Anaerobic respiration

Which statements about alcohol are correct?

May/June 2015

Which word equation represents anaerobic respiration in yeast?

May/June 2015

Fig. 1.1 illustrates how temperature influences the rate at which yeast cells in a nutrient solution give off bubbles of a gas.

May/June 2015

In the production of alcohol, why is it necessary to keep air out of the fermenter?

May/June 2016

During alcohol production, why must the fermenter be kept free of air?

May/June 2016

What is produced during anaerobic respiration in muscles?

May/June 2017

The diagram shows a simple apparatus that could be used to make alcohol. What function does the U-shaped tube filled with water serve?

May/June 2017

The diagram illustrates stages involved in cheese production. During which stage does pH fall significantly?

May/June 2017

Yeast is used in bread-making. Why is there little or no alcohol in the bread?

May/June 2018

Which chemicals are formed during anaerobic respiration in yeast cells?

May/June 2018

Which of the following statements about anaerobic respiration in humans is correct?

May/June 2019

Waste products from microorganisms are used in the making of bread and yoghurt. Which waste products from microorganisms are involved in these processes?

May/June 2019

A seal is a mammal that lives mainly in the sea. Its breathing and respiration are very much like those of a human, but when it dives to chase and catch fish, it can remain underwater for as long as 20 minutes. The graph shows how the percentage concentrations of oxygen and carbon dioxide, together with the concentration of lactic acid, change in a seal’s blood over a 40 minute period while it dives to hunt and catch fish.

May/June 2019

Four flasks are sterilised and arranged as shown. Which flask will show evidence of fermentation (anaerobic respiration) after one hour?

May/June 2022

Four flasks are sterilised and arranged as shown. Which flask will show evidence of fermentation (anaerobic respiration) after one hour?

May/June 2022

Which equation represents the type of respiration that can lead to an ‘oxygen debt’ in muscles during vigorous exercise?

May/June 2023

The diagram illustrates apparatus arranged for the production of alcohol by fermentation. What is the function of the layer of oil?

May/June 2023

During anaerobic respiration in yeast cells, what substance is used, and which substances are formed?

May/June 2023

Which equation shows anaerobic respiration in humans?

May/June 2024

What substance is made during anaerobic respiration in muscles?

May/June 2024

What feature is characteristic of anaerobic respiration in humans?

May/June 2025

During a sprint race, athletes can experience sharp muscle pain because the respiring cells generate

Oct/Nov 2016

Two distinct strains, A and B, from the same microorganism species are used to make bread and beer (an alcoholic drink). Fig. 1.1 shows the amount of gas given off by the strains while they are in use.

Oct/Nov 2016

Describe and explain the benefits to a person of the bodily changes that occur during physical activity such as a 400 m running race.

Oct/Nov 2016

When there is a shortage of which substance does anaerobic respiration occur?

Oct/Nov 2017

In what way do bacteria turn milk into yoghurt?

Oct/Nov 2017

Two containers, X and Y, were each filled with the same amount of dough mixture for bread making. Yeast was added to the mixture in Y. The containers were then placed in a warm place for two hours. The diagram shows how they looked after this period. Which substance made by the yeast is responsible for the difference between containers X and Y?

Oct/Nov 2017

Following a meal, the pH in the mouth falls. Which statement best explains this fall?

Oct/Nov 2017

Containers X and Y each contained the same amount of dough mixture for bread-making. Yeast was added to the mixture in Y. Both containers were then kept in a warm place for two hours. The diagram shows what they looked like after this time. Which substance made by the yeast is responsible for the difference between containers X and Y?

Oct/Nov 2017

By the breakdown of two molecules of glucose in anaerobic respiration, how many molecules of lactic acid will be produced?

Oct/Nov 2018

By what process does anaerobic respiration in muscle cells lead to a decrease in blood pH?

Oct/Nov 2018

In the production of which materials is yeast used?

Oct/Nov 2018

While an athlete is racing, the muscles in the legs need more energy than aerobic respiration can provide. Which substance accumulates in the leg muscles and leads to pain?

Oct/Nov 2019

As cheese is produced, the pH of milk decreases and this makes the milk proteins coagulate. What is the principal reason for the pH becoming lower?

Oct/Nov 2019

Which equation shows anaerobic respiration in humans?

Oct/Nov 2019

Which products are formed during anaerobic respiration in yeast?

Oct/Nov 2020

Anaerobic respiration occurs when which substance is absent?

Oct/Nov 2020

The apparatus illustrated is used to produce alcohol by anaerobic respiration. What do P, Q and R represent?

Oct/Nov 2020

Yeast is used in alcohol production. What is the other product formed in this process?

Oct/Nov 2021

What is the principal function of yeast in the production of beers and wines?

Oct/Nov 2021

Which equation shows anaerobic respiration in yeast?

Oct/Nov 2022

Two containers, X and Y, were each given the same amount of dough mixture for bread-making. Yeast was added to the mixture in Y. Both containers were then kept in a warm place for two hours. The diagram shows how they looked after this time. Which substance made by the yeast causes the difference between the dough in X and Y?

Oct/Nov 2022

Fitness training for athletes lowers the need for anaerobic respiration. It also increases the speed at which lactic acid is removed after exercise. The table gives the concentration of lactic acid in the blood of four different athletes. They exercise for 20 minutes and then rest for the following 70 minutes. The lactic acid concentration is measured in $\text{mg per }100\,\text{cm}^3$ of blood. Starting with the fittest athlete and ending with the least fit, which sequence is correct?

Oct/Nov 2022

Two containers, X and Y, were each filled with the same quantity of dough mixture for bread-making. Yeast was added to the mixture in Y. Both containers were then kept in a warm place for two hours. The diagram shows how they looked after this period. Which substance made by the yeast is responsible for the difference between the dough in X and Y?

Oct/Nov 2022

Lions are carnivorous mammals that prey on other animals. A lion’s forelimb is built on the same basic plan as a human arm.

Oct/Nov 2022

What substances are produced by anaerobic respiration in muscle?

Oct/Nov 2023

Which label indicates the site where lactic acid is broken down?

Oct/Nov 2023

Which apparatus can be used to investigate how carbon dioxide is produced by the anaerobic respiration of yeast?

Oct/Nov 2023

Three flasks were arranged as shown at $35\,^{\circ}\text{C}$. A balloon was fitted to the mouth of each flask. Flask 1 contains water, yeast and sugar. Flask 2 contains water and sugar. Flask 3 contains water and yeast. The degree of balloon inflation was noted after one hour. In what order are the balloons arranged from the one that is most inflated to the one that is least inflated?

Oct/Nov 2023

Yeast obtains energy for growth and reproduction by breaking down sugar (glucose) through anaerobic respiration: glucose → carbon dioxide + alcohol In human food, sugar is added to give a sweet taste. If the diet contains too much sugar, diseases can develop. Sugar substitutes are available and taste as sweet as sugar. A student chose to find out whether yeast could use a sugar substitute for respiration. Three test-tubes were arranged as shown in Table 1.1. Each test-tube was given a label so that it could be recognised. The level of the mixtures in each test-tube was marked with a water-resistant marker. This showed the starting level. When yeast respires, bubbles of gas are produced and trapped in the mixture, causing the level of the mixture to rise up the test-tube. The student used a large beaker as a water-bath to keep the temperature of the test-tubes constant in this investigation. The temperature of the water at the start was $35\,^{\circ}\text{C}$. The intention was to keep this temperature the same throughout the investigation by adding hot or cold water. The three test-tubes were placed in the water-bath, and a timer was started. At 5 minutes, 10 minutes and 15 minutes, the distances moved by the mixtures from the starting levels were measured and recorded. The temperature of the water-bath was also recorded. Fig. 1.1 shows the lower parts of the test-tubes at 5 minutes and the water-bath thermometer reading at 5 minutes. Fig. 1.2 shows the results for 10 and 15 minutes recorded in the student’s notebook.

Oct/Nov 2024

During strenuous exercise, lactic acid accumulates in the muscles. Blood flowing away from these muscles will contain a high concentration of lactic acid. Which process is responsible for removing most of the lactic acid from the blood?

Oct/Nov 2025

The apparatus shown is used to investigate the volume of gas produced by yeast during anaerobic respiration. What is the reason for covering the yeast mixture with a thin layer of oil during this investigation?

Oct/Nov 2025

Bread is produced from a blend of flour, sugar, water and yeast. The mixture is kept in a warm place so that it can rise before it is baked. Which process causes the bread to rise?

Oct/Nov 2025