2023 Cambridge IGCSE Biology (0610) Practice Paper with Answers

Which row correctly identifies the products of anaerobic respiration in yeast cells and in human muscle cells?

Four cylinders of potato tissue, each of equal initial mass of 5.0 g, were placed in sucrose solutions of different concentrations. After one hour, the final mass of each cylinder was measured:

- Cylinder W: final mass 5.8 g
- Cylinder X: final mass 5.2 g
- Cylinder Y: final mass 4.8 g
- Cylinder Z: final mass 4.1 g

In which solutions did water leave the potato cells by osmosis?

What is the correct pathway of an oxygen molecule as it diffuses from the lumen of an alveolus into the blood?

Which row correctly matches a region of the alimentary canal with its function?

Which statement describes how DNA controls the production of a specific protein in a cell?

A student draws a plant cell. The actual length of the cell is 0.08 mm. The student's drawing of the cell has a length of 40 mm. What is the magnification of the student's drawing?

Which row correctly compares natural selection and artificial selection?

Which statement describes the effect of a very high temperature (above \(60^\circ\text{C}\)) on an enzyme-controlled reaction?

A respirometer is used to measure the rate of respiration in germinating seeds. It contains potassium hydroxide solution to absorb carbon dioxide. During the experiment, the level of liquid in the capillary tube moves towards the test-tube containing the seeds. Which process causes this movement of liquid?

Four cylinders of potato tissue were weighed and placed in sucrose solutions of different concentrations: \(0.0\text{ mol/dm}^3\), \(0.2\text{ mol/dm}^3\), \(0.4\text{ mol/dm}^3\), and \(0.6\text{ mol/dm}^3\). After two hours, they were reweighed and the percentage change in mass was calculated. In which solution would the potato cylinders show the greatest increase in mass, and in which solution would they show the greatest decrease in mass?

Which row correctly shows the approximate percentages of oxygen, carbon dioxide, and nitrogen in expired air under normal resting conditions?

An aquatic plant was placed in a beaker of water under a light source. The rate of photosynthesis was determined by counting the number of oxygen bubbles released per minute. Which modification would increase the rate of bubble production?

Where is amylase produced, and where does it carry out its function in the human digestive system?

Which statement correctly describes the relationship between DNA, genes, and chromosomes?

A student observes a palisade mesophyll cell under a microscope. The actual length of the cell is \(0.08\text{ mm}\). In the student's drawing, the cell is \(40\text{ mm}\) long. What is the magnification of the drawing?

Which statement about natural selection is correct?

During vigorous exercise, human muscle cells respire anaerobically. Yeast cells also undergo anaerobic respiration when oxygen is absent. Which row correctly compares the products of anaerobic respiration in human muscle cells and in yeast cells?

Four similar cylinders of potato tissue were immersed in sucrose solutions of different concentrations: \(0.0\text{ mol/dm}^3\), \(0.2\text{ mol/dm}^3\), \(0.6\text{ mol/dm}^3\), and \(0.8\text{ mol/dm}^3\) for two hours. Which solution concentration would cause the potato cells to become flaccid and show the greatest percentage decrease in mass?

What are the changes in the volume of the thorax and the pressure in the lungs when a person inhales?

At a certain light intensity, a plant has a photosynthetic rate of 25 units at \(15\text{ }^\circ\text{C}\) and \(0.04\%\) \(\text{CO}_2\). When the temperature is increased to \(25\text{ }^\circ\text{C}\) (with \(\text{CO}_2\) kept at \(0.04\%\)), the rate remains 25 units. When the \(\text{CO}_2\) concentration is increased to \(0.1\%\) (at \(15\text{ }^\circ\text{C}\)), the rate increases to 45 units. Which factor is limiting the rate of photosynthesis at \(15\text{ }^\circ\text{C}\) and \(0.04\%\) \(\text{CO}_2\)?

Which row correctly describes the production, storage, and site of action of bile in the human digestive system?

A student measures a drawing of a plant cell. The measured width of the drawing is \(48\text{ mm}\). The actual width of the plant cell is \(80\text{ }\mu\text{m}\). What is the magnification of the drawing?

The sequence of bases in a short section of a DNA template strand is: \(\text{A-T-G-C-C-G-T-A-A}\). What is the sequence of bases in the mRNA strand transcribed from this DNA template?

Which statement describes a feature that is characteristic of natural selection but NOT of artificial selection?

A student places epidermal cells of a red onion in a highly concentrated sucrose solution. Which row correctly describes the net movement of water and the appearance of the cells after 30 minutes?

Red blood cells were placed into two different solutions: distilled water and a \(5.0\%\) concentrated salt solution. Which row correctly describes the changes observed in the appearance of these cells?

Which statement correctly describes aerobic respiration?

Yeast cells and human muscle cells can both perform anaerobic respiration when oxygen is absent. Which row correctly identifies the chemical products of anaerobic respiration in each of these cell types?

How do the structural features of an alveolus and its associated capillary network maximize the rate of diffusion of oxygen into the blood?

Which sequence of events correctly describes the synthesis of a protein from the genetic code in DNA?

A micrograph shows a mitochondrion. The actual length of the mitochondrion is \(2.5\ \mu\text{m}\). The image length of the mitochondrion in the micrograph is \(5.0\text{ cm}\). What is the magnification of this micrograph?

The rate of an enzyme-controlled reaction was monitored at various temperatures. Which statement correctly explains why the rate of reaction drops rapidly to zero at temperatures significantly above the optimum temperature?

Which row correctly identifies the products of anaerobic respiration in yeast cells and human muscle cells, and the relative amount of energy released per glucose molecule compared to aerobic respiration?

Four cylinders of potato tissue, each with an initial length of 40 mm, are placed into four different test-tubes containing sucrose solutions of different concentrations. After two hours, the lengths of the potato cylinders are measured. Tube 1 (0.0 mol/dm3) has a final length of 43 mm. Tube 2 (0.2 mol/dm3) has a final length of 41 mm. Tube 3 (0.5 mol/dm3) has a final length of 39 mm. Tube 4 (0.8 mol/dm3) has a final length of 37 mm. Which concentration is closest to the sucrose concentration inside the potato cells?

The list shows some of the structures through which a molecule of oxygen passes as it travels from the trachea to a red blood cell in a capillary: 1. Alveolar wall, 2. Bronchiole, 3. Bronchus, 4. Capillary wall. Which sequence represents the correct path taken by the oxygen molecule?

An experiment is set up to investigate the effect of light intensity on the rate of photosynthesis of an aquatic plant under different conditions of temperature and carbon dioxide concentration. Condition X: 15 degrees Celsius and 0.04% carbon dioxide. Condition Y: 25 degrees Celsius and 0.04% carbon dioxide. Condition Z: 25 degrees Celsius and 0.15% carbon dioxide. At high light intensities, the rate of photosynthesis is higher in Condition Z than in Condition Y, but it is the same in Condition X and Condition Y. Which factor is limiting the rate of photosynthesis at high light intensities in Condition Y?

Which row correctly identifies where bile is produced, where bile is stored, and where bile acts in the human alimentary canal?

A structural protein consists of a chain of 240 amino acids. What is the minimum number of bases in the coding region of the mRNA molecule, and the minimum number of base pairs in the DNA gene required to code for this protein?

A student uses a light microscope to view a plant palisade cell. The image of the cell under the microscope has a length of 7.5 cm. The actual length of the palisade cell is 150 \(\mu\text{m}\). What is the magnification of the image?

Which statement is a feature of artificial selection but not of natural selection?

Fig. 1.1 shows a setup used to investigate anaerobic respiration in yeast.

(a) Define the term *anaerobic respiration*. [2]

(b) Compare anaerobic respiration in yeast cells with anaerobic respiration in human muscle cells during vigorous exercise. [4]

(c) Yeast is widely used in bread-making. Explain how the products of anaerobic respiration in yeast contribute to the process of making bread and explain why bread is not an alcoholic food product. [4]

(d) During an investigation, yeast produced \( 12.0\text{ cm}^3 \) of carbon dioxide in 10 minutes at 20°C. When the temperature was increased to 30°C, the volume of carbon dioxide produced in 10 minutes was \( 27.6\text{ cm}^3 \). Calculate the percentage increase in the rate of carbon dioxide production. Show your working. [3]

A student investigated the effect of different sucrose concentrations on the mass of sweet potato cylinders.

(a) Define *osmosis* with reference to water potential. [3]

(b) A sweet potato cylinder had an initial mass of 4.50 g. After being placed in a 0.8 mol/dm³ sucrose solution for 2 hours, its final mass was 3.78 g. Calculate the percentage change in mass of this cylinder. Show your working. [3]

(c) Explain, in terms of water potential, why the sweet potato cylinder decreased in mass when placed in the 0.8 mol/dm³ sucrose solution. [4]

(d) Describe how the student could use a graph of percentage change in mass against sucrose concentration to determine the concentration of sucrose that is equal to the internal water potential of the sweet potato cells. [3]

The gas exchange system in humans is adapted to maximize the rate of diffusion of respiratory gases.

(a) State three structural features of the alveoli that adapt them for efficient gas exchange. [3]

(b) Explain how goblet cells and ciliated cells work together to protect the lungs from pathogens and dust. [4]

(c) Emphysema is a chronic lung disease often caused by long-term tobacco smoking. Explain how emphysema affects gas exchange in the lungs. [4]

(d) Table 3.1 shows the percentage of oxygen and carbon dioxide in inspired and expired air.

| Gas | Inspired air (%) | Expired air (%) |
|---|---|---|
| Oxygen | 21.0 | 16.0 |
| Carbon dioxide | 0.04 | 4.00 |

Explain the differences in the percentages of oxygen and carbon dioxide between inspired and expired air. [2]

Photosynthesis is the process by which plants manufacture carbohydrates.

(a) Write the balanced chemical equation for photosynthesis. [3]

(b) Describe how a student could investigate the effect of light intensity on the rate of photosynthesis in an aquatic plant, such as *Elodea*. [4]

(c) Explain why, at high light intensities, the rate of photosynthesis in a plant may reach a plateau (level off) and no longer increase. [3]

(d) Outline the role of chlorophyll in photosynthesis and name the mineral ion required by plants to synthesize it. [3]

The human digestive system is specialized for physical and chemical digestion.

(a) Identify the specific region of the human alimentary canal where:
(i) Amylase, lipase, and trypsin are all secreted. [1]
(ii) Bile is stored before being released into the duodenum. [1]
(iii) The majority of water is absorbed. [1]

(b) Describe the role of bile in the digestion of fats. [4]

(c) Explain how the structure of a villus is adapted to maximize the absorption of digested food molecules. [5]

(d) State the function of lacteals located inside the villi. [1]

DNA is the genetic material that carries instructions for the synthesis of proteins.

(a) Describe the structure of a DNA molecule. [4]

(b) Define the term *gene*. [2]

(c) Explain how the sequence of bases in a gene determines the specific structure of a protein, including the roles of mRNA and ribosomes. [5]

(d) Explain why a change in the DNA base sequence of a gene can result in an enzyme that does not function. [2]

Complete all practical tasks, record all experimental observations in the spaces provided, and complete the design task. ### Question 1 Yeast cells respire glucose or sucrose, releasing carbon dioxide and transferring hydrogen to hydrogen-acceptor molecules. Methylene blue is a blue dye that acts as an artificial hydrogen acceptor; it becomes colourless when reduced by respiring yeast cells. You are going to investigate the effect of different concentrations of sucrose solution on the rate of respiration in yeast. You are provided with: - Active yeast suspension, labelled **Yeast** - 10% sucrose solution, labelled **S1** - Distilled water, labelled **Water** - 0.1% methylene blue solution, labelled **Indicator** - Test-tubes, syringes, a water bath maintained at 35 °C, and a stopwatch. **(a)** Describe how you would prepare 10 cm³ of a 5% sucrose solution using the 10% sucrose solution (**S1**) and distilled water (**Water**). [2] **(b)** A student performed the investigation using 10% (**S1**), 5%, 2% and 0% (distilled water) sucrose solutions. The student mixed 5 cm³ of yeast suspension, 5 cm³ of the respective sucrose solution, and 1 cm³ of methylene blue solution in a test-tube. The tube was placed in a water bath maintained at 35 °C. The time taken for the methylene blue to lose its blue colour and turn colourless was recorded using a stopwatch. Three trials were carried out for each concentration. **(i)** Prepare a table to record the results of this investigation. Your table must show: - the concentration of sucrose solution (%) - the volume of 10% sucrose solution (**S1**) used to prepare 10 cm³ of each solution (cm³) - the volume of distilled water used to prepare 10 cm³ of each solution (cm³) - the time taken for the blue colour to disappear for each of the three trials (seconds) - the mean time taken (seconds). [4] **(ii)** The student recorded the following raw times: - For 10% sucrose: 145 s, 151 s, 148 s - For 5% sucrose: 280 s, 292 s, 286 s - For 2% sucrose: 580 s, 610 s, 595 s - For 0% sucrose: Did not decolourise after 15 minutes (900 s) in all three trials. Calculate the mean time taken for the 10% sucrose solution to decolourise. Show your working. [2] **(iii)** Calculate the rate of respiration for the 10% and 5% sucrose solutions using the formula: \(\text{Rate} = \frac{1000}{\text{mean time in seconds}}\). State the unit of rate as \(\text{s}^{-1}\). Show your working. [3] **(c)** State three variables that must be controlled in this investigation to ensure valid results. [3] **(d) (i)** Identify one potential source of error in this method. [1] **(ii)** Suggest an improvement to overcome the error identified in **(d)(i)**. [1] **(e)** Yeast respiration is affected by temperature. Design an investigation to find the effect of temperature on the rate of anaerobic respiration in yeast. [4]

Complete all practical tasks, record all experimental observations in the spaces provided, and complete the design task. ### Question 2 Potato tissue is composed of cells containing cell walls, cell membranes, cytoplasm, a vacuole, and starch grains. An investigation was carried out to study the effect of placing potato cylinders in different concentrations of sodium chloride (salt) solution. Potato cylinders of equal initial length (50.0 mm) were prepared and placed in test-tubes containing five different concentrations of sodium chloride solution (0.0, 0.2, 0.4, 0.6 and 0.8 mol dm⁻³). The cylinders were left in the solutions for 60 minutes. They were then removed, blotted dry with paper towels, and their final lengths were measured. The results are shown in Table 2.1. Table 2.1 - Concentration 0.0 mol dm⁻³: Initial length 50.0 mm, Final length 54.0 mm, Change in length +4.0 mm, Percentage change +8.0% - Concentration 0.2 mol dm⁻³: Initial length 50.0 mm, Final length 52.0 mm, Change in length +2.0 mm, Percentage change +4.0% - Concentration 0.4 mol dm⁻³: Initial length 50.0 mm, Final length 49.5 mm, Change in length -0.5 mm, Percentage change -1.0% - Concentration 0.6 mol dm⁻³: Initial length 50.0 mm, Final length 47.5 mm, Change in length -2.5 mm, Percentage change -5.0% - Concentration 0.8 mol dm⁻³: Initial length 50.0 mm, Final length 45.5 mm, Change in length -4.5 mm, Percentage change -9.0% **(a) (i)** Plot a line graph on a grid of the percentage change in length (y-axis) against the concentration of sodium chloride solution (x-axis). [4] **(ii)** Use your graph to estimate the concentration of sodium chloride solution at which there is no change in length of the potato cylinders. [1] **(iii)** Explain, in terms of osmosis, why the potato cylinder in the 0.0 mol dm⁻³ solution increased in length. [3] **(iv)** Explain why calculating the percentage change in length is better than using the raw change in length when comparing samples of potato tissue. [1] **(b)** Describe how you would carry out a food test to show that potato cells contain starch. State the reagent used and the positive result. [2] **(c)** Fig. 2.1 represents a photomicrograph of a potato cell containing starch grains. The length of one large starch grain in the photomicrograph is measured as 42 mm. The actual length of this starch grain is 0.07 mm. Calculate the magnification of the starch grain in the photomicrograph. Show your working using the formula \(\text{Magnification} = \frac{\text{Image size}}{\text{Actual size}}\). [2] **(d)** Fig. 2.2 shows a diagram of a potato cell. The cell has a thick cell wall drawn with a double line, a thin inner cell membrane, a large central vacuole, and five oval starch grains of different sizes inside. In the space below, make a large, clear line drawing of this potato cell. Do not label the drawing. [4] **(e)** Design an experiment using model agar blocks to investigate the effect of surface area to volume ratio on the rate of diffusion. [3]