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IB Biology HL A3.1 Diversity of Organisms Questions

Practise IB Biology HL A3.1 with classification and data questions on domains, kingdoms, shared characteristics and genetic, species and ecosystem biodiversity.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Classify organisms using shared morphological or population features, binomial naming, shared genus and dichotomous keys or character matrices.
  • Decide species membership from interbreeding, fertile offspring, gene flow and genetic evidence, and evaluate limits caused by hybrids, fossils, isolation or asexual and horizontal gene transfer.
  • Interpret ploidy, chromosome-number change, fusion, fission and polyploidy, and construct or analyse karyograms using chromosome structure, sex and abnormalities.
  • Explain shared and variable traits using genes, chromosomes, genome sequences, haplotypes and SNPs, including mutation, duplication and divergence of genome regions.
  • Compare genome sizes and gene numbers, explain why genome size need not track complexity, and evaluate model-organism choices for whole-genome sequencing.
  • Identify environmental DNA analysis as an application of DNA barcoding for detecting species.

Covered syllabus points

A3.1.1—Variation as defining feature of lifeA3.1.2—Species as groups with shared traitsA3.1.3—Binomial systemA3.1.4—Biological species conceptA3.1.5—Difficulties in distinguishing speciesA3.1.6—Diversity in chromosome numbersA3.1.7—Karyotyping and karyogramsA3.1.8—Unity and diversity of genomes within speciesA3.1.9—Diversity of eukaryote genomesA3.1.10—Comparison of genome sizesA3.1.11—Whole genome sequencingA3.1.12 (HL)—Difficulties with biological species conceptA3.1.13 (HL)—Chromosome number as shared traitA3.1.14 (HL)—Dichotomous key developmentA3.1.15 (HL)—Environmental DNA barcodes

Question 1

[Maximum number: 2]

The diagram shows the range of heights and brain sizes found in four groups of hominids.

Figure for Question 1 — IB Biology HL

Distinguish between the characteristics of the Australopithecus and H. erectus using the data.

Question 2

[Maximum number: 5]

The table shows the number of amino acids that are different in the sequences of the protein FOXP2 from a human compared with four other primate species.

Table for Question 2 — IB Biology HL

Question (a)

(a)

Identify the total number of different genera named in the table.

[ 1 ]

Question (b)

(b)

Using evidence from the diagrams, justify the hypothesis that chromosome 2 in humans arose from the fusion of chromosomes 12 and 13 with a shared primate ancestor.

[ 4 ]

Question 3

[Maximum number: 2]

A species is often defined as a group of similar individuals that interbreed in nature and produce fertile offspring. Discuss some problems with the use of this definition.

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