Inheritance, Probability & Punnett Squares — Drills · Grade 7 Science
Chapter: Genes, Cell Division & HeredityWhat these drills covers
By the end of Inheritance, Probability & Punnett Squares you should be able to:
- I can explain inheritance, probability & punnett squares.
- I can use evidence, a model, and stated assumptions to support a biological explanation.
4 questions, multiple choice, numeric and written answer, each with a worked explanation.
Vocabulary used: genotype, heterozygous, homozygous, dominance, probability.
Problem 1
Which genotype is heterozygous at the fictional region?
- AA
- aa
- Aa
- A alone as a full diploid genotype
Answer and explanation
Aa
Aa contains two different versions at the studied region.
Problem 2
In the stipulated Aa×Aa complete-dominance model, what percent of offspring events are expected to be aa?
Answer and explanation
25 %
One of four equally probable combinations is aa: 1/4×100=25%.
Problem 3
What can an Aa parent contribute at the studied region?
Answer and explanation
Either A or a, one version per gamete in the stipulated model.
Problem 4
Does dominance make an Aa parent transmit A more than half the time in this model?
Answer and explanation
No. Dominance concerns phenotype expression, while the supplied gamete probabilities remain one half A and one half a.