Classification & Evolution Flashcards
What are the 7 taxonomic groups?
Kingdom Phylum Class Order Family Genus Species
Why do scientists classify organisms?
- To identify species
- To predict characteristics
- To find evolutionary links
What are species?
A group of organisms that are able to reproduce to produce fertile offspring
What is a mule/hinny?
Infertile offspring - not a species
Why are mules infertile?
Their cells contain an odd number of chromosomes. This means that meiosis and gamete production cannot take place correctly as all chromosomes must pair up
What were the issues before classification systems were used?
- Organisms may have more than one common name
- Different names in different languages
- Common names don’t provide information about relationships between organisms
What is binomial nomenclature?
The system in which two terms are used to denote a species of living organism
What does the first word of the species name indicate?
The genus
What does the second word of the species name indicate?
The specific name - organism’s species
How should an organism’s scientific name be presented?
- Italics
- Handwritten = underline name, lowercase with the exception of the first letter of genus’ name
What are the 5 kingdoms?
Prokaryotae Protoctista Fungi Plantae Animalia
How are organisms classified as prokaryotae?
- Cell type = prokaryotic
- Body organisation = unicellular
- Type of nutrition = autotrophic/heterotrophic
- No membrane-bound organelles
- E.g. bacteria
How are organisms classified as protoctista?
- Cell type = eukaryotic
- Body organisation = unicellular
- Type of nutrition = autotrophic/heterotrophic
- Membrane-bound organelles present
- E.g. algae
How are organisms classified as fungi?
- Cell type = eukaryotic
- Body organisation = multicellular
- Type of nutrition = heterotrophic
- Membrane-bound organelles present
- E.g. yeast
How are organisms classified as plantae?
- Cell type = eukaryotic
- Body organisation = multicellular
- Type of nutrition = autotrophic
- Membrane-bound organelles present
- E.g. angiosperms
How are organisms classified as animalia?
- Cell type = eukaryotic
- Body organisation = multicellular
- Type of nutrition = heterotrophic
- Membrane-bound organelles present
- E.g. birds
What is the current classification system used by scientists?
Three Domain System - Carl Woese
When was the word ‘kingdom’ renamed ‘domain’?
1990
How are the organisms in the 3 different domains different?
Unique form of rRNA and different ribosomes:
- Eukarya: 80s ribosomes and RNA polymerase with 12 proteins
- Archaea: 70s ribosomes and RNA polymerase with 8-10 proteins
- Bacteria: 70s ribosomes and RNA polymerase with 5 protein sugar
What are the 6 kingdoms?
The Prokaryotae kingdom divides into 2 - Archaebacteria and Eubacteria
Give 2 facts about Archaebacteria
- Can live in extreme environments
- E.g. hot thermal vents, anaerobic conditions and highly acidic environments
Give 2 facts about Eubacteria
- Found in all environments
- Chemically different from Archaebacteria
What is phylogeny?
The name given to the evolutionary relationships between organisms
Give 5 pieces of evidence used for phylogeny
1- Genetics (e.g. DNA) - compare base sequence, the higher the % match the more closely related they are
2- Biochemistry (e.g. antibodies/enzymes) - compare tertiary structure, more similar = more related
3- Anatomy - observable physical characteristics
4- Behaviour
5- Embryology - how the embryo develops
Give 3 advantages of phylogenetic classification
- Can be done without reference to Linnaean Classification
- Produces a continuous tree whereas classification requires discrete taxonomical groups
- The hierarchical nature of Linnaean classification can be misleading as it implies different groups within the same rank are equivalent
What is variation?
The differences in characteristics between organisms
What is interspecific variation?
Differences between members of different species
What is intraspecific variation?
Differences between organisms within a species
What are the two types of causes of variation?
- Genetic causes
- Environmental causes
Give 3 genetic causes of variation
- Mutations
- Meiosis
- Random fertilisation
What is discontinuous variation?
- Individuals fall into discrete groups with no intermediates
- Controlled by a single gene with a few alleles
- E.g. blood group
How is discontinuous variation represented?
Bar chart
What is continuous variation?
- A characteristic that can take any value within a range
- Variation is smooth and continuous (not discrete)
- E.g. height and weight
How is continuous variation represented?
Line graph
What are normal distribution curves?
When continuous variation data are plotted onto a graph, they usually result in the production of a bell-shaped curve
Give 4 characteristics of a normal distribution
- The mean, mode and median are the same
- Has a ‘bell shape’
- 50% of value are less than mean and 50% are greater
- Most values lie close to the mean value
When is a student’s t test carried out?
This is used to compare the means of data values of 2 populations
When is a spearman’s rank correlation coefficient carried out?
This is used to consider the relationship between 2 sets of data
What are adaptations?
Characteristics that increase the organism’s chance of survival and reproduction in its environment
What are the 3 types of adaptations?
- Anatomical adaptations (physical features)
- Behavioural adaptations (the way an organism acts)
- Physiological adaptations (processes that take place inside an organism)
Give 4 examples of anatomical adaptations
1- Body covering
2- Camouflage
3- Teeth
4- Mimicry
Give 3 examples of behavioural adaptations
1- Survival behaviours (e.g. playing dead)
2- Courtship (attract a mate)
3- Seasonal behaviours (organisms cope with changes in environment). They include:
• Migration
• Hibernation
What are the 2 main categories of behavioural adaptations
- Innate behaviour (inherited through genes)
- Learned behaviour
Give 3 examples of physiological adaptations
- Poison production
- Antibiotic production
- Water holding
What are analogous structures?
Structures that have adapted to perform the same function but have a different genetic origin
When does convergent evolution take place?
When unrelated species begin to share similar traits
Explain how comparative biochemistry provides evidence of evolution
- Changes in highly conserved molecules can help identify evolutionary links, such as ribosomal RNA
- Species that are closely related have the most similar DNA/proteins, distantly related have far fewer similarities
Give 3 examples of convergent evolution
1- Marsupial and placental mice (both are small, agile climbers that live in dense ground cover and forage at night for small food items)
2- Flying phalangers and squirrels (both are gliders that eat insects and plants. Their skin is stretched between their forelimbs and hind to provide a large SA for gliding from trees)
3- Marsupial and placental moles (both burrow through soft soil to find worms and grubs, both have a streamlined body shape and modified forelimbs for digging)
