IB Biology A3.1: Diversity of Organisms

Guiding Questions

• What is a species?
• Genome Diversity: Patterns within and between species.

Linking Questions

• Species Persistence: Causes for species persistence or extinction.
• Variation Patterns: Continuous and discontinuous variation in species.

Key Topics

A3.1.1 Variation Between Organisms

• Organism: Define organism.
• Variation: Define variation.
• Sources of Genetic Variation:
  • Mutation
  • Gene flow
  • Sexual reproduction
• Types of Variation:
  • Discrete vs. Continuous variation
• Comparative Variation: Variation within and between species.

A3.1.2 Species Identification

• Morphological Species Concept: Define species based on shared traits.

A3.1.3 Binomial Nomenclature

• Definition: System for naming organisms.
• Formatting Rules:
  1. Genus capitalized
  2. Species lowercase
  3. Italics used
  4. Latin or Latinized form
• Scientific Naming: Preferred over local names for consistency.

A3.1.4 Biological Species Concept

• Definition: Based on reproductive isolation.
• Limitations: Hybrids and geographical separation issues.

A3.1.5 Speciation

• Definition: Process by which new species arise.
• Distinguishing Populations: Challenges due to non-interbreeding populations.

A3.1.6 Chromosome Diversity

• Species Characteristic: Chromosome number as a distinguishing feature.
• Diploid Cells: Even chromosome numbers typical.
• Human vs. Chimpanzee Chromosomes:
  • Humans: 46 chromosomes
  • Chimpanzees: 48 chromosomes
  • Evidence of human chromosome 2 fusion from ancestral chromosomes.

A3.1.7 Karyotyping

• Definitions:
  • Karyotype
  • Karyogram
• Chromosome Pairing:
  • Size
  • Banding pattern
  • Centromere position
• Sex Determination: Using karyogram.

A3.1.8 Genomic Unity and Diversity

• Definitions:
  • Genome
  • Gene
  • Allele
• SNPs: Cause and effect of single-nucleotide polymorphisms.

A3.1.9 Eukaryote Genomes

• Genome Size: Larger does not mean more genes.
• Genomic Variation: Within and between species.

A3.1.10 Genome Size Comparison

• Measurement Units: For genome size.
• Complexity Relationship: Use databases to study gene number vs. complexity.

A3.1.11 Genome Sequencing

• Definitions: Sequence in genetics.
• Technological Advances: Faster DNA sequencing.
• Applications: Various uses of genome sequencing.
• Ethics: Considerations of genome sequencing.

AHLA3.1.12 Sexual vs. Asexual Reproduction

• Comparison: Differences between sexual and asexual reproduction.
• Biological Species Concept Difficulties:
  • Asexual species (e.g., dandelions)
  • Horizontal gene transfer in bacteria.

AHLA3.1.13 Chromosome Number in Species

• Reproduction: Maintains chromosome number.
• Sterile Offspring Example: Donkey and horse mating produces sterile mule.

AHLA3.1.14 Dichotomous Keys

• Use: Identification of specimens.
• Development: Create keys for local species.

AHLA3.1.15 Environmental DNA Barcoding

• Definitions:
  • DNA barcode
  • Environmental DNA
• Applications: Identification using DNA barcoding.

Additional Resources

• Quizlet Study Set: Coming soon!
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