Classification

Question 1

Biological Classification

Answer 1

Classification is based on the idea that members of the same group share characteristics that are not present in members outside the group.

Question 2

What is Taxonomy?

Answer 2

The study of classification

Question 3

Why classify?

Answer 3

• Provides methods of sorting, so that similar or related organisms are grouped together
• See patterns and trends to better understand relationships between organisms
• Allow biologists to analyse information about organisms (data collection, comparison, evaluation)
• Allows biologists to communicate with one another

Question 4

Levels of Classification

Answer 4

Domain
Kingdom
Phylum (Phyla)
Class
Order
Family
Genus
Species

Question 5

Three Domains

Answer 5

Eukarya, Archaebacteria and Bacteria

Question 6

What are the features of eukaryotes? (Containing Domain Eukarya)

Answer 6

Contains DNA with a nucleus and membrane bound organelles

Question 7

What are the features of prokaryotes? (With domains and Kingdoms Archae and Bacteria)

Answer 7

No nucleus or membrane bound organelles

Question 8

Binomial naming

Answer 8

A binomial name consists of two parts:

• a generic name (genus) and
• A specific name (species sometimes name of person who found the organism)

Question 9

Physical characteristics to classify

Answer 9

Morphology is used to classify organisms with similar physical features together. For example dogs can be classified using colour and size.

Question 10

Methods of Reproduction to classify - Among Mammals?

Answer 10

This aims to classify organisms using asexual (without production of gametes) and sexual reproduction (mixing of gametes) and their specific methods of reproduction and whether they lay eggs or give birth live or have specific structures (e.g. placenta).

Mammals:
Eutherian (placental) mammals: give birth to live young after gestation (inside the mother)
Marsupials: give birth to live young at very early developmental stage. Then develop in a pouch on the belly of the mother until mature enough to survive outside
Monotremes: lay eggs

Question 11

Molecular Sequence to classify

Answer 11

DNA and Protein sequences are used to put a signification to the relationships between species

DNA - Looks at base sequencing.

Protein - Looks at amino acid sequencing

Question 12

What Kingdoms does the Eukarya Domain Include

Answer 12

Animalia, Plantae, Protista and Fungi

Question 13

What Domain and Kingdom names do prokaryotes include?

Answer 13

Archae and Bacteria

Question 14

What does Protista include?

Answer 14

Includes
amoebae

Question 15

What are Archae?

Answer 15

Microscopic
single-celled
organisms
known for
living in extreme
environments

Question 16

Why classify organisms?

Invasive Species?

Answer 16

Better understand relationships between organisms

Allow biologists to analyse/research information about organisms

The third reason is that classifying organisms allows biologists to communicate with one another.

Finally, classification means invasive species can be identified more easily and accurately

Question 17

Porifera Example and Characteristics

Answer 17

Sponges

Asymmetrical (no definite symmetry)

Body is multicellular, with few tissues and no
organs

Cells and tissues surround a water-filled space
but there is no true body cavity

All are sessile (as an adult, live attached to
something)

Reproduce sexually or asexually

Question 18

Cnidaria Examples and Characteristics

Answer 18

Jellyfish, sea anemones and corals

Radially symmetrical (body plan is circular with
structures that radiate out)

Gastrovascular cavity with single opening that
serves as both mouth and anus

Reproduce sexually or asexually

Simple, net-like nervous system

Live in aquatic environments, mostly marine

Question 19

Platyhelminthes Example and Characteristics

Answer 19

Flatwroms

Bilaterally symmetrical (left and right halves of
body are mirror images)

Gastrovascular cavity with single opening that
serves as both mouth and anus

Body has three layers of tissues, with organs

Body without cavity

Body has blind gut (mouth but no anus)

Flattened body shape

Question 20

Mollusca Example and Characteristics

Answer 20

Molluscs

Biterally symmetrical

Body without cavity

Body has through gut (with mouth and anus)

Uses muscular foot for locomotion

Open circulatory system with heart and aorta

Question 21

Annelida Example and Characteristics

Answer 21

Earthworms

Bilaterally symmetrical

Body has more than two cell layers, tissues and
organs

Body cavity, nervous system and closed
circulatory system

Body has through gut (with mouth and anus)

Question 22

Nematoda Example and Characteristics

Answer 22

Roundworms

Bilaterally symmetrical

Cylindrical morphology

Body covered by tough cuticle (of collagen and
chitin)

Alimentary canal (digestive system) with mouth
and anus, but no circulatory system

Found in most aquatic habitats, soil, moist
tissues of plants, and body fluids and tissues of animals

Question 23

Arthropoda

Answer 23

Scorpions

Usually bilaterally symmetrical

Segmented

Hard exoskeleton (external skeleton) of protein and chitin

Most have through gut (with mouth and anus)

Jointed appendages (body parts attached to
main trunk such as arms, legs, wings); have
3–400+ pairs of jointed legs

Question 24

Echinodermata Example and Characteristics

Answer 24

Starfish

1 Five-rayed symmetry, mostly radial, sometimes
bilateral
2 Body has more than two cell layers, tissues and
organs
3 Thin epidermis covering an endoskeleton; most
species prickly due to skeletal bumps and spines
4 Most have short, through gut (with mouth and
anus)
5 Body shape highly variable, but with no head

Question 25

Chordata Example and Description

Answer 25

1 Ninety per cent are vertebrates (have
backbones), but Chordata does include two
invertebrate groups
2 Have the following features during development
(possibly as embryo): * pharyngeal slits: series of openings
connecting inside of throat to outside of
‘neck’; often, but not always, used as gills
* dorsal nerve cord: bundle of nerve fibres
running down the ‘back’; connects brain with
lateral muscles and other organs
* notochord: cartilaginous rod running
underneath nerve cord
* post-anal tail
3 Closed circulatory system with blood
transported in arteries, veins and capillaries
4 Bilaterally symmetrical

Question 26

What are characteristics of dichotomous keys

Answer 26

Dichotomous keys are tools used to identify organisms.

They involve choosing between a series of two options until an organism is identified. Yes or no questions which decide options

Question 27

Cladistics

Answer 27

Organisms are classified into groups that reflect their evolutionary history.

This classification is based on the fact that related organisms share Physical characteristics.

Phylogenetic trees made using this technique are known as cladograms.

Question 28

Cladistical Assumptions

Answer 28

The more closely related two organisms are, the more characteristics they will share.

Some characteristics that are shared by a group will not be present in more distantly related groups.

When there are multiple possible ways that organisms can be related, the simplest explanation is the most likely to be correct. This is because if a feature is shared between organisms, it is more likely that this feature evolved once in a common ancestor than independently for each organism.

Question 29

What is a character matrix?

Answer 29

Allows for + - to show if a group/s has one/many specific characteristics. Tabulate

Question 30

DNA technology impact

Answer 30

Supports previous classification or reclassifies of organisms

Provides clarity as to when certain groups evolved

Allows classification down to many more levels than the traditionally recognised taxa; i.e. prefixes super- (above) and sub- (below) - additional ranks (e.g. subphylum) and some newer taxa (e.g. tribe)