Fungal cells and plant cells contain mitochondria. A scientist investigated the effect of sugar on respiration in yeast cells. One flask contained $$$100 \mathrm{~cm}^{3}$$$ of a sugar solution and another flask contained $$$100 \mathrm{~cm}^{3}$$$ of water. Both flasks contained the same mass of yeast. The temperature was maintained at $$$25^{\circ} \mathrm{C}$$$. The scientist used the apparatus shown in Fig. 1.1. Fig. 1.1 Fig. 1.2 is a graph of the results of the investigation. Fig. 1.2 (i) Using the gradient shown in Fig. 1.2, calculate the rate of carbon dioxide gas produced by the yeast in a sugar solution between 10 minutes and 15 minutes. Include the unit. Space for working. ............................................................ . (ii) Suggest the reason for the oil layer in the apparatus shown in Fig. 1.1. ....................................................................................................................................... . ....................................................................................................................................... . ................................................................................................................................. (iii) State one reason why no more carbon dioxide gas was produced after 35 minutes by the yeast in a sugar solution, shown in Fig. 1.2. ....................................................................................................................................... . ....................................................................................................................................... . ................................................................................................................................. (iv) The scientist repeated the investigation using yeast and the sugar solution at a temperature of $$$95^{\circ} \mathrm{C}$$$. Explain why no carbon dioxide was produced at a temperature of $$$95^{\circ} \mathrm{C}$$$. ....................................................................................................................................... . ....................................................................................................................................... . ....................................................................................................................................... . ....................................................................................................................................... . ....................................................................................................................................... . ....................................................................................................................................... . ....................................................................................................................................... . ....................................................................................................................................... . .................................................................................................................................

Biology

IGCSE&ALevel

CAIE

Exam No：0610_s24_qp_42 Year：2024 Question No：IGCSE&ALevel Biology2024IG0070

Answer:

Knowledge points:

11.1.1 List the features of gas exchange surfaces in humans, limited to large surface area, thin surface, good blood supply and good ventilation with air

11.1.10 Explain the role of goblet cells, mucus and ciliated cells in protecting the gas exchange system from pathogens and particles

11.1.2 Name and identify the lungs, diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries

11.1.3 State the differences in composition between inspired and expired air, limited to oxygen, carbon dioxide and water vapour Use limewater as a test for carbon dioxide to investigate the differences in composition between inspired and expired air

11.1.4 Investigate and describe the effects of physical activity on rate and depth of breathing

11.1.5 Name and identify the internal and external intercostal muscles

11.1.6 State the functions of the cartilage in the trachea

11.1.7 Explain the role of the ribs, the internal and external intercostal muscles and the diaphragm in producing volume and pressure changes in the thorax leading to the ventilation of the lungs

11.1.8 Explain the differences in composition between inspired and expired air

11.1.9 Explain the link between physical activity and rate and depth of breathing in terms of the increased carbon dioxide concentration in the blood, detected by the brain, causing an increased rate of breathing

11.2 pending

13.1.1 State that urea is formed in the liver from excess amino acids

13.1.10 Outline the structure and functioning of a kidney tubule, including

13.1.11 Explain dialysis in terms of salt balance, the maintenance of glucose concentration and the removal of urea

13.1.12 Describe the use of dialysis in kidney machines

13.1.13 Discuss the advantages and disadvantages of kidney transplants, compared with dialysis

13.1.2 State that carbon dioxide is excreted through the lungs

13.1.3 State that the kidneys excrete urea and excess water and salts

13.1.4 Explain that the volume and concentration of urine produced is affected by water intake, temperature and exercise

13.1.5 Identify on drawings, diagrams and images, the ureters, bladder and urethra

13.1.6 Describe the role of the liver in the assimilation of amino acids by converting them to proteins, including plasma proteins, e.g. fibrinogen

13.1.7 Define deamination as the removal of the nitrogen-containing part of amino acids to form urea

13.1.8 Explain the need for excretion, limited to toxicity of urea and carbon dioxide

13.1.9 Outline the structure of the kidney, limited to the cortex, medulla and ureter

Answer:

Knowledge points:

Solution:

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