Evolution & classification

What is classification

The organisation of living things into groups according to their similarities

What is taxonomy

The study of the principles behind classification

What are the 7 taxonomic groups

• Domain

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

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What is the classification timeline and what each person proposed

1. Aristotle- Classified organisms into two kingdoms animals and plants

2. Carl Linnaeus- Proposed the 7 taxonomic groups and binomial GS names

3. Ernst Haekel- Proposed a third kingdom the Protoctista

4. Robert Whittaker- Proposed 5 kingdom model prokaryote, protoctista, fungi, plantae and animalia

5. Carl Woese- Proposed a 6 kingdom model Eubacteria, Archaebacteria, protoctista, fungi, plants and animals.

What are the characteristics of prokaryotes (bacteria)

• Unicellular with no bound organelles, only plasmids and small ribosomes

• Most have cell wall made of peptidoglycan

• None have chloroplasts except cyanobacteria

• Have flagella for movement

• Absorb nutrients through cell wall

What are the characteristics of protoctista (amoeba)

• Mainly unicellular with membrane bound organelles and nucleus

• Some have a cell wall made of cellulose and chloroplasts

• Have cilia or flagella for movement

• Acquire nutrients through autotrophic or heterotrophic ways or are parasitic

• Made of hyphae

What are the characteristics of fungi (yeast, mould)

• Unicellular or multicellular with membrane bound organelles and nucleus

• Have cell wall made of chitin

• Have no movement mechanisms

• Acquire nutrients from decaying matter (saprotrophic) and some are parasitic

• Store food as glycogen

What are the characteristics of plantae (plants)

• Multicellular with membrane bound organelles and nucleus

• Have cell wall made of cellulose

• All have chloroplasts

• Acquire nutrients through photosynthesis (autotrophic)

• Store food as starch

What are the characteristics of animalia (animals)

• Multicellular with membrane bound organelles and nucleus

• No cell wall

• Contractile proteins in muscular organs

• Acquire nutrients through ingestion

• Store food as glycogen

What is the difference between Eukarya, Archaea and Bacteria

What is a species

A group of organisms that reproduce to produce fertile offspring

What are hybrids

infertile due to an odd number of chromosomes as meiosis does not take place properly as chromosomes don’t line up

What is speciation

• The evolutionary process by which new and distinct species arise from a single ancestral species due to becoming isolated

• The two populations may have different environments so different selection pressures so evolve differently by natural selection

What is the process of evolution

1. Variation within individuals in a species due to mutation

2. Characteristic from mutation is advantageous against individuals environmental pressures

3. More likely to survive and reproduce to pass on advantageous allele

4. Over many generations, advantageous alleles become more common in the population

What does heterotrophic mean

Organisms that obtain food by consuming other organisms or organic matter e.g. animalia, protoctista and fungi

What does autotrophic mean

Organisms that make their own food from inorganic substances (usually via photosynthesis) e.g. plantae and some protoctista

What does saprotrophic mean

Organisms that feed on dead/decaying organic matter by external digestion e.g. fungi and some bacteria

Why is three domain classification system preferred over the five kingdom system

• Classifies species which are more closely related together

• There are key differences between Archaea and bacteria so need to be classified differently

• Bacteria and archaea have different structure such as different cell membrane

What is the difference in DNA between eukaryotic cells and prokaryotic cells

• Eukaryotic cells DNA associated with histone proteins

• DNA is not circular

• DNA in chromosomes

What advantages does using binomial naming give

• Standardises classification across the world

• Each organism has its own unique name

• Avoids confusion in naming species

• Simplifies communication between different languages