Biology A Level OCR A; Classification and Evolution

What is the binomial system?

A system that uses the genus name and the species name

Avoids confusion when naming organisms

What is classification?

Process of placing living things into groups

Why do we classify things?

- For convenience

- Make the study of living things more manageable

- Make it easier to identify organisms

- Helps to view the evolutionary relationships (phylogeny) between species

What is the order of the modern classification hierarchy?

- Domain

- Kingdom

- Phylum

- Class

- Order

- Family

- Genus

- Species

What are the three domains?

- Archaea

- Eubacteria

- Eukarya

What are the five main kingdoms?

- Plantae

- Animalia

- Fungi

- Protocista

- Prokaryote

What is the kingdoms that possess a nucleus?

Plantae, Animalia, Fungi, protocista

What kingdom has no nucleus?

Prokaryote

Does it become easier or harder to classify new species' as you go down the taxonomy hierarchy?

As you go down the modern classification hierarchy, it becomes harder and harder to;

- Separate closely related species

- Place a species accurately

- Therefore a more and more detailed description is needed

What is the binomial naming system?

Using the genus and species names together

How can you tell the genus name of the binomial name?

Genus name will be;

- First name

- Have a capital letter

How must the binomial system be portrayed?

Stand out, either in,

- Italics (primary option)

- Underlined (secondary option)

Who devised the binomial naming system?

Carl Linnaeus

What occurred before the binomial name?

Common name system

What does binomial mean?

In two (parts)

Why was the common name system terrible, did not work well?

- Same organism may have a completely different common name is different parts of one country

- Different common names of the same species were used in different countries

Why were there an addition of different common names of the same species between countries?

Translation of languages/dialects gave many different names for the same species

What language was used to place species in the taxonomy?

Latin

What does using latin as the universal language for the taxonomy mean?

Avoids potential confusion between names for the same species (common names)

What is the biological definition of species?

A group of organisms that can freely interbreed to produce fertile offspring

What is the phylogenic definition of species?

A group of individual organisms that are very similar in;

- Appearance

- Anatomy

- Physiology

- Biochemistry

- Genetics

What was the old classification system based on?

- Appearance

- Anatomy

Did the old classification provide classification?

Yes, however mistakes were common

What, in the earliest attempts of classification, was the first classification system?

- Plant

- Animal

How were animals subdivided?

- Living and moving through air

- Living and moving in water

- Living and moving on land

Example of animals that were incorrectly group?

Everything; i.e. penguins and a giraffe, killer whale and squid, eagle and a mosquito

When was classification developed beyond observable features?

17th century, with the help of microscopes.

What was the general acceptance of kingdoms at the start of classification? (repeated question)

2 kingdoms only; plants and animals.

If you got this wrong, go and get some sleep

Where were single celled organisms grouped in?

Animals

What were fungi originally classified as?

Plants

What are the five kingdoms?

- Prokaryote

- Protoctista

- Fungi

- Plantae

- Animalia

What is the description of prokaryote that allows them to be classified?

- No nucleus

- Loop of DNA that is non-linear

- Naked DNA, not histone proteins

- No membrane-bound organelles

- Have smaller ribosomes than other groups

- Have cells smaller than eukaryotes

- May be free living or parasitic

What is the description of protoctists that allows them to be classified?

- Eukaryotic

- Mostly single celled but can be multicellular

- Show a variety of forms

- Show various plant-like or animal-like features

- Are mostly free living

- Have autotrophic and/or heterotrophic nutrition

- Commonality; do not qualify to belong to any of the other four kingdoms

What is the description of fungi that allows them to be classified?

- Eukaryotic

- Exists as single celled yeasts or they have a mycelium with hyphae

- Have walls made of chitin

- Have a cytoplasm that is multinucleate

- Mostly free living and saprophytic

What are yeasts?

Single celled fungi, reproduced by budding

What are saprophytic fungi?

Cause decay of organic matter

What is the description of plantae that allows them to be classified?

- Eukaryotic

- Multicellular

- Cells surrounded by a cellulose plant wall

- Autotrophic

- Contains chlorophyll

What is the description of animalia that allows them to be classified?

- Eukaryotic

- Multicellular

- heterotrophic

- Usually able to move around

Remember card (flip)

Remember to describe the differences between these five kingdoms, memorise.

What is convergent evolution?

Unrelated species evolve similar traits due to their similar environments even though they live in different parts of the world

What research allows more evidence to classify different species?

- Protein cytochrome C

- DNA

- Three domain classification

What can differences between biological molecules be used to study?

- Evolutionary relationships (Phylogeny)

- Evolution of a species

Where is cytochrome C used in?

Respiration

Do all organisms that respire use cytochrome C?

Yes

Is cytochrome C a protein that is identical in all organisms?

No, the primary structure of cytochrome C can vary between species to species

When comparing two cytochrome C proteins from two different species, what can we conclude?

- If sequences are the same, then the two species are closely related

- If the sequences are different, the two species are not closely related

What is the trend between cytochrome C of two species and differences between the amino acid primary structure sequence?

The more differences in sequences, the less closely related the two species are

Is the amino acid sequence of cytochrome C in humans and chimpanzees the same?

Yes

Is the amino acid sequence of cytochrome C in humans and the dogfish the same?

No, there are 11 differences in the primary structure of the human cytochrome C and the dogfish cytochrome C

What biological molecule provides genetic code? (easiest question you could answer)

DNA

What is a feature of DNA that can allow cross-referencing between the genetic codes of different species?

That DNA is universal

What are changes of bases in DNA?

Mutations

What is the trend between how closely related two species are and the differences between the DNA sequence of the two species?

- The more similar a sequence of DNA is compared to another sequence, the more closely related those two species are.

- The more differences of a sequence of DNA and another sequence of DNA, the less closely related those two species are

Which biological molecule is more accurate to study how closely two species are related, cytochrome C or DNA?

DNA

What new classification was introduced by Carl Woese? What was it based on?

Three domain classification; based on a detailed study of the ribosomal RNA gene

What evidence supports Carl Woese differences between bacteria and archaea?

Each have different structures of their ribosomes

What are the main differences between bacteria and archaea?

- Different cell membrane structures

- Different internal structures of the flagella

- Different enzymes (i.e. RNA polymerase)

- No proteins bound to the genetic material of bacteria (i.e. histone proteins)

- Different mechanisms for DNA replication and for synthesising RNA

What features does archaea share with eukaryotes?

- Similar enzymes (RNA polymerase) for synthesising RNA

- Similar mechanisms for DNA replication and synthesising RNA

- Production of some proteins than bind to their DNA

What part of the differences did Woese signify?

RNA and DNA mechanisms.

What is phylogeny?

The study of the evolutionary relationships between organisms

What are the two types of classifications?

1. Artificial classification

2. Natural classification

What are the features of artificial classification?

- Based on only a few characteristics

- Does not reflect any evolutionary relationships

- Provides limited information

- But it is stable

What group will closely related species be placed within?

A genus.

What group will multiple closely related genera be place in?

A family

What are ranked groups following each known as?

Hierarchy

What are the features of natural classification?

- Uses many characteristics

- reflects evolutionary relationships

- Provides a lot of useful information

- May change with advancing information

What does phylogeny involve?

Studying how closely related different species are

What is the term called for when species belong to one phylogenic group (i.e. a common ancestor)?

Monophyletic

Can common ancestors be regarded as some who lives in the present (today)?

Absolutely not.

Confused? If me and you are homo sapiens, we cannot say we evolved from gorillas. What we can say is that gorillas and humans evolved form the same common ancestor.

Still confused? In theory, yes, if you artificially preserved a common ancestor in a indefinite zoo that lived forever and let its other relatives of the same species live on to evolve to other species, you theoretically contradict common ancestors, however evolution is constant in nature therefore common ancestors cannot live in the present

In theory, does a snake and a human share a common ancestor?

Yes, around 300 to 400 million years ago

(you won't be asked this specific question in your exam)

Could I say, humans evolved from apes?

No, but apes and humans share a common ancestor

What is natural selection?

Explains how features of the environment applies a selective force on the reproduction of individuals in a population

Was the theory of evolution originally Darwins idea? What exactly did he do?

No, but Darwin displayed a mechanism to the world of the process

Why were people against Darwin and his proposed mechanism of the theory of evolution?

As during Victorian Britain, his theory went against religious belief

What was Darwins actual mechanism called?

(not a trick question, just use your common sense and what you learnt from GCSE)

Natural selection

Where did Darwin understand natural selection?

Galapagos islands

What made Darwin realise natural selection?

1. Found different variations of finches on each island

2. Concluded that one species of finch had arrived on the islands and then formed different species per island

Who is Russel Wallace?

A naturalist who independently came to the same conclusion as Darwin

What was Darwins book called?

The Origin of Species

What four observations did Darwin make?

1. Offspring generally appear similar to their parents

2. No two individuals are identical

3. Organisms have the ability to produce large numbers of offspring

4. Populations in nature tend to remain fairly stable in size

What are Darwins conclusion that relate to survival of the fittest?

- There is a struggle to survive

- Better adapted individuals survive and pass on their characteristics

- Over time, a number of changes give rise to a new species

What are the two main types of evidence for evolution?

- Fossil evidence

- Biological molecules evidence

What facts do fossils show?

- World was inhabited by species that were different from those present today

- Old species have died out and new species have risen

- New species that have appeared are similar to the older species found in the same place

Why were more modern species surviving moreso than the old species in fossils?

The new species has variations that were better adapted to the environment

What differences usually occurred between old and new species?

Many fossil species were much larger than modern species

How are biological molecules an example as evidence for evolution?

- All organisms in the world have the same or similar biological molecules

- Two closely related species will have separated recently if their biological molecules are identical/similar

- As species separate with differences, biological molecules are likely to be different

- Protein difference correlates with how different two species are (i.e. cytochrome C)

What does species having the same/similar biological molecules suggest?

All species in the world originated from one original ancestor

How can DNA be used as evidence for evolution?

Number of similarities between gene sequences shows how closely related two species are

In percentage, how does comparison of human DNA and other primates show?

- Chimpanzees differ 1.2% of humans

- Gorillas differ 1.6% of humans

- Baboons differ 6.6% of humans

What is continuous variation?

Variation where there are two extremes and a full range of values in between

What is discontinuous variation?

Where there are distinct categories and nothing in between

What is environmental variation?

Variation caused by response to environmental factors, i.e. light intensity

What is genetic variation?

Variation caused by possessing a different combination of alleles

What is interspecific variation?

Differences between species

What is intraspecific variation?

Variation between members of the same species

What is variation?

Presence of variety; differences between individuals

How can twins appear different?

- Subsequent replication of DNA and cell divisions may have introduced changes to the DNA showing genetic variation

- Slight environmental differences in the womb or after birth from the environment can show physical variation

What variation can there be within a intraspecies?

- Eye colour

- Hair colour

- Skin colour

- Nose shape

Is genetic diversity directly correlated to intraspecific variation?

Yes

In continuous variation, where are most individuals close to?

(a level maths people; think normal distribution!)

The mean value