Evolution and biodiversity flashcards

Evolution is the change in heritable characteristics of populations over successive generations, driven primarily by natural selection. Students must understand how variation arises through mutation and sexual reproduction, and how differential reproductive success leads to allele frequency changes over time. Speciation occurs when populations become reproductively isolated and diverge sufficiently to form new species. Classification organises living organisms into a hierarchy of taxa based on shared characteristics and evolutionary relationships. Phylogenetic trees and cladograms represent these relationships, with clades defined by shared derived characteristics. Biodiversity encompasses species richness, genetic diversity and ecosystem variety. Students should appreciate how human activity threatens biodiversity and understand the value of conservation, as well as the evidence supporting evolutionary theory including the fossil record, comparative anatomy and molecular data.

1. Card 1

   What is the definition of evolution in biology?

   Evolution is the change in heritable characteristics of a population over successive generations, resulting in altered allele frequencies through time.

2. Card 2

   What are the four conditions required for natural selection to occur?

   There must be variation in a population, traits must be heritable, individuals must compete for survival, and some variants must have greater reproductive success.

3. Card 3

   How does a new species arise through allopatric speciation?

   A population becomes divided by a geographical barrier, preventing gene flow. Each group evolves independently until reproductive isolation is complete and a new species forms.

4. Card 4

   What is the difference between analogous and homologous structures?

   Homologous structures share common ancestry but may differ in function. Analogous structures perform similar functions but evolved independently with no shared origin.

5. Card 5

   What does a cladogram show?

   A cladogram shows hypothetical evolutionary relationships between organisms based on shared derived characteristics, grouping them into clades that each include a common ancestor and all its descendants.

6. Card 6

   What is the binomial nomenclature system?

   A two-part naming system where every organism is given a genus name followed by a species name, written in italics with the genus capitalised, e.g. Homo sapiens.

7. Card 7

   What is the correct order of taxonomic hierarchy from broadest to most specific?

   Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species — a useful mnemonic is 'Dear King Philip Came Over For Good Soup'.

8. Card 8

   How does sexual reproduction contribute to variation within a population?

   Meiosis produces genetically unique gametes through independent assortment and crossing over; random fertilisation then combines alleles unpredictably, generating extensive variation.

9. Card 9

   What is the biological species concept?

   A species is defined as a group of organisms that can interbreed to produce fertile offspring and are reproductively isolated from other such groups.

10. Card 10

    What is adaptive radiation?

    Adaptive radiation is the rapid diversification of one ancestral species into many species, each adapted to a different ecological niche, as seen in Darwin's finches.

11. Card 11

    Why is molecular evidence considered strong support for evolution?

    Closely related species share more similar DNA sequences and amino acid sequences in proteins, reflecting recent common ancestry and divergence through mutation over time.

12. Card 12

    What are the three components of biodiversity?

    Biodiversity includes species richness (number of species), genetic diversity (variation within species), and ecosystem diversity (variety of habitats and ecological communities).

• Students often write that individual organisms evolve or adapt during their lifetime, when in fact evolution acts on populations across generations through changes in allele frequencies.
• A common error is confusing analogous and homologous structures, particularly assuming that structural similarity always indicates close evolutionary relationship rather than convergent evolution.
• Many students incorrectly treat the taxonomic hierarchy as fixed and absolute, not realising that classification schemes are revised as new molecular and phylogenetic evidence emerges.

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