2024 Cambridge IGCSE Biology (0610) 模擬試題連答案詳解

Which changes will increase the rate of diffusion of oxygen into an active muscle cell? 1. An increase in the temperature of the cell. 2. An increase in the surface area of the cell membrane. 3. A decrease in the concentration of oxygen inside the cell.

What is the primary function of the amniotic sac and amniotic fluid during human pregnancy?

A person walks out of a dark room into bright sunlight. Which row correctly describes the response of the iris muscles and the change in pupil size?

The rate of photosynthesis in a glasshouse crop is limited by carbon dioxide concentration. Which modification inside the glasshouse would most effectively increase the rate of photosynthesis?

A plant shoot is illuminated from one side. Which statement correctly describes the distribution of auxin and its effect on the cells in this shoot?

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

Which structural feature of an intestinal villus is correctly matched with its adaptation for absorption?

By which process does carbon dioxide leave an active respiring muscle cell, and how does its concentration in the cell compare to that in the surrounding capillary blood?

The table shows the concentration of a solute inside four different animal cells and in the surrounding extracellular fluid.

$$\begin{array}{|c|c|c|} \hline \text{Cell} & \text{Concentration in cytoplasm / mmol dm}^{-3} & \text{Concentration in extracellular fluid / mmol dm}^{-3} \\\\ \hline \text{W} & 2 & 12 \\\\ \hline \text{X} & 12 & 2 \\\\ \hline \text{Y} & 5 & 8 \\\\ \hline \text{Z} & 8 & 5 \\\\ \hline \end{array}$$

Through which cell membrane will there be the fastest net movement of this solute **into** the cell by diffusion?

Which pathway correctly shows the route taken by a sperm cell from its site of production until it can fertilise an egg cell?

A person is looking at a star in the night sky. They then look down to read a message on their mobile phone screen.

Which changes must occur in the ciliary muscles and the suspensory ligaments to focus on the mobile phone screen?

At a very low light intensity, a plant was supplied with an increased concentration of carbon dioxide. However, the rate of photosynthesis did not change.

What was the limiting factor for photosynthesis under these conditions?

A plant shoot is growing with light shining from one side only.

Which statement correctly describes the movement of auxin and the resulting growth of the shoot?

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

$$\begin{array}{|c|c|c|} \hline & \text{Products in human muscle cells} & \text{Products in yeast cells} \\\\ \hline \text{A} & \text{lactic acid only} & \text{alcohol (ethanol) and carbon dioxide} \\\\ \hline \text{B} & \text{lactic acid and carbon dioxide} & \text{alcohol (ethanol) only} \\\\ \hline \text{C} & \text{alcohol (ethanol) and carbon dioxide} & \text{lactic acid only} \\\\ \hline \text{D} & \text{lactic acid only} & \text{lactic acid and carbon dioxide} \\\\ \hline \end{array}$$

Which row correctly matches a structure inside a villus of the small intestine with the primary nutrient it is adapted to absorb and transport?

$$\begin{array}{|c|c|c|} \hline & \text{Structure of villus} & \text{Nutrient absorbed and transported} \\\\ \hline \text{A} & \text{lacteal} & \text{fatty acids and glycerol} \\\\ \hline \text{B} & \text{lacteal} & \text{glucose and amino acids} \\\\ \hline \text{C} & \text{blood capillary} & \text{fatty acids and glycerol} \\\\ \hline \text{D} & \text{epithelium} & \text{glycogen and proteins} \\\\ \hline \end{array}$$

Which set of alveolar conditions would result in the fastest rate of diffusion of oxygen from the alveoli into the blood capillaries?

$$\begin{array}{|c|c|c|c|} \hline & \text{Surface area of alveoli} & \text{Distance for diffusion} & \text{Concentration gradient of oxygen} \\\\ \hline \text{A} & \text{large} & \text{small} & \text{large} \\\\ \hline \text{B} & \text{large} & \text{large} & \text{small} \\\\ \hline \text{C} & \text{small} & \text{small} & \text{large} \\\\ \hline \text{D} & \text{small} & \text{large} & \text{small} \\\\ \hline \text{/em}\n\end{array}$$

Four identical agar cubes containing universal indicator are placed into beakers of hydrochloric acid under different conditions. Which combination of conditions will result in the indicator changing color throughout the cube in the shortest time?

A cell is surrounded by a solution containing dissolved oxygen. The concentration of oxygen outside the cell is greater than the concentration inside the cell. Which change would decrease the rate of diffusion of oxygen into the cell?

Which pathway correctly describes the route taken by sperm from their site of production until they exit the male body?

A person walks from a dark room into bright sunlight. Which row correctly describes the response of the iris muscles and the pupil?

An experiment was set up to investigate the rate of photosynthesis in Elodea (water plant) at different light intensities. Carbon dioxide concentration and temperature were kept constant. At high light intensities, the rate of photosynthesis remained constant even when light intensity was increased further. What could explain this observation?

A seedling is placed horizontally in a dark box. After several days, the shoot grows upwards and the root grows downwards. Which statement correctly explains the role of auxin in the downward growth of the root?

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

Which feature of a villus is correctly matched with its role in the absorption of digested food?

Four agar cubes of different sizes are prepared using an alkaline solution containing phenolphthalein indicator, which turns pink in alkaline conditions. The cubes are then placed into a beaker of dilute hydrochloric acid. The cube sizes (side lengths) are 1 cm, 2 cm, 3 cm, and 4 cm respectively. Which cube will be the first to turn completely colorless?

Which combination of factors will result in the fastest rate of diffusion across a cell membrane?

Which statement correctly compares human sperm cells and human egg cells?

When a person walks from a dark room into bright sunlight, how do the muscles in the iris of the eye respond to protect the retina from damage?

An experiment is conducted using an aquatic plant, Elodea, to measure the rate of photosynthesis by counting the number of oxygen bubbles released per minute. The distance of the light source from the plant is varied. Why does the rate of bubble production decrease as the light source is moved further away?

A plant shoot is placed horizontally in a dark box. After several days, the shoot is observed growing upwards. Which statement explains this gravitropic response?

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

Which feature of a villus in the small intestine is correctly matched with its adaptation for absorption?

An investigation is carried out to study the diffusion of a dye into cubes of agar. Which combination of factors will result in the shortest time for the dye to diffuse completely to the center of an agar cube?

Which statement correctly describes the process of diffusion?

What is the correct pathway taken by sperm cells from their site of production to where they leave the male body?

A person walks out of a dark cinema into bright afternoon sunlight. Which row correctly describes the responses of the iris muscles and the change in pupil size?

A plant is kept at a constant favorable temperature of \(20\ ^\circ\text{C}\) with high light intensity, but at a low atmospheric carbon dioxide concentration of \(0.04\%\). The rate of photosynthesis is found to be constant and does not increase when light intensity is increased further. What is the limiting factor for photosynthesis under these conditions?

A plant shoot is placed horizontally in a dark room. Which statement correctly explains the subsequent growth of the shoot?

Which statement about anaerobic respiration is correct?

Which structure in a villus of the small intestine is correctly matched to the substance(s) it absorbs?

A student investigated the rate of diffusion using agar cubes containing phenolphthalein indicator and sodium hydroxide solution. The indicator turns pink in alkaline conditions and colorless in acidic conditions. The student prepared two cubes: Cube A (1 cm x 1 cm x 1 cm) and Cube B (2 cm x 2 cm x 2 cm). Both cubes were submerged in a beaker of dilute hydrochloric acid. (a) Calculate the surface area to volume ratio (SA:V) for both Cube A and Cube B. Show your working. (b) Predict and explain the difference in the time taken for the pink color to completely disappear in Cube A compared to Cube B. (c) State three other factors, besides surface area to volume ratio, that influence the rate of diffusion of substances into or out of living cells.

The process of human sexual reproduction relies on specialized gametes that undergo fertilization to form a zygote. (a) Describe how the structure of a human sperm cell is adapted to its function of reaching and fertilizing an egg. (b) Explain the process of fertilization, starting from the moment the sperm contacts the jelly coat of the egg cell to the formation of a diploid zygote. (c) State where fertilization normally occurs in the female reproductive system, and describe how the resulting embryo reaches the uterus and implants.

A person walking out of a dark cinema room into bright, direct sunlight experiences immediate changes in their eyes to adjust to the light levels. They then focus on a distant sailboat on the horizon. (a) Describe the reflex pathway and pupil changes that occur as the person steps into the bright sunlight, explaining the action of the muscles in the iris. (b) Explain how the focus of the eye changes when the person looks from a near object to a distant sailboat. (c) Contrast the functions of rod cells and cone cells in the retina.

An experiment was set up to investigate the effect of light intensity on the rate of photosynthesis in the aquatic plant Elodea. (a) Write the balanced chemical equation for photosynthesis. (b) Explain why measuring the rate of gas bubble production is only an approximation of the actual rate of photosynthesis. (c) Describe how the student could adapt this experimental setup to investigate the effect of temperature on the rate of photosynthesis, indicating three variables that must be kept constant.

Plants use hormones to coordinate their growth responses to external stimuli. (a) Define the term phototropism. (b) State and explain the expected phototropic response of an intact oat coleoptile that is exposed to unilateral light from the right side. (c) Explain the role of auxin in coordinating this phototropic response, describing where it is synthesized, how it moves, and how it affects cell development on different sides of the shoot.

Respiration can occur anaerobically when oxygen levels are limiting. (a) Write the word equation for anaerobic respiration in yeast and the word equation for anaerobic respiration in human muscle cells. (b) During intense exercise, lactic acid builds up in human muscle tissues. Explain how the body processes and removes this lactic acid after exercise has ceased, referring to the concept of oxygen debt. (c) Describe how the anaerobic respiration of yeast is utilized in the bread-making process, explaining the fate of each product.

### Part 1: Diffusion in Agar Cubes

A student investigated the effect of temperature on the rate of diffusion using agar cubes containing universal indicator. The agar cubes are initially red (acidic). When placed in an alkaline sodium hydroxide solution, the sodium hydroxide diffuses into the cubes, changing the color of the universal indicator from red to purple.

The student used five agar cubes, each measuring \(10\text{ mm} \times 10\text{ mm} \times 10\text{ mm}\).
Each cube was placed in a beaker containing \(50\text{ cm}^3\) of \(0.1\text{ mol/dm}^3\) sodium hydroxide solution at a different temperature: 20°C, 30°C, 40°C, 50°C, and 60°C.
After exactly 10 minutes, the cubes were removed and carefully sliced in half.
The distance that the purple color had penetrated from the outer surface of each cube was measured using a ruler.

Figure 1.1 shows a diagram representing the cross-section of the agar cube that was incubated at 30°C. The central shaded region represents the remaining red (acidic) agar, and the outer border represents the purple region where sodium hydroxide has diffused.

*(Note: Assume the outer square of Figure 1.1 in your printed exam sheet measures exactly \(40\text{ mm}\) on each side, and the inner square measures \(20\text{ mm}\).)*

**(a)** (i) Draw a large, clean, outline diagram of the cross-section of the agar cube shown in Figure 1.1. On your drawing, use a label line and the letter **D** to indicate the region where the sodium hydroxide has diffused. [3]

(ii) The actual size of the agar cube's side was \(10\text{ mm}\). Using the provided print dimension of \(40\text{ mm}\) for the outer square side, calculate the magnification of Figure 1.1. Show your working. [2]

**(b)** Table 1.1 shows the results of the student's investigation.

**Table 1.1**
| Temperature (°C) | Distance diffused (mm) | Rate of diffusion (mm/min) |
|---|---|---|
| 20 | 1.5 | 0.15 |
| 30 | 2.5 | 0.25 |
| 40 | 3.5 | **[Calculate]** |
| 50 | 4.5 | 0.45 |
| 60 | 5.5 | 0.55 |

(i) Calculate the rate of diffusion at 40°C. Write down the value and show your working. [1]

(ii) Plot a line graph on grid paper of the rate of diffusion (y-axis) against temperature (x-axis). [5]

(iii) State the relationship shown by your graph between temperature and the rate of diffusion. [1]

**(c)** (i) Identify two variables that were kept constant in this investigation. [2]

(ii) State one safety precaution that should be taken when handling sodium hydroxide solution, and give a reason for this precaution. [1]

**(d)** A student wants to find out how the surface area to volume ratio affects the rate of diffusion. Plan an investigation to determine the effect of the surface area to volume ratio of agar cubes on the rate of diffusion of sodium hydroxide. [5]

### Part 2: Photosynthesis in Pondweed

A student investigated the effect of light intensity on the rate of photosynthesis in *Elodea* (pondweed).

The apparatus was set up as follows:
- A piece of pondweed was placed upside down in a boiling tube containing 0.2% sodium hydrogencarbonate solution.
- A light source (lamp) was positioned at different distances from the boiling tube: 10 cm, 20 cm, 30 cm, 40 cm, and 50 cm.
- At each distance, the pondweed was allowed to adjust for 5 minutes, and then the number of bubbles of gas released from the cut stem was counted for 3 minutes.

**(a)** State the purpose of using sodium hydrogencarbonate solution in this investigation rather than distilled water. [1]

**(b)** Table 2.1 shows the results of the investigation.

**Table 2.1**
| Distance from light source (cm) | Number of bubbles in 3 minutes (Replicates) | Mean number of bubbles per minute |
|---|---|---|
| 10 | 138, 141, 135 | 46.0 |
| 20 | 93, 14 (anomaly), 87 | **[Calculate]** |
| 30 | 54, 56, 52 | 18.0 |
| 40 | 30, 29, 31 | 10.0 |
| 50 | 15, 14, 16 | 5.0 |

(i) Explain why the student should exclude the reading of 14 bubbles at a distance of 20 cm when calculating the mean. [1]

(ii) Calculate the mean number of bubbles per minute for a distance of 20 cm, excluding the anomalous value. Show your working. [2]

(iii) Calculate the relative light intensity (\(I\)) at a distance of 20 cm (which is \(0.2\text{ m}\)) using the formula:

\[I = \frac{1}{d^2}\]

where \(d\) is the distance in meters. Show your working and state the unit. [2]

**(c)** (i) Explain why counting bubbles is not an entirely accurate method of measuring the volume of gas produced during photosynthesis. [1]

(ii) Describe how the student could modify the apparatus to measure the volume of gas released more accurately. [2]

(iii) State the chemical test used to confirm that the gas produced is oxygen. [2]

**(d)** Plan an investigation to determine the effect of temperature on the rate of photosynthesis in pondweed. [6]

**(e)** Figure 2.1 shows a photomicrograph of a palisade mesophyll cell from the leaf of *Elodea*.
The actual length of this palisade cell is \(0.05\text{ mm}\).
The student made a drawing of this cell, which measured \(45\text{ mm}\) in length.

Calculate the magnification of the student's drawing. Show your working. [3]