Edexcel International A Level Biology
Edexcel International A Level Biology Plant Structure and Function, Biodiversity and Conservation Exam Questions
Free Edexcel International A Level Biology exam questions for Plant Structure and Function, Biodiversity and Conservation, with a mark scheme for every pack. Covers plant cell ultrastructure, starch and cellulose, xylem and sclerenchyma, mineral ions, drug testing, biodiversity, classification, natural selection and conservation.
Plant Structure and Function, Biodiversity and Conservation 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.
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About Edexcel International A Level Biology Plant Structure and Function, Biodiversity and Conservation
This topic is part of Unit 2 (Cells, Development, Biodiversity and Conservation) of Edexcel International A Level Biology. It starts with plant cell ultrastructure and how starch and cellulose suit their roles, then the structure of xylem vessels and sclerenchyma fibres and the uses of plant fibres. You study the importance of water and mineral ions, and the history and stages of drug testing. The second half covers biodiversity, including species richness and the index of diversity, adaptations, natural selection, Hardy-Weinberg, classification and the three domains, and conservation through zoos and seed banks. Practicals on fibre tensile strength and plant antimicrobial properties link to this topic.
What you need to know
- Plant cells Plant cells have a cellulose cell wall, middle lamella, plasmodesmata, pits, chloroplasts, amyloplasts and a large vacuole surrounded by the tonoplast.
- Starch and cellulose Starch (alpha glucose, amylose and amylopectin) is compact for energy storage. Cellulose (beta glucose, straight chains with hydrogen bonds) forms microfibrils for strength.
- Xylem and fibres Xylem vessels transport water and mineral ions and are strengthened by lignin; sclerenchyma fibres provide support. Plant fibres are strong and can be used sustainably.
- Minerals and drugs Nitrate, calcium and magnesium ions are needed for growth. Drug testing has moved from Withering's digitalis trials to modern phased trials with double-blind and placebo controls.
- Biodiversity and selection Index of diversity D = N(N - 1) / sum of n(n - 1). Heterozygosity index measures genetic diversity. Natural selection changes allele frequencies; Hardy-Weinberg estimates them.
- Classification and conservation The three domains are Bacteria, Archaea and Eukarya; new classifications are validated by peer review. Zoos and seed banks conserve species through breeding programmes, research and reintroduction.
Common mistakes in Plant Structure and Function, Biodiversity and Conservation
- Saying xylem vessels are living; they are dead hollow tubes.
- Confusing amylose with amylopectin; amylopectin is branched with 1,6 glycosidic bonds.
- Describing placebos as harmful; a placebo has no active drug and is used as a control.
- Assuming a high number of species always means high diversity; the index of diversity also considers evenness.
- Forgetting that seed banks only work for seeds that tolerate drying and freezing.
Try three Plant Structure and Function, Biodiversity and Conservation exam-style questions
1. A pond contains three species with 8, 8 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) = 56 + 56 + 12 = 124; D = 380 / 124 = 3.06.
2. Explain why magnesium ions are needed for plant growth. (2 marks)
Show the mark scheme answer
Magnesium is needed to make chlorophyll; without it leaves become yellow and photosynthesis is reduced.
3. Describe how you would investigate the antimicrobial properties of plant extracts. (4 marks)
Show the mark scheme answer
Crush plant material with ethanol to make an extract; soak paper discs in the extract and in ethanol as a control; place discs on agar spread with bacteria using aseptic technique; incubate and measure the clear zones.
Plant Structure and Function, Biodiversity and Conservation FAQs
What does Edexcel International A Level Biology Plant structure and function, biodiversity and conservation cover?
It covers plant cells, starch and cellulose, xylem and fibres, mineral ions, drug testing, biodiversity, natural selection, classification and conservation.
Which unit is it examined in?
It is examined in Unit 2, Cells, Development, Biodiversity and Conservation, and related practical skills are also assessed in the practical units.
Which calculations do I need for this topic?
You need the index of diversity, the heterozygosity index and the Hardy-Weinberg equations, plus mean tensile strength from practical data.
