90 exam-style questions on Inheritance — topic D3.2 of Continuity and change in the IB Biology syllabus — with answers and explanations. Samples below; the full set is free with an account.
Restriction enzymes are useful in genetic engineering because they:
Answer: Cut DNA at specific base sequences
Restriction endonucleases cut DNA at specific base sequences. Staggered cuts leave single-stranded 'sticky ends' that can base-pair with complementary ends of other DNA, allowing fragments to be recombined.
In bacterial gene cloning, a plasmid is used mainly as a:
Answer: Vector carrying a gene into a cell
Plasmids are small circular DNA molecules that replicate independently in bacteria. A gene inserted into a plasmid vector can be taken up by host cells and expressed or copied along with the plasmid.
A codon on an mRNA molecule consists of
Answer: three bases
Each codon of three bases specifies one amino acid (or a stop signal).
The human ABO blood group system is an example of
Answer: multiple alleles
Three alleles (Iᴬ, Iᴮ, i) exist in the population; Iᴬ and Iᴮ are codominant, i is recessive.
In peas, the allele for round seeds (R) is dominant to the allele for wrinkled seeds (r). A plant of genotype Rr is crossed with a plant of genotype rr. What is the expected phenotypic ratio of the offspring?
Answer: 1 round : 1 wrinkled
Half the gametes of the Rr parent carry R and half carry r, while all gametes of rr carry r, giving equal numbers of Rr and rr offspring. The 3:1 ratio comes from crossing two heterozygotes.
A woman of blood group A with genotype IAi has children with a man of blood group B with genotype IBi. Which blood groups are possible in their children?
Answer: A, B, AB and O
The four gamete combinations give IAIB (AB), IAi (A), IBi (B) and ii (O), so all four groups can appear. Students often forget that two heterozygous parents can produce group O.
That was 6 of 90 Inheritance questions.
Practise all 90 freeDistinguishAO2 · 1–4 marks
Make the difference clear for BOTH terms — a definition of one of them is only half an answer.
OutlineAO2 · 1–4 marks
A brief account or summary: the main points in two or three sentences, no evaluation.
DrawAO1 · 1–2 marks
A labelled, accurate drawing with a ruler where lines are straight; axes and units on a graph.
90 Inheritance questions — free with an account. Spaced repetition, streaks and full exam simulations included.
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