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GCSE Biology > Biology: Inheritance, Variation and Evolution > Flashcards

Biology: Inheritance, Variation and Evolution Flashcards

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1
Q

what are chromosomes

A

long molecules of DNA

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2
Q

what is DNA

A

chemical that all of the genetic material in a cell is made up of

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3
Q

what do chromosomes always come in

A

pairs

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4
Q

how many chromosomes do humans have

A

46

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5
Q

what is a gene

A

small section of DNA found on a chromosomes

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6
Q

what do genes do

A

contain instructions for cells to make a specific protein

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7
Q

what is a genome

A

entire set of genetic material in an organism

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8
Q

what is DNA made up of

A

the monomer nucletide

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9
Q

what does a nucleotide contain

A

one sugar molecule, one phosphate molecule and one base

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10
Q

what does the sugar and phosphate molecule do in the nucleotide

A

forms the backbone of the DNA strands

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11
Q

what are the bases within a nucleotide

A

A, T, C, G

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12
Q

what do the bases do

A

pair up with a base on the opposite side of the double helix called complementary pairing

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13
Q

which bases pair with which

A

A always pairs with T

C always pairs with G

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14
Q

what does the order of the bases decide

A

order of amino acids in a protein

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15
Q

other than coding protein what does DNA do

A

non coding parts switch genes on and off

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16
Q

what is mRNA

A

molecule that acts as a messenger between DNA and ribosomes carrying code for how to make protein

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17
Q

give 3 general uses of proteins in the body

A

Enzymes
Hormones
Structural Protein

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18
Q

what are mutations

A

random changes in an organisms DNA

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19
Q

what do mutations do

A

change the sequence of the DNA bases

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20
Q

what are the three examples of mutations

A

Insertions
Deletions
Substitutions

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21
Q

what are Insertion mutations

A

a new base is inserted into the DNA base sequence where it shouldn’t be

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22
Q

what are deletion mutations

A

when a random base is deleted from the DNA sequence

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23
Q

what are substitution mutations

A

random base in the DNA sequence is changed to a different base

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24
Q

what are the two types of reproduction

A

sexual

asexual

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25
Q

what is sexual reproduction

A

involves the fusion of male and female gametes. Because there are two parents the offspring contains a mixture of their parent’s genes

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26
Q

what is asexual reproduction

A

one parent that replicates their own DNA to clone themselves. The offspring is genetically identical to the parent

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27
Q

how does sexual reproduction happen

A

meiosis

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28
Q

how does asexual reproduction happen

A

mitosis

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29
Q

which organisms reproduce asexually

A

bacteria, plants some animals

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30
Q

which organisms reproduce sexually

A

most animals and some flowering plants

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31
Q

what are gametes

A

sex cells that contain only one copy of chromosomes

X and Y

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32
Q

what is the first step of meiosis

A

before the cell divides it duplicates its genetic information. After this duplication the chromosomes arrange themselves in pairs

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33
Q

what is the second stage of meiosis

A

the first division in meiosis happens as the chromosome pairs line up in the centre of the cell

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34
Q

what is the third stage of meiosis

A

the pairs are pulled apart so each new cell has only one copy of each chromosome.

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35
Q

what is the fourth stage of meiosis

A

the chromosomes line u agiain in the centre of the cell and the arms of the chromosomes are pulled apart for the second division

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36
Q

what is the end product of meiosis

A

four gamete cells with only a single set of chromosomes in it

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37
Q

what happens to the cell that is produced when gamete cells fuse together

A

the resulting cell divides by mitosis to make a copy of itself multiple times to create an embryo

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38
Q

what are the four advantages of sexual reproduction

A

there is variation between parents and offspring
Variation increases a species chances of surviving
Properly adapted individuals are more likely to breed
Selective breeding can be used to get a certain trait which speeds up natural selection

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39
Q

what are the four advantages of asexual reprroduction

A

only need one parent
uses less energy
faster
many offspring can be produced

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40
Q

how many pairs of chromosomes are matched pairs

A

22

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41
Q

what is the 23rd pair of chromosomes for

A

It decides your sex

42
Q

what sex is the XY chromosome

A

Male

43
Q

what sex is the XX chromosome

A

Female

44
Q

what is an allele

A

different versions of genes

45
Q

what is homozygus

A

when you have two of the same allele

46
Q

what is hetrozygus

A

when you have two different versions of a gene

47
Q

what two types of allele are there

A

dominant and recessive

48
Q

what is genotype

A

combination of alleles you have

49
Q

what is phenotype

A

characteristics you have

50
Q

what allele causes cystic fibrosis (mucus blocks airways)

A

recessive allele

51
Q

what allele causes polydactyly (extra fingers or toes)

A

dominant allele

52
Q

what are the three reasons against embryonic screening

A

prejudice against people with disorders
parents might want to chose a more desirable child
expensive

53
Q

what are the three reasons for embryonic screening

A

stop people suffering
saves money for treating disorders
laws to stop parents being to prejudice

54
Q

what did Gregor Mendel do

A

genetic experiments with peas

55
Q

what three important conclusions did Mendel reach

A

Characteristics in plants are determined by hereditary units
Hereditary units are passed onto offspring unchanged from both parents
Hereditary units can be recessive or dominant

56
Q

what are the two types of variation

A

genetic variation

environmental variation

57
Q

what causes genetic variation

A

different genes

58
Q

what causes environmental variation

A

conditions in the environment for example sunlight

59
Q

what else can cause variation

A

Mutations

60
Q

what is the theory of evolution

A

All of today’s species have evolved from simple life forms that first started to develop over three billion years ago

61
Q

what is speciation

A

development of a new species

62
Q

what is extinction

A

no individuals of a species remain

63
Q

what 5 things can cause extinction

A 
Environment changes too quickly
New predator kills them all
New disease kills them all
Can't compete with another species for food
Catastrophic event kills them all
64
Q

what is natural selection

A

where the species that is most adapted and suited to its environment survives and reproduces passing on its characteristics developing them further

65
Q

what is selected breeding

A

take the organisms that have the desired traits or characteristics and you breed them together to produce an offspring with the desired characteristics

66
Q

why is selective breeding bad

A

reduces the gene pool so that the species is less likely to be able to adapt to a change

67
Q

what is genetic engineering

A

transfer genes responsible for a desired characteristic from one organism to another so that it gains the desired characteristic

68
Q

what is the first step of genetic engineering

A

Useful gene is isolated and cut from one organism’s genome using enzymes and inserted into a vector

69
Q

what is the second step of genetic engineering

A

The vector is usually a virus or bacterial plasmid and is introduced to the target organism and the gene is inserted

70
Q

why is genetic engineering controversal

A

The new genes may have unforeseen side effects which pass onto future generation

71
Q

give 3 cons of GM crops

A

Reduce farmland biodiversity
Unsafe as we dont fully understand the effects on health
The transplanted genes get out into environment making pests immune to pesticides

72
Q

give 3 pro of GM crops

A

Characteristics can increase the yield
Engineered to contain more nutrients we lack
Currently we have encountered no problems

73
Q

What is cloning

A

Where you recreate an organism that is genetically identical to its parent

74
Q

What are the two methods for cloning plants

A

Tissue Culture

Cuttings

75
Q

How does tissue culture work

A

Few plants cells put in a growth medium with hormones and they grow into new plants which are clones of their parents

76
Q

what are the benefits of Tissue Culture

A

Plants made very quickly
Very little space required
Grown all year

77
Q

How does cuttings work

A

take cuttings from good parent plants and then plant them to reproduce clones of parent

78
Q

what are the benefits of cuttings

A

Produced quickly
Produced cheaply
Simpler than tissue culture

79
Q

what two ways can you clone an animal

A

Embryo transplant

Adult cell cloning

80
Q

how does embryo transplant work

A

take sperm and egg cells form two best animals
artificially fertilise egg to produce embryo then split it to produce multiple clones
Cloned embryos implanted into surrogates

81
Q

how does adult cell cloning work

A

take unfertilised egg cell and remove nucleus
insert nucleus taken form adult skin cell
stimulate egg with electric shock to produce embryo
implant embryo into surrogate

82
Q

what are the 3 issues surrounding cloning

A

reduces gene pool
cloning could produce unhealthy offspring
humans could be cloned in future with severe problems

83
Q

what are fossils

A

remains of plants and animals

84
Q

what are the three ways fossils form in rocks

A

gradual replacement by minerals
casts and impression
preservation where no decay happens

85
Q

how does gradual replacement by minerals happen

A

things like bones dont decay easily and last long time when buried. They are eventually replaced by minerals as they decay forming rock like substance. Surrounding sediments also turn to rock

86
Q

how does casts and impressions happen

A

organism is buried in soft material. This material later hardens around organism as it decays leaving a cas or impression of itself

87
Q

how does preservation happen

A

in amber and tar pits there is no oxygen or moisture so decay microbes cant survive. In glaciers its too cold and peat bogs are too acidic

88
Q

what is a species

A

group of similar organisms that can reproduce to give fertile offspring

89
Q

when does speciation occur

A

populations of the same species become so different that they can no longer successfully interbreed to produce fertile offspring

90
Q

what two things lead to speciation

A

Isolation and Natural selection

91
Q

how do bacteria become resistant to antibiotics

A

overtime they adapt and evolve to become resistant to antibiiotics

92
Q

what is an example of a superbug

A

MRSA

93
Q

what are the two reasons for antibiotic resistant bacteria emerging

A

Overuse of antibiotics

Inappropriate use of antibiotics

94
Q

what is classification

A

organising living organisms into groups

95
Q

what is the order of classifications from largest to smallest

A

domain –> kingdom –> phylum –> class –> family–> Genus –> species

96
Q

what are the three domains

A

Archaea
Bacteria
Eukaryota

97
Q

what are archaea

A

primitive bacteria normally found in extreme places

98
Q

what is the Binomial system

A

System that determines how organisms are named

99
Q

what does the first part of the binomial name refer to

A

genus the organism belongs to

100
Q

what does the second part of the binomial name refer to

A

species of the organisms

GCSE Biology (7 decks)

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