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

what is meant by a hierarchy?

Answer 3

larger groups contain smaller groups
with no overlap

Question 4

how is taxonomy done?

Answer 4

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 5

8 taxa

Answer 5

domain
kingdom
phylum
class
order
family
genus
species

Question 6

binomial naming system (+ use)

Answer 6

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 7

what is courtship behaviour?

Answer 7

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

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

means it can be used to classify organisms

allows species recognition and prevent interbreeding
= reproduction more successful = fertile offspring

Question 8

technologies used for classifying evolutionary relationships

Answer 8

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

• genome sequencing
• immunology

Question 9

how can genome sequencing be used to classify organisms

Answer 9

base sequences on DNA
base sequence of mRNA
amino acid sequence

more similar = more closely related

those less closely related have had time to introduce mutations into DNA, making it less similar

Question 10

how can immunology be used to classify evolutionary relationships?

Answer 10

immunological comparisons
- similar proteins = similar shape so bind to same antibodies
- antibodies for a human protein will bind more to a closely related organisms proteins as they have more similar shapes

more antigen antibodies complexes (more binding) = more closely related

Question 11

how can proteins be analysed to determine genetic relationships?

Answer 11

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

Question 12

what is biodiversity?

Answer 12

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 13

what is a community?

Answer 13

all the populations of different species in a habitat

Question 14

difference between species richness and index of diversity

Answer 14

both show the number of different species in a community

index also shows the population sizes of each species

Question 15

what is species richness?

Answer 15

measure of the number of different species in a community

take random sample
count number of different species

simple measure of biodiversity
- doesn’t take into account number of individuals in each species

Question 16

index of diversity

Answer 16

shows 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 17

why are ecosystem with a high index of diversity more stable?

Answer 17

have a higher number of species in a community, and are equally sized species populations

more resilient to environmental changes

Question 18

ways agriculture is made more productive

Answer 18

removing hedgerows = bigger fields
monoculture = cans specialise
fertilisers and pesticides increase yields

Question 19

how does agriculture reduce biodiversity? (5)

Answer 19

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 20

balancing agriculture and conservation

Answer 20

conservation aims to protect biodiversity

eg legal protection to endangered species
protected areas

Question 21

ways of measuring genetic diversity

Answer 21

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

Question 22

what is genetic diversity?

Answer 22

number of different alleles of genes in a population

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

Question 23

what can affect allele frequency in a population?

Answer 23

natural selection
founder effect
genetic bottleneck
genetic drift (chance)

Question 24

genetic bottleneck

Answer 24

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

survivors reproduce and large population created from few individuals
with reduced genetic diversity (fewer alleles)
(founder effect)

Question 25

founder effect

Answer 25

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 of different alleles
- can increase genetic disease if with a mutated allele

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

Question 26

natural selection

Answer 26

changes allele frequency overtime
increases advantageous alleles in a population
= organisms more adapted

• individuals with beneficial allele (better adapted to selection pressures) 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

(beneficial allele from a random mutation, if harmful, dies out as organisms die)

Question 27

adaptations due to natural selection

Answer 27

behavioural - way an organism acts
eg basking in sun to keep warm

psychological - processes within an organism
eg hibernation

anatomical - structural features of an organism
eg camouflage

leads to evolution as organisms become better adapted to their environment
have increased chance of survival

Question 28

ways of studying genetic diversity

Answer 28

observable characteristics
- less reliable, only infer relationships

base sequence of DNA
- abstract from nucleus

base sequence of mRNA
- easier as abstracted from cytoplasm
- create complementary strand (DNA sequence)

amino acid sequence
- easier to obtain proteins than DNA
- proteins evolve much slower, more likely to be similar to ancestors

more similar = more closely related

Question 29

directional selection

Answer 29

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 30

stabilising selection

Answer 30

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

Question 31

why is there variation between and within species?

Answer 31

variation between species as they have different genes

variation within species as they have different alleles
or face different selection pressures in the environment

Question 32

random vs systematic sampling

Answer 32

random
- points chosen by chance (eg grid and using random number generator)
- avoids bias

systematic
- chose areas to sample
- bias, could chose areas with less or more species
- creates unrepresentative sample

Question 33

calculating % cover

Answer 33

count number of squares in quadrat with species
each square = 1%

Question 34

calculating abundance of species

Answer 34

count number of quadrats with species
number with species / number of quadrats
eg 3/10 = 30%

Question 35

what is a gene pool

Answer 35

complete range of allele in a population