Classification and biodiversity

Question 1

describe phylogenetic classification

(phylogenetic tree on page 2)

Answer 1

biologists use a phylogenetic method to group organisms based on evolutionary history

closely related organisms share a more recent common ancestor and will be in the same groups

they are also likely to share physical characteristics

these relationships can be depicted in a phylogenetic tree

Question 2

define classification

Answer 2

is the placing of organisms into groups

larger groups are divided up into progressively smaller groups, forming a hierarchy

Question 3

define hierarchy

Answer 3

a system of ranking in which small groups are nested components of larger groups

Question 4

define taxonomy and taxon

Answer 4

taxonomy - the identification and naming of organisms

taxon - each group within a classification system is called a taxon

Question 5

give the hierarchy of biological classification

(Dumb Kids Playing Catch On Freeway Go Splat)

Answer 5

domain
kingdom
phylum
class
order
family
genus
species

(largest taxon starts at domain, as you go down the list the species becomes more closely related until you reach the smaller/smallest taxa)

Question 6

why are taxa (plural) discrete?

Answer 6

at any level of classification, an organism belongs in one taxon and no other

Question 7

give the hierarchical classification of humans

Answer 7

d - eukarya/eukaryote
k - animalia
p - chordata
c - mammal
o - primates
f - hominidae
g - homo
s - Homo sapiens

Question 8

why are classification systems important?

Answer 8

helps to infer evolutionary relationships, indicating that organisms in the same taxon are closely related

improves scientific communication by providing concise terms like ‘bird’ instead of long descriptive sentences on a species

they are tentative and may change as scientific knowledge advances

Question 9

use the velvet worm as an example to explain how classification of species can change

Answer 9

velvet worms have a soft body and jointed limbs

this means they have characteristics of both Annelida and Arthropoda

their discovery required a new phylum to be defined (onychophora)

Question 10

what has recent biochemical evidence shown?

Answer 10

the kingdom prokaryotae should be split into two separate groups based on some fundamental biochemical differences
all other organisms have eukaryotic cells

Question 11

what has this biochemical evidence of the splitting of the prokaryotae kingdom led to?

Answer 11

led to the development of a scheme of classification which suggests all organisms evolved along three distinct lineages, called domains

the organisms of each domain share a distinctive, unique pattern of ribosomal RNA, which establishes their close evolutionary relationship

Question 12

how many domains are there?

Answer 12

three: two for prokaryotes, one for eukaryotes

Question 13

name and describe the three domains

Answer 13

bacteria (eubacteria) - the true bacteria such as e.coli and salmonella

archaea (archaebacteria) - extremophile bacteria living in diverse conditions such as high temperature, pH, salinity and pressure

eukaryota - all eukaryotic organisms, including plants, animals, fungi and protoctists

Question 14

what are the 5 kingdoms?

Answer 14

prokaryota
protoctista
fungi
animalia
plantae

Question 15

describe prokaryota and list some of their features

Answer 15

microscopic organisms

single celled

all bacteria and cyanobacteria (blue-green algae)

70s ribosomes, no membrane bound organelles, no nuclear envelope, no cellulose/chitin in cell walls, slime coat, flagella and plasmids sometimes present

Question 16

describe protoctista

Answer 16

mainly single celled ( some multicellular organisms)

lack tissue differentiation

e.g. plankton, spirogyra, amoeba

Question 17

describe fungi

Answer 17

have cell walls made of chitin and can reproduce both asexually and sexually

sexual reproduction produces spores, helping fungi to adapt to changing environments

examples include single-celled yeast and moulds like Penicillium and mushrooms which have hyphae that form a mycelium (fungal body)

both multicellular and single-celled

Question 18

describe animalia

Answer 18

Multicellular organisms with nervous coordination and no cell walls

35 animal phyla, each with diverse body plans e.g. annelida, chordata and arthropoda

Question 19

describe plantae

Answer 19

multicellular organisms that photosynthesise and have cell walls made of cellulose

e.g. mosses, ferns, conifers, flowering plants (angiosperms)

Question 20

members of each phylum have a distinct body plan (definition)

give examples

Answer 20

annelida - soft bodied & segmented

arthropoda - chitinous exoskeleton & jointed limbs

chordata - contains animals with vertebrates

Question 21

define class

Answer 21

sub group of phylum combining taxa with a distinct level of complexity

Question 22

define genus

Answer 22

group of similar organisms

Question 23

define species (important)

Answer 23

a group of phenotypically similar organisms that can interbreed to produce fertile offspring

Question 24

what does taxonomy allow us to do?

Answer 24

discover and describe biological diversity

investigate evolutionary relationships

classify organisms based on these relationships

Question 25

why was the binomial system introduced?

Answer 25

to avoid confusion from different organisms having the same name carl linnaeus gave them 2 names

Question 26

what are the three advantages of the binomial system?

Answer 26

Unambiguous naming latin - usable worldwide indicates relatedness when species share part of their name

Question 27

how to use the binomial system?

Answer 27

each organism has two names : genus and species the genus name is capitalised and comes first the species name is lowercase and comes second write the full name the first time, then abbreviate always use italics (or underline if handwritten)