classification and biodiversity

Question 1

phylogeny

Answer 1

study of evolutionary history of a group of organisms

all organisms evolved from shared common ancestors
tree shows relationships

first branch shows common ancestor of all family members
closely related species diverged most recently

Question 2

what is taxonomy?

Answer 2

study of classification
naming organisms and organising them into groups
takes into account phylogeny (evolutionary relationships)

easier to identify and study them

Question 3

how is taxonomy done?

Answer 3

levels of groups (taxon) used to classify organisms
arranged into hierarchy with largest groups at top
- only belong to one group at each level, no overlap

highest = domain - eukarya, bacteria and archaea

as move down
- more groups but fewer organisms in each
- more closely related

Question 4

8 taxa

Answer 4

domain
kingdom
phylum
class
order
family
genus
species

Question 5

binomial naming system (+ use)

Answer 5

genus name (capital letter)
species name (lower case)

written in italics or underlined

all organisms given one internationally accepted scientific name in latin
- avoid confusion of common names

Question 6

what is courtship behaviour?

Answer 6

carried out by organisms to attract a mate of the same species

eg butterfly’s releasing chemicals or displays

species specific - only members of same species will do snd respond to that behaviour
- more closely related = more similar

means it can be used to classify organisms

allows members of dame species to recognise each other and prevent interbreeding
- reproduction more successful = fertile offspring

Question 7

technologies used for classifying evolutionary relationships

Answer 7

used to be done by observable characteristics now based of DNA sequences

genome sequencing
- DNA base sequence compared
- more closely related = more similar

comparing amino acids sequences
- sequence determined by base sequence
- so closely related have more similar sequences

immunological comparisons
- similar proteins = similar shape so bind to same antibodies
- proteins from organisms more similar will bind to same antibody

Question 8

how can genetics be used to classify organisms

Answer 8

base sequences on DNA
base sequence of mRNA
amino acid sequence

more similar = more closely related

Question 9

how can proteins be analysed to determine genetic relationships?

Answer 9

proteins made from amino acid sequence
sequence determined by DNA base sequence
so more similar proteins = more similar DNA, so more closely related

Question 10

what is biodiversity?

Answer 10

variety of living organisms in an area

high = lots of different species

measured by
- species richness (doesn’t consider population sizes)
- index of diversity

Question 11

what is a community?

Answer 11

all the populations of different species in a habitat

Question 12

what is species richness?

Answer 12

measure of the number of different species in a community

simple measure of biodiversity
- but biodiversity also affects by population size

Question 13

index of diversity

Answer 13

relationship between number of species in a community and the number of individuals in each species

N = total number of organisms of all species
n = total number of organisms of each species

Question 14

how does agriculture reduce biodiversity? (5)

Answer 14

woodland clearance
- increase area of farmland
- reduces number of trees
- removes habitats so less species

hedgerow removal
- increase area by making small fields into larger ones
- removes plants
- removes habitats so reduces species

pesticides
- directly kills pests
- species that feed on pests loose food source, die

herbicides
- reduces plant species (weeds)
- and species that feed on them

monoculture
- reduce variety of species
- supports fewer organisms (less food source)

Question 15

balancing agriculture and conservation

Answer 15

conservation aims to protect biodiversity

eg legal protection to endanger species
protected areas

Question 16

ways of measuring genetic diversity

Answer 16

• frequency of observable characteristics
• base sequence of DNA
• base sequence of mRNA (amino acids)
• proteins coded for by DNA and mRNA

Question 17

what is genetic diversity?

Answer 17

number of different alleles of genes in a population

increased by:
- mutations
- gene flow (introduction of alleles by migration and breeding)

Question 18

genetic bottleneck

Answer 18

event that causes big reduction in a population
reduces number of alleles in gene pool
sp reduces genetic diversity

survivors reproduce and large population created from few individuals (founder effect)

Question 19

founder effect

Answer 19

when a few organisms from a population start a new colony
- only a small number of different alleles in the initial gene pool

frequency of alleles change, may be more but less variety
- can increase genetic disease if with a mutated allele

occur due to:
- migration (leading to geographical isolation)
- genetic bottleneck

Question 20

natural selection

Answer 20

increases advantageous alleles in a population
= organisms more adapted

• individuals with beneficial allele more likely to survive and reproduce
• genes and beneficial allele passed on
• greater proportion of next generation inherit allele
• they are also more likely to survive and reproduce

frequency of beneficial allele increases from generation to generation

Question 21

adaptations due to natural selection

Answer 21

behavioural - way an organism acts

psychological - processes within an organism
eg hibernation

anatomical - structural features of an organism
eg blubber

all increase its chance of survival

Question 22

directional selection

Answer 22

individuals with alleles for extreme characteristics more likely to survive and reproduce

could be in response to environmental changes

eg antibiotic resistance
those with resistance allele survive, passed on, increased number with resistance allele

Question 23

stabilising selection

Answer 23

individuals with characteristics towards middle of range more likely to survive and reproduce

occurs when environment isn’t changing - reduces range of phenotypes

eg human birth weights
those with mid weights more likely to survive, range smaller