IB biology - Topic 5

Homologous Structures

Similar structures due to similar ancestry; Arise via divergent evolution; E.g. Pentadactyl Limb

Analogous structures

-\> the opposite of homologous structures. Similar structures due to convergent evolution (similar functionality). E.g. Fins of shark and whale

Divergent Evolution (adaptive radiation)

the rapid evolutionary diversification of a single ancestral line

It occurs when members of a single species occupy a variety of distinct niches with different environmental conditions

Benefits of Taxonomy

-Gives organisms globally recognised name
-Can display relationships between organisms (allows evolutionary predictions)
-easier to collect, sort, and group info

Rules of Binomial nomenclature

-First name is the genus name (group of species that share characteristics)
-Second name is the species specific name
-Genus name begins with capital and species name in lowercase
-in italics
-After referenced once, genus name can be shortened to first letter

Hierarchy of Taxa

-Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

The 3 Domains

- Eukaryota
- Archaea
- Eubacteria

Natural Classification

Grouping organisms based on morphological similarities

Phyla of Invertebrate animals

- Porifera
- Cnidaria
- Platyhelminthes
- Annelida
- Mollusca
- Arthropoda
- Chordata

Porifera

- Lack symmetry, no mouth, no anus, pores through body, cylindrical Eg. Sea Sponge

Features of Cnidaria

- Radial Symmetry (symmetry radiates from central point)
- Aquatic
- One mouth, no anus
- Stinging cells
- Tentacles
- Eg. Jellyfish

Platyhelminthes (Invertebrate animals)

- Bilateral symmetry
- Unsegmented
- Flattened body shape
- One mouth, no anus
- Often parasitic
- Eg. Tapeworm

Arthropods (Invertebrate animals)

- bilateral symmetry
- Exoskeleton
- Segmented bodies
- Heart on dorsal side of body
- Eg. Shrimp, spider, insects

Amphibians (Vertebrate animals)

-moist skin permeable to water and gases
-simple lungs
-four legs when adult
-external fertilisation
-larval stage in water, adult on land
-do not maintain constant body temperature

Reptile

-Impermeable skin
-Lungs
-Four legs in most species
-Internal fertilisation
-four legs in most species
-do not maintain constant body temperature

Bird

-skin with feathers
-Lungs
-limbs
-two legs, two limbs
-internal fertilisation
-beak, no teeth
-maintain constant body temperature

Mammal

-skin with hair, lungs four legs, or two legs, and two arms, internal fertilisation ,Maintain constant body temperature

Annelida (Invertebrate animals)

- Bilateral symmetry
- seperate mouth and anus
- bristles often present
- Segmented body
- Eg. Earthworm, leeches

Mollusca (Invertebrate animals)

- Soft bodies
- Vascular foot
-seperate mouth and anus
- Shell may be present
-no segmentation
- Eg. Snail and slugs

Dichotomous Key

- Each statement has 2 choices
- Leads from obvious features within an organism to more specific characteristics

Domain

one of the 3 major categories of life: archaea, bacteria and eukaryotes

Kingdom

a taxonomic group that contains one or more phyla

Phylum

a subdivision od a kingdom, composed of one or more classes of organism

Class

A subdivision of a phylum, a class is composed of one or more orders of organism

Order

a subdivision of a class, composed of one or more families of organism

Family

a subdivision of an order: composed of onre or more genera

Genus

A subdivision of family: composed of one or more species

Species

A group of related organisms that can successfully interbreed in the wild

Archaea

- Proteins similar to histones bound to DNA
- Presence of introns: present in some genes
- Not made of peptidoglycan (cell walls)

Vertebrate phylum

-reptiles
-mammals
-fish
-amphibians
-birds

Bacteria

- No histones associated with DNA
- Presence of introns: rare/absent
- Made of chemical called peptidoglycan (cell walls)

Binomial nomenclature

agreed upon system for naming organisms consisting of genus and species, allows identification and comparison of organisms

Viruses

non-living biological entities that have infectious properties - non-living pathogens

Coniferophyta

-vascular tissue present, seeds from ovules (found in female cones), roots present

Byrophyta

-no vascular tissue, spores produced in capsules, no roots but instead have root hairs (rhizoids), simple leaves and stems (eg moss)

Angiospermaphyta

- Has vascularisation
- Has leaves, roots & stems
- Reproduce through seeds produced in ovules within flowers
- Flowering plants + grasses

Filicinophyta

- Roots are present
- Short and non-woody stems
- Leaves are divided into pairs (leaflets)
- Vascular tissue is present
- Spores produced in sporangia on the underside of the leaves

Natural Selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Variation

the range of phenotypes within a population

Antibiotics

a chemical produced by microbes to kill off competing microbes.

Causes of variation

Mutation, meiosis and sexual reproduction

Key components of natural selection

Inherited variation,
Competition,
Environmental pressurers,
Adaptations,
Genotype frequency,
Eventually all this leads to evolution

Examples of natural selection

1) Peppered moths
2) Antibiotic resistance in bacteria
3) Changes to the beak sizes of finches in Daphne Major

Overproduction of offspring

Organisms produce more offspring than can be supported by limited resources

Population

A group organisms of the same species living in a particular area at the same time

Evolution

Process of biological change by which descendants come to differ from their ancestors.

Species

Group of organisms that can reproduce together to produce fertile offspring

Trait

A characteristic that an organism can pass on to its offspring through its genes.

Diversity

Differences in a population

Artificial Selection

When humans breed organisms for specific traits

Variation

Any difference between individuals of the same species.

Competition

Occurs for food, space, and other resources

Homologous structures

Similar structures that related species have inherited from a common ancestor

Adaptations

instinctive characteristics or features that organisms use for survival

Mutation

A change in the genetic sequence (DNA) - substitution, insertion, or deletion of bases

Meiosis

The reduction of chromosomes through a process of cell division.

Evolution

The process of cumulative change in the heritable characteristic of a population

Heritable

The changes must be passed on genetically from one generation to the next (implying that evolution

Speciation

If enough changes occur in a population, a new species arises in the process and will no longer be able to interbreed from their pre-existing population

Fossil record

The accumulation of evidence from remains and traces, such as skeletons and footprints which shows a cumulative change in a species' evolution

Divergent Evolution

When two or more species sharing a common ancestor become more different over time (Eg. Finches) Share the same ancestors

Homologous structures

Structures in different species that are similar because of common ancestry.

Adaptive Radiation

Occurs when similar but distinct species evolve relatively rapidly to occupy new niches

Polymorphism

Different versions of a species (Eg. black and white moths)

Gradualism

The theory that evolution occurs slowly but steadily