGE2.

  • cell signalling
  • controls entry/exit to cell
• Explain why the plants wilted, even though they were given a lot of water

  • solution would lower water potential
  • less water enters root cells by osmosis
  • plants lose more water than it gains
• Explain why plants growing in high light intensity require more water than plants growing in shade, even when the temperatures are the same.

  • high light intensity increases rate of photosynthesis
  • more stomata open to allow gas exchange
• Which of the following statements, A to D, describes the movement of water across plant roots?

  The symplast pathway requires water to cross partially permeable membranes.
• Which of the following statements, A to D, describes and explains the relative yield of ATP in anaerobic and aerobic respiration?

  Anaerobic respiration produces less ATP per molecule of glucose because NAD is not regenerated in oxidative phosphorylation.
• A teacher told his students that the human body makes the equivalent of its own mass in ATP every day. Explain why, at the end of the day, only a small proportion of the students’ mass was ATP.

  • ATP is constantly recycled
  • because ATP is , broken down
  • ATP used to provide energy for , (named) metabolic reactions
• Which of the options is not a function of the liver?

  storage of excess amino acids as protein
• Which of the statements about the control of blood glucose is correct?

  Glucagon stimulates the conversion of glycogen to glucose by liver cells.
• Which of the statements about enzyme catalysed reactions is true?

  Binding of a substrate to the active site can weaken bonds in the substrate