National 5 (Scotland) · National 5 Biology

Skills and Applying Knowledge

32 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 32 questions

  1. A scientist records the dry mass of seedlings grown with and without fertiliser. Which is the dependent variable?
  2. Why is a control experiment included in an investigation?
  3. Repeating an experiment several times and calculating a mean improves what?
  4. The table shows the mass of a potato cylinder in different salt solutions. The mass change is +4% at 0.0 M, 0% at 0.2 M, and −6% at 0.4 M. At which concentration is the cell sap closest to isotonic wi…
  5. A cell has a mass of 4 µg and divides by mitosis. Its two daughter cells each have a mass of 2 µg. A new cell grows to a mass of 4 µg before dividing again. After three rounds of division, how many ce…
  6. A section of DNA has 30% adenine. What percentage of the bases are guanine?
  7. A DNA strand has 12 bases. How many amino acids can it code for if each amino acid needs three bases?
  8. The graph shows the rate of an enzyme-controlled reaction at 10, 20, 30, 40 and 60 °C, with peak activity at 40 °C. Which statement is a valid conclusion?
  9. A heart beats 72 times per minute and pumps 70 cm³ of blood per beat. What is the cardiac output?
  10. A student measures a leaf cell as 0.05 mm under a microscope with magnification ×400. What is the length of the image?
  11. A food chain has 5000 kJ of energy in the producers. If 10% is transferred at each level, how much energy reaches the secondary consumers?
  12. Pie chart: 36 of 120 beetles caught in a pitfall trap are a certain species. What angle represents that species?
  13. The arteries are thick-walled and elastic, while the veins have valves. Which is the best explanation of this difference?
  14. Insulin is produced by genetically engineered bacteria. Which of the following describes the process?
  15. A person with high blood glucose after a meal has a faulty pancreas. Which sequence correctly shows the response in a healthy person?
  16. The percentage of bees in a population with a resistant gene rose from 5% to 40% over five years after a pesticide was used. Which statement is the best explanation?
  17. Two parents who both carry the recessive cystic fibrosis allele (Cc × Cc) have a child who does not have the disorder. What is the probability that this child is a carrier?
  18. Two Bb parents have two children. What is the probability that both children have the genotype bb?
  19. A plant is grown in bright light at 15 °C and its photosynthesis rate does not rise when the light is increased further. Raising the temperature to 25 °C increases the rate. What was limiting the rate…
  20. Producers in a field fix 20 000 kJ of energy per square metre per year. Primary consumers take in 2 400 kJ and secondary consumers take in 288 kJ. What percentage of the primary consumers' energy reac…
  21. In a food chain grass → rabbit → fox, disease kills most of the foxes. What is the most likely short-term effect?
  22. A red blood cell and a plant cell are placed in distilled water. The red blood cell bursts but the plant cell does not. What explains the difference?
  23. A student weighs a potato cylinder at 5.0 g and, after 24 hours in a salt solution, 4.4 g. What is the percentage change in mass?
  24. Starch is mixed with amylase at pH 4, 7 and 10. After 2 minutes only the pH 7 tube no longer turns the iodine solution blue-black. What conclusion can be drawn?
  25. An athlete has a resting cardiac output of 5000 cm³ per minute and a heart rate of 50 beats per minute. What is the stroke volume?
  26. Pondweed releases 12 cm³ of oxygen in 8 minutes. What is the rate of photosynthesis?
  27. A heterozygous brown-eyed father (Bb) and a blue-eyed mother (bb) have three children. What is the probability that all three have brown eyes?
  28. An enzyme is boiled for five minutes and then cooled to its optimum temperature, but its activity does not return. What is the best explanation?
  29. The nitrate concentration in soil water is 0.5 mM and in a root hair cell it is 2.0 mM, yet nitrate continues to enter the cell. Which process is involved, and what would stop it?
  30. A grassland of 2000 m² is sampled with twenty 1 m² quadrats, which contain 60 plants of one species in total. What is the best estimate of the population in the whole field?
  31. A lamp is moved from 10 cm to 20 cm from a pondweed. Light intensity is inversely proportional to the distance squared. By what factor does the light intensity fall?
  32. Five repeats give bubble counts of 12, 13, 12, 25 and 14. The 25 is anomalous. What is the mean without it?

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