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biology > inheritance ,variation snd evolution > Flashcards

inheritance ,variation snd evolution Flashcards

1
Q

what is variation?

A

Differences in the characteristics of individuals in a population is called variation

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2
Q

what are the two causes of variation within species?

A

Genetics
Environment
A mixture of both of the above

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3
Q

what is genetic variation?

A

Variations in the genotypes of organisms of the same species due to the presence of different alleles

Create differences in phenotypes

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4
Q

What creates genetic variation in a species?

A

spontaneous mutations

sexual reproduction

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5
Q

what is a mutation?

A

A random change the base sequence in DNA which results in genetic variance

they occur continuously

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6
Q

State the three types of gene mutation

A

Insertion
deletion
substitution

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7
Q

how may a gene mutation affect an organism phenotype?

A

Neutral mutation does not change the sequence of amino acids. Protein structure and function same. No effect on phenotype.

Mutations may cause a minor change in an organism phenotype, e.g. change in eye colour

Mutations may completely change the sequence of amino acid. This may result in a non-functional protein. Severe changes to phenotype.

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8
Q

what is the consequence of a new phenotype caused by a mutation being suited to an environmental change?

A

There will be a rapid change in the species

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9
Q

What is evolution?

A

A gradual change in the inherited traits within a population overtime

Occur occurs due to natural selection which may result in the formation of new species

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10
Q

outline the theory of natural selection

A
  1. Genetic variation is this due to spontaneous mutations.
  2. Selection pressures e.g. competition disease exist
  3. Random mutation gives an organism as selective advantage.
  4. Organism is better adapted to the environment and survives.
  5. Organisms reproduce, passing on its beneficial alleles
  6. Frequency advantageous alleles increase.
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11
Q

how do two populations become different species?

A

When their phenotypes become different to the extent that they can no longer interbreed to produce fertile offspring

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12
Q

What is selective breeding?

A

The process by which humans artificially select organisms with a desirable characteristics and breed them to produce offspring with similar phenotypes

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13
Q

outline the main steps involved in selective breeding

A
  1. Identify a desired characteristics.
  2. Select parent organisms that show the desire traits and breed them together.
  3. Select offspring with the desire trait and breed them together.
  4. Process repeated until all offspring have the desired traits.
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14
Q

give examples of characteristics selected for selective breeding

A

disease resistance in crops
Higher milk or meat production in animals
Gentle nature im domestic dogs
Large flowers

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15
Q

What is the main advantage of selective breeding?

A

crops produce a higher yield of grain
Cows produce a greater supply of milk
Plants produce larger fruit
Domesticated animals

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16
Q

other than in agriculture where else is selective breeding useful

A

In medical research

In sports, e.g. horse racing

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17
Q

outline the disadvantages of selective breeding

A

reduction in the gene pool

Inbreeding results in genetic disorders

Development of other physical problems, e.g. Respiratory problems in Bulldogs.

Potential to unknowningly select harmful recessive alleles

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18
Q

What is genetic engineering?

A

The modification of the genome of an organism by the insertion of a desired gene from another organism – genes from chromosomes of humans and other organisms can be cut out and transfer to cells of other organisms

Enable the formation of an organism with beneficial characteristics

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19
Q

Give an example of uses for genetically modified plants

A

disease resistance
Produce larger fruit

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20
Q

What is used for genetically modified bacteria cells?

A

To produce human insulin to treat diabetes mellitus

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21
Q

describe the benefits of genetic engineering

A

Increase crop yeilds for growing population

Useful in medicine

GM crops produce scarce resources

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22
Q

Describe the risk of genetic engineering

A

long-term effects on consumption of GM crops unknown

Negative environmental impacts e.g. reduction in biodiversity, impact on food chain, contamination of non-GM crops forming super weeds

late onset health problems in GM animals

GMC’s are expensive. LEDCs may be unable to find them or may become dependent on businesses that sell them.

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23
Q

what is the name for crops that have had their genes modified?

A

genetically modified crops, e.g. those modified to be resistant to insect attack and herbicides

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24
Q

what is Bacillus thuringiensis

A

insect larvae are harmful to crops

BT is a bacterium which secrets attacking that kills insect larvae

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25
Q

how is genetic engineering used to protect crops against insects?

A

The gene for toxin production in BT can be isolated and inserted into the DNA of crops

BT crops now secrete the toxin which kills any insect lavae that feed on it

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26
Q

What are the benefits of BT crops?

A

increase crop yields

Lessons the need for artificial insecticides

BT Thompson is specific to a certain insect larvae so it is not harmful to the other organisms that ingested

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27
Q

What are the risk of BT crops?

A

long-term effects of consumption of BT crops unknown

Insect larvae may become resistant to the BT toxin

Killing insect larvae reduces by a diversity

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28
Q

describe the process of genetic engineering

A
  1. DNA is cut at a specific base sequences by restriction enzymes to create sticky ends.
  2. vector DNA cut using the same restriction enzymes to create complementary sticky ends 
    3.ligase enzymes join the sticky ends of the DNA and DNA forming recombinant DNA
  3. Recombinant DNA mixed with and” taken up“ by target cells
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29
Q

what is a vector?

A

A structure that delivers the desired gene into the recipient cell, e.g. plasmids, viruses

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30
Q

how can plants be cloned?

A

Taking plant cutting

Tissue culture

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31
Q

what is tissue culture?

A

Using small groups of cells from a part of a plant to grow identical new plants

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32
Q

describe how plants are grown using tissue culture

A

1.Select a plant that shows desired characteristics
2. Cut multiple small sample pieces from Meristem tissue.
3. Grow in a petri dish containing growth medium.
4. Transfer to compost for further growth.

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33
Q

what must be insured when preparing tissue cultures?

A

Ensure aseptic conditions to prevent contamination by microorganisms

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34
Q

what does the growth medium contain?

A

Nutrients and growth hormones

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35
Q

What are the advantages of growing plant by tissue culture?

A

fast and simple process

Requires little space

Enables the growth of many plant clients with the same desirable characteristics

Useful in the preservation of endangered plant species

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36
Q

what are the disadvantages of growing plants by tissue culture?

A

Reduction in the gene pool

Plant clones often have low survival rate

could unknowingly increase the presence of harmful recessive alleles

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37
Q

describe the plant cutting methods of plant cloning

A

Older but simpler method than tissue culture

Gardeners use this method to produce many identical new plants from a parent plant

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38
Q

detail the process of the plant cutting method of plant cloning

A
  1. A branch is cut off from the parent plant.
  2. The lower leaves of the branch are removed and the stem is planted.
  3. Plant hormones are used to encourage new root development.
  4. A plastic bag is used to cover the new plant to keep it warm
  5. New route and a new plant is formed after a few weeks.
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39
Q

What does embryo transplanting involve?

A

pre-specialised cells from a developing animal embryo a split apart

The resulting separate but identical embryos are transplanted into host mothers

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40
Q

Describe how adult cell cloning is performed

A
  1. The nucleus is removed from an unfertilised egg cell.
  2. The nucleus from an adult body cell, such as a skin cell, is inserted into the egg cell
  3. An electric shock stimulates the nucleated egg cell to divide and it forms an embryo.
  4. The embryo cell contains the same genetic information as the adult body cell.
  5. When the embryo is a ball of cells, it is inserted into the uterus of an adult female to continue developing.
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41
Q

Outline the theory of evolution by natural selection

A

individual of species show a wide range of variation for a characteristic

Those were the characteristic most suited to the environment will survive breed most successively

The desirable characteristic that has enabled the individual to survive a passed on to their offspring

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42
Q

Why was Darwin’s theory of evolution not accepted initially?

A

most people believed in creationism

Insufficient evidence to prove the theory

The mechanism of variation and inheritance was not known at the time

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43
Q

What was Lamark’s theory of inheritance?

A

That changes during the lifetime of an organism can be inherited

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44
Q

what is speciation?

A

The formation of a new species when two populations become so vary that they cannot interbreed to produce fertile offspring

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45
Q

What is the definition of species?

A

A group of organisms with similar characteristics which are able to inbreed to produce fertile offspring

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46
Q

Outline the process of speciation through geographic isolation

A

two populations of the same species are separated geographically

Geographic isolation prevent into breeding and mixing of genes between the populations

Due to different selection pressures, different mutations occur producing different phenotype is in each population

Overtime the two populations may evolve so that they are not able to interbreed

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47
Q

Why is genetic variation important in speciation?

A

genetic variation produces phenotypic variations some of which are better suited to the environment and are selected for

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48
Q

How did Mendel study inheritance?

A

breeding experiments on plants and analysing the ratio of characteristics in offspring

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49
Q

Why was Mendel’s work not recognised until after his death?

A

he could not explain the mechanism of inheritance, as chromosomes were only discovered after his death

It was not communicated well to other scientists and not published in a reputable scientific journal

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50
Q

State two kinds of evidence used to show evolution

A

fossils
Antibiotic resistance in bacteria

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51
Q

How are fossils formed?

A

parts of an organism that have not decayed due to conditions needed for decay being absent

Parts of an organism that has been replaced by minerals as a decade, e.g. bones

Traces of organisms are preserved, covered in sediment and becoming rock

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52
Q

why are there few chases of early life forms left behind?

A

There are most softbodied

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53
Q

how do fossils act as evidence for evolution?

A

Scientists can identify the ages of the fossils and use them to show how organism change overtime

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54
Q

What do branches in evolutionary trees indicate?

A

Where speciation has occurred

55
Q

what is extinction?

A

Where there are no individuals of species still alive

56
Q

State the factor is that may lead to extinction

A

New disease
Predation
Competition
Changes to the environment
Catastrophic events

57
Q

What enables bacteria to evolve quickly?

A

The fast rate of their reproduction

58
Q

Outline the process of antibiotic resistant bacteria evolving

A

mutations occur in bacteria producing genetic variation

Certain strains are resistant to antibiotics and are not killed when they antibiotic is applied

Resistance strain survive and reproduce

Overtime the population of the resistant strains increase

59
Q

why are resistant strains of bacteria dangerous?

A

People have no immunity to them, and there is no effective treatment

60
Q

State an example of resistant strain of bacteria

A

MRSA

61
Q

What can be done to reduce the rate of development of antibiotic resistant bacteria?

A

refrained from inappropriately prescribing antibiotics, e.g. viral diseases

Patient should complete the prescribed course of antibiotics

Restrict agriculture uses of antibiotics

62
Q

why is it difficult to keep up with the emerging resistant strains?

A

Developing antibiotics have a high cost and take a long time to develop

63
Q

What are the classes of organisms as determined by Carl Linnaeus?

A

Kingdom,phylum, class, order, family, genus,species

64
Q

Which features are living creatures traditionally classified by?

A

By their structure and characteristics

65
Q

what is the binomial system of naming organisms?

A

genus name followed by species name

66
Q

Why were new classification models proposed?

A

development in microscopy allowed better examination of internal structure

Improvement in understanding of biochemical processes

67
Q

State the three domains

A

archaea
eukarya
bacteria

68
Q

which organisms belong in a domain archaea

A

Bacteria, usually living in extreme environments

69
Q

Which organisms belong in the domain bacteria?

A

Bacteria

70
Q

which kingdoms belong in domain eukartya

A

Plant
Animals
Fungi
Protests

71
Q

how are evolutionary trees created?

A

By examining the DNA of different species and analysing how similar the sequences are

72
Q

what is sexual reproduction

A

type of reproduction

Involves the production of gametes by meiosis

a gamete from each parent fusses to form a zygote

Genetic information from each guy is mixed so the resulting zygote is unique

73
Q

what are gametes

A

sex cells

haploid

74
Q

what is meiosis?

A

Form of cell division involved in the formation of gametes in reproductive organs

Chromosomes number is half

Involves two divisions

75
Q

What must occur prior to meiosis?

A

interphase-cookies of genetic information made during this process

76
Q

What happens during the first stage of meiosis?

A

chromosome pairs lineup along the cell equator

The pair of chromosome is separated and moved to opposite poles of the cell

Chromosome number is halved

77
Q

what happens during the second stage of meiosis?

A

Chromosomes lineup along the cell equator

The chromatids are separated and move to the opposite poles of cell

For unique haploid gametes are produced

78
Q

Why is meiosis important for sexual reproduction?

A

it increases genetic variation

It ensures that the zygote formed at fertilisation is diploid

79
Q

describe fertilisation and its resulting outcome

A

Gametes joined together to restore the normal number of chromosomes and the new cell, then divides by mitosis

As the embryo develop cells differentiate

80
Q

What is the advantage of sexual reproduction?

A

it creates genetic variation in offspring, increasing the probability of species adapting to surviving environmental changes

Natural selection can be speeded up by humans in selective breeding to increase food production

81
Q

Describe the disadvantages of sexual reproduction

A

two parents are required. This makes reproduction difficult in endangered populations are in species which exhibit solitary lifestyles.

More time and allergies required to a few offspring are produced

82
Q

what is asexual reproduction?

A

Type of reproduction

Involves mitosis only

Produce genetically identical offspring known as daughter cells

83
Q

Describe the advantages of asexual reproduction

A

Only one parent is required

lots of offspring can be produced in a short period of time, enabling the rapport, colonisation of an area and reducing competition from other species

Requires less energy and time as do not need to meet

84
Q

What is the disadvantage of asexual reproduction?

A

No genetic variation reducing the probability of a species being able to adapt to environment change

85
Q

Describe the circumstances in which malaria parasites reproduce sexually and asexually

A

sexual reproduction in the mosquito

Asexual reproduction in the human host

86
Q

describe the circumstances in which fungi reproduce sexually and asexually

A

Asexual reproduction by spores

Sexual reproduction to give variation

87
Q

describe the circumstances in which plants reproduce sexually and asexually

A

Sexual reproduction to produce seeds

Asexual reproduction by runners or bulb division

88
Q

What is DNA?

A

A double stranded polymer of nucleotides, wound to a form a double helix

The genetic material of the cell found its nucleus

89
Q

describe genome

A

The entire genetic material of an organism

90
Q

Why is it understanding the human genome important?

A

The whole human genome has been studied and is important for the development of medicine in the future

-Searching for genes linked to different types of disease
-understanding and treating and inherited disorders
-Chasing human migration patterns from the past

91
Q

what is a chromosome?

A

A long coiled molecule of DNA that carries genetic information in the form of genes the hair

92
Q

 how many chromosomes do human body cells have?

A

46

93
Q

how many chromosomes do human gametes have?

A

23

94
Q

define gene

A

A small section of DNA that codes for a specific sequence of amino acids which undergo polymerisation to form a protein

95
Q

what are the monomers of DNA?

A

Nucleotides

96
Q

what are DNA nucleotides made up of?

A

Common sugar
Phosphate group
One of four bases: A, T,C or G

97
Q

State the full names of the far base is found in nucleotides

A

Adenine
Thymine
Cytosine
Guanine

98
Q

Describe how nucleotides interact to form a molecule of DNA

A

sugar and phosphate molecules drawing to form a sugar phosphate backbone in each DNA strand

Base connected to each other

complementary base pairs joined by weak hydrogen bonds

99
Q

Explain how a gene codes for a protein

A

A sequence of three bases in a gene forms a triplet

each triplet codes for amino acid

The order of amino acids determines the structure and function of protein formed

100
Q

why is the ‘folding’ of amino acids important in proteins such as enzymes

A

The folding of amino acids determines the shape of the active site which must be highly specific to the shape of its substrate

101
Q

What is protein synthesis?

A

The formation of a protein from a gene

102
Q

What are the two stages of protein synthesis?

A

transcription
Translation

103
Q

what does transcription involve?

A

The formation of mRNA from a DNA template

104
Q

Outline transcription

A
  1. DNA double helix unwinds
  2. RNA polymerase binds to specific base sequence of non-coding DNA in front of a June and moves along the DNA strand.
  3. RNA a polymerase joins three RNA nucleotides to complementary bases on the coding DNA strand
    4.mRNA formation complete.mRNA detach and leaves the nucleus
105
Q

what does translation involve?

A

A ribosome joints amino acids in specific order dictated by mRNA to form a protein

106
Q

Outline translation

A

1.mRNA attaches to a ribosome
2. Ribosome reads the mRNA bases in triplets. Each triplet codes for one amino acid which is brought to the ribosome by a tRNA molecule
3.A polypeptide chain is formed from the sequence of amino acid which joined together

107
Q

What is a mutation?

A

A random change in the base sequence of DNA which results mostly in no change to the protein coated for, or genetic variance of the protein

Mutations occur continuously

108
Q

describe the effect of a gene mutation in coding DNA

A

if a mutation changes the amino acid sequence, protein structure and function may change

If a mutation does not change amino acid sequence, there is no effect on protein structure or function

109
Q

what is non-coding DNA?

A

DNA which does not code for a protein but instead controls gene expression

110
Q

describe the effect of a gene mutation in non-coding DNA

A

Gene expression may be alter, affecting protein production and the resulting phenotype

111
Q

what are alleles

A

Different versions of the same gene

112
Q

What is a dominant allele

A

A version of a gene were only one copies needed for it to be expressed

113
Q

what is a recessive allele?

A

A version of a jim where two copies are needed for it to be expressed

114
Q

What is meant when an organism is homozygous?

A

when an organism has two copies of the same allele

115
Q

what is meant when an organism is heterozygous?

A

When an organism has two different version of the same gene

116
Q

what is a genotype?

A

The genes present for a trait

117
Q

what is the phenotype?

A

The visible characteristic

118
Q

how are dominant alleles presented in a punnet square?

A

They are represented using uppercase letters

119
Q

how are recessive alleles represented in a punnet square?

A

They use the lowercase version of the same letter as the dominant allele

120
Q

what is the problem with single gene crosses?

A

Most characteristics are controlled by multiple alleles rather than just one

121
Q

what is an inherited disorder?

A

A disorder caused by the inheritance of certain alleles

122
Q

give two examples of inherited disorders

A

Polydactyly – having extra fingers or toes – caused by a dominant allele

Cystic fibrosis – a disorder of cell membranes – caused by a recessive allele

123
Q

how are embryo screened for inherited disorders?

A

during IVF, one cell removed and tested for disorder causing alleles. If the cell doesn’t have any indicator of alleles, then the originating embryo is implanted into the uterus.

124
Q

what are the ethical issues concerning embryo screening?

A

It could lead to beliefs in society that being disabled or having a disorder is less human or associated with inferiority

The destruction of embryos within inherited disorder is seen by some as murder as these will go onto to become human beings

It could be viewed as part of the concept of designer babies as it may be the parents convenience or wishes rather than the child well-being

125
Q

what are the economic issues concerning embryo screening?

A

Cost of possible treatment and medication will need to be considered if it is known that a child will have an inherited disorder and financial support explored if necessary

126
Q

What are the social issues concerning embryo screaming?

A

social care for children with inherited disorders may need to be considered if parents are unable to provide care

If an employee is found to have an inherited disorder and is terminated, this can prevent a child and its parents from potentially suffering in the future due to this disorder

127
Q

what is gene therapy?

A

The insertion of a normal allele into the cell of a person with inherited disorder to functionally replace the faulty allele

128
Q

What are the ethical issues concerning gene therapy?

A

some people believe that is going against and playing God

The introduced genes could enter sex cells and so be past the future generations

129
Q

what are sex chromosomes

A

a pair of chromosome that determine sex

males have X Y
females have two X

130
Q

Why does the inheritance of a Y chromosome means that an embryo develops into a male?

A

Testee development in an embryo is stimulated by gene present on the Y chromosome

131
Q

what is a sex linked characteristics

A

A characteristic that is coded for by an allele found on a sex chromosome 

132
Q

why are the majority of genes found on the X chromosome rather than the Y chromosome?

A

The X chromosome is bigger than the Y chromosome so more genes are carried on it

133
Q

Why are men more likely to show the phenotype for recessive sex linked trait than women

A

many genes are found on the X chromosome that have no counterpart on the Y chromosome

Woman XX have two alleles for each sex gene whereas men have XY often only have one alley

Only one recessive allele is required to produce a recessive phenotype in males

biology (10 decks)

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