Respiration (A-level only)
A student used a respirometer containing potassium hydroxide (KOH\text{KOH}KOH) solution to measure the rate of aerobic respiration in a population of active woodlice (Oniscus asellus).
During an experiment lasting 4 hours4\text{ hours}4 hours, a sample of 15 g of woodlice absorbed 5.4 × 10-3 cm3 of oxygen.
Apart from time, identify two measurements the student would need to make to determine the volume of oxygen absorbed by the woodlice in cm3\text{cm}^3cm3.
Calculate the rate of oxygen uptake by these woodlice in cm3 g−1 hour−1\text{cm}^3\text{ g}^{-1}\text{ hour}^{-1}cm3 g−1 hour−1. Give your answer in standard form (scientific notation).
A student investigated the rate of aerobic respiration in germinating mung beans (Vigna radiata) using a simple respirometer.
The germinating seeds were placed in a boiling tube connected to a capillary tube containing a colored indicator droplet. Potassium hydroxide solution was placed in the boiling tube to absorb any carbon dioxide produced, so that any pressure change was solely due to oxygen uptake.
At the start of the experiment (t=0t = 0t=0), the student recorded the position of the right edge of the indicator droplet as 1.8 cm1.8\text{ cm}1.8 cm on the ruler. The respirometer was placed in a water bath at 25∘C25^\circ\text{C}25∘C for 40 minutes40\text{ minutes}40 minutes.
The diagram below shows the final position of the indicator droplet and the centimeter ruler.
Use this information to calculate the rate of oxygen consumption in mm s−1\text{mm s}^{-1}mm s−1.
Give your answer in standard form and to 222 significant figures. Show your working.
A student investigated the rate of anaerobic respiration in yeast using a sucrose solution.
The student completely filled a small test tube with the yeast and sucrose mixture, inverted it inside a larger tube, and placed it in a water bath at 35∘C35^\circ\text{C}35∘C for 20 minutes20\text{ minutes}20 minutes. During this time, a bubble of carbon dioxide gas collected at the top of the small test tube.
The diagram below shows the bubble of carbon dioxide produced and a centimeter ruler aligned with the tube.
Use the information provided to calculate the rate of carbon dioxide production in mm s−1\text{mm s}^{-1}mm s−1.
Give your answer in standard form and to 2 significant figures. Show your working.
A student used a respirometer containing potassium hydroxide (KOH\text{KOH}KOH) solution to measure the rate of aerobic respiration in germinating mung beans.
During an experiment lasting 24 hours24\text{ hours}24 hours, a sample of 25 g25\text{ g}25 g of mung beans absorbed 4.8×10−3 cm34.8 \times 10^{-3}\text{ cm}^34.8×10−3 cm3 of oxygen.
Apart from time, identify two measurements the student would need to make to determine the volume of oxygen absorbed by the mung beans in cm3\text{cm}^3cm3.
Calculate the rate of oxygen uptake by these mung beans in cm3 g−1 hour−1\text{cm}^3\text{ g}^{-1}\text{ hour}^{-1}cm3 g−1 hour−1. Give your answer in standard form (scientific notation).
A student set up the respirometer shown below to measure the rate of aerobic respiration in a population of woodlice (Oniscus asellus).
During a measuring period of 6 hours6\text{ hours}6 hours, the coloured liquid in the capillary tubing moved a distance of 4.5 cm.
The diameter of the lumen (internal bore) of the capillary tubing was 0.4 mm.
The volume of a cylinder is given by πr2l\pi r^2 lπr2l, where π \pi\,π is 3.14 and l=l =l= length.
Calculate the rate of oxygen consumption by the woodlice in cm3 hour−1\text{cm}^3\text{ hour}^{-1}cm3 hour−1. Give your answer in standard scientific notation. Show your working.
A student used a respirometer to determine the rate of oxygen consumption of active woodlice. Over a measurement interval of 40 minutes40\text{ minutes}40 minutes, the coloured liquid in the capillary tube was observed to move a distance of 3.6 cm3.6\text{ cm}3.6 cm.
The internal diameter of the capillary tube lumen was 0.5 mm0.5\text{ mm}0.5 mm.
The volume of a cylinder is calculated using the formula πr2l\pi r^2 lπr2l, where π=3.14\pi = 3.14π=3.14 and lll represents length.
Calculate the rate of oxygen consumption in cm3 hour−1\text{cm}^3\text{ hour}^{-1}cm3 hour−1. Show your working and give your answer to an appropriate number of significant figures.
A student investigated the rate of aerobic respiration in germinating pea seeds using a respirometer containing potassium hydroxide solution to absorb carbon dioxide.
The student placed the germinating seeds inside the respirometer chamber and connected it to a horizontal capillary tube containing a small droplet of colored liquid. The apparatus was placed in a water bath at 20∘C20^\circ\text{C}20∘C for 18 minutes18\text{ minutes}18 minutes. As the seeds absorbed oxygen, the colored liquid droplet moved along the tube towards the chamber.
The diagram below shows the positions of the colored liquid droplet at the start (0 min0\text{ min}0 min) and at the end (18 min18\text{ min}18 min) of the experiment, alongside a centimeter ruler aligned with the capillary tubes.
Use the diagram to calculate the rate of droplet movement in mm s−1\text{mm s}^{-1}mm s−1.
Give your answer in standard form and to 222 significant figures. Show your working.
Scientists investigated the effect of long-term endurance training on skeletal muscle fibres in humans. They compared biopsy samples from the vastus lateralis muscle of elite marathon runners (endurance-trained) with those of sedentary individuals (untrained control). The sections of muscle fibres were stained to show the activity of cytochrome c oxidase, an enzyme in the electron transport chain of aerobic respiration. Darker staining indicates higher enzyme activity.
Suggest one reason for the average difference in staining intensity between the muscle fibres of the endurance-trained runners and the sedentary individuals.
The endurance-trained runners were able to sustain prolonged high-intensity aerobic exercise for much longer than the sedentary group. Explain why.
The scientists determined the mean diameter of the muscle fibres using an optical microscope. The circular field of view had an area of 2.01 mm22.01\text{ mm}^22.01 mm2. The diameter of this circular area was equal to the width of 25 muscle fibres lined up side-by-side. Use Area=πr2\text{Area} = \pi r^2Area=πr2 to calculate the mean diameter of a muscle fibre in micrometres (μm\mu\text{m}μm). Show your working.
A cyclist completed an incremental ramp fitness test on a stationary ergometer. The work rate (exercise intensity) was increased every 2 minutes. The test finished when the cyclist reached exhaustion. During the test, the fraction of oxygen in expired air (FEO2F_EO_2FEO2) and the fraction of carbon dioxide in expired air (FECO2F_ECO_2FECO2) were measured.
Figure 1 shows the results of the cyclist's test.
The respiratory compensation point (RCP) is a marker of high-intensity exercise tolerance when hyperventilation occurs to compensate for metabolic acidosis, significantly altering the composition of expired gases.
The RCP can be identified as the point when there is a systematic, sharp increase in the fraction of oxygen in expired air (FEO2F_EO_2FEO2) without any further increase in the fraction of carbon dioxide in expired air (FECO2F_ECO_2FECO2).
Use Figure 1 to determine the time after the exercise started when the cyclist reached RCP.
Calculate the ratio of FEO2F_EO_2FEO2 to FECO2F_ECO_2FECO2 in expired air at this time. Show your working.
Scientists investigated the metabolic adaptations of avian muscle tissues for long-distance flight. They compared biopsy samples from the pectoralis (breast) muscle of migratory bar-tailed godwits (capable of non-stop endurance flight) with those of domestic chickens (non-migratory controls). The sections of muscle fibres were stained to show the activity of succinate dehydrogenase, an enzyme in the citric acid cycle of aerobic respiration. Darker staining indicates higher enzyme activity.
Suggest one reason for the average difference in staining intensity between the muscle fibres of the migratory godwits and the non-migratory domestic chickens.
The migratory godwits were able to sustain continuous high-intensity flight across oceans for several days, whereas the domestic chickens could only sustain short bursts of flapping. Explain why.
The scientists determined the mean diameter of the muscle fibres using an optical microscope. The circular field of view had an area of 2.85 mm22.85\text{ mm}^22.85 mm2. The diameter of this circular area was equal to the width of 32 muscle fibres lined up side-by-side.
Use Area=πr2\text{Area} = \pi r^2Area=πr2 to calculate the mean diameter of a muscle fibre in micrometres (μm\mu\text{m}μm). Show your working.
Respiration (A-level only) Questions
Practise AQA A Level Biology Respiration (A-level only) with exam-style questions for A Level Biology. 18 questions, matched to the AQA A Level Biology (7402) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.