Genetics and heredity practice
QCE Biology · Original practice questions with worked solutions
All genetics and heredity practice questions
50 original questions · Page 2 of 3
- Q74 · Original practice · 5 marksGenetics and heredityA muscle cell and a nerve cell contain the same genome but produce different sets of proteins.
- Q75 · Original practice · 5 marksGenetics and heredityThe diagram shows expression of a hypothetical HOX gene in six segments of an embryo. In this species, the gene helps establish segment identity. Shading represents expression, not a DNA-sequence difference.
- Q76 · Original practice · 6 marksGenetics and heredityThe pedigree shows a fully penetrant trait with no new mutations. Choose among autosomal dominant, autosomal recessive and X-linked recessive inheritance. Use A for the normal dominant allele if a recessive model applies.
- Q77 · Original practice · 5 marksGenetics and heredityThe pedigree traces a known X-linked recessive trait. Assume complete penetrance and no new mutations. Use for the normal allele and for the trait allele.
- Q78 · Original practice · 6 marksGenetics and heredityA person with blood group A and a person with blood group B have a child with blood group O. For ABO inheritance, and are codominant and both dominate .
- Q79 · Original practice · 6 marksGenetics and heredityIn a hypothetical flower, three independently assorting loci contribute additively to pigment. Each upper-case allele adds one pigment unit. An plant is crossed with an plant. Their offspring are then crossed with one another; the histogram shows 256 offspring of this second cross.
- Q80 · Original practice · 6 marksGenetics and heredityA bacterial plasmid has a replication origin, an antibiotic-resistance marker and one unique restriction site. An investigator wants to insert gene X at that site.
- Q81 · Original practice · 6 marksGenetics and heredityPCR begins with 5 double-stranded copies of a target region. Assume ideal doubling each cycle until the stated comparison.
- Q82 · Original practice · 6 marksGenetics and heredityThe gel shows DNA profiles at two inherited loci. Each individual has two distinct bands at each locus; one allele at each locus is inherited from each parent. Assume no new mutations and that the child’s mother is M. A, B and C are possible fathers.
- Q95 · Original practice · 8 marksGenetics and heredityIn a hypothetical beetle, functional allele G is dominant and produces a green-pigment enzyme. Allele g changes the mRNA codon CAA (glutamine) to UAA (stop), producing a non-functional enzyme. Both parents are green and have genotype Gg. A 600 bp DNA test fragment is cut into 400 bp and 200 bp fragments for G; g lacks the restriction site and remains 600 bp.…
- Q96 · Original practice · 9 marksGenetics and heredityIdentical starting seed mixtures are placed in wet and dry microhabitats. At the end, plant counts are shown. In species A, gene X has the same DNA sequence in both microhabitats, but dry-site cells have more transcription-factor binding at its promoter and ten times more X mRNA. Use .
- Q100 · Original practice · 10 marksGenetics and heredityAn investigator wants bacteria to make a eukaryotic luminescent protein. Its complete RNA coding region has exons of 150 and 240 nucleotides, including the start codon and one final stop codon, separated in the original gene by a 100-nucleotide intron. The intron contains an early stop and the host cannot splice it. Candidate plasmids have a 1810 bp vector b…
- Q110 · Original practice · 1 markGenetics and heredityTwo DNA samples contain the same percentages of A, T, G and C. Which additional information is required to determine whether a particular gene has the same base sequence in both samples?
- Q111 · Original practice · 1 markGenetics and heredityA UV-induced DNA mutation occurs in a skin cell. The cell divides and passes the mutation to its daughter skin cells. No gamete or gamete-forming cell carries the mutation. Which statement is supported?
- Q112 · Original practice · 1 markGenetics and heredityFor one chromosome pair, a meiosis produces four gametes: two contain both homologues and two contain neither. No other error occurs. The most likely error is
- Q113 · Original practice · 1 markGenetics and heredityA coding region gains one nucleotide and later loses one nucleotide downstream. Translation starts at the original start codon, and no new stop codon is introduced between the two changes. What happens to the reading frame downstream of both changes?
- Q114 · Original practice · 1 markGenetics and heredityAt one autosomal locus, allele F produces protein form F and allele S produces protein form S. FS heterozygotes produce both forms, each detectable separately. Which inheritance pattern is shown?
- Q135 · Original practice · 5 marksGenetics and heredityInitially, both strands of one double-stranded DNA molecule carry a stable label. New nucleotides carry no label. Replication is semiconservative: each daughter molecule contains one template strand and one newly synthesised strand. DNA completes two rounds of replication with no loss or exchange of label.
- Q136 · Original practice · 5 marksGenetics and heredityLetters in the diagram represent chromosome segments containing genes. A misaligned exchange between homologous chromosomes produces two chromatids from an original segment order ABCDE. The centromeres remain intact.
- Q137 · Original practice · 5 marksGenetics and heredityA hypothetical species has three homologous chromosome pairs. Consider independent assortment without crossing over. Each pair provides a choice of one maternally or one paternally inherited homologue in a gamete. Assume those choices are independent and homologues can be distinguished.
- Q138 · Original practice · 5 marksGenetics and heredityA primary RNA transcript is written 5′ to 3′ as exon 1 AUGGA, intron UCUCU, exon 2 ACUUUAA. These two exons form the complete coding region, with one start and one terminal stop codon. Ignore the cap and poly-A tail. Use the code excerpt.
- Q139 · Original practice · 5 marksGenetics and heredityCells with the same DNA sequence are tested under four conditions. A specific activating transcription factor is either absent or supplied. The promoter is in open or compact chromatin. The table gives relative mRNA abundance; background values of 1–3 are considered similarly low for this experiment.
- Q140 · Original practice · 6 marksGenetics and heredityThe pedigree shows a known fully penetrant X-linked dominant trait. Allele causes the trait; does not. There are no new mutations. Individual I-2 is unaffected.
- Q141 · Original practice · 7 marksGenetics and heredityOne autosomal coat-colour locus has three alleles with the dominance order . A parent is crossed with a parent. The phenotype is determined by the highest-ranking allele present.