B2a - classification

Question 1

How are organisms classified(7)

Answer 1

Kingdom,phylum,class,order,family,genus,species

Question 2

Whyisitdifficulttoplaceorganismsintodistinctgroups

Answer 2

thevarietyoflifeisacontinuousspectrumwhichmakesitdifficulttoplaceorganismsintodistinctgroups

Question 3

Explaintheimportanceofclassificationofspecies

Answer 3

makesiteasiertoidentifyevolutionaryandecologicalrelationshipsbetweenanimalsandspecies

Question 4

Describe the systemsofclassifyingorganisms(6)

Answer 4

Natural
-basedonevolutionarylinks
-organismswith commonancestrygroupedtogether

Artificial

• basedonvisiblefeatures
• makes agroupoforganismseasiertoidentif

Question 5

WhathastheuseofDNAsequencinginformationledto?(2)

Answer 5

biologistsrealisedthatsomeorganismsaremorecloselyrelatedthanoriginallythought

leads to reclassification of some organisms toformmoreaccuratelinksbetweenorganisms

Question 6

Whydosystemsofclassificationchangeovertime(2)

Answer 6

toformmoreaccuratelinksbetweenorganismsasbiologistslearnmoreaboutorganisms(e.g. theirgeneticsandthesequence oftheirDNAbases)
-throughwhichwerealisethatsomeorganismsaremorecloselyrelatedthanoriginallythought

Question 7

Howcanevolutionaryrelationshipsbetweenorganismsbedisplayed

Answer 7

usingevolutionarytrees

Question 8

Howcantheevolutionaryrelationshipsoforganismsinagroupbemodelled(3)

Answer 8

byanalysingmultiplecharacteristicsandlookingforsimilaritiesanddifferences

the more characteristics analysed, the more accurate the evolutionary tree model becomes

ICT has facilitated analysing multiple characteristics

Question 9

Define the term species

Answer 9

agroupoforganismswhicharecapableofinterbreedingtoproducefertileoffspring

Question 10

Describethebinomialsystemofnamingspecies(4)

Answer 10

eachspeciesisknownbya2 ­partname

• firstnameisthegenus
• 2ndnameidentifiesa singlespecies

itistheinternationalbasisofnamingspeciesandpreventsconfusion

Question 11

Explainsomeoftheproblemsofclassifyingorganismsintospecies(8)

Answer 11

Hybrids

• when members of two species interbreed
• are infertile, so cannot be classed as a species

Organismsthatonlyreproduceasexually(e.g. bacteria)

• do not interbreed - does not fit the definition of a species
• biologists classifythemasdiffspecies,basedoncharacteristics

Evolutionisacontinuousprocess
-organismsareslowlychangingandcaneventuallybecomenewspecies

Question 12

Describe closely related species(2)

Answer 12

Shares arelativelyrecentcommonancestor

may have different features if they live in different types of habitats

Question 13

Howcansimilaritiesanddifferencesbetweenspeciesbeexplained(2)

Answer 13

Ecological relationships
-e.g. similarities between different organisms that live in the same habitat

Evolutionary relationships
-e.g. relations between animals that live in different habitats