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Biology Revision 🌱 > Chapter 15 > Flashcards

Chapter 15 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what did Gregor Mendel do?

A

he noticed that characteristics in pea plants were passed down from one generation to the next

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2
Q

why did no one understand Mendel’s theory at first?

A

no one knew about chromosomes or genes

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3
Q

when was Mendel’s work finally accepted?

A

16 years after his death (1884)

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4
Q

what happened in the late 19th century?

A

behaviour of chromosomes during cell division was observed

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5
Q

what were the three conclusions Mendel reached?

A
  1. characteristics in plants are determined by ‘hereditary units’
  2. Hereditary units were passed, unchanged, from parents to offspring ( one unit from each parent )
  3. Hereditary units can be dominant or recessive and there must be two recessive for it to show
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6
Q

what happened in the early 20th century?

A

it was observed that there were striking similarities between chromosomes and Mendel’s ‘units’. His ‘unit’ was discovered to be a gene

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7
Q

what were Mendel’s hereditary units?

A

genes

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8
Q

who were in the rivalling teams studying DNA?

A

Rosalind Franklin and Maurice Wilkins

James Watson and Francis Crick

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9
Q

what were Franklin and Wilkins doing?

A

they were looking at the structure of DNA using x-rays

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10
Q

what were Watson and Crick doing?

A

they were trying to build a 3D model of DNA to explain how it works

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11
Q

how was the double helix model of DNA discovered?

A

Watson and Crick used Franklin’s picture (without her permission)

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12
Q

what is Lamarck’s theory of evolution?

A

the more an organism uses a certain feature, the more it develops and grows (eg long giraffe neck)
these useful characteristics are then passed onto the animal’s children

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13
Q

what was the main problem with Lamarck’s idea?

A

his experiments didn’t support his hypothesis - eg if you dye a hamster pink, its offspring won’t be born with pink fur because the new characteristic won’t have been passed on

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14
Q

what is the accepted theory of evolution?

A

all of today’s species have evolved from simple life forms that started to develop 3 billion years ago

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15
Q

what impact did the South American rheas have on Darwin?

A

there were two different types of bird in two different environments - this would support natural selection

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16
Q

under the Linnean system of classification, what was the largest group?

A

a kingdom

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17
Q

what did Carl Woese do?

A

proposed the idea of the 3-domain system

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18
Q

how were new models of classification developed?

A

knowledge and understanding of biochemical processes, and microscopes improved

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19
Q

what were the three domains in Woese’s system?

A

Archaea
Bacteria
Eukaryota

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20
Q

what are archaea?

A

primitive forms of bacteria

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21
Q

example of archaea?

A

extremophiles

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22
Q

how many kingdoms are in the archaea domain and what are they?

A

1 - archaebacteria

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23
Q

what are bacteria?

A

true bacteria and cynobacteria (can synthesise)

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24
Q

example of bacteria

A

e.coli

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25
Q

how many kingdoms are in the bacteria domain and what are they?

A

1 - eubacteria

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26
Q

what are eukaryota?

A

organisms with nuclei that contain the genetic material

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27
Q

example of eukaryota

A

animals

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28
Q

how many kingdoms are in the eukaryota domain and what are they?

A

protista
fungi
plants
animals

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29
Q

what are evolutionary trees?

A

a diagram showing how species are related to eachother

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30
Q

how are evolutionary trees for living animals created?

A

by looking at DNA

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31
Q

how are evolutionary trees for extinct animals created?

A

by using fossil records

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32
Q

what is classification?

A

the grouping of organisms according to their similarities

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33
Q

what did Carl Linnaeus propose?

A

a classification system where organisms were grouped according to their characteristics

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34
Q

what were the 7 groups Linnaeus created?

A 
Kingdom
Phylum
Class
Order
Family
Group
Species
35
Q

what is a species?

A

a group of organisms that can breed to produce fertile offspring

36
Q

under what system are organisms named?

A

the bi-nomial system

37
Q

who proposed the bi-nomial system?

A

Linnaeus

38
Q

what language is the bi-nomial naming system in?

A

latin

39
Q

what are three rules for writing scientific names?

A

the first name is the genus and is written with a capital letter
the second name is the species and is written without a capital
the name is underlined when hand written or in italics when printed

40
Q

why were new models of classification proposed?

A

improvements in understanding and knowledge of biochemical processes
improvements in microscopes

41
Q

how do bacteria become antibiotic resistant?

A

they develop a mutation which allows them to survive, breed and pass on the resistant allele, leading to a whole species becoming resistant

42
Q

what is a superbug?

A

a bacteria strain that is resistant to most known antibiotics

43
Q

example of a superbug

A

MRSA

44
Q

3 ways to prevent more strains of resistant bacteria being created

A

not overusing antibiotics
patients must finish their whole course of antibiotics
the agricultural use of antibiotics is being restricted

45
Q

why is it important to finish the whole course of antibiotics?

A

to ensure all bacteria are destroyed, so none are left to mutate and become resistant

46
Q

what do antibiotics do to contribute to antibiotic resistance?

A

they create a situation where the competitors have been killed so these bacteria have an advantage and increase in numbers

47
Q

examples of hygiene to stop spreading bacteria 3

A

medical staff should wash hands regularly
infected individuals should be isolated
visitors should wash hands thoroughly

48
Q

problems with the development of new antibiotics

A

progress is slow and expensive

49
Q

what is the main cause of extinction throughout history?

A

changes to the environment and climate

50
Q

how can we tell when there have been mass extinctions?

A

fossil evidence - huge numbers of species will disappear

51
Q

when was the most recent mass extinction and what happened?

A

65 million years ago, dinosaurs became extinct

52
Q

what is the main idea of what caused the extinction of dinosaurs?

A

a giant asteroid hitting earth

53
Q

evidence to support the idea of an asteroid killing dinosaurs 3

A

huge crater in mexico
lots of iridium found - only when asteroid strikes
there is a layer of rock created by crater debris across the world

54
Q

why would an asteroid kill the dinosaurs

A 
huge fires, eruptions etc spurt gas into atmosphere 
this made everywhere dark
drop in temperatures = global winter
plants died
dinosaurs died
55
Q

why is the fossil record very limited?

A

only small bits of bones have been found for some species

56
Q

what is extinction?

A

the permanent loss of all members of a species

57
Q

how will a species become extinct?

A

as conditions change, new species evolve and survive

the old, unadapted species will eventually die out

58
Q

how can a new predator cause mass extinction?

A

if a species can’t evolve quickly enough and the predator is powerful, it will eradicate a species

59
Q

5 reasons for extinction

A 
the environment changes too quickly
a new predator
a new disease
competition from another species
a catastrophic event
60
Q

what is a fossil?

A

remnants of organisms from long ago that are found in rocks or ice

61
Q

what are the three ways in which fossils are created?

A

gradual replacement by minerals
casts and impressions
preservation

62
Q

how do fossils form by replacement by minerals?

A

body parts that don’t decay easily (eg teeth, bones etc) will last a long time
eventually they will be replaced by minerals
these minerals are shaped like the original part

63
Q

how do fossils form by casts and impressions?

A

an organism is buried in a soft material (eg clay)
they clay will later harden
the organism decays
a cast is left

64
Q

why do fossils form in glaciers?

A

its too cold for the decay causing microbes to operate

65
Q

why do fossils form in amber?

A

there is no oxygen or moisture so decay causing microbes can’t survive

66
Q

why do fossils form in peat bogs?

A

they are too acidic for the decay microbes

67
Q

how is a fossil discovered?

A

the organism dies and is buried in layers of rock
the skeleton becomes mineralised and turns into rock
the rocks shift inside the earth whilst still holding the fossil
due to erosion, it is gradually exposed

68
Q

why is the fossil record incomplete? 3

A

many of the earliest forms of life were soft bodied, meaning they would leave little fossil evidence behind
most organisms didn’t fossilise (the conditions needed were rare)
there are many fossils still to be found

69
Q

what is the most common way in which populations of a species become isolated?

A

geographical isolation

70
Q

examples of geographical isolation? 3

A

a new mountain range
a new river
formation of an island

71
Q

what is environmental isolation?

A

where the climate that one organism lives in will change but it won’t elsewhere

72
Q

what is speciation?

A

the development of a new species

73
Q

how do you know when speciation has occured?

A

the offspring of interbreeding are infertile

74
Q

process of speciation

A

populations are isolated by a barrier
conditions on either side of the barrier will be different
each population shows genetic variation
different alleles will be successful (different natural selection)
these organisms will be successful and pass on these alleles
different characteristics will become more common

75
Q

why did Darwin panic after receiving news from Wallace?

A

their ideas were similar and he didn’t want to lose credit

76
Q

which scientist suggested speciation?

A

Alfred Russel Wallace

77
Q

what characteristic of animals was the main piece of evidence to support Wallace’s theory?

A

the warning colours used by animals to deter predators are a successful characteristic developed by natural selection

78
Q

how did Darwin gather evidence to support his ideas? 3

A

he analysed animals and plants he had seen on the different islands to show variation
he bred pigeons to show how characteristics could be inherited
he built up a network of supporting fellow scientists

79
Q

how have new discoveries helped support Darwin’s theory?

A

we now know that phenotypic variations are caused by genetic variations caused by mutations
these beneficial variations are passed on to offspring via natural selection

80
Q

what is the idea of survival of the fittest?

A

the organisms with the most suitable characteristics for the environment would be more successful competitors and so more likely to survive

81
Q

3 reasons why people disagreed with Darwin’s theory

A

it went against religious beliefs
there wasn’t enough evidence to convince scientists
he couldn’t explain how variation and inheritance happened

82
Q

how did the finches on the Galapagos islands support Darwin’s ideas?

A

there were similarities between them all but each species was specially adapted to their habitat

83
Q

what were Darwin’s 3 main ideas?

A

the individuals in a species show a wide range of variation for a characteristic
the environment can’t support too many offspring so the fittest and best adapted will survive
these successful organisms will pass on the characteristics that made them survive

Biology Revision 🌱 (18 decks)

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