Total marks: 100 · Duration: 105 minutes · Tier: Higher
Instructions to candidates
- Use black ink or ball-point pen.
- Answer all questions.
- 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 100.
- The marks for each question are shown in brackets.
- In questions marked with an asterisk (*), marks will be awarded for your ability to structure your answer logically, showing how the points that you make are related or follow on from each other where appropriate.
- This paper covers Edexcel GCSE (9–1) Biology Paper 1 content, topics 1 to 5: key concepts in biology; cells and control; genetics; natural selection and genetic modification; and health, disease and the development of medicines.
Paper
Question 1 — Cells and microscopy (10 marks)
(a) Which structure in a bacterial cell contains a small number of extra genes? [1 mark]
A chromosomal DNA B plasmid C ribosome D flagellum
(b) Describe the functions of ribosomes and mitochondria in a cell. [2 marks]
(c) Explain two ways in which a sperm cell is adapted to its function. [2 marks]
(d) In a core practical, a student views a cell with a light microscope. On the student's drawing, the cell is 45 mm long. The real cell is 15 μm long. Calculate the magnification of the drawing. [2 marks]
(e) Explain why an electron microscope can show the internal structure of mitochondria but a light microscope cannot. [1 mark]
(f) (i) Convert 15 μm into millimetres. [1 mark]
(ii) Write 15 μm in metres, in standard form. [1 mark]
Question 2 — Enzymes and food (10 marks)
(a) In a core practical, a student investigates the effect of pH on the activity of amylase. He mixes amylase, starch and a buffer solution, and removes a drop every 10 seconds to test with iodine solution.
(i) Describe how the student knows when the starch has all been broken down. [2 marks]
(ii) At pH 6, the starch is all broken down after 50 s. Calculate the rate of reaction, using rate = 1000 ÷ time. [1 mark]
(iii) Explain why amylase has an optimum pH. [2 marks]
(b) A student burns 0.50 g of a peanut under a boiling tube containing 25 g of water. The temperature of the water rises by 18 °C.
Calculate the energy released per gram of peanut. Use: energy (J) = mass of water (g) × 4.2 × temperature change (°C). [3 marks]
(c) Name the reagent used to test for reducing sugars. [1 mark]
(d) Explain why lipase can break down lipids but not proteins. [1 mark]
Question 3 — Osmosis (10 marks)
In a core practical, a student places potato cylinders in sucrose solutions of different concentrations for 40 minutes and records the percentage change in mass.
| Sucrose concentration (mol/dm³) | 0.0 | 0.2 | 0.4 | 0.6 | 0.8 |
|---|---|---|---|---|---|
| Change in mass (%) | +8 | +2 | −4 | −9 | −12 |
(a) One cylinder had a mass of 4.00 g at the start and 3.84 g at the end. Calculate the percentage change in mass. [2 marks]
(b) Use the data to estimate the concentration of sucrose that is equal to the concentration of the potato cell contents. Explain how you found your answer. [2 marks]
(c) Explain why the cylinder in 0.8 mol/dm³ sucrose solution lost mass. [2 marks]
(d) Give one source of error in this practical and suggest how to reduce it. [2 marks]
(e) Give one example of active transport in humans. [1 mark]
(f) Explain why cells that are specialised for absorption have a large surface area. [1 mark]
Question 4 — Cell division, growth and stem cells (10 marks)
(a) Describe what happens in each stage of mitosis: prophase, metaphase, anaphase and telophase. [4 marks]
(b) Explain how a cancer tumour develops. [2 marks]
(c) A baby's mass is on the 50th percentile line of a growth chart. What does this mean? [1 mark]
(d) (i) Give one difference between embryonic stem cells and adult stem cells. [1 mark]
(ii) Name the tissue in plants that contains stem cells. [1 mark]
(iii) Give one risk of using stem cells to treat a patient. [1 mark]
Question 5 — The nervous system (10 marks)
(a) A person steps on a sharp object and lifts their foot. Describe the pathway of the impulse in this reflex arc. [4 marks]
(b) Explain how an impulse passes from one neurone to the next across a synapse. [2 marks]
(c) State the function of:
(i) the cerebellum [1 mark]
(ii) the medulla oblongata. [1 mark]
(d) Explain why it is difficult to treat damage to the spinal cord. [2 marks]
Question 6 — DNA and inheritance (10 marks)
(a) Describe the structure of a DNA molecule. [2 marks]
(b) In a core practical, a student extracts DNA from strawberries. Describe how the student could do this. [3 marks]
(c) A woman with blood group A (genotype IᴬIᴼ) and a man with blood group O (genotype IᴼIᴼ) have a child. Use a genetic diagram to find the probability that the child has blood group A. [2 marks]
(d) Explain why red–green colour blindness is more common in males than in females. [2 marks]
(e) What is meant by the genome of an organism? [1 mark]
Question 7 — Evolution and classification (10 marks)
(a)* Fossils of Ardipithecus ramidus ("Ardi", about 4.4 million years old), Australopithecus afarensis ("Lucy", about 3.2 million years old) and the remains found by Richard Leakey's team (about 1.6 million years old) are evidence for human evolution, as are stone tools found with them.
Explain how this evidence supports the theory of human evolution. [6 marks]
(b) (i) Name the three domains in the modern classification system. [1 mark]
(ii) Explain why scientists replaced the five-kingdom system with the three-domain system. [2 marks]
(c) Give one reason why many people did not accept Darwin's theory of evolution when it was published. [1 mark]
Question 8 — Selective breeding and genetic modification (10 marks)
(a) (i) Describe how a farmer could use selective breeding to produce wheat with a high yield. [2 marks]
(ii) Give one disadvantage of selective breeding. [1 mark]
(b) Describe how bacteria are genetically engineered to produce human insulin. [3 marks]
(c) Some crop plants have been genetically modified to produce Bt toxin, which kills insects that eat them. Give one advantage and one disadvantage of growing Bt crops. [2 marks]
(d) Give one advantage of producing plants by tissue culture. [1 mark]
(e) Give one advantage of using biological control instead of chemical pesticides. [1 mark]
Question 9 — Communicable disease and immunity (10 marks)
(a) Name the type of pathogen that causes tuberculosis. [1 mark]
(b) Describe how cholera is spread, and give one way of reducing its spread. [2 marks]
(c)* A person is infected by a pathogen they have never met before. Some years later, the same pathogen infects them again, but they show few or no symptoms.
Describe how the body responds to the first infection, and explain why the second infection causes few or no symptoms. [6 marks]
(d) Name the enzyme in tears that destroys bacteria. [1 mark]
Question 10 — Non-communicable disease and medicines (10 marks)
(a) A man has a mass of 85 kg and a height of 1.75 m.
(i) Calculate his body mass index (BMI). Use: BMI = mass (kg) ÷ (height (m))². [2 marks]
(ii) A BMI from 25 to 29.9 is classed as overweight. What does his BMI suggest about his health risks? [1 mark]
(b) His waist measurement is 96 cm and his hip measurement is 100 cm. Calculate his waist : hip ratio. [1 mark]
(c) Explain how drinking too much alcohol over many years can damage the liver. [1 mark]
(d) Give one advantage and one disadvantage of treating cardiovascular disease with lifestyle changes rather than surgery. [2 marks]
(e) Describe the stages in developing a new medicine, from discovery to approval for use. [3 marks]