A student extracts DNA from a sample of kiwi fruit cells. During the extraction, detergent is added to the cells. The student observes that the extracted DNA forms a white, stringy precipitate. Explain why DNA is found in the nucleus of the kiwi fruit cells and describe the relationship between nucleotides, genes and chromosomes.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
DNA can be extracted from fruit cells using a simple laboratory procedure. Detergent is added to disrupt the cell membranes, releasing the cell contents.
Model answer (4 marks)
DNA is found in the nucleus because it is carried on chromosomes, which are located in the nucleus.
Nucleotides are the monomers that make up DNA.
A gene is a length of DNA that codes for the production of a specific protein.
A chromosome is a long, coiled molecule of DNA that carries genetic information in the form of genes; chromosomes contain many genes.
Nucleotides are the monomers that make up DNA.
A gene is a length of DNA that codes for the production of a specific protein.
A chromosome is a long, coiled molecule of DNA that carries genetic information in the form of genes; chromosomes contain many genes.
Examiner tips
- Use the exact terms ‘nucleus’, ‘chromosomes’, ‘nucleotides’, ‘gene’, ‘chromosome’ as the mark scheme expects.
- Show the logical link: nucleus → chromosomes → DNA → nucleotides → genes.
- Keep each point brief and to the point to fit the 4‑mark structure.
Common mistakes
- Mixing up the location of DNA (e.g., saying it is in the cytoplasm instead of the nucleus).
- Using vague phrases like ‘genetic material’ instead of ‘DNA’.
- Omitting the relationship that chromosomes contain many genes.
Mark scheme (4 marks)
- DNA is found in the nucleus because it is carried on chromosomes, which are located in the nucleus
- Nucleotides are the monomers / building blocks that make up DNA
- A gene is a length of DNA that codes for the production of a specific protein
- A chromosome is a long, coiled molecule of DNA that carries genetic information in the form of genes / chromosomes contain many genes
Key terms in this question
nucleotides · gene · chromosome · nucleus · DNA
Related
- All Edexcel GCSE Biology (1BI0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →