Heredity and evolution — Intermediate

Score: 0 / 11

Level 2: Intermediate

Explain, apply, analyse, sequence — connect ideas, read patterns, use rules in new contexts (bridge to Year 11).

1. Why does meiosis (rather than mitosis alone) increase genetic variation in sexually reproducing species?

   A)DNA is replicated without error before divisions, and crossing over makes homologues genetically identicalB)It shuffles alleles (e.g. crossing over, assortment) and halves chromosome number so fertilisation combines two genomesC)Crossing over removes variation by aligning sister chromatids to the same alleleD)Meiosis operates mainly in somatic tissues whenever cells need to repair damage

2. Two heterozygotes Bb × Bb (complete dominance, B dominant). What fraction of offspring are expected to be homozygous dominant?

   A)1/4B)1/2C)3/4D)1/8

3. A student says: Organisms evolve because they try hard to survive. Which response is most accurate?

   A)Partly true — sustained effort can direct which mutations appear in gametesB)Misleading — evolution ceased in natural populations once modern humans appearedC)Natural selection acts on existing variation; individuals do not “choose” beneficial mutations in that simplistic wayD)True — whenever the environment changes, the whole population adapts in lockstep regardless of variation

4. Comparative DNA sequences between species support evolution when:

   A)Housekeeping genes are identical in all species, so sequences carry no phylogenetic signalB)Closely related species share more sequence similarity than very distant onesC)Mutation rates are the same in every lineage, so similarity always reflects convergence onlyD)Only non-coding regions can be compared between species

5. In a population of bacteria exposed to antibiotics, resistant forms may become more common over time mainly because:

   A)Low doses of antibiotic quickly remove resistance plasmids from the whole populationB)Resistance arises anew in every cell the moment the drug appears, with no heritable basisC)All cells are genetically identical, so survival is purely random with respect to genotypeD)Heritable variation exists; resistant lineages survive and reproduce better under selection

6. Fossil sequences in rock layers can support evolution by showing:

   A)Older layers sometimes contain simpler or different forms than younger layersB)Stasis in index fossils proves species never change through timeC)Biostratigraphy shows every layer formed in a single catastrophic event on one calendar dayD)Body fossils form only in igneous rock, so sequences are unavailable

7. Which pair best contrasts mitosis and meiosis?

   A)Mitosis produces haploid gametes after two consecutive divisionsB)Mitosis halves chromosomes; meiosis doubles themC)Mitosis maintains chromosome number in somatic cell division; meiosis halves chromosome number for gametesD)Both end with four genetically identical diploid cells

8. DNA replication before mitosis ensures each daughter cell receives:

   A)Half the parent DNA with no duplicationB)A full complement of genetic material (same species chromosome number when all goes correctly)C)Only messenger RNA copiesD)Random single strands unrelated to the parent

9. Mutation can be important in evolution because it:

   A)Guarantees adaptation in one generationB)Removes all genetic variationC)Only affects body cells that are inheritedD)Introduces new alleles; selection and other processes can change frequencies over time

10. In complete dominance, a heterozygote Aa for a trait typically shows:

    A)The dominant phenotypeB)A perfect blend always midway between both homozygotesC)The recessive phenotypeD)No phenotype

11. Speciation often involves:

    A)Instant identical copies of one parent species everywhereB)Loss of all variation in a populationC)Accumulated differences and reproductive barriers so groups no longer interbreed freelyD)Only behavioural change with no genetic basis

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