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Biology Revision 🌱 > Chapter 15 > Flashcards

Chapter 15 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
how many kingdoms are in the bacteria domain and what are they?
1 - eubacteria
26
what are eukaryota?
organisms with nuclei that contain the genetic material
27
example of eukaryota
animals
28
how many kingdoms are in the eukaryota domain and what are they?
protista fungi plants animals
29
what are evolutionary trees?
a diagram showing how species are related to eachother
30
how are evolutionary trees for living animals created?
by looking at DNA
31
how are evolutionary trees for extinct animals created?
by using fossil records
32
what is classification?
the grouping of organisms according to their similarities
33
what did Carl Linnaeus propose?
a classification system where organisms were grouped according to their characteristics
34
what were the 7 groups Linnaeus created?
``` Kingdom Phylum Class Order Family Group Species ```
35
what is a species?
a group of organisms that can breed to produce fertile offspring
36
under what system are organisms named?
the bi-nomial system
37
who proposed the bi-nomial system?
Linnaeus
38
what language is the bi-nomial naming system in?
latin
39
what are three rules for writing scientific names?
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
why were new models of classification proposed?
improvements in understanding and knowledge of biochemical processes improvements in microscopes
41
how do bacteria become antibiotic resistant?
they develop a mutation which allows them to survive, breed and pass on the resistant allele, leading to a whole species becoming resistant
42
what is a superbug?
a bacteria strain that is resistant to most known antibiotics
43
example of a superbug
MRSA
44
3 ways to prevent more strains of resistant bacteria being created
not overusing antibiotics patients must finish their whole course of antibiotics the agricultural use of antibiotics is being restricted
45
why is it important to finish the whole course of antibiotics?
to ensure all bacteria are destroyed, so none are left to mutate and become resistant
46
what do antibiotics do to contribute to antibiotic resistance?
they create a situation where the competitors have been killed so these bacteria have an advantage and increase in numbers
47
examples of hygiene to stop spreading bacteria 3
medical staff should wash hands regularly infected individuals should be isolated visitors should wash hands thoroughly
48
problems with the development of new antibiotics
progress is slow and expensive
49
what is the main cause of extinction throughout history?
changes to the environment and climate
50
how can we tell when there have been mass extinctions?
fossil evidence - huge numbers of species will disappear
51
when was the most recent mass extinction and what happened?
65 million years ago, dinosaurs became extinct
52
what is the main idea of what caused the extinction of dinosaurs?
a giant asteroid hitting earth
53
evidence to support the idea of an asteroid killing dinosaurs 3
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
why would an asteroid kill the dinosaurs
``` huge fires, eruptions etc spurt gas into atmosphere this made everywhere dark drop in temperatures = global winter plants died dinosaurs died ```
55
why is the fossil record very limited?
only small bits of bones have been found for some species
56
what is extinction?
the permanent loss of all members of a species
57
how will a species become extinct?
as conditions change, new species evolve and survive | the old, unadapted species will eventually die out
58
how can a new predator cause mass extinction?
if a species can't evolve quickly enough and the predator is powerful, it will eradicate a species
59
5 reasons for extinction
``` the environment changes too quickly a new predator a new disease competition from another species a catastrophic event ```
60
what is a fossil?
remnants of organisms from long ago that are found in rocks or ice
61
what are the three ways in which fossils are created?
gradual replacement by minerals casts and impressions preservation
62
how do fossils form by replacement by minerals?
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
how do fossils form by casts and impressions?
an organism is buried in a soft material (eg clay) they clay will later harden the organism decays a cast is left
64
why do fossils form in glaciers?
its too cold for the decay causing microbes to operate
65
why do fossils form in amber?
there is no oxygen or moisture so decay causing microbes can't survive
66
why do fossils form in peat bogs?
they are too acidic for the decay microbes
67
how is a fossil discovered?
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
why is the fossil record incomplete? 3
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
what is the most common way in which populations of a species become isolated?
geographical isolation
70
examples of geographical isolation? 3
a new mountain range a new river formation of an island
71
what is environmental isolation?
where the climate that one organism lives in will change but it won't elsewhere
72
what is speciation?
the development of a new species
73
how do you know when speciation has occured?
the offspring of interbreeding are infertile
74
process of speciation
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
why did Darwin panic after receiving news from Wallace?
their ideas were similar and he didn't want to lose credit
76
which scientist suggested speciation?
Alfred Russel Wallace
77
what characteristic of animals was the main piece of evidence to support Wallace's theory?
the warning colours used by animals to deter predators are a successful characteristic developed by natural selection
78
how did Darwin gather evidence to support his ideas? 3
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
how have new discoveries helped support Darwin's theory?
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
what is the idea of survival of the fittest?
the organisms with the most suitable characteristics for the environment would be more successful competitors and so more likely to survive
81
3 reasons why people disagreed with Darwin's theory
it went against religious beliefs there wasn't enough evidence to convince scientists he couldn't explain how variation and inheritance happened
82
how did the finches on the Galapagos islands support Darwin's ideas?
there were similarities between them all but each species was specially adapted to their habitat
83
what were Darwin's 3 main ideas?
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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