A-Level Edexcel Biology AS Simple Probability

A-Level Edexcel Biology AS Simple Probability
Pearson Edexcel International Advanced Subsidiary/Advanced Level in Biology, Issue 2, February 2021Biology XBI11/YBI11

Review A-Level Edexcel Biology simple probability through the available inheritance-style probability evidence, including 1 in 2, 50:50 and 0.5 outcomes.

How this is tested

  • state simple biological probabilities as 1 in 2, 50:50, 50 percent or 0.5

Question 2(b)

[Maximum number: 1]

Most Bengal tigers are orange with black stripes but there is a very small number of Bengal tigers that are white with black stripes.

The photograph shows a white Bengal tiger with black stripes.

Figure for Question 2(b) — Edexcel A-Level Biology AS

White tiger offspring are produced by two Bengal tigers that each carry at least one recessive allele for a gene affecting coat colour.

The pedigree diagram shows the phenotypes in one family of tigers, bred in captivity.

Figure for Question 2(b) — Edexcel A-Level Biology AS

Key female orange tiger female white tiger male orange tiger male white tiger

State the probability that the next tiger born to these two parents will be female.