Respiration Banker

1. (a) What are the products of anaerobic respiration in yeast?A lactic acid onlyB alcohol (ethanol) and carbon dioxideC carbon dioxide and waterD lactic acid and carbon dioxide [1]

1. (a) Write the word equation for anaerobic respiration in human muscle cells. [1]
2. (b) State when muscle cells respire anaerobically. [1]
3. (c) Anaerobic respiration releases much less energy per glucose molecule than aerobic respiration. Suggest why. [1]

1. (a) Give three differences between aerobic respiration and anaerobic respiration in human muscle. [3]

1. (a) State two ways in which humans use anaerobic respiration by yeast. [2]
2. (b) Name the gas produced by yeast that makes bread rise. [1]

1. (a) After a race, lactic acid is removed from the blood. In which organ is most of it broken down using oxygen?A kidneyB liverC lungsD stomach [1]

A baker in Multan mixed flour, water, sugar and yeast to make 50 cm³ of dough. After 1 hour in a warm place the dough had a volume of 120 cm³.

1. (a) Calculate the percentage increase in volume of the dough. [2]
2. (b) Explain why the dough rises. [2]
3. (c) Explain why the dough was left in a warm place rather than a refrigerator. [2]
4. (d) State what happens to the alcohol made by the yeast when the dough is baked. [1]

An athlete in Islamabad ran a 400 m race. At the end of the race her blood lactic acid concentration was 12.0 mmol per dm³. After resting for 45 minutes it was 3.0 mmol per dm³.

1. (a) Calculate the mean rate at which the lactic acid concentration fell during the 45 minutes. Give your answer in mmol per dm³ per minute. [2]
2. (b) Explain why lactic acid built up in the athlete's blood during the race. [2]
3. (c) Describe how the oxygen debt is repaid after the race. [3]

Yeast was mixed with sugar solutions of different concentrations at 30 °C. Each tube was connected by a delivery tube to a tube of water, and the bubbles of gas were counted for one minute, three times.Sugar concentration / %: 0 | 2 | 4 | 6 | 8Bubbles per minute, count 1: 0 | 8 | 17 | 25 | 26Bubbles per minute, count 2: 0 | 10 | 19 | 24 | 27Bubbles per minute, count 3: 0 | 9 | 18 | 26 | 25

1. (a) Calculate the mean number of bubbles per minute for each sugar concentration. [2]
2. (b) Describe the effect of sugar concentration on the rate of respiration of the yeast. [2]
3. (c) Explain why the bubbles at 0 % sugar were zero. [1]
4. (d) Explain why counting bubbles is not an accurate way to measure the volume of gas, and suggest a better method. [2]

Equal samples of bread dough, each 20 cm³, were placed in measuring cylinders in water baths at different temperatures. The volume was read after 30 minutes.Temperature / °C: 15 | 25 | 35 | 45 | 60Volume after 30 min / cm³: 24 | 31 | 40 | 34 | 20

1. (a) Calculate the increase in volume of the dough at each temperature. [2]
2. (b) Calculate the percentage increase in volume at 35 °C. [1]
3. (c) Explain why the dough at 60 °C did not rise. [2]
4. (d) State two variables that should be kept the same. [2]

Relative molecular masses: glucose = 180, ethanol = 46, carbon dioxide = 44.

1. (a) Write the balanced chemical equation for anaerobic respiration in yeast. [2]
2. (b) Calculate the mass of ethanol produced when 90 g of glucose is completely respired anaerobically by yeast. [2]
3. (c) Calculate the mass of carbon dioxide produced from the same 90 g of glucose. [1]

A flask of glucose solution and yeast, closed with a cotton wool plug, was placed on a top-pan balance at 30 °C.Time / min: 0 | 15 | 30 | 45 | 60Mass of flask / g: 250.00 | 249.86 | 249.62 | 249.36 | 249.12Assume that all the mass lost is carbon dioxide released by anaerobic respiration of the yeast.

1. (a) Calculate the total mass of carbon dioxide lost in 60 minutes. [1]
2. (b) Calculate the mean rate of mass loss over the 60 minutes, in g per minute, to 3 significant figures. [1]
3. (c) Use the equation C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ to calculate the mass of glucose respired. (Mr: glucose 180, CO₂ 44) [2]
4. (d) Explain why the cotton wool plug was used instead of a rubber bung. [2]

At a distillery near a sugar mill in Sindh, molasses (a sugary waste from sugar cane) is diluted and mixed with yeast in closed tanks to make ethanol, which is sold as a fuel.

1. (a) Explain why air is kept out of the fermentation tanks. [2]
2. (b) Explain why the temperature of the tanks is controlled at about 30–35 °C. [2]
3. (c) Fermentation stops after some days even though the yeast is still present. Suggest two reasons. [2]

A student's breathing rate was recorded at rest and after 3 minutes of skipping.At rest: 14 breaths per minuteEnd of exercise: 382 minutes after: 305 minutes after: 2210 minutes after: 15

1. (a) Calculate the percentage increase in breathing rate from rest to the end of the exercise. [2]
2. (b) Explain why the breathing rate stayed above the resting rate for several minutes after exercise. [3]

Two vacuum flasks were set up with a thermometer in each.Flask A: germinating peas – 21.0 °C at the start, 26.5 °C after 3 daysFlask B: boiled peas – 21.0 °C at the start, 21.0 °C after 3 days

1. (a) Calculate the temperature rise in flask A. [1]
2. (b) Explain why the temperature in flask A increased. [2]
3. (c) Explain the purpose of flask B. [1]
4. (d) Both sets of peas were rinsed in dilute disinfectant. Suggest why. [1]

Air was drawn slowly through two tubes and then bubbled through limewater.Tube X: germinating peasTube Y: the same volume of glass beads

1. (a) State what happens to the limewater in tube X. [1]
2. (b) Explain your answer to (a). [1]
3. (c) State why glass beads were used in tube Y. [1]

1. (a) Which observation shows that carbon dioxide is present?A limewater turns milkyB hydrogencarbonate indicator turns from red to purpleC blue cobalt chloride paper turns pinkD iodine solution turns blue-black [1]

1. (a) In a respirometer containing germinating seeds and soda lime, a drop of coloured liquid in the capillary tube moves towards the seeds. Why?A The seeds produce carbon dioxide, which pushes the liquid.B The seeds take in oxygen and the carbon dioxide they release is absorbed by the soda lime.C The soda lime releases oxygen, which the seeds absorb.D The seeds release water vapour, which condenses. [1]

Eight woodlice were placed in a respirometer containing soda lime, kept in a water bath at 25 °C. The coloured drop in the capillary tube (internal radius 0.5 mm) moved 24 mm in 5 minutes.

1. (a) Calculate the volume of oxygen used in 5 minutes. Use volume = πr²l, where l is the distance moved. Give your answer to 1 decimal place. [2]
2. (b) Calculate the rate of oxygen use in mm³ per minute, to 2 decimal places. [1]
3. (c) State the role of the soda lime. [1]
4. (d) Suggest why the apparatus was left for 10 minutes in the water bath before the readings were started. [1]

Hydrogencarbonate indicator is red in normal air, yellow when carbon dioxide concentration is high and purple when it is low. Four sealed tubes, kept in the dark, each contained 5 cm³ of red indicator and a gauze platform holding:A: ten maggotsB: glass beadsC: germinating mung bean seedsD: boiled mung bean seeds

1. (a) Predict the colour of the indicator in each tube after 2 hours. [4]
2. (b) Explain the colour in tube C. [2]

Yeast in glucose solution was connected to a gas syringe at 35 °C.Time / min: 0 | 2 | 4 | 6 | 8 | 10Volume of gas / cm³: 0 | 6 | 14 | 22 | 27 | 30

1. (a) Calculate the mean rate of gas production between 2 and 6 minutes, in cm³ per minute. [2]
2. (b) Describe how the rate changes after 6 minutes and suggest why. [2]
3. (c) Name the gas collected. [1]

A respirometer with 2 g of fly larvae and soda lime was placed in water baths at different temperatures. The distance moved by the drop in 10 minutes was recorded.Temperature / °C: 10 | 15 | 20 | 25 | 30Distance in 10 min / mm: 6 | 11 | 17 | 9 | 34

1. (a) Identify the anomalous result and suggest a reason for it. [2]
2. (b) Calculate the rate of movement of the drop at 30 °C in mm per minute. [1]
3. (c) Calculate how many times greater the distance was at 30 °C than at 10 °C, to 1 decimal place. [1]
4. (d) Explain why the rate of respiration increased with temperature. [2]
5. (e) Suggest two improvements to make the results more reliable. [2]

You are provided with dried yeast, 5 % glucose solution, boiling tubes with delivery tubes, gas syringes, water baths, thermometers, a stopwatch and vegetable oil.

1. (a) Plan an investigation to find the effect of temperature on the rate of anaerobic respiration of yeast. [6]

Twenty wheat grains had a total dry mass of 5.40 g. Twenty similar grains were germinated in the dark for 6 days, then dried in an oven; their dry mass was 4.32 g.

1. (a) Calculate the percentage decrease in dry mass. [2]
2. (b) Explain why the dry mass decreased. [2]
3. (c) Explain why dry mass, rather than fresh mass, was measured. [1]

1. (a) In which part of a cell does most aerobic respiration take place?A nucleusB mitochondriaC ribosomesD cell membrane [1]

1. (a) Write the word equation for aerobic respiration. [2]
2. (b) Write the balanced chemical equation for aerobic respiration. [2]

1. (a) Which process in the human body does NOT need energy from respiration?A contraction of musclesB active transport of glucose in the small intestineC diffusion of oxygen into the blood in the alveoliD building proteins from amino acids [1]

1. (a) State four uses of the energy released by respiration in the human body. [4]
2. (b) Define aerobic respiration. [2]

1. (a) Muscle cells in the legs of a cyclist contain many mitochondria. Explain why. [2]
2. (b) The middle piece of a sperm cell is packed with mitochondria. Suggest why. [1]
3. (c) Name the two substances that the blood must bring to muscle cells for aerobic respiration. [2]

Relative molecular masses: glucose 180, oxygen 32, carbon dioxide 44, water 18.C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

1. (a) Calculate the mass of oxygen needed to respire 36 g of glucose completely. Give your answer to 1 decimal place. [2]
2. (b) Calculate the mass of carbon dioxide produced, to 1 decimal place. [1]
3. (c) Show that mass is conserved in this reaction. [1]

For this question, assume that aerobic respiration releases 16.0 kJ per gram of glucose and anaerobic respiration in muscle releases 0.8 kJ per gram of glucose.

1. (a) Calculate how many times more energy is released per gram of glucose by aerobic respiration than by anaerobic respiration. [1]
2. (b) Calculate the mass of glucose needed to release 400 kJ by (i) aerobic respiration and (ii) anaerobic respiration. [2]
3. (c) Use these figures to explain why muscles cannot rely on anaerobic respiration for long periods. [2]