Biology · Unity and diversity

A3.1 — Diversity of organisms

Biology · SL / HL · syllabus-mapped notes

1. A3.1.1

   Variation between organisms as a defining feature of life

   Explain why variation between individuals is a defining feature of life.

2. A3.1.2

   Species as groups of organisms with shared traits

   Define a species as a group sharing traits, the original morphological concept.

3. A3.1.3

   Binomial system for naming organisms

   Explain the binomial system for naming organisms, and its conventions.

4. A3.1.4

   Biological species concept

   State the biological species concept, and discuss the difficulties with it.

5. A3.1.5

   Difficulties distinguishing between populations and species due to divergence of non- interbreeding populations during speciation

   Explain why deciding whether two diverging populations are separate species can be arbitrary.

6. A3.1.6

   Diversity in chromosome numbers of plant and animal species

   State that chromosome number varies between species, using humans and chimpanzees.

7. A3.1.7

   Karyotyping and karyograms

   Classify chromosomes in a karyogram, and evaluate the evidence that human chromosome 2 arose by fusion.

8. A3.1.8

   Unity and diversity of genomes within species

   Explain what a genome is, and how genomes vary within a species.

9. A3.1.9

   Diversity of eukaryote genomes

   Explain how eukaryote genomes vary in size and in base sequence.

10. A3.1.10

    Comparison of genome sizes

    Compare genome size with organism complexity using data from a database.

11. A3.1.11

    Current and potential future uses of whole genome sequencing

    Outline the current and potential future uses of whole genome sequencing.

12. A3.1.12

    Difficulties applying the biological species concept to asexually reproducing species and to bacteria that have horizontal gene transfer

    Explain why the biological species concept fails for asexual species and for bacteria.

13. A3.1.13

    Chromosome number as a shared trait within a species

    Explain why species with different chromosome numbers rarely produce fertile hybrids.

14. A3.1.14

    Engagement with local plant or animal species to develop a dichotomous key

    Develop a dichotomous key for local plant or animal species.

15. A3.1.15

    Identification of species from environmental DNA in a habitat using barcodes

    Explain how environmental DNA and barcodes identify the species present in a habitat.