2023 Cambridge IGCSE Biology (0610) Practice Paper with Answers

The table shows the initial and final mass of four potato chips placed in four sucrose solutions of different concentrations.

$$\begin{array}{|c|c|c|} \hline \text{potato chip} & \text{initial mass / g} & \text{final mass / g} \\ \hline 1 & 2.5 & 2.8 \\ \hline 2 & 2.5 & 2.5 \\ \hline 3 & 2.5 & 2.2 \\ \hline 4 & 2.5 & 2.0 \\ \hline \end{array}$$

Which potato chip was placed in a solution with a water potential equal to that of the potato cells?

A student uses a potometer to measure the rate of water uptake of a leafy shoot. Under which combination of environmental conditions will the rate of water uptake be the slowest?

Which row correctly describes the state of the heart valves and the direction of blood flow when the ventricles contract?

A healthy person's glomerular filtrate contains glucose, but their urine does not. Which process is responsible for this difference?

Which row correctly matches the biological molecule with its monomer subunits and the positive result for its diagnostic test?

In humans, the allele for wet earwax ($$W$$) is dominant to the allele for dry earwax ($$w$$). A heterozygous father and a homozygous recessive mother have a child. What is the probability that their child will have dry earwax?

Consider the following food chain:

$$\text{phytoplankton} \rightarrow \text{zooplankton} \rightarrow \text{small fish} \rightarrow \text{herring} \rightarrow \text{seal}$$

Which organism represents both a secondary consumer and is at the third trophic level?

Which statement correctly describes the effect of pH on enzyme activity?

Which row correctly describes the features of active transport?

Which statement correctly explains why the wall of the left ventricle of the human heart is thicker than the wall of the right ventricle?

Under which combination of environmental conditions will the rate of transpiration in a plant be lowest?

Where in the human body is urea produced, and what is the source material from which it is formed?

A mother has blood group A and genotype \(I^A I^O\). The father has blood group B and genotype \(I^B I^O\). What is the probability that their first child will have blood group O?

Which statement describes a major advantage of conserving plant species in a seed bank rather than as grown plants in a botanical garden?

How does increasing the temperature from 20 °C to 35 °C affect an enzyme-catalysed reaction?

In the genetic modification of bacteria to produce human insulin, what is inserted into the bacterial cells to produce the hormone?

An epidermal strip from a red onion leaf is placed in a concentrated sucrose solution. Which observation correctly describes the appearance of the cells after 30 minutes?

The table shows the time taken for a starch-amylase mixture to turn completely yellow-brown when tested with iodine solution at different temperatures. At which temperature is the amylase activity the highest? (10 degrees C: 15 minutes, 25 degrees C: 8 minutes, 40 degrees C: 2 minutes, 55 degrees C: no change after 30 minutes)

A potometer is used to measure the rate of water uptake in a leafy shoot. Which set of environmental conditions will produce the lowest rate of transpiration?

Which statement correctly explains why the muscle wall of the left ventricle is thicker than the muscle wall of the right ventricle?

Which row correctly identifies the process that produces urea, the organ where it is produced, and the organ where it is excreted from the body?

A liquid food sample is tested. It gives a blue color with Benedict’s reagent after heating, a blue-black color with iodine solution, and a purple color with Biuret reagent. What does the sample contain?

In pea plants, the allele for tall height (T) is dominant to the allele for dwarf height (t). If a heterozygous tall plant is crossed with a dwarf plant, what is the probability that an offspring will be dwarf?

Consider this food chain: microscopic algae -> water flea -> small fish -> kingfisher. Which organism represents the secondary consumer?

The table shows some features of three processes by which substances move across cell membranes.

$$\begin{array}{|c|c|c|c|} \hline \text{process} & \begin{array}{c} \text{requires energy} \\ \text{from respiration} \end{array} & \begin{array}{c} \text{moves molecules against a} \\ \text{concentration gradient} \end{array} & \begin{array}{c} \text{movement of water} \\ \text{molecules only} \end{array} \\ \hline 1 & \text{no} & \text{no} & \text{no} \\ \hline 2 & \text{yes} & \text{yes} & \text{no} \\ \hline 3 & \text{no} & \text{no} & \text{yes} \\ \hline \end{array}$$

Which row correctly identifies processes 1, 2 and 3?

Which statement about enzymes is correct?

Why is the muscular wall of the left ventricle thicker than the muscular wall of the right ventricle in the human heart?

Which row correctly describes active and passive immunity?

$$\begin{array}{|c|c|c|} \hline & \text{active immunity} & \text{passive immunity} \\ \hline \text{A} & \begin{array}{c} \text{produced by the injection of} \\ \text{ready-made antibodies, providing} \\ \text{long-term protection} \end{array} & \begin{array}{c} \text{produced by infection with a} \\ \text{pathogen, providing} \\ \text{short-term protection} \end{array} \\ \hline \text{B} & \begin{array}{c} \text{produced by infection with a} \\ \text{pathogen, providing} \\ \text{short-term protection} \end{array} & \begin{array}{c} \text{produced by the transfer of} \\ \text{antibodies from mother to baby,} \\ \text{providing long-term protection} \end{array} \\ \hline \text{C} & \begin{array}{c} \text{produced by a vaccine containing} \\ \text{weakened pathogens, providing} \\ \text{long-term protection} \end{array} & \begin{array}{c} \text{produced by the injection of} \\ \text{ready-made antibodies, providing} \\ \text{short-term protection} \end{array} \\ \hline \text{D} & \begin{array}{c} \text{produced by the transfer of} \\ \text{antibodies from mother to baby,} \\ \text{providing short-term protection} \end{array} & \begin{array}{c} \text{produced by a vaccine containing} \\ \text{weakened pathogens, providing} \\ \text{long-term protection} \end{array} \\ \hline \end{array}$$

What is the correct pathway taken by a urea molecule from the site of its production until it is excreted from the human body?

A cross between a heterozygous tall pea plant ($Tt$) and a homozygous short pea plant ($tt$) is carried out. What is the expected ratio of phenotypes in the offspring?

Which sequence of events is correct during the genetic modification of bacteria to produce human insulin?

Which combination of environmental conditions would result in the highest rate of transpiration in a plant?

$$\begin{array}{|c|c|c|c|} \hline & \text{humidity} & \text{temperature} & \text{wind speed} \\ \hline \text{A} & \text{high} & \text{high} & \text{low} \\ \hline \text{B} & \text{low} & \text{low} & \text{high} \\ \hline \text{C} & \text{low} & \text{high} & \text{high} \\ \hline \text{D} & \text{high} & \text{low} & \text{low} \\ \hline \end{array}$$

Four equal-sized cylinders of potato tissue were placed in four sucrose solutions of different concentrations: 0.1 mol/dm³, 0.3 mol/dm³, 0.5 mol/dm³, and 0.7 mol/dm³. After two hours, the percentage change in mass of each cylinder was calculated. Which cylinder was placed in the most concentrated sucrose solution?

The rate of transpiration in a plant was measured under different environmental conditions. Which combination of factors will result in the lowest rate of transpiration?

An enzyme-catalysed reaction was carried out at different pH values while keeping all other variables constant. The rate of reaction was measured. At pH 2, the rate was very high. At pH 7, the rate was zero. Which enzyme is most likely responsible for this reaction?

Which chamber of the human heart has the thickest muscular wall, and into which blood vessel does it directly pump blood?

Which substances are filtered from the blood in the glomerulus into the Bowman's capsule of a healthy human kidney?

In a species of plant, the allele for red flowers (R) is dominant to the allele for white flowers (r). A heterozygous red-flowered plant is crossed with a white-flowered plant. What is the expected ratio of phenotypes in the offspring?

The list shows two food chains in an ecosystem:

1. Oak tree → Caterpillar → Blue tit → Hawk
2. Oak tree → Aphid → Ladybird → Blue tit

Which organism occupies the trophic levels of both secondary consumer and tertiary consumer?

During the production of human insulin using genetically modified bacteria, which structure is cut using restriction enzymes to allow the insertion of the human insulin gene?

1 (a) Active transport and diffusion are two methods by which substances move across cell membranes. Table 1.1 lists several features of these processes. Complete Table 1.1 by placing a tick (✓) in the correct column(s) for each feature. Some features may apply to one process, both processes, or neither process.

Table 1.1
Feature | Active transport | Diffusion
- movement of particles can occur down a concentration gradient | |
- requires energy released from respiration | |
- requires transport proteins in cell membranes | |
- occurs in non-living systems | |

(b) Explain why active transport is important in root hair cells.

(c) Describe how the rate of diffusion of oxygen into an animal cell is affected by:
(i) the concentration gradient of oxygen
(ii) the surface area of the cell membrane.

2 (a) Define the term transpiration.

(b) Explain how water moves upwards in xylem vessels, with reference to cohesion, adhesion, and transpiration pull.

(c) A student investigated the effect of wind speed on the rate of water uptake (transpiration rate) in a leafy shoot. Table 2.1 shows the results of this investigation.

Table 2.1
Wind speed / m s^{-1} | Rate of transpiration / g h^{-1}
0.5 | 1.2
1.5 | 2.6
2.5 | 4.1
3.5 | 5.2

Explain why the rate of transpiration increases as the wind speed increases from 0.5 m s^{-1} to 3.5 m s^{-1}.

(d) State two environmental factors, other than wind speed, that affect the rate of transpiration.

3 (a) Fig. 3.1 represents a diagrammatic cross-section through a human heart.
(i) State the name of the muscular wall that separates the left and right sides of the heart and describe its function.
(ii) Explain why the muscular wall of the left ventricle is much thicker than the muscular wall of the right ventricle.

(b) Describe the pathway taken by a red blood cell as it travels from the vena cava, through the heart chambers, to the lungs, and out through the aorta.

(c) Suggest two ways a doctor can monitor the activity of a patient's heart.

4 (a) Urea is a nitrogenous waste product excreted by the kidneys. Describe how urea is formed in the human body.

(b) State the name of:
(i) the blood vessel that carries deoxygenated blood away from the kidneys
(ii) the component of blood that transports dissolved urea to the kidneys.

(c) Describe the process of ultrafiltration and selective reabsorption in a kidney nephron.

(d) State why glucose is present in the fluid entering the nephron but is not normally found in the urine of a healthy person.

5 (a) State the chemical elements present in:
(i) carbohydrates
(ii) proteins.

(b) Table 5.1 shows three large biological molecules, the simpler molecules they are broken down into during digestion, and the enzymes that catalyse these reactions. Complete Table 5.1 by filling in the missing information.

Table 5.1
Large biological molecule | Simpler product molecules | Digestive enzyme
Starch | Maltose | (i)
Lipids (fats and oils) | (ii) | Lipase
Proteins | (iii) | Protease

(c) Explain why the rate of an enzyme-catalysed reaction decreases rapidly at temperatures above the optimum temperature.

6 (a) Outline the role of the placenta in supporting the growth and development of a fetus.

(b) The Rhesus blood group system is determined by a single gene. The allele for Rhesus-positive (D) is dominant to the allele for Rhesus-negative (d).
A Rhesus-negative woman has a child with a heterozygous Rhesus-positive man.
(i) State the genotype of the Rhesus-negative woman.
(ii) Complete a Punnett square to show the possible genotypes and phenotypes of the offspring of this couple.
(iii) State the probability that the child will be Rhesus-positive.

(c) Explain the difference between homozygous and heterozygous genotypes.

7 (a) State what is meant by the term endangered species.

(b) Farmers sometimes apply excessive amounts of chemical fertilisers to crop fields. Explain how the runoff of these fertilisers into a nearby lake can lead to eutrophication and the death of fish.

(c) Describe the role of seed banks in conserving endangered plant species.

### 1 A student investigated the nutrient content of three plant extracts:
- extract **X**
- extract **Y**
- extract **Z**

The student performed three food tests on each extract:

**Test 1: Testing for reducing sugars**
- Benedict's reagent was added to each extract and the tubes were placed in a hot water-bath for five minutes.
- *Observations:* Extract **X** and **Y** remained blue. Extract **Z** turned brick-red.

**Test 2: Testing for starch**
- Iodine solution was added to each extract on a white tile.
- *Observations:* Extract **X** turned blue-black. Extract **Y** and **Z** remained brown.

**Test 3: Testing for protein**
- Biuret reagent was added to each extract.
- *Observations:* Extract **Y** and **Z** turned purple. Extract **X** remained blue.

(a) (i) Prepare a table to record the observations for all three tests on each extract. Do not include conclusions in your table. [5]

(a) (ii) Using the observations, state which nutrients are present in each extract. [3]
- extract **X**:
- extract **Y**:
- extract **Z**:

(a) (iii) Identify one safety hazard associated with Test 1. [1]

(b) The concentration of vitamin C and fat in three different fruit juices, **P**, **Q**, and **R**, was determined.

It was found that:
- Juice **P** contained vitamin C only.
- Juice **Q** contained fat only.
- Juice **R** contained both vitamin C and fat.

(b) (i) State the reagent used when testing for vitamin C. [1]

(b) (ii) Describe the method for the emulsion test for fats. [2]

(b) (iii) The results for one of the juices are shown in Table 1.1.

**Table 1.1**
| test | observation |
|---|---|
| vitamin C | the solution remains blue / does not decolourise |
| fat | a cloudy white emulsion has formed |

Identify the juice from the results provided in Table 1.1. [1]
- juice:

(b) (iv) Explain how you identified the juice from the results provided in Table 1.1. [1]

(c) Three types of fresh fruit juices (pineapple, papaya, and kiwi) contain different concentrations of the enzyme protease. Protease catalyses the breakdown of protein (such as in gelatin or milk protein) to form soluble, clear products.

Plan an investigation to compare the concentrations of protease in the three types of fruit juice. [6]

### 2 (a) The nutrient content of diet can affect hemoglobin levels in the blood.

In a study, the dietary iron intake and hemoglobin levels of 100 male athletes were monitored over one year. The athletes were all between 18 and 30 years of age.

The scientists:
- calculated the mean daily iron intake for each athlete
- measured the change in hemoglobin concentration in their blood using standard lab assays.

The results for five of the athletes are shown in Table 2.1.

**Table 2.1**
| mean daily iron intake for each athlete / mg per day | mean change in hemoglobin concentration / g per dm³ per year |
|---|---|
| 5 | -8.5 |
| 10 | -4.2 |
| 15 | -0.5 |
| 20 | +1.5 |
| 25 | +3.8 |

(a) (i) Plot a line graph on a grid of the data in Table 2.1. [4]
*(Note: For this online question, outline the scales you would choose for both axes and describe the shape of the resulting curve.)*

(a) (ii) State two conclusions for the data in Table 2.1. [2]

(a) (iii) Identify the independent variable in this investigation. [1]

(a) (iv) Describe two variables that the scientists should have considered when selecting athletes for the study. [2]

(a) (v) Suggest a reason for a large number of athletes (100) being included in the study. [1]

(a) (vi) State one way this study is not representative of the general population. [1]

(a) (vii) A student stated that more athletes were gaining hemoglobin than were losing hemoglobin. Explain why this statement may not be correct for the data in this study. [1]

(b) Fig. 2.1 is a photograph of a broad bean seed.

$$\text{Line PQ runs from the top-left tip to the bottom-right tip across the seed. (Magnification } \times 1.5\text{)}$$

(b) (i) Make a large drawing of the seed shown in Fig. 2.1. [4]

(b) (ii) The length of line PQ represents the length of the seed in Fig. 2.1.
- Measure the length of line PQ on the photograph. Assume the measured length of line PQ is 90 mm.
- Use your measurement and the formula to calculate the actual length of the seed.
$$\text{magnification} = \frac{\text{length of line PQ on Fig. 2.1}}{\text{actual length of the seed}}$$
Give your answer to three significant figures. Show your working. [3]

(b) (iii) Fig. 2.2 shows a seed of the same species grown under nitrogen-deficient conditions.
State one way the seed in Fig. 2.2 would be different from the healthy seed in Fig. 2.1. [1]