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5.1 Inheritance

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Question 21

Potato plants can be grown from true potato seeds produced from sexual reproduction. They can also be grown from seed potatoes (tubers), which are produced by asexual reproduction.

a.

Which two statements explain why commercial growers usually choose to plant asexual tubers rather than true seeds?

Tick (✓\checkmark✓) two boxes.

  • Potatoes grown from tubers will grow and produce a harvest much faster than those grown from true seeds.
  • The grower will be guaranteed that the yield and cooking quality of the potatoes matches the parent plant.
  • Potato plants grown from true seeds do not require chlorophyll for photosynthesis.
  • Potato plants grown from true seeds can grow without absorbing mineral ions.
  • Potato plants grown from true seeds will all be genetically identical clones of the parent plant.
[2]
b.

In a potato field, growers noticed that some plants developed severe leaf rolling and purple discoloration.

Complete the sentences to show three key biological explanations for these symptoms. Use words from the list below:

alleleantibioticantigenmutagenpathogenphenotype \text{allele} \quad \text{antibiotic} \quad \text{antigen} \quad \text{mutagen} \quad \text{pathogen} \quad \text{phenotype} alleleantibioticantigenmutagenpathogenphenotype
  • The leaf rolling symptoms represent the plant's observable ____________, caused by the disease.
  • The infectious agent causing this disease is a biological ____________.
  • Some potato varieties are resistant because they possess a specific ____________ that provides immunity.
[3]
c.

Potato leafroll disease was suspected to be infectious in the 19th century, but scientists could not confirm it was caused by a virus until the mid-20th century.

Suggest why it took so long to identify the virus as the causative agent.

[1]
d.

The potato leafroll virus is spread by green peach aphids, which are insects that feed on the phloem sap of potato plants.

To control the spread of this viral disease, growers can use two approaches:

  • Systematically dig up and burn (rogue) any potato plants showing symptoms.
  • Spray the fields with chemical insecticides to target the aphids.

Explain how these two different methods would control the disease. Discuss the advantages and disadvantages of each method.

[6]
Markscheme

5.1 Inheritance Questions

  1. GCSE
  2. /Biology
  3. /5.1 Inheritance

97 exam-style questions on OCR GCSE Biology 5.1 Inheritance, covering 5.1.1 The genome, 5.1.2 Environment and phenotype, 5.1.3 Variants and mutations, 5.1.4 How genetic variants influence phenotype, 5.1.5 Asexual and sexual reproduction, 5.1.6 Haploid and diploid, 5.1.7 Meiotic cell division, 5.1.8 Single gene inheritance, 5.1.9 Predicting single gene crosses, 5.1.10 Sex determination, 5.1.11 Multiple gene inheritance, and 5.1.12 Development of our understanding of genetics. Each one has a worked solution and a mark scheme showing where the marks go.

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