5.3 Classification of biodiversity

Understanding:- The binomial system of names for species is

universal among biologists and has been agreed and developed at a series of congresses

- When species are discovered they are given scientific names

- Taxonomists classify using taxa- All organisms classified into 3 domains- Principal taxa for classifying eukaryotes are:

kingdom, phylum, class, order, family, genus, species

- In a natural classification the genus and higher taxa have all evolved from one common ancestor

- Taxonomists sometimes reclassify groups of species when new evidence shows a previous taxon contains species evolved from a different ancestor

- Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group

Nature of science:- Cooperation and collaboration between

groups of scientists: scientists use the binomial system to identify a species rather than the many different local names

Applications- Classification of one plant and one animal

species from domain to species level- External recognition features of

bryophytes, filicinophytes, coniferophytes and angiospermophytes

- Recognition features of porifera, cnidaria, platyhelminthes, annelide, mollusca and arthropoda, chordata

- Recognition of features of birds, mammals, amphibians, reptiles and fish

Skills- Construction of dichotomous keys for use

in identifying specimens

Why are supermarkets organised like this?

Classification…All living things arranged into

groups according to their similarities

HOW DO IDENTIFY LIVING THINGS?

MRS NERG

Remember MRS NERG?

7A Signs of life - The meaning of life

S = SENSITIVITYLiving things notice and react to changes intheir surroundings. They can respond to light, heat, sound, taste, sight or touch.

R = RESPIRATIONLiving things need energy to carry out thefunctions that keep them alive.

M = MOVEMENT

Living things are able to move about. Animals move from place to place. Plants move by responding to light.

7A Signs of life - The meaning of life

R = REPRODUCTIONLiving things produce offspring.

G = GROWTHLiving things grow, increasing in size and complexity.

N = NUTRITIONLiving things need to take in food.

E = EXCRETIONLiving things have to get rid of unwanted waste products.

The 3 domains

1. Eukaryotes2. Eubacteria (prokaryote)3. Archaea (prokaryote)

Complete the table

Feature Bacteria Archaea Eukaryota

Histones associated with DNA

Presence of introns

Structure of cell walls

Cell membrane differences

Complete the table

Feature Bacteria Archaea Eukaryota

Histones associated with DNA

Absent Proteins similar to histones bound to

DNA

Present

Presence of introns Rare or absent Present in some genus

Frequent

Structure of cell walls

Made of chemical called

peptidoglycan

Not made of peptidoglycan

Not always presentNot made of

peptidoglycan

Cell membrane differences

Glycerol-ester lipids; unbranched side chains; d-form

of glycerol

Glycerol-ether lipids; unbranched side chains; l-form

of glycerol

Glycerol-ether lipids; unbranched side chains; d-form

of glycerol

Classification

Eukaryotes are classified using principal taxa

KP

CrispsOnlyFor

Good Students

Kingdom Phylum

ClassOrder FamilyGenus

Species

Who am I?

Try to guess who this is…

AnimaliaChordata

MammaliaCarnivoraCanidae

Canislupus

Kingdom Phylum

ClassOrder FamilyGenus

Species

Naming species

The same species can have many different local names.

Lords and ladiesCuckoo pint

Devils and angelsCows and bulls

Willy LilySnakes meat

Arum maculatum

Naming species

Cooperation and collaboration between scientists

Ensures all scientists use same names

Decided by different animal and plant

congresses

Binomial systemUse two names: the genus and species

Rules:1. Genus name begins

with upper case letter and species name with lower case

2. Italics3. Can be abbreviated

once used already: A.maculatum

Classify organisms in a way that closely follows evolution

Members of a genus should have a common ancestor

Members of the group share many characteristics

Unnatural classification – grouping birds, bats and insects because they fly

Flight evolved separately in these groups and they have very big differences otherwise

Natural classification

1. Identification of species is easierGo through each taxa step by step – assign a kingdom, then a phylum etc…Dichotomous keys can be used to help with the processCould do no easily with unnatural classification

2. Prediction of characteristicsInherited similar characteristics from common ancestorCould not do this if we used unnatural classificationE.G find a new species of bat – we know it has mammalian features (could not do if grouped with birds)

Advantages of natural classification

New evidence may show that members do not share a common ancestor

Split group up into more taxa

(or two groups are found to be more similar – merge the groups)

Reclassification

We group all living things are group due to their similarities…

Creating the dichotomous key

What are these?

BIRDS

What are these?

MAMMALS

What are these?

FISH

We can create a dichotomous key to split these animals up.

To do this we need to ask questions about them to find their differences.

How are fish, mammals and birds different?

BIRDSFeathers

MAMMALSFur

FISHScales

This is how we construct a dichotomous key…

Does it have

scales?

no

yes

Does it have

feathers? yes

no

Your task

You need to be able to read classification trees and be able to create your own.

1. Complete the two classification worksheets (you need to do both of them yourself)

2. Create your own classification key using 5 animals from the cards provided

3. Look at page 265 in your book and complete the example of the second type of

dichotomous key