Edexcel A Level Biology A (Salters-Nuffield)
Edexcel A Level Biology A Topic 4: Biodiversity and Natural Resources Exam Questions
Free Edexcel A Level Biology A exam questions for Topic 4: Biodiversity and Natural Resources, with a mark scheme for every pack. Covers biodiversity measures, adaptation, natural selection, Hardy-Weinberg, classification, plant cell structure, starch and cellulose, plant fibres, drug testing and conservation.
Topic 4: Biodiversity and Natural Resources exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
StemUp mark scheme flashcards
A-Level Biology Flashcards for 2027 Onwards
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Then test yourself with the questions on this page.
From £10.99View flashcards
About Edexcel A Level Biology A Topic 4: Biodiversity and Natural Resources
Topic 4 of Edexcel A Level Biology A (Salters-Nuffield) explores biodiversity and how humans use plants. You learn how to measure biodiversity using species richness, the index of diversity and the heterozygosity index, how adaptations and natural selection relate to niche, and how the Hardy-Weinberg equation is used. Classification includes the three domain system and the role of the scientific community in validating new evidence. The plant section covers plant cell ultrastructure, starch and cellulose, xylem and sclerenchyma, the uses of plant fibres, mineral ions and the history of drug testing. Conservation through zoos and seed banks is also covered. Several core practicals come from this topic.
What you need to know
- Biodiversity Species richness is the number of species. Index of diversity D = N(N - 1) / sum of n(n - 1). Heterozygosity index H = number of heterozygotes / number of individuals in the population.
- Adaptation and selection Organisms have anatomical, physiological and behavioural adaptations to their niche. Natural selection changes allele frequencies, and the Hardy-Weinberg equation estimates allele and genotype frequencies.
- Classification The three domains are Bacteria, Archaea and Eukaryota. New molecular evidence is checked through peer review, journals and conferences before it is accepted.
- Plant cells and polysaccharides Plant cells have a cellulose cell wall, chloroplasts, amyloplasts, a vacuole and tonoplast, plasmodesmata and pits. Starch stores energy; cellulose microfibrils give strength.
- Plant fibres and minerals Xylem and sclerenchyma fibres contain lignin. Nitrate, calcium and magnesium ions are needed for growth. Plant fibres and starch can be used to make sustainable products.
- Drug testing and conservation Withering's digitalis work was an early drug trial; modern trials have phases with double-blind and placebo controls. Zoos and seed banks conserve endangered species through captive breeding, research and reintroduction.
Common mistakes in Topic 4: Biodiversity and Natural Resources
- Using species richness alone to compare biodiversity; the index of diversity also accounts for the number of individuals of each species.
- Confusing the heterozygosity index with the index of diversity; H measures genetic diversity within a population.
- Saying cellulose is made of alpha glucose; it is made of beta glucose joined by 1,4 glycosidic bonds.
- Describing a double-blind trial as one where patients do not know what they receive; neither the patients nor the doctors know.
- Forgetting that seed banks store seeds dried and at low temperature to keep them viable.
Try three Topic 4: Biodiversity and Natural Resources exam-style questions
1. A sample contains three species with 10, 6 and 4 individuals. Calculate the index of diversity using D = N(N - 1) / sum of n(n - 1). (3 marks)
Show the mark scheme answer
N = 20 so N(N - 1) = 380; sum of n(n - 1) = 90 + 30 + 12 = 132; D = 380 / 132 = 2.88.
2. Explain how the structure of cellulose makes it suitable for plant cell walls. (3 marks)
Show the mark scheme answer
Beta glucose with alternate molecules inverted forms long straight chains; chains held together by many hydrogen bonds; form microfibrils with high tensile strength.
3. Describe how you would investigate the tensile strength of plant fibres. (4 marks)
Show the mark scheme answer
Extract fibres of the same length from the plant; attach one end to a clamp and hang masses from the other; add masses one at a time until the fibre breaks; repeat with several fibres and calculate a mean; keep fibre length and diameter the same.
Topic 4: Biodiversity and Natural Resources FAQs
What does Edexcel A Level Biology A Topic 4: Biodiversity and Natural Resources cover?
It covers measuring biodiversity, adaptation, natural selection, Hardy-Weinberg, classification, plant cell structure, plant fibres and minerals, drug testing, and conservation by zoos and seed banks.
Which paper is Topic 4 examined in?
At A Level, Year 1 topics (Topics 1 to 4) can be assessed in both Paper 1 and Paper 2, and every topic can also appear in Paper 3, which includes questions on a pre-released scientific article and practical skills.
Which calculations do I need for Topic 4?
You need the index of diversity, the heterozygosity index and the Hardy-Weinberg equations, and you should be able to calculate means and use them to compare samples.
