IB Biology SL D3.2.9 Abo Blood Groups Questions

Use IA, IB and i allele relationships to explain codominance and predict ABO genotypes, phenotypes and family outcomes in IB Biology SL D3.2.9.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Explain that ABO blood groups use three alleles (IA, IB and i), with IA and IB codominant and i recessive, producing four phenotypes.
  • Deduce parental genotypes and predict offspring ABO genotypes, phenotypes or probabilities from a stated family or Punnett-grid cross.

IB Biology SL D3.2.9 Abo Blood Groups Questions question 1

[Maximum number: 3]

Both the genome and the environment of an organism affect its growth and development. Variation between individuals of a species can be continuous or discrete (discontinuous). Mitosis produces identical cells for growth and meiosis allows for variation.

The micrographs show onion and whitefish cells in mitosis.

Figure for Question IB Biology SL D3.2.9 Abo Blood Groups Questions question 1 — IB Biology SL

Blood group in humans is an example of discrete (discontinuous) variation. Explain the inheritance of ABO blood groups in humans.

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