Topic 3.1 Classification

Question 1

Principles of classification

Answer 1

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 2

What do scientists use to classify?

Answer 2

-Anatomical/physical features eg. pentadactyl limb
-Fossil evidence
-Biochemical analysis of proteins
-Biochemical analysis of DNA/RNA

Question 3

Phylogenetic

Answer 3

The study of evolutionary history and the relationships among or within groups of organisms.

Question 4

Binomial names

Answer 4

Two parts:
-Genus; uppercase letter (generic name)
-Species; lowercase letter (specific name)
Written in italics (or underlined)

Question 5

Why classify?

Answer 5

We need an internationally recognised way of referring to any particular living organism.
We solve these problems by classifying the living world, putting organisms in groups based on their similarities and differences.
(A good classification system will also make ancestral relationships clear).

Question 6

What is taxonomy?

Answer 6

-The science of describing, classifying and naming living organisms
-People often use analogous features to classify organisms (features that look similar and have the same features, but aren’t of the same biological origin

Question 7

The main taxonomic groups:
The archaea domain;
Archaebacteria

Answer 7

Ancient bacteria thought to be early relatives of the eukaryotes.
They were thought to be found in extreme environments, but scientists are increasingly finding them everywhere- particularly in soil.
Normally reproduce asexually.

Question 8

The main taxonomic groups:
The bacteria domain;
Eubacteria

Answer 8

The true bacteria are what we normally think of when we are describing the bacteria that cause disease, and which are so useful in the digestive systems of many organisms and in recycling nutrients.
They normally reproduce asexually.

Question 9

The main taxonomic groups:
The eukaryotic kingdoms;
Protoctist

Answer 9

Very diverse group of microscopic organisms.
Some are heterotrophs (eat other organisms) and some are autotrophs (make their own food by photosynthesis).
Some are animal-like, some are plant-like and some are like fungi.
They normally reproduce asexually.

Question 10

The main taxonomic groups:
The eukaryotic kingdoms;
Fungi

Answer 10

Contains multicellular and unicellular organisms.
All heterotrophs.
Most are saprophytic and some are parasitic.
They have chitin, not cellulose in their cell walls.

Question 11

The main taxonomic groups:
The eukaryotic kingdoms;
Animalia

Answer 11

All heterotrophs that move their whole bodies around during at least one stage of their life cycle.
These include the invertebrates; eg. insects, molluscs, worms etc and the vertebrates; eg. fish, amphibians, reptiles, birds, mammals.

Question 12

The main taxonomic groups:
The eukaryotic kingdoms;
Plantae

Answer 12

All multicellular.
Almost all autotrophs (makes own food by photosynthesis).
Both sexual and asexual reproduction occurs.

Question 13

The binomial system

Answer 13

Originally used by Linnaeus, is now used universally among biologists.
The fist name is the genus and the seconds name is the species or specific name which identifies the organism precisely.

Question 14

A genus

Answer 14

A genus is a group of species that all share common characteristics, but enough differences for you to see why they are a separate species.
It is not always easy to tell species within a genus apart.

Question 15

Biochemical relationships

Answer 15

-Biochemical relationships are increasingly being used to support or clarify the relationships based on morphology (eg. counting hairs on the foreleg of a fly)
-Scientists need to analyse the structures of many chemicals as well as the DNA to identify the inter relationships between groups of organisms
-This is known as phylogeny
-Proteins are key molecules in these analyses

Question 16

Gel electrophoresis- method

Answer 16

-A variation of chromatography which can be used to separate DNA and RNA fragments, proteins or amino acids according to their size and charge
-The chemical to be compared are placed in wells in a gel medium in a buffering solution, with known DNA or RNA, proteins or amino acids to aid identification.

Question 17

Gel electrophoresis- results

Answer 17

For identifying DNA:
-Add DNA fragments to a gel dye (which will fluoresce when placed under UV light)
-An electric current is passed through the DNA moves towards the. positive anode (because of the negative charge on the phosphate groups)
-Once electrophoresis is complete, the plate is placed under UV light; the DNA fluoresces so the pattern of the different bands can be identified.

Question 18

Breed

Answer 18

A group of animals of the same species that have different characteristics that make them different to other members of that species.

Question 19

Variety

Answer 19

A group of plant of the same species that have different characteristics that make them a different to other members of that species.

Question 20

The Biological Species concept

Answer 20

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

Question 21

Speciation

Answer 21

Speciation occurs when a group within a species separates from other members of its species and develops its own unique characteristics.

Question 22

Modified species definition

Answer 22

-A group of organisms with Simi;ar characteristics that are all potentially capable of breeding to produce fertile offspring
-A group of organisms in which genes can flow between individuals

Question 23

Genetic species model

Answer 23

-Based on shared evolutionary relationships between species.
-In this model, members of a species have a shared evolution and are evolving together.
-It is not easy to apply as there is not always a clear evolutionary pathway for a particular organism.

Question 24

Mate-recognition model

Answer 24

A concept based on unique fertilisation systems, including mating behaviour. The difficulty with this is that many species will mate or cross-pollinate other species and may even produce fertile offspring, but nevertheless different species.

Question 25

Ecological species model

Answer 25

Based on the ecological niche occupied by an organism. This is not a very robust way of identifying species, as niche definitions vary and many species occupy more than one niche.

Question 26

The reasons why species must be identified

Answer 26

-Identifying a species in which an organism belongs to is a very useful biological tool
-They allow people throughout the world to communicate with each other about certain species
-It also help with newly identified species which has not yet been classified
-Information Technology (IT) plays a vital role in this classification using identification apps or instruments that could identify DNA

Question 27

The importance of DNA

Answer 27

-In DNA sequencing the base sequences of the genome of an organism is worked out
-DNA sequencing can reveal lots of genetic information, helping to identify genes as well as mutation that can cause disease
-DNA sequencing leads to DNA profiling which looks at non-coding areas of DNA to identify patterns
-These patterns are unique to individual but the similarities of patterns can be used to identify relationships between individuals and sometimes even between species.

Question 28

DNA profiling

Answer 28

-Looks at non-coding areas of DNA to identify patterns
-Similarity of patterns used to identify relationships between individuals and species
-May be used in crime scenes by taking a sample of DNA from the crime scene and comparing it to DNA of suspects

Question 29

Bioinformatics

Answer 29

-Is the development of software and computing tools needed to organise and analyse raw biological data
-It makes sense of and uses information generated in DNA sequencing and profiling
-Can compare entire genomes and look for where mutations have resulted in divergence in the phylogenic tree

Question 30

Food crime

Answer 30

-Caviar is a luxury food customers would most likely pay a lot of many for
-Beluga caviar is the most expensive and best kind
-Scientists discovered through DNA profiling that a quarter of tins claiming to contain beluga caviar and charging a premium price for them actually contains a different, lower quality caviar belonging to a different species.

Question 31

DNA barcodes

Answer 31

A method of species identification using a short section of DNA to form a specific gene or genes.
(It looks at short genetic sequences from a common genome of a particular group of organisms)

Question 32

What is evolution?

Answer 32

The process by which different kinds of living organisms are believed to have developed from earlier forms during the history of the earth.

Question 33

Fossil DNA and human evolution

Answer 33

Scientists can extract DNA for fossils under 100,000 years old and analyse it using the polymerase chain reaction (which amplifies minute traces of DNA) and profiling.
—> Comparing DNA from Neanderthal fossils and DNA of modern humans has shown that neanderthals aren’t our direct ancestors (interbreeding between the two did take place)

Question 34

DNA, lice and human evolution

Answer 34

-Modern humans have 3 types of parasitic lice: head lice, pubic lice and body lice
-Head lice and body lice are related to chimpanzee lice
-Pubic lice is related to gorilla lice
-DNA evidence suggests human had head lice with chimpanzee louse ancestors (they evolved from chimpanzee louse), and pubic lice have gorilla louse ancestors, long before they began wearing woven clothes and body lice evolved
-So the ability to weave clothes was developed long after most of our body hair was lost

Question 35

New models support old theories

Answer 35

Scientists use evidence from the DNA analysis of many species to help build diagrams that model the evolution of species from a common ancestor.

Question 36

The role of the scientific community

Answer 36

-When an article is submitted to a scientific journal it goes through a process of peer review, where it is read by a number of experts to see if its reliable and can be published.
(A paper should provide enough information for other scientists to carry out similar investigations so conclusions can be validated)
-At scientific conferences scientists working on the same field get together to discuss ideas

Question 37

How can we analyse evolutionary relationships genetically?

Answer 37

1) Gel electrophoresis
2) DNA sequencing
3) Bioinformatics

Question 38

How does DNA sequencing work?

Answer 38

DNA is broken into small fragments, terminated at different lengths by fluorescently marked nucleotides, then duplicated using PCR. The fragments undergo gel electrophoresis, with the smallest fragments travelling furthest, meaning we can read the base sequence of the fragment according to distance travelled.