2023 Cambridge IGCSE Biology (0610) 模拟试题及答案详解

An individual walks from a brightly lit outdoor garden into a dark corridor. Which row describes the changes that occur in the iris muscles and the diameter of the pupil?

A student accidentally touches a hot object and quickly pulls their hand away. What is the correct pathway of the nervous impulse in this reflex action?

Which list contains only substances that pass across the placenta from the maternal blood to the fetal blood?

During the human menstrual cycle, which hormone triggers ovulation and which gland secretes it?

Villi are specialized structures found in the small intestine that facilitate the absorption of digested food. Which row correctly matches a structural feature of a villus to its adaptation for absorption?

Which conservation measure is most effective for managing wild fish stocks sustainably?

A population of yeast is grown in a laboratory flask with a constant supply of nutrients. After a period of rapid growth, the population reaches the stationary phase. What directly causes the population to enter this phase?

Which row correctly describes the homeostatic responses in a human skin when the external temperature drops?

When a person moves from a dark room into bright sunlight, their pupils constrict to protect the retina. Which row correctly describes the state of the iris muscles during this pupil reflex?

Which statement describes how an impulse is transmitted across a synapse from one neurone to the next?

The placenta allows the exchange of substances between the maternal blood and the fetal blood. Which substance moves from the fetal blood to the maternal blood across the placenta?

What is the primary effect of the sudden surge in luteinising hormone (LH) concentration during the female menstrual cycle?

Which structure in a villus is responsible for absorbing fatty acids and glycerol into the lymphatic system?

Four statements about the adaptations of the small intestine for absorption are listed.

1. It has millions of villi which increase the surface area.
2. The epithelial wall of each villus is only one cell thick.
3. Lacteals absorb amino acids directly into the bloodstream.
4. It is long, providing a large surface area and more time for absorption.

Which statements are correct?

Which practice would be most effective as a conservation measure to sustainably manage wild fish stocks?

Why is it important to conserve ecosystems and maintain genetic diversity in wild populations?

A person walks out of a dark room into bright sunlight.

Which row shows the correct response of the iris muscles and the change in pupil diameter?

| | circular muscles of iris | radial muscles of iris | pupil diameter |
| :--- | :--- | :--- | :--- |
| **A** | contract | relax | decreases |
| **B** | contract | relax | increases |
| **C** | relax | contract | decreases |
| **D** | relax | contract | increases |

Which substances move from the maternal blood to the fetal blood across the placenta?

What is the main function of the lacteal in a villus of the small intestine?

Which measures can be used to prevent the overexploitation of fish stocks to ensure sustainable fishing?

1. introducing a closed season for fishing
2. increasing the mesh size of nets
3. using drift nets with small mesh size
4. introducing legal quotas on the weight of fish caught

What happens to the shunt vessels and arterioles in the skin when a person enters a cold environment?

| | shunt vessels | skin arterioles | blood flow to skin capillaries |
| :--- | :--- | :--- | :--- |
| **A** | constrict | dilate | increases |
| **B** | constrict | constrict | decreases |
| **C** | dilate | constrict | decreases |
| **D** | dilate | dilate | increases |

Which row correctly identifies the hormones that repair and maintain the lining of the uterus during the menstrual cycle?

| | hormone that repairs the uterus lining | hormone that maintains the uterus lining |
| :--- | :--- | :--- |
| **A** | LH | FSH |
| **B** | oestrogen | progesterone |
| **C** | progesterone | oestrogen |
| **D** | FSH | LH |

Which row correctly matches a region of the digestive system with its function?

| | region of the digestive system | function |
| :--- | :--- | :--- |
| **A** | stomach | absorption of amino acids |
| **B** | gall bladder | production of bile |
| **C** | liver | production of bile |
| **D** | pancreas | absorption of water |

Which environmental consequences can result directly from deforestation?

1. increased risk of flooding
2. increased concentration of carbon dioxide in the atmosphere
3. increased biodiversity
4. increased risk of soil erosion

Which row shows the correct states of the iris muscles and the change in pupil size when a person walks from a dark room into a brightly lit corridor?

The table shows some features of synaptic transmission. Which row is correct?

Which hormone is correctly paired with its main function during the human menstrual cycle?

Which physical changes at puberty are stimulated by testosterone and estrogen?

Which row correctly identifies the main nutrients absorbed by the blood capillaries and the lacteals within a villus of the small intestine?

Which row correctly identifies the main organs where mechanical digestion of food and chemical digestion of lipids occur?

Some human actions in conservation are listed.
1. Using fishing nets with a large mesh size
2. Introducing a closed season for fishing during breeding periods
3. Increasing the use of chemical fertilisers in nearby agricultural fields

Which of these actions help to manage fish stocks sustainably?

Which factor causes a population of yeast cells in a closed culture to enter the stationary phase of growth?

A student accidentally steps on a sharp pin and quickly lifts their foot. Which sequence shows the correct pathway of the nervous impulse during this reflex action?

When a person walks from a dark room into bright sunlight, which changes occur in the iris of the eye to protect the retina from damage?

Which group of substances passes from the mother's blood to the fetal blood across the placenta?

Which row correctly pairs a menstrual cycle hormone with its site of production and its main function?

Villi are small projections in the small intestine that facilitate absorption. Which products of digestion are absorbed directly into the lacteal of a villus?

Which features of the small intestine wall adapt it for a high rate of absorption of digested nutrients?

1. Villi and microvilli to increase surface area.
2. An epithelium that is only one cell thick to reduce diffusion distance.
3. A rich blood capillary network to maintain a steep concentration gradient.

Which conservation measure helps to maintain sustainable wild fish stocks specifically by preventing the capture of young, immature fish?

Which of the following describes a key role of tropical rainforests in maintaining global climate stability?

1 (a) The human eye adjusts to focus on near and distant objects.

(i) Name the process of focusing on objects at different distances.

(ii) Describe the changes that occur in the eye when focusing on a near object.

(b) Photoreceptors in the retina detect light intensity and colour.

(i) Compare the roles of rod cells and cone cells in vision.

(ii) Describe how an impulse is transmitted across a synapse from a photoreceptor cell to a sensory neurone.

(c) Some reflexes do not involve the brain.

(i) Define the term reflex action.

(ii) State one advantage of reflex actions.

2 (a) During the menstrual cycle, hormones regulate the thickening and shedding of the uterus lining.

(i) Name the hormone that stimulates the development of follicles in the ovary.

(ii) Explain the roles of progesterone and oestrogen in preparing the uterus for pregnancy.

(b) In-vitro fertilisation (IVF) is a fertility treatment used when couples have difficulty conceiving naturally.

(i) Outline the main steps involved in the process of IVF.

(ii) Discuss one social or ethical implication of IVF treatment.

(c) Sperm cells and egg cells are adapted for their functions.

State two structural differences between a sperm cell and an egg cell.

3 (a) The ileum is adapted for the absorption of digested food molecules.

(i) Explain how the structure of a villus increases the efficiency of absorption.

(ii) Describe the absorption of fatty acids and glycerol into the lymphatic system.

(b) Glucose and amino acids are absorbed into the capillary network of the villi.

(i) Distinguish between the mechanisms of diffusion and active transport in the absorption of glucose.

(ii) State the name of the blood vessel that transports these absorbed nutrients directly to the liver.

(c) Assimilation is the movement of digested food molecules into the cells of the body where they are used, becoming part of the cells.

State three ways the liver processes glucose after absorption.

4 (a) Human activities have led to many species becoming endangered.

(i) State three reasons why a species may become endangered.

(ii) Explain how captive breeding programmes can help conserve endangered animal species.

(b) Plant species are also at risk of extinction and are conserved using seed banks.

(i) Describe the role of seed banks in conserving plant biodiversity.

(ii) Explain why seeds are kept in cold, dry conditions in seed banks.

(c) Sustainable development meets the needs of people without damage to the environment.

Identify two resources that can be managed sustainably.

5 (a) Microorganisms are widely used in biotechnology.

(i) State two reasons why bacteria and fungi are suitable for use in biotechnology.

(ii) Write the balanced chemical equation for anaerobic respiration in yeast.

(b) Biofuels can be produced using plant materials and yeast.

(i) Explain how yeast is used to produce ethanol for biofuel.

(ii) Discuss one environmental advantage and one environmental disadvantage of using biofuels instead of fossil fuels.

(c) Pectinase is an enzyme used in the production of fruit juice.

(i) State the substrate and the product of the reaction catalysed by pectinase.

(ii) Explain why heating pectinase to high temperatures before adding it to fruit pulp would prevent it from functioning.

6 (a) In humans, the ABO blood group system is determined by three alleles: \(I^A\), \(I^B\), and \(I^O\).

(i) Explain what is meant by the term codominance, using blood groups as an example.

(ii) A man with blood group A (heterozygous) and a woman with blood group B (heterozygous) have a child.

Construct a genetic diagram to show the possible genotypes and phenotypes of their offspring.

(b) Sickle-cell anaemia is another genetic condition.

(i) Describe the symptoms of sickle-cell anaemia.

(ii) Explain why the allele for sickle-cell anaemia is maintained in human populations in areas where malaria is common.

**Answer all questions. Use a black or dark blue pen. Show your working where required.**

**1** A student investigated the effect of temperature on the rate of anaerobic respiration in yeast.

They used the following method:
- Set up a water bath at a constant temperature.
- Mix $10\text{ cm}^3$ of a $5\%$ active yeast suspension with $10\text{ cm}^3$ of a $10\%$ glucose solution in a reaction tube.
- Add a $2\text{ mm}$ layer of liquid paraffin (oil) on top of the mixture.
- Connect the reaction tube via a delivery tube to a gas syringe.
- Leave the tube in the water bath for 5 minutes to equilibrate, then record the volume of gas collected after exactly 10 minutes.
- Repeat the experiment at different temperatures: $20^\circ\text{C}$, $30^\circ\text{C}$, $40^\circ\text{C}$, $50^\circ\text{C}$, and $60^\circ\text{C}$.

The student recorded the following volume of gas collected after 10 minutes:
- At $20^\circ\text{C}$: $3.4\text{ cm}^3$
- At $30^\circ\text{C}$: $7.2\text{ cm}^3$
- At $40^\circ\text{C}$: $11.6\text{ cm}^3$
- At $50^\circ\text{C}$: $4.8\text{ cm}^3$
- At $60^\circ\text{C}$: $0.8\text{ cm}^3$

**(a) (i)** Prepare a table to record these results. [4]

**(a) (ii)** Plot a line graph on a grid to show the effect of temperature on the volume of gas collected. [4]

**(a) (iii)** State the temperature at which the rate of anaerobic respiration was the highest. With reference to your graph and enzyme theory, explain the difference in gas production between $40^\circ\text{C}$ and $60^\circ\text{C}$. [3]

**(b) (i)** State the purpose of adding the liquid paraffin layer on top of the yeast-glucose mixture. [1]

**(b) (ii)** Identify the independent variable and the dependent variable in this investigation. [2]

**(c)** Plan an investigation to determine the effect of glucose concentration on the rate of anaerobic respiration in yeast. [6]

**2** A student investigated the density of stomata on the leaves of a privet plant (*Ligustrum vulgare*).

They applied clear nail varnish to a small area of both the upper and lower surfaces of a leaf. Once dry, they peeled off the varnish using clear tape and placed it on a microscope slide to create a replica of the epidermis. The replica was viewed under a microscope at $\times 400$ magnification, and the number of stomata in three different fields of view was counted for each surface.

Their counts were as follows:
- **Upper surface epidermis replica:**
- Field 1: 1 stoma
- Field 2: 2 stomata
- Field 3: 0 stomata

- **Lower surface epidermis replica:**
- Field 1: 13 stomata
- Field 2: 15 stomata
- Field 3: 14 stomata

**(a) (i)** Calculate the mean number of stomata for both the upper and lower surfaces of the leaf. Show your working. [2]

**(a) (ii)** State a conclusion based on these results. [1]

**(a) (iii)** Explain how the difference in stomatal distribution between the upper and lower surfaces is an adaptation that helps land plants survive. [2]

**(b) (i)** At $\times 400$ magnification, the field of view of the microscope is a circle with a diameter of $0.46\text{ mm}$.
Calculate the area of this field of view in $\text{mm}^2$.
Use the formula:
$$\text{Area} = \pi r^2$$
where $\pi = 3.14$ and $r$ is the radius of the field of view.
Show your working. Give your answer to two significant figures. [3]

**(b) (ii)** Using your calculated area from **(b)(i)** and the mean number of stomata on the lower surface from **(a)(i)**, estimate the stomatal density (number of stomata per $\text{mm}^2$) on the lower surface of the leaf. Show your working. [2]

**(c) (i)** Draw a large, clear diagram of a single stoma as seen under a microscope: it consists of a central pore surrounded by two bean-shaped guard cells, each containing several small circular chloroplasts and a thicker cell wall on the side facing the pore. [4]

**(c) (ii)** Label one guard cell and the stomatal pore on your drawing. [2]

**(d)** Describe how you would test a leaf to show that it has been photosynthesising by testing for the presence of starch. [4]