Total marks: 110 · Duration: 120 minutes
Instructions to candidates
- Use black ink or ball-point pen.
- Answer all questions.
- Answer the questions in the spaces provided.
- In calculations, show all your working and give the unit of your answer.
- You may use a calculator.
- For multiple-choice parts, choose one answer, A, B, C or D.
- Where a question describes apparatus, a graph or a diagram in words, you may find it helpful to sketch it.
Information
- The total mark for this paper is 110.
- The marks for each question are shown in brackets.
- This paper covers the Pearson Edexcel International GCSE (9–1) Biology (4BI1) specification content that is assessed in Paper 1: the nature and variety of living organisms; structure and functions in living organisms; reproduction and inheritance; ecology and the environment; and the use of biological resources.
Paper
Question 1 — The variety of living organisms (10 marks)
(a) Which group of organisms has cells with walls made of chitin and feeds by secreting enzymes onto its food? [1 mark]
A bacteria B fungi C plants D protoctists
(b) Give two features of the structure of a bacterial cell. [2 marks]
(c) Name one protoctist that is a pathogen. [1 mark]
(d) Describe the structure of a virus, and explain why viruses cannot reproduce on their own. [3 marks]
(e) (i) Give one use of the bacterium Lactobacillus in food production. [1 mark]
(ii) Describe how the fungus Mucor obtains nutrients from bread. [2 marks]
Question 2 — Cells, biological molecules and enzymes (10 marks)
(a) Name the part of a cell that:
(i) controls the movement of substances into and out of the cell [1 mark]
(ii) is the site of protein synthesis. [1 mark]
(b) Name the chemical elements present in carbohydrates. [1 mark]
(c) (i) Describe the test for starch, and give the positive result. [1 mark]
(ii) Describe the test for glucose, and give the positive result. [2 marks]
(d) A student investigates the effect of temperature on the digestion of starch by amylase. She records the time taken for all the starch to be digested.
| Temperature (°C) | 20 | 30 | 40 | 50 | 60 |
|---|---|---|---|---|---|
| Time taken (s) | 180 | 90 | 45 | 120 | starch not digested |
(i) Calculate the rate of reaction at 40 °C, using rate = 1 ÷ time. Give the unit. [1 mark]
(ii) Explain why the starch is not digested at 60 °C. [2 marks]
(iii) Explain why the student cannot conclude that the optimum temperature of amylase is exactly 40 °C. [1 mark]
Question 3 — Movement of substances into and out of cells (10 marks)
(a) Explain two differences between diffusion and active transport. [2 marks]
(b) A student fills a bag of Visking tubing with 20% sucrose solution and attaches a capillary tube to the top. The bag is placed in a beaker of distilled water. After 30 minutes, the level of liquid in the capillary tube has risen.
Explain why the level rises. [3 marks]
(c) A student cuts cubes of agar jelly with sides of 1 cm, 2 cm and 3 cm.
(i) Calculate the surface area to volume ratio of the 2 cm cube. [2 marks]
(ii) Explain why large multicellular organisms need specialised exchange surfaces and a transport system. [2 marks]
(d) Give one factor, other than surface area, that increases the rate of diffusion. [1 mark]
Question 4 — Plant nutrition (10 marks)
(a) Write the balanced chemical symbol equation for photosynthesis. [2 marks]
(b) A student tests a variegated leaf (with green and white areas) for starch after the plant has been in light for several hours.
(i) Describe how the student tests the leaf for starch. [4 marks]
(ii) Only the green areas of the leaf turn blue-black. What does this show? [1 mark]
(c) State why plants need:
(i) nitrate ions [1 mark]
(ii) magnesium ions. [1 mark]
(d) On a cold, sunny day, increasing the light intensity does not increase the rate of photosynthesis of a plant. Explain why. [1 mark]
Question 5 — Human nutrition (10 marks)
(a) A student burns 1.0 g of a crisp under a boiling tube containing 20 cm³ of water. The temperature of the water rises from 21 °C to 55 °C.
Calculate the energy released per gram of crisp. Use: energy (J) = mass of water (g) × 4.2 × temperature change (°C). (1 cm³ of water has a mass of 1 g.) [3 marks]
(b) The value calculated is much lower than the value on the packet. Explain two reasons why. [2 marks]
(c) Name the products of the digestion of protein. [1 mark]
(d) Explain how bile helps the digestion of fat. [2 marks]
(e) Explain why dietary fibre is an important part of a balanced diet. [1 mark]
(f) Name one source of vitamin D, other than food. [1 mark]
Question 6 — Respiration and gas exchange (10 marks)
(a) A student places germinating peas in one vacuum flask and boiled peas in a second vacuum flask. Both sets of peas were rinsed in disinfectant. After three days, the temperature in the first flask is 26 °C and in the second flask is 20 °C.
(i) Explain the difference in temperature. [2 marks]
(ii) Explain why the peas were rinsed in disinfectant. [1 mark]
(b) A leaf is placed in a tube of red hydrogencarbonate indicator and left in the dark for several hours. Explain the colour of the indicator at the end. [2 marks]
(c) Explain three ways in which the alveoli are adapted for efficient gas exchange. [3 marks]
(d) Explain how two substances in tobacco smoke harm the body. [2 marks]
Question 7 — Transport (10 marks)
(a) Describe the roles of phagocytes and lymphocytes in defending the body against pathogens. [2 marks]
(b) (i) Name the chamber of the heart that pumps blood to the body. [1 mark]
(ii) Explain why this chamber has a thicker wall than the right ventricle. [1 mark]
(c) During exercise, a student's heart rate rises from 70 beats per minute to 140 beats per minute.
(i) Calculate the percentage increase in heart rate. [2 marks]
(ii) Explain why the heart rate increases during exercise. [2 marks]
(d) Describe the pathway of water from the soil to the air around a leaf. [2 marks]
Question 8 — Coordination and response (10 marks)
(a) Give two differences between nervous responses and hormonal responses. [2 marks]
(b) Describe how the iris responds when a person walks into bright light. [2 marks]
(c) A plant shoot is lit from one side. Explain how auxin causes the shoot to grow towards the light. [3 marks]
(d) Describe how vasoconstriction reduces heat loss from the body in cold conditions. [2 marks]
(e) Give one effect of adrenaline on the body. [1 mark]
Question 9 — Reproduction and inheritance (10 marks)
(a) Give two ways in which a wind-pollinated flower is adapted for pollination. [2 marks]
(b) Name the three conditions needed for seeds to germinate. [1 mark]
(c) In a plant, the allele for purple flowers (P) is dominant to the allele for white flowers (p). A plant with genotype Pp is crossed with a plant with genotype pp.
Use a genetic diagram to find the percentage of offspring expected to have white flowers. [2 marks]
(d) In a family, two parents who do not have a genetic condition have a child who has the condition. Explain what this shows about the allele that causes the condition. [2 marks]
(e) A human body cell contains 46 chromosomes. How many chromosomes are in each cell produced by meiosis? [1 mark]
(f) Give one reason why sexual reproduction produces variation. [1 mark]
(g) What is an allele? [1 mark]
Question 10 — Ecology and the environment (10 marks)
(a) A student estimates the population of a plant in a field 50 m long and 40 m wide. She places twenty 1 m² quadrats at random and counts a total of 64 plants.
Estimate the number of plants in the field. [2 marks]
(b) The table shows the energy at three trophic levels in a food chain.
| Trophic level | Producers | Primary consumers | Secondary consumers |
|---|---|---|---|
| Energy (kJ per m² per year) | 25 000 | 2 500 | 200 |
Calculate the percentage efficiency of energy transfer from primary consumers to secondary consumers. [2 marks]
(c) Explain how fertiliser running off farmland into a lake can cause the death of fish. [4 marks]
(d) Give two effects of large-scale deforestation on the environment. [2 marks]
Question 11 — Use of biological resources (10 marks)
(a) Describe how bacteria can be genetically modified to produce human insulin. [4 marks]
(b) The genetically modified bacteria are grown in an industrial fermenter. Explain why:
(i) the temperature is controlled [1 mark]
(ii) aseptic conditions are used [1 mark]
(iii) air is pumped into the fermenter. [1 mark]
(c) Describe the role of Lactobacillus in making yoghurt. [1 mark]
(d) In winter, some farmers burn paraffin heaters in their glasshouses. Explain how this increases the yield of crops. [2 marks]