CLASSIFICATION AND EVOLUTION

Define classification

The organisation of living organisms (or other items) into groups, according to their shared similarities

Define taxonomy

The study of the principles behind classification

How many taxonomic levels are there in the current system of classification?

8

What are the eight tax economic levels in order?

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

What are the three domains?

Eukaryotae

Eubacteria

Archaea

What are the five kingdoms?

Animalia

Plantae

Fungi

Protoctista

Prokaryotae

Which kingdom is the odd one out and why?

Prokaryotae bc they are single celled organisms, that do not have a nucleus

What are the main characteristics of the kingdom Animalia?

- Multicellular

- heterotrophic feeders so no chlorophyll

- no cell walls

- complex cell structure with nucleus

What are the main characteristics of the kingdom Plantae?

- multicellular

- autotrophic feeders using chlorophyll

- cell walls made of cellulose

- complex cell structure with nucleus

What are the main characteristics of the kingdom Fungi?

- multicellular

- cell wall is not made of cellulose

- saprophytic feeders so no chlorophyll

- complex cell structure with nucleus

What are the main characteristics of the kingdom Protoctista?

- mostly unicellular (a few are multicellular)

- complex cell structure with nucleus

What are the main characteristics of the kingdom Prokaryotae?

- unicellular

- simple cell structure with no nucleus

Describe the phylum taxonomic group

Major subdivision of the kingdom

A file contains all the groups of organisms that have the same body plan (e.g. have a backbone.)

Describe the class taxonomic group

A group of organisms that all possess the same general traits (e.g. same number of legs.)

Describe the order taxonomic group

A subdivision of the class using additional information about the organisms (e.g. the class of mammals is divided into meat eaters (order Carnivora) and plant eaters (order Herbivora))

Describe the family taxonomic group

A group of closely related genera (e.g. within the order Carnivora, there is the "dog" family and the "cat" family)

Describe the genus taxonomic group

A group of closely related species

Describe the species taxonomic group

The basic unit of classification. All members of a species show some variation, but all are essentially the same

What is the mnemonic used for memorising the order of the taxonomic groups?

King

Prawn

Curry

Or

Fat

Greasy

Sausage

OR (small to large so be careful)

Small

Green

Frogs

Often

Catch

Princess

Kisses

Fill in the gaps.

___1___ is the universal language of biologists. Every species has a __2__ name. Each organism is given two names - ___3___ and ___4___.

The names are written in ___5___ (or underlined) with the ___6___ name first (always spelt with a ___7___ letter), and the ___8___ name second (___9___ case).

1. Latin

2. Binomial

3. Genus

4. species

5. italics

6. Genus

7. capital

8. species

9. lower

What were early classification systems based on?

observable features

Who was Carolus Linnaeus? What was he known as?

18th cent., Swedish botanist/physician/zoologist. Known as the "Father of modern taxonomy"

How did Carolus Linnaeus classify plants and animals?

According to similarities in form

What are the two kingdoms Carolus Linnaeus divided living things into?

Plants and animals

What did Carolus Linnaeus divide each of the two kingdoms into and what were these then divided into?

He divided each kingdom into genera (plural of genus)

Then divided these into species

What system did Carolus Linnaeus design to name organisms?

Binomial nomenclature

What does binomial nomenclature mean?

"two names" "system of naming"

What did the three kingdom system introduce and why?

The three kingdom system introduced the kingdom Protoctista bc microorganisms were discovered through microscopes

How was the five kingdom system developed?

More was learned about the cell structure in organisms (due to electron microscopes) and so bacteria were taken out of the Protoctista kingdom and fungi were taken out of the plant kingdom

Describe the features of the Prokaryotae kingdom?

- no nucleus

- loop of DNA that is not arranged in linear chromosomes

- have naked DNA (DNA that is not associated with histone proteins)

- have no membrane bound organelles

- have smaller ribosomes than in other groups

- have cells smaller than those of eukaryotes

- may be free living or parasitic (some cause diseases)

Describe the features of the Protoctista kingdom?

- eukaryotic

- mostly single celled (algae are multicellular)

- show a wide variety of forms (the only thing that all protoctists have in common is that they do not qualify to belong to any of the other four kingdoms)

- show various plant-like or animal-like features

- are mostly free living

- have autotrophic or heterotrophic nutrition (some photosynthesise, some ingest prey, some feed using extracellular enzymes, some are parasites

Describe the features of the Fungi kingdom?

- eukaryotic

- can exist as single cells (called yeasts) all they have a mycelium that consists of hyphae

- have walls made of chitin

- have cytoplasm that is multinucleate

- are mostly free living and saprophytic (this means that they cause decay of organic matter)

Describe the features of the Plantae kingdom?

- eukaryotic

- multicellular

- have cells surrounded by a cellulose cell wall

- are autotrophic (absorb simple molecules and build them into larger organic molecules)

- contain chlorophyll

Describe the features of the Animalia kingdom?

- eukaryotic

- multicellular

- heterotrophic (digest large organic molecules to form molecules for absorption)

- are usually able to move around

What is the biological definition of a species?

Group of organisms that can freely interbreed to produce fertile offspring

What is the phylogenetic definition of a species?

Group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry, and genetics (share common ancestor)

What is the molecular evidence that led to a new classification system?

- DNA

- cytochrome C

- rRNA

How is biochemistry used in classification?

How different or similar the DNA or RNA of living organisms can be evidence for how closely related they are in evolutionary terms.

If any organism shares the same sequence of bases on DNA or RNA, then the protein made will be the same as well. So if 2 species share many base sequences, they will be more closely related.

What is cytochrome C?

protein used in respiration (all organisms respire (apart from some bacteria), so they all contain this protein)

How can cytochrome c be used to compare 2 species for classification?

samples of cytochrome c can be analysed to find out which amino acids are present - if the 2 samples are the same, then the 2 species are closely related, many difference = less closely related

look at diagram on notes!!!

What has genetic analysis shown?

All organisms (apart from Prokaryotes) have sections of DNA within genes that aren't used by the cell

What did the discovery from genetic analysis lead to?

Carl Woese propose to all organism should be divided into three domains

What are the three domains proposed by Carl Woese?

Archaea, Eubacteria, Eukarya

What is the Archaea domain?

Cells with no nucleus, genes contain unused sections of DNA

What is the Eubacteria domain?

Cells with no nucleus, genes do not contain unused sections of DNA

What is the Eukarya domain?

Cells with a nucleus, genes do contain unused sections of DNA

What is a cladogram?

Shows evolutionary relationship between organisms. The closer to the branches, the more closely related they are (the more similar their DNA is)

LOOK AT DIAGRAM ON HANDOUT

What are the structural differences between Eubacteria and the other two domains (Archaea and Eukarya)?

- different cell membrane structure

- flagella with different internal structure

- different RNA polymerase

- no proteins bound to genetic material

- different mechanisms for DNA replication and synthesising RNA

What are the features that Archaea share with the Eukarya?

- similar RNA polymerase

- similar mechanisms for DNA replication and for synthesising RNA

- production of some proteins that bind to their DNA

Define phylogeny

The study of the evolutionary relationship between organisms

Define common ancestor

The most recent individual from which a set of organisms in a group are directly descended

DIAGRAM ON HANDOUTS

Define monophyletic

The term used to describe all organisms that have evolved from the same species

Define natural selection

The term used to explain how features of the environment apply a selective force on the reproduction of individuals in a population

What did Charles Darwin see on his expedition on the HMS Beagle that led to his theory of evolution through natural selection?

- all organisms overproduce

- but population remain fairly constant, so some offspring must die

- all organisms show variation (the ones who are best adapted to their environment are more likely to survive and breed)

- some characteristics are inherited (well adapted parents may pass on useful characteristics to future generations which could eventually evolve into new species)

- Evolution is a consequence of natural selection

What are the sources of evidence for evolution?

- from studies of embryology

- biochemistry

- observations

- anatomical studies

- fossil record

- Studies of DNA

- Geographic distribution

How do fossils occur?

- fossils occur and layers of rock, with the youngest usually on top, and the oldest in deeper layers.

- on occasion, bucking of rocks can reverse these layers in relatively small areas, but radioactive dating methods can help to identify the proper sequence of ages

What does the fossil record show us?

- the world was inhabited by species that were different to the species present now

- overtime, species have died out in similar ones have formed (found in the same place)

- more modern species had variations that meant they were better adapted to the environment

Fill in the gaps about the biochemical evidence for evolution.

All living organisms contain ___1___ / ___2___.

The genetic code is ____3____, which means that the instructions for making proteins are the ___4___ for all living things

Species that are closely related have similar ___5___ ___6____.

______7_____ is a protein that is needed for cellular respiration.

The structure of this protein (due to the amino acid sequence) ____8____ between species.

Organism is most closely related will have the same type of ____9____.

1. DNA

2. RNA

3. universal

4. same

5. DNA

6. sequences

7. cytochrome c

8. varies

9. cytochrome c

Who was African Eve?

a woman who lived in Africa between 130 000 - 200 000 yrs ago, and passed on mitochondria DNA (mtDNA) to all humans living today.

Where is mtDNA located?

Inside mitochondria

How is mtDNA passed on?

Along the maternal line (sperm cell only gives its nucleus during fertilisation)

fill in the gap.

All of the mtDNA in the cells of a person's body are _____ of his/her mother's mtDNA

copies

What are the main differences between mtDNA and nuclear DNA?

mtDNA:

- found in mitochondria

- inherited from Mum only

- more likely to mutate

- more of it in a cell

Nuclear DNA:

- found in nucleus

- inherited from both Mum and Dad

- less likely to mutate

- less of it in the cell

Define variation

Differences observed between individuals

Define interspecific variation

Difference differences between species. (This may be very easy to observe or only identified by comparing DNA or RNA.)

Define intraspecific variation

Differences between members of the same species

More genetic diversity =

More intraspecific variation

Define continuous variation

Where there are two extremes and a full range of value values in between

How is continuous variation regulated?

By more than one gene

How is continuous variation modified?

By the environment

What are examples of continuous variation?

Human height, width of oak tree leaves, length of stalk of a mushroom, number of flagella on a bacterium

How is continuous variation shown?

Using a histogram

Define discontinuous variation

Where there are distinct categories and nothing in between

How was discontinuous variation regulated?

By a single gene

Can discontinuous variation be modified by the environment?

No

What are examples of discontinuous variation?

- gender: mammals or male or female; plants are male, female, or hermaphrodite

- human ABO blood group system (A, B, AB, or O)

- some bacteria have flagella, others don't

How is discontinuous variation shown?

Bar chart

What are the causes of variation?

Genetics, environment, and a combination

Define genetic variation

Variation caused by possessing a different combination of alleles.

Each individual of a species will have inherited different combinations of alleles from their parents (unless they are identical twins)

Define environmental variation

Variation caused by response to environmental factors (such as light intensity or food availability)

How can many characteristics be affected by a combination of genes and the environment?

Changes in the environment can directly affect which genes are active (e.g. "C" gene the controls the development of pigment in Himalayan rabbits is only active when temperature is low)

What are the three statistical techniques that can be applied to variation data?

Standard deviation, student t-test, correlation coefficient

What is standard deviation?

A measure of the spread of data around the mean

What is a student's t-test?

A test used to compare 2 means

What is correlation coefficient? Which value means perfect correlation?

A measure of how closely two sets of data are correlated. A value of one means perfect correlation.

To investigate variation you need to... a population?

Sample

What are the two calculations you can carry out to measure? How much variation there is in a sample?

- mean

- Standard deviation

LOOK AT DIAGRAMS ON HANDOUT

What is the formula for calculating standard deviation?

SD NOTES ON HANDOUT

What is a student's t-test used for?

To compare 2 means and to work out if the difference between them is significant or not

Define null hypothesis

There is no significant difference between the means of the two sets of data

Define adaptation

A characteristic that enhances survival in a habitat

What are the three different types of adaptation?

Anatomical

Behavioural

Physiological/biochemical

Define anatomical adaptations

Structural features to aid survival

Define behavioural adaptations

Ways that behaviour is modified for survival

Define physiological/biochemical adaptations

The way that processes work in the body to aid survival