Evolution Mock Test – Class 12 Biology

1. A chapter-wide analysis yields four observations: abiotic experiments form organic molecules, fossils document branching lineages, Hardy-Weinberg deviations reveal population genetic change, and molecular plus embryological evidence supports common ancestry. Which statement best integrates these observations?

2. A small island is founded by individuals in whom allele R is unusually common. Many generations later, repeated immigration from a mainland population where R is rare causes the island frequency to decline steadily. Which sequence of processes best explains the history?

3. Study the cultural chronology below.

Which conclusion best integrates the records?

4. Use the following text-described vertebrate figure. An early reptile node divides into Branch P and Branch Q. Branch P contains pelycosaur- and therapsid-associated forms and ends in mammalian descendants. Branch Q contains thecodont- and dinosaur-associated forms and also gives rise to surviving reptilian and bird lineages. Which conclusion is best supported?

5. Suppose direct evidence from one Homo habilis-associated specimen strongly indicated meat consumption. How should the earlier statement that Homo habilis "probably did not eat meat" be treated?

6. A population departs from Hardy-Weinberg expectations immediately after a large influx of reproducing migrants with very different allele frequencies. Which conclusion is better supported than merely stating that "some evolutionary force" acted?

7. Dinosaurs are best represented in the broad evolutionary account as:

8. A common ancestral finch stock gives rise to several island forms with differently shaped beaks specialised for seeds, insects and plant material. The pattern most directly represents:

9. Assess the following statements about the later reptilian history.
I. Major dinosaur groups disappeared around .
II. Uncertainty about the precise cause of their extinction does not imply uncertainty that the extinction occurred.
III. Survival of smaller reptilian groups is compatible with extinction of major dinosaur branches.
IV. Dinosaur disappearance means all reptilian lineages became extinct at the same time.

10. Arrange the following broad events in the most appropriate evolutionary order.
P. Reptilian reproduction becomes less dependent on open water through a resistant terrestrial egg.
Q. Reptiles diversify extensively on land.
R. Some reptilian descendants later become highly adapted to aquatic life.
S. Ichthyosaur-like marine reptiles occur during the later reptilian history.

11. Two identical bacterial populations initially contain a rare heritable resistant variant. Population P is repeatedly exposed to an antibiotic, while Population Q is maintained without that antibiotic. After several generations, resistance becomes common only in P. The result most directly indicates that:

12. Arrange the following events into the most coherent Darwinian sequence under resource limitation.
P. More offspring are produced than available resources can support.
Q. Individuals compete under limiting conditions.
R. Heritable variants differ in reproductive success.
S. Favoured variants become more frequent over generations.

13. A plant evolutionary diagram shows an early vascular lineage giving rise to three branches. Branch P terminates early, Branch Q persists into several later geological periods, and Branch R arises later from within Q and then diversifies. Which interpretation is correct?

14. Oparin-Haldane proposed a gradual chemical origin of organic complexity, whereas Miller recovered amino acids from a simulated primitive-Earth system. Which statement best describes the relationship between the proposal and the experiment?

15. The wings of a bird and a butterfly are considered analogous as wings because they:

16. A population has genotype frequencies , and . Allele frequencies calculated from these data are and . Which conclusion is best supported?

17. Evaluate the statements below about directional selection.
I. Phenotypes toward one end of a range may receive a reproductive advantage.
II. The population mean can shift toward the favoured extreme.
III. Both extremes must be favoured equally over the intermediate phenotype.
IV. The post-selection distribution need not remain centred on the original mean.

18. Examine the evolutionary comparison below.

Which comparison provides the clearest evidence of convergence?

19. Assertion: Comparing protected sterilised broth with broth later exposed to viable microbes helps distinguish spontaneous appearance from contamination.
Reason: The protected broth is assumed to be permanently unable to support microbial growth even after viable microbes are introduced.

20. Malthusian reasoning relevant to Darwin's theory begins with the observation that:

21. A palaeontologist finds a younger fossil with a mixture of features also present in two older related lineages. Which conclusion is most defensible without additional branching evidence?

22. Before a severe drought begins, a plant population already contains a rare heritable variant that improves water conservation. During the drought, carriers leave far more offspring than other plants, and the variant rapidly increases. The strongest inference is that:

23. A geological diagram shows a plant lineage splitting into several branches, some of which terminate in older periods while others persist into much younger strata. What is the most appropriate interpretation?

24. Consider the following statements.
I. Founder effect is a form of genetic drift.
II. A neutral allele can become unusually common in founders by chance.
III. Founder effect requires the overrepresented allele to improve reproductive success.
IV. Genetic drift can also occur in small populations that were not newly founded.

25. Island species are morphologically diverse, yet each island lineage is genetically closer to related species on the nearest mainland than to ecologically similar species on distant islands. Which interpretation best fits the evidence?

26. If a reptilian lineage lost the protection against drying normally provided by its terrestrial egg while all other features remained unchanged, the most immediate expected consequence would be:

27. A geological plant figure shows two sister branches arising from an earlier vascular-plant lineage. Branch P continues through several later geological periods, while Branch Q terminates much earlier. This difference most directly indicates that:

28. In a population at Hardy-Weinberg equilibrium, and . The expected frequencies of AA, Aa and aa respectively are:

29. Study the fossil distribution below in an undisturbed sedimentary sequence.

Which inference is best supported by the complete pattern?

30. After several generations of stabilising selection, a phenotype-frequency distribution is expected to become ______ around approximately the same intermediate value.

31. Industrial melanism and antibiotic resistance involve very different organisms and environmental pressures. Which causal feature is shared by both?

32. A population initially satisfies Hardy-Weinberg expectations. A large migration event introduces individuals from a population with very different allele frequencies, and the migrants reproduce. Which statement is most accurate immediately after this gene-flow episode?

33. A Hardy-Weinberg population has . A large migration event changes the allele frequency to . If the population subsequently reaches Hardy-Weinberg proportions at the new allele frequencies, what is the expected heterozygote frequency at that later state?

34. Two heritable genotypes, P and Q, are tested in two environments.

Which conclusion best fits the data?

35. A breeder selects individuals for a feature that has a heritable component but is also strongly influenced by nutrition. The selected parents are raised under unusually rich diets, while their offspring are raised under average conditions. Which result would provide the clearest evidence of a genuine inherited response to selection?

36. A simplified reconstruction of plant history is shown below.

Which conclusion best integrates the records?

37. Two evolutionary trees are described. Tree P begins with one marsupial ancestor and branches into several ecological forms. Tree Q begins with one placental ancestor and also branches into several ecological forms. One marsupial branch and one placental branch independently become very similar predators. Which interpretation fits the complete pattern?

38. A newly discovered sequence of strata contains different characteristic organisms in older and younger layers, including many extinct forms not present today. Which claim of strict special creation would this pattern challenge most directly?

39. A thorn of Bougainvillea and a tendril of Cucurbita arise from the same basic organ origin but serve different functions. Their relationship provides evidence for:

40. Assess the following statements about resistance evolution under human-applied chemicals.
I. Resistant variation may already be present before exposure.
II. A newly arising heritable resistant variant can also be favoured if exposure continues.
III. Selection means that every exposed organism intentionally becomes resistant.
IV. Resistant variants can increase rapidly when they reproduce more successfully under treatment.

41. Assertion: Strong resemblance between a marsupial ecological form and a placental counterpart need not indicate recent common ancestry of the paired forms.
Reason: Similar ecological pressures can independently favour comparable adaptations in distinct evolutionary lineages.

42. Assertion: Haeckel's strong recapitulation interpretation is not accepted as a literal description of vertebrate development.
Reason: Shared early embryonic features can occur even though embryos do not pass through the fully formed adult stages of ancestral species.

43. Assess the following statements about Alfred Wallace.
I. He independently reached an explanation based on natural selection.
II. His observations included work associated with the Malay region.
III. His evolutionary explanation required species to remain permanently fixed.
IV. His conclusions converged substantially with Darwin's explanation of evolutionary change.

44. Early mammals occur in the fossil record before the major disappearance of dinosaurs, yet mammalian diversity becomes much greater afterward. Which claim is most defensible?

45. An extinct fossil form from older strata shares several structural features with a living group, but it also differs from modern members in important characters. The strongest evolutionary inference is that:

46. Which combination of the following statements about Homo sapiens is valid?
I. African origin is associated with the lineage.
II. Dispersal carried populations into other regions.
III. Modern Homo sapiens is placed within an ice-age interval of about .
IV. Later widespread distribution requires independent origin in every region occupied.

47. A new allele X first appears in Population P through mutation. Several generations later, X is detected for the first time in Population Q immediately after migrants from P reproduce there. Which relation is most appropriate?

48. Match each reproductive pattern with its expected selection outcome. A Column II entry is used once.

49. Evaluate the statements below about broad evolutionary chronology.
I. A record from is older than one from .
II. Jawless fishes are placed later than the early invertebrate record.
III. Seaweeds with a few plants are placed around .
IV. The appearance of fishes requires that invertebrates had already become extinct.

50. Arrange the following broad records from earlier to later according to the stated evolutionary chronology.
P. Invertebrates
Q. Jawless fishes
R. Seaweeds with a few plants