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BIOLOGY A LEVEL > CHAPTER 10 - CLASSIFICATION AND EVOLUTION > Flashcards

CHAPTER 10 - CLASSIFICATION AND EVOLUTION Flashcards

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1
Q

What are the 7 taxonomic groups (linnaean classification)

A

Kingdom, Phylum, Class, Order, Family, Genus, Species
(Ellis method)

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2
Q

Why do scientists classify organisms

A

To identify species
To predict characteristics
Find evolutionary links

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3
Q

What is a species defined as

A

A group of organisms that are able to reproduce to produce fertile offspring

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4
Q

State two reasons why classification is important

A

Enables scientists to share information / makes communication easy

provides information about an organism, based on members of the same group

allows accurate identification of an organism

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5
Q

Ligers are the offsprings of male lions and female tigers. Suggest two reasons why ligers are not classified as a species but their parents are

A

Ligers cannot reproduce to produce more ligers therefore they are not a species

Both lions and tigers reproduce to produce fertile offspring, therefore they are species

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6
Q

The loganberry (Rubus loganobaccus) is the fertile offspring of the blackberry (Rubus ursinus) and the raspberry (Rubus idaeus). Explain why the Loganberry is difficult to classify into a taxonomic group

A

Both parents are members of the same genus (Rubus)

but different species (ursinus and idaeus)

Two different species cannot produce fertile offspring / according to the taxonomic classification system the loganberry should not be fertile

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7
Q

What are the general features of prokaryotae

A

Unicellular
No nucleus or membrane mound organelles
Rings of ‘naked’ DNA
Small ribosomes
No visible feeding mechanism

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8
Q

What are the general features of protoctista

A

Mainly unicellular

Nucleus and other membrane bound organelles

Some contain chloroplasts

Some can move using flagella, cilia or amoeboid mechanisms but others are sessile

Nutrients acquired by photosynthesis

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9
Q

What are the general features of fungi

A

Unicellular or multicellular

A nucleus and other membrane bound organelles, with a chitin cell wall

No chloroplasts

No mechanism for locomotion

Most have a body or mycelium made up of threads or hyphae

Saprophytic - absorb decaying material

Store food as glycogen

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10
Q

What are the general features of plantae

A

Multicellular

A nucleus and other membrane-bound organelles including chloroplasts

All contain chlorophyll

Most dont move, although gametes of some plants move using cilia or flagella

Autotrophic - organisms make their own food

Store food as starch

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11
Q

What are the general features of Animalia

A

Multicellular

Nucleus and other membrane bound organelles

No cell wall

No chlorplasts

Move with aid of cilia, flagella or contractile proteins (eg. muscular organs)

Heterotrophic - ingest food

Food stored as glycogen

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12
Q

State two differences between fungi and plants

A

Plants have chloroplasts / chlorophyll, whereas fungi do not

plants are autotrophs, whereas fungi are heterotrophs

fungi may be unicellular, plants are always multicellular

fungi store food as glycogen, whereas plants store food as starch

plant cell walls are composed of cellulose, whereas fungi cell walls are composed of chitin

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13
Q

Explain why prokaryotes are now classified as two separate domains

A

Advances in biological techniques have identifies large differences in composition

ribosomes/rRNA differ

cell walls differ – peptidoglycan not found in archaea

Old classification does not show correct phylogeny

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14
Q

What are the three systems of classifying

A

3 domain system
6 kingdom system
5 kingdom system
(pg 239)

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15
Q

Explain why prokaryotes are now classified as two separate domains

A

Advances in biological techniques have identifies large differences in composition

ribosomes/rRNA differ

cell walls differ – peptidoglycan not found in archaea

old classification does not show correct phylogeny

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16
Q

Describe how and why classification systems have changed over time

A

Living organisms classified into two kingdoms based on major differences in characteristics

for example, those that moved and ate (animals) and those that didn’t (plants)

scientific advances/use of microscope allowed smaller details to be observed

organisms divided into five kingdoms

Plants, animals, fungi, protoctista, prokaryotes

Advances in science allowed DNA and proteins to be studied

Provided evidence for evolutionary relationships

Three domain system proposed

Relevant scientists mentioned (Linnaeus, Whittaker, Woese)

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17
Q

What is phylogeny

A

Evolutionary relationships between organisms

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18
Q

What are some advantages of phylogenetic classification

A

It takes into account evolutionary relationships that might not be obvious by just looking at characteristics

it forms a continuous tree so organisms do not have to be forced into groups

is not hierarchical therefore different groups on the tree are represented according to their evolutionary position – and can thus be compared

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19
Q

State the main difference between early classification systems and systems based on phylogeny

A

Historical classification systems based on physical characteristics / niche occupancy, whereas phylogeny based on evolutionary relationships

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20
Q

What is evolution

A

The way in which organisms evolve or change over many years as a result of natural selection

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21
Q

What evidence is there for evolution

A

Palaeontology and fossil records
Comparative anatomy
Comparative biochemistry

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22
Q

How are fossils formed

A

Animal and plant remains are preserved in rocks,

Time of existence can be determined by amount of rock build up on top

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23
Q

What evidence is provided by the fossil record

A

Timeline, of simpler organisms buried deeper in the rock and more complex higher up

Sequence matches ecological links - eg. plants are found before animals

Anatomy can show how closely related organisms have evolved from the same ancestor eg. zebra/horse and rhino

Allows relationships between extinct and living organisms to be investigated

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24
Q

What is one issue in the fossil record

A

It is incomplete, partly due to soft bodied organisms decomposing before having a chance to fossilise

25
Q

What are homologous structures, what is an example, and how does it show divergent evolution

A

Structure that appears superficially different (and may perform different functions) in different organisms but has the same underlying structure

eg. Pentadactyl limb

Evolved form a common ancestor and have to adapt to new habitats

26
Q

What are the two most commonly studied biochemistry molecules in comparing species relationships

A

Cytochrome c - protein in respiration

rRNA - ribosomal RNA

27
Q

What is the hypothesis of neutral evolution

A

Most of the variability in the structure of a molecule doesn’t affect its function

28
Q

Describe what is shown on a phylogenetic tree

A

A diagram used to show evolutionary relationships between organisms

the closer the branches of the tree the closer the evolutionary relationships - meetings of lines are called nodes

29
Q

Describe two advantages and two disadvantages of using the fossil record as a source of evidence for evolution

A

Advantages:
radioisotopes can be used to date fossils
changes can be tracked over time
chronological order apparent in rock strata.

Disadvantages:
many organisms decompose quickly before they have a chance to fossilise/
destroyed by volcanoes/ destroyed by earthquakes

30
Q

Describe how the work of three scientists was used in the development of the theory of evolution

A

Lyell – suggested that fossils were actually evidence of animals that had lived millions of years ago.

Hutton – proposed theory of uniformitarianism.

Darwin – came up with theory of evolution by natural selection through observations in Galapagos islands / jointly published theory.

Wallace – came up with theory of evolution by natural selection in Borneo/jointly published theory

31
Q

Explain how comparative biochemistry provides evidence of evolution

A

Study of similarities and differences in proteins and nucleic acid/DNA of an organism

changes in highly conserved molecules can help identify evolutionary links

such as cytochrome C / ribosomal RNA

species that are closely related have the most similar DNA and proteins /distantly related have far fewer similarities

32
Q

What is interspecific variation

A

Variation between members of different species

33
Q

What is infraspecific variation

A

Differences between organisms within a species

34
Q

What are the factors that cause variation

A

Differences in the genetic material an organism inherits from its parents leads to genetic variation

Environment in which it lives, this causes environmental variation

35
Q

What are the Genetic causes of variation

A

Differing Alleles
Mutations
Meiosis - Independent Assortment and Crossing over
Sexual reproduction - mix of alleles inherited
Chance- many gametes produced by parents

36
Q

What is an example of environmental causes of variation

A

pH of soil, which causes changes in flower colour

37
Q

Name two human characteristics with variation caused solely by the environment

A

scar, tattoo, dyed hair

38
Q

Name two human characteristics with variation cause solely by genetics

A

eye colour, blood group, lobed or lobeless ears

39
Q

Explain some of the causes of variation of human hair

A

Caused by a combination of genetics and the environment

Genes determine the natural colour of hair and texture, e.g. curly/straight

Environment affects final appearance, e.g. if hair is cut, dyed, or lightened by sunlight

40
Q

Explain more genetic variation is more common in organisms that reproduce sexually

A

Individuals produced by asexual reproduction are clones/genetically identical to parents

no fertilisation so no mixture of genetic material

meiosis does not take place/ no production of gametes

DNA can only be altered as a result of mutation

41
Q

What is discontinuous variation

A

value at either end of a spectrum, no middle value

eg. an animal sex either Male or Female
or shape of a bacteria

42
Q

What is continuous variation

A

A characteristic which can take any value within a range
eg. weight or height
(can be influenced by environmental factors)

43
Q

What types of ways are there of showing variation

A

Distribution curve
Standard deviation
T-tests
Spearman’s rank

44
Q

what are some adaptations

A

Anatomical adaptations - physical features

Behavioural adaptations - The way an organism acts, inherited or learnt from their parents

Physiological adaptations - processes that take place inside an organism

45
Q

What are some examples of anatomical adaptations

A

Body covering - eg. hair, scales, spines, feathers

Camouflage

Teeth - type of teeth present

Mimicry eg. markings of another species

46
Q

What are some adaptations of marram grass

A

Curled or rolled leaves, to minimise surface area of moist tissue

Hairs on the inside surface of leaves to trap moist air

Stomata sunk into pits

Thick waxy cuticle on the leaves and stems

47
Q

What are some examples of behavioural adaptations

A

Survival behaviours - eg. rabbit freezing when it has been seen

Courtship - dancing etc…

Seasonal behaviours - migration and hibernation

48
Q

What categories to behavioural adaptations fall into

A

Innate behaviour - inherited through genes eg. web building of spiders

Learned behaviour - learnt through experience or observing other animals. otters using stones to hammer shells

49
Q

What are some examples of physiological adaptations

A

Poison production - hunting or protection

Antibiotic production - kill off bacteria

Water holding - especially in arid environments

50
Q

What are analogous structures, what is an example, and how does it prove convergent evolution

A

they have adapted to perform the same function but have a different genetic origin

Tail fins of whale and a fish perform the same role

Takes place when unrelated species begin to share similar traits, adapting to a niche

51
Q

State the difference between analogous and homologous structures

A

Characteristics which show discontinuous variation are purely controlled by genetics/no environmental influence (except scars/tattoos just environment)

Normally controlled by a single gene

Characteristics which show continuous variation are controlled by a combination of genetic and environmental causes

Controlled by a number of genes/ polygenes

52
Q

Which of the following is an example of convergent evolution, and explain your answer
Insect wing and bird wing
Bat wing and human arm

A

Insect and bird wing – both have evolved to fly to escape predators/hunt for food

53
Q

State and explain how marsupial moles and placental moles provide evidence for convergent evolution

A

They have analogous structures – anatomical features that perform the same function in different organisms, but have a different origin

Any two from: Both burrow through soft soil to find insects

Both have a streamlined body shape, and modified forelimbs for digging

Both have velvety fur which allows smooth movement through the soil

54
Q

What is the process for natural selection

A

Variation in an organism from mutation occurs

Organism whose characteristic best suited to selection pressure will survive and reproduce

Successful organisms pass on successful alleles

Process repeated for every generation, increasing frequency of successful allele

Over a long period, this can lead to an evolution of a new species

55
Q

What are some examples of modern evolution

A

Antibiotic-resistant bacteria
Peppered moths
Sheep blowflies
Flavobacterium

56
Q

State three selection pressures that may be experienced by a plant species

A

availability of light / water / nutrients / carbon dioxide / space, risk of being eaten, disease, ability to cross-pollinate

57
Q

Describe the process of natural selection

A

Variations exist within a population

those with the best characteristics survive AND reproduce

characteristics are passed onto their offspring through genes

58
Q

DDT is a chemical insecticide that was used to kill mosquitoes to prevent the spread of malaria. Several years after its introduction large populations of mosquitoes became DDT resistant. Explain how this occurred.

A

A mutation occurred / existed in the mosquitos DNA which made them DDT resistant

these organisms survived exposure to DDT and reproduced

mutation which caused resistance is passed onto their offspring

frequency of the DDT-resistant allele increases in the population

59
Q

Examples state and explain the positive and negative effect on humans of recent examples of evolution in some species

A

Flavobacterium digests nylon waste

positive – used to clean up factory waste
bacteria e.g. MRSA – antibiotic resistance

negative – no longer killed using current medical treatment
sheep blowfly – insecticide resistant

negative – no longer killed by insecticide so increased sheep death

BIOLOGY A LEVEL (24 decks)

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