4.3 - C - Classification And Evolution

Question 1

Define accuracy
Define precision
Define error of measurement

Answer 1

Accuracy - how closeness of agreement there is between a result and the true value (the true value is usually not known).
Precision - a measure of how close the repeats are to one another.
Error of measurement - is the difference between an individual measurement and the true value.

Question 2

Why do we classify organisms?

Answer 2

For convenience for more manageable study of organisms.
To make it easier to identify organisms.
To help see relationships between organisms.

Question 3

List the 8 taxonomic (taxa) groups we use for classification.
Explain them.

Answer 3

Domain - the highest taxonomic rank. There are 3 domains.
Kingdom - there are 5 main kingdoms.
Phylum - a major subdivision of the kingdom. A phylum contains all the groups of organisms that have the same body plan eg: vertebrae.
Class - a group of organisms that all possess the same general traits eg: number of legs.
Order - a subdivision of the class using additional information about the organisms eg: The class mammal is divided into Carnivora and Herbivora.
Family - a group of closely related genera eg: within Carnivora there’s the dog family and cat family.
Genus - a group of closely related species.
Species - The basic unit of classification. All members of the species show some variations, but all are essentially the same.

Question 4

Which end of the taxonomic groups has the least variation and which has the most? What does this also mean they have?

Answer 4

Domain - least related ‐ most variation.

Species - most related - least variation.

Question 5

What are the 3 domains?

Answer 5

Archaea
Eubacteria (prokaryote)
Eukaryotae

Question 6

What are the 5 kingdoms?

Give characteristics and an example for each.

Answer 6

Plantae (plant) - eukaryotes, multicellular, autotrophic nutrition, cellulose cell walls, fertilised eggs develop into multicellular embroys. Contain chlorophyll - tree.
Animalia (animal) - eukaryotes, multicellular, heterotrophic feeders, no cell walls,fertilised eggs develop into blastula, move freely - frog.
Fungi - eukaryotes, mostly multicellular (yeast unicellular), saprophyticfeeders, chitin cell walls, reproduce with spores, multinucleate cytoplasm, have a mycelium made up of hyphae - fungus on an orange.
Protoctista (protist) - eukaryotes, mostly single celled, have autotrophic and heterotrophicfeeders, variety of different forms ‐ DO NOT FIT INTO ANY OTHER KINGDOM, DISPLAY FEATURES OF MULTIPLE KINGDOMS! - paramecium.
Prokaryotae - prokaryotes (no nulceus ‐ loop of naked DNA no histones), no membrane bound organelles, smaller 70S ribosomes, smaller than eukaryotes, may be free living or parasitic - bacteria.

Question 7

What was accepted in 1988?

What was proposed in 1990?

Answer 7

A five‐kingdom system of classification.

A three domain system.

Question 8

Why do classification systems change over time?

Answer 8

Scientific knowledge changes as new discoveries are made.
Technological developments lead to new discoveries.
Named technological development; e.g. microscopes, new DNA technology.
Differences of opinion amongst biologists/scientists.

Question 9

What are the 2 types of name that animals have?

Give an example of each for the same organism.

Answer 9

Common names (e.g. cat) and Latin names (Felis catus).

Question 10

Why are Latin names used for naming organisms?

What are the limitations of using common names?

Answer 10

It acts as a universal language ‐ everyone in the world uses it.
Same species can have different common names in different places,
Different languages would give different common names (e.g. Katze),
Same common name could be used for different sp. in different places.

Question 11

Define taxonomy

Answer 11

The study of the principles behind classification ‐ the study
of the differences between species (physical and genetic).

Question 12

Define phylogeny

Answer 12

The study of the evolutionary relationships between organisms, the study of how closely related they are.

Question 13

What are heterotrophic feeders?
What are autotrophic feeders?
What are saprotrophic feeders?
Give examples for each.

Answer 13

Organisms that eat and digest other organisms - animals.
Organisms that use photosynthesis to make own food - plants.
Organisms that digest other organisms outside the body (using enzymes) - yeast.

Question 14

What does modern classification reflect?

Answer 14

Evolutionary relationships (phylogeny) between organisms.

Question 15

What can evolutionary trees show us?

Answer 15

When 2 species separated and evolved from common ancestors (a ‘branch’ in the ‘tree’.) The more recent the common ancestor, the more closely related the 2 species. The closer 2 species on the tree, the more related they are.

Question 16

What is the biological definition of a species?

What is the phylogenetic definition of a species?

Answer 16

A group of organisms that can freely interbreed to produce fertile offspring.
A group of individual organisms that are very similar in appearance, anatomy, physiology, biochemistry and genetics.

Question 17

Explain the binomial name

Answer 17

First word: Genus (capital letter)
Second word: species (little letter)
Written in italics or underlined

Question 18

What is a binomial system?

Who devised it?

Answer 18

A system that uses the genus name and the species name to avoid confusion when naming organisms.
Carl Linnaeus.

Question 19

Define classification

Answer 19

The process of sorting living things into groups of similar
organisms. It reflects how closely related they are and evolutionary
relationships.

Question 20

Define convergent evolution

Answer 20

Where 2 unrelated species could adapt in similar ways and therefore look very similar.

Question 21

Briefly explain one way in which biochemistry is used in modern classification

Answer 21

Cytochrome C is a protein used by all living organisms in the process of respiration. However it is not identical in all species. The amino acids in this can be identified. If we compare the sequence of amino acids in samples from two different species, then we can draw conclusions:
If the sequences of the same, the two species must be closely related,
Is the species are different, the two species I’m not so closely related,
The more differences found between the sequences, the less closely related the 2 species.

Question 22

How is Bacteria different from Archaea and Eukaryotae?

Answer 22

Bacteria have:
A different cell membrane structure,
Flagella with a different internal structure,
Different enzymes (RNA polymerase) for synthesising RNA,
No proteins bound to the genetic material,
Different mechanisms for DNA replication and for synthesising RNA.

Question 23

What features do Archaea share with eukaryotes?

Answer 23

Similar enzymes (RNA polymerase) for synthesising DNA,
Similar mechanisms for DNA replication and synthesising RNA,
Production of some proteins that bind to the DNA.

Question 24

Define artificial classification

Answer 24

The ordering of organisms into groups on the basis of non-evolutionary features eg: putting all the yellow flowers on one page so it’s quicker for the user to identify.

Question 25

What 4 statements describe artificial classification?

Answer 25

It’s based on only a few characteristics,
It does not reflect any evolutionary relationships,
It provides limited information,
It is stable.

Question 26

What 4 statements describe natural classification?

Answer 26

It uses many characteristics,
It reflects evolutionary relationships,
It provides a lot of useful information,
It may change with advancing knowledge.

Question 27

Define natural selection

Answer 27

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

Question 28

Explain why the appearance and anatomy of Fungi made their

classification difficult for early taxonomists

Answer 28

They don't move freely (like plants),
Hyphae resemble roots,
Digest food (like animals) rather than photosynthesising.

Question 29

What more recent developments have helped us to determine that Fungi are neither plant nor animals?

Answer 29

Physiology ‐ how living things work,
Biochemistry,
Genetics.

Question 30

What were early classification systems based on?

What were the limitations of this?

Answer 30

Appearance and anatomy.

It’s easy to make mistakes and easy to place relatively distant species in the same groups

Question 31

Briefly explain one way in which genetics is used in modern classification

Answer 31

The genetic code (order of bases in DNA) is universal ‐ a sequence in one gene in one organism codes for the same protein in any organism.
We can compare the DNA of different species.
The more similar the genetic code = more related and visa versa.
This has been useful to correct relationships we had previously got
wrong or clarify those we weren’t sure of.

Question 32

How were the 3 domains theorised?

Answer 32

By studying RNA

Question 33

What are Prokaryotes divided into?

Answer 33

True bacteria (Eubacteria)
Archaea (Archaebacteria)

Question 34

How do fossils provide evidence for evolution?

Answer 34

Fossils show that organisms have charged over time.
Methods such as carbon dating can be used to work out how old fossils are.
The oldest rocks contain the simplest species.
The fossil record shows many organisms that no longer exist but where
intermediates between the oldest common ancestors and modern species.

Question 35

Why are fossil records incomplete?

Answer 35

Fossils don’t always form,
Soft tissue doesn’t fossilise,
Many haven’t been found.

Question 36

Explain molecular evidence for evolution

Answer 36

DNA extracted from fossils can show similarities between organisms if they have a similar base sequence; this implies they share a common ancestor.
Similar cytochrome C primary structure shows similarities between organisms ‐ implies they share a common ancestor.

Question 37

Explain other evidence for evolution

Answer 37

e.g. many modern animal species share a physiological similarity ‐ the pentadactyl limb (5 ‘fingered’) suggesting that they share common ancestors.
We can see evolution in action e.g. bacteria becoming resistant to antibiotics.

Question 38

Define variation

Answer 38

Differences within a species or between different species

Question 39

State and explain the two causes of variation

Answer 39

Genetic variation - combination of alleles inherited will not be the same as any other individual (expect individuals made form asexual reproduction and identical twins) ‐ mutations can also cause genetic variation.
Environmental variation ‐ any variation caused by anything other than genetic differences, the environment causes e.g. scars, direction roots grown in response to water.

Question 40

What is most variation a result of?

Answer 40

A combination of genetic and environmental factors

Question 41

State and explain the 2 forms of variation.

Give examples for each.

Answer 41

Continuous variation - variation where there are 2 extremes and a full range of values in between.
No defined categories/distinct groups,
There is a range ‐ any value is possible,
Caused by genes and the environment,
Quantitative (has to be measured rather than counted).
Eg: height, leaf length, number of flagella on a bacterium.
Discontinuous variation - where there are distinct categories and nothing in between.
Discrete categories with no intermediates,
Caused by one (or very few) genes,
No (very little) environmental effects cause it,
Qualitative.
Eg: gender, if an organism has a certain thing, human blood groups.

Question 42

What are the two types of variation?

Define them.

Answer 42

Intraspecific variation - variation within a species

Interspecific variation - variation within different species

Question 43

What type of graph must discontinuous data be plotted on?

Answer 43

A bar graph

Question 44

What is a student’s t-test used for?

Answer 44

To compare means

Question 45

What is an adaptation?

Answer 45

A feature or characteristic that enhances survival and long‐term
reproductive success

Question 45

What are the 3 types of adaptations?

Answer 45

Anatomical adaptations (anatomy) - structural features.
Behavioural adaptations - the ways that behaviour is modified for survival.
Physiological adaptations (physiology) - affect the way that processes work.

Question 46

Define natural selection

Answer 46

‘Selection’ by the environment of individuals that show certain favourable variations. These individuals will survive to reproduce
and pass on their variations to the next generation.

Question 47

Define speciation

Answer 47

The formation of a new species from a pre‐existing one

Question 48

What will a well adapted organism be able to do?

Answer 48

Find enough water,
Find enough food or photosynthesise well,
Gather enough nutrients,
Defend itself from predators and diseases,
Survive the physical conditions of its environment, such as changes in temperature, light and water availability,
Respond to changes in its environment,
Have sufficient energy to allow successful reproduction.

Question 48

What are pesticides?

How do they work?

Answer 48

Pesticides are chemicals which are deigned to kill insects which may be causing harm to a crop. The insecticide supplies a very strong selective pressure, killing any insects who are not resistant to the pesticide. Individuals whom are resistant stand a chance of surviving and passing on this favourable characteristic onto the next generation, this can quickly cause a population to become resistant.

Question 49

State 3 problems with pesticide resistance.

Give 4 examples.

Answer 49

Accumulation of pesticides in food chains.
Destruction of crops.
Cost to the farmer.
Availability of food, predators, disease, pesticides.

Question 50

Define selective pressure

Answer 50

An external factor that drives evolution in a particular direction. It might cause competition between individuals or cause some organisms to die whilst others survive.

Question 52

What 4 particular observations did Darwin make?

Answer 52

Offspring generally appear similar to their parents.
No 2 individuals are identical.
Organisms have the ability to produce large numbers of offspring.
Populations in nature tend to remain fairly stable in size.

Question 54

Summarise Darwin’s conclusions into 4 points

Answer 54

There is a struggle to survive (competition / selective pressures).
Better adapted individuals survive (others die).
Characteristics are passed on to the next generation.
Over time, advantageous characteristics are passed on and may give
rise to a new species.

Question 55

Explain how natural selection works

Answer 55

Mutation creates alternative versions of a gene (alleles).
This creates genetic intraspecific variation between the individuals of a species.
Once variety exists, then the environment can ‘select’. When resources are scarce, the environment will select those variations (characteristics) that give an advantage. There is a selection pressure.
Individuals with an advantageous characteristic will survive and reproduce. Therefore they pass on their advantageous characteristics (inheritance).
The next generation will have a higher proportion of individuals with the successful characteristics. Over time, the group of organisms becomes well adapted to its environment.