Diversity of Organisms Notes
Diversity of Organisms
Introduction
The central question is: What contributes to the diversity of organisms?
Overall Plan for Documentary
Create a 5-minute documentary about the variation of life on Earth.
Focus on a specific species.
Use the DP syllabus to explain variation and diversity.
Address all questions within the slideshow.
Cite all sources.
Utilize Flex Clip for documentary creation and an AI voice generator (Top Media).
A David Attenborough-style narration is desired.
Resources
Diversity of organisms OSC
A3.1 Species diversity
Theme A: Unity and Diversity
Topic A.3: Organisms
Subtopic A.3.1
Mr. Guerra
IB Biology - SL & HL A3.1 Diversity of organisms
IB Biology Interactive Lecture A3.1 Diversity of organisms
NEW 2025 EXAM
Variation Between Organisms
A3.1.1 - Variation between organisms is a defining feature of life.
Examples: Dogs are dogs, kids are kids, and tulips are tulips.
Individuals possess unique DNA and gene expression, leading to differing exterior and interior traits.
This is known as variation.
Variation facilitates classification.
Variation can be continuous or discontinuous.
Classification Based on Differences
A3.1.1 - Variation between organisms as a defining feature of life
Classification categories:
Feeding habits
Habitat
Movement
Daily activity (nocturnal, diurnal)
Risk: venomous or harmless
Anatomy: plant/animal/vertebrate/invertebrate
Morphology
A3.1.1 - Variation between organisms as a defining feature of life
Morphology - physical appearance of organisms is where scientists generally start with classification.
Taxa
A3.1.1 - Variation between organisms as a defining feature of life
Taxa - categories into which organisms are placed.
Example: unicellular or multicellular
Taxonomical Hierarchy
A3.1.1 - Variation between organisms as a defining feature of life
Taxa range from general to specific.
The order is Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
Examples of Domains: Eukarya, Archaea, Bacteria
Examples of Kingdoms: Protista, Animalia, Plantae, Fungi, Archaebacteria, Eubacteria
Phase 1: Variation Between Organisms
A3.1.1 Variation between organisms as a defining feature of life
No two individuals are identical.
Variation patterns are complex.
These patterns are the basis for naming and classifying organisms.
Tasks:
Describe the organism.
Describe the variation of this organism.
List sources of genetic variation within this species.
Compare variation within and between species.
Choose an animal to study.
Phase 1 Vocabulary
Species
Variation
Trait
Morphology
Evolution
What is a Species?
A3.1.2 - Species as groups of organisms with shared traits
Carolus Linnaeus:
18th-century professor of medicine and botany
Started uniform naming system based in Latin or Greek
Based entirely on physical features
Species defined as groups of organisms with shared traits.
Binomial Naming System
A3.1.3 - Binomial system for naming organisms
Binomial Nomenclature:
“Bi” = two
“Nomial” = name
“Nomenclature” = system to name things
All organisms have two names:
Italics
The first name is capitalized.
The second name is lower case.
Example: Homo sapiens
Benefits of Binomial Naming System
A3.1.3 - Binomial system for naming organisms
Prevents confusion
Each organism has ONE name
Names are recognized universally
Stability in the system - changes are rarely permitted
Example: Homo sapiens
Phase 2 Tasks
A3.1.2 and A3.1.3
Define binomial nomenclature.
State four rules of binomial nomenclature formatting.
Outline why the binomial naming system is used in science rather than local names.
Use the morphological naming system to name both of your species
Explain why the naming system is used rather than local names
Phase 2 Vocabulary
Binomial Nomenclature
Genus and Species
Morphology
Interbreed
Biological Species Concept
A3.1.4 - Biological species concept
What is a species?
Organisms that can interbreed with each other and produce fertile offspring
Nature of Science Considerations
A3.1.4 Biological species concept
Philosophical questions arise regarding species definitions.
"Is all we are doing simply naming things?"
"Do the categories we use actually exist in reality or just in our minds?"
"Is the difficulty of agreeing on a definition a fault of the limitations of language?"
"Is it possible to use the same term (species) for organisms that exist today and to express how their populations evolved over time?"
Debate continues due to the diversity of life.
Phase 3 Tasks
A3.1.4—Biological species concept
Explain how species meet requirements according to the biological species concept.
Discuss challenges when using this concept.
Phase 3 Vocabulary
Species
Fertile Offspring
Hybrid
Populations vs. Species
A3.1.5 - Difficulties distinguishing between populations and species due to divergence of non-interbreeding populations during speciation
Biological Species Concept - Reproductive Isolation
A3.1.4 - Biological species concept
Emphasizes reproductive isolation.
Members of one species don’t normally breed successfully with members of another species.
Isolation can be due to various factors (physical, behavioral, ecological, or genetic barriers).
Other contributing factors:
Ecological niche (unique niche can lead to a new distinct species)
Genetics - technology allows a closer look
Molecules that the organism can produce (similar organisms can produce similar molecules to reproduce)
Lineage when discussing extinct species
Key Terms
A3.1.5 - Difficulties distinguishing between populations and species due to divergence of non-interbreeding populations during speciation
Speciation - splitting of species into two or more different species
Population - a group of organisms in the same species, living in the same area, able to interbreed
Speciation Details
A3.1.5 - Difficulties distinguishing between populations and species due to divergence of non-interbreeding populations during speciation
Usually VERY gradual
Minor differences until two groups can no longer breed
Changes during process may be imperceptible
End result is two species who can no longer breed with one another
Distinction between populations and species can be ambiguous.
Phase 4 Tasks
A3.1.5—Difficulties distinguishing between populations and species due to divergence of non- interbreeding populations during speciation
Understand that speciation is the splitting of one species into two or more.
It usually happens gradually rather than by a single act, with populations becoming more and more different in their traits.
It can therefore be an arbitrary decision whether two populations are regarded as the same or different species.
Locate your species in its natural environment. Research if your species has become a new species gradually over time through speciation.
Describe how this change slowly happened.
Describe how the species was separated over time.
Phase 4 Vocabulary
Population
Diverge
Interbreed
Species
Separation-land, river, mountain, ocean
Fertile Offspring
Evolve
Environment
Gradual
Speciation
Phase 5: Genetic Variation
How many chromosomes does your species have?
How does this differ from humans?
Why do species have different numbers of chromosomes?
Phase 5: Vocabulary
Genome
Chromosome