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Biology paper 2 > Inheritance, Variation and Evolution > Flashcards

Inheritance, Variation and Evolution Flashcards

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1
Q

What is mitosis

A

The formation of two identical cells from one cell

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2
Q

What is meiosis

A

The formation of four non-identical cells from one cell

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3
Q

Give 3 advantages each for sexual and asexual reproduction

A

Sexual
- Produces variation is offspring
- Survival advantage when environment changes
- Possible to carry out selective breeding

Asexual
- Only one parent needed
- Many identical offspring
- Faster than sexual, uses less energy

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4
Q

Give 3 examples of organisms that reproduce sexually and asexually

A
  • Strawberry- flowers(S) runners (A)
  • Daffodil- Flowers (S) bulbs (A)
  • Malarial parasite (A) in humans (S) in mosquitos
  • Fungi (A) in spores, (S) in mycelium
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5
Q

Describe the structure of a DNA nucleotide

A
  • Has a sugar (pentagon shape)
  • Phosphate group (circle)
  • Base
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6
Q

Give the 2 pairs of nitrogenous bases in DNA

A

Adenine and Thymine (A+T)
Cytosine and Guanine (C+G)

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7
Q

Describe how DNA codes for an amino acid

A

Bases come in groups of 3
Each “codon” codes for one amino acid

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8
Q

Explain how protein synthesis occurs

A

DNA is transcribed to make mRNA
mRNA leaves nucleus
Ribosomes “read” the codons and translate using tRNA
tRNA recruits the amino acid indicated by the triplet codon

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9
Q

Give 4 possible impacts of a mutation in the DNA

A
  • No change
  • Change to expression pattern, tells the cell how much of the protein to make
  • Knock out mutation
  • Change of structure. Protein still works, but differently. (evolution occurs)
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10
Q

Name 4 types of cloning

A

Tissue culture
Adult cell
Cuttings
Embryo transplant cloning

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11
Q

Describe how tissue culture is carried out

A

Small groups of cells are grown in a fluid or petri dishes with a grown medium to produce lots of identical plants

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12
Q

Give 2 examples of there tissue culture is used

A

Preserving rare plant species
Commercially in nurseries

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13
Q

Describe how cuttings are carried out

A

Small section of plants removed that contains meristem
Cutting placed in rooting powder before planting

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14
Q

Describe how embryonic transplant cloning is carried out

A

Sexual reproduction in petri dish to produce embryo
The embryo is split
Put separately into uterus of host mothers
Herd of identical offspring.

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15
Q

Describe how the offspring of embryo transplant cloning compare to one another and to their mother

A
  • Offspring are identical
  • Only share 50% of DNA with their mother
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16
Q

Describe the process of adult cell cloning

A

Enucleate egg cell (remove nucleus from egg cell)
Transfer nucleus of body cell from organism you want to clone
Electric shock to start division
Transfer embryo to uterus of host mother

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17
Q

Describe how the offspring of adult cell cloning compare to the somatic cell donor, the egg cell donor and the host mother

A

Somatic cell donor - 100%
Egg cell donor - 0%
Host mother - 0%

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18
Q

What is the theory of evolution

A

Charles Darwin’s theory that all species have evolved from simple life forms that first developed more than three billion years ago

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19
Q

What is evolution

A

Change in the inherited characteristics of a population over time through a process of natural selection

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20
Q

Describe the three key components of his theory

A
  • Variation within a species
  • Some are best suited to survive and breed
  • characteristics are passed on to the next generation
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21
Q

Give three reasons why Darwin’s ideas were only gradually accepted

A
  • Contradicted religion
  • Insufficient evidence
  • Mechanism not known for 50 years on how variation was happening
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22
Q

Describe Jean-Baptiste Lamark’s theory of evolution

A
  • Theory of use and disuse
  • If an organism used a body part in its lifetime, this would be enlarged in its offspring
  • Theory doesn’t prove how evolution happens
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23
Q

What contribution did Alfred Russel Wallace make to evolutionary science?

A

Independently proposed theory of natural selection
Research about warning colouration
Speciation

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24
Q

What contribution did Gregor Mendel make to evolutionary science?

A
  • Breeding experiments
  • Early genetic theory
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25
Q

What name did Mendel give to genes

A

Units

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26
Q

Why would some plants have bright berries

A

To attract animals to eat it and help spread seeds

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27
Q

Explain why more deforestation for agriculture and fuel is occurring in tropical regions than temperate regions

A

increasing human population/ standard of living so more food/fuel required

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28
Q

Why is only 10% of the energy passed between trophic levels

A
  • Some is lost in waste through processes like respiration
  • Not all of the energy is consumed, for instance primary consumers don’t eat all the leaves from a tree
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29
Q

What structures in bacterial cells are likely to carry the genetic information that gives these bacteria resistance?

A

Plasmids

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30
Q

How to prevent antibiotic resistance

A
  • do not prescribe antibiotics for mild infections because they will get better due to the body’s normal immune system
  • do not prescribe antibiotics for viral infections / colds / flu because antibiotics do not kill viruses
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31
Q

How is a sperm cell adapted to its function

A
  • Flagella so it can swim to the egg
  • Lots of mitochondria to release energy for movement
32
Q

Describe the process of meiosis

A

The cell makes copies of its chromosomes (double the amount of genetic information)
The cell divides into 2 cells, with half the chromosomes (46)
The cells divide again to give 4 gametes with 23 chromosomes
That are genetically different

33
Q

What is a gene

A

A section of DNA that codes for a protein

34
Q

What is a genome

A

All the genes coding for all of the proteins within an organism

35
Q

What are enzymes

A

Biological catalysts that speed up rate of reaction

36
Q

What are hormones

A

Chemical messengers that send signals around the body

37
Q

What is a structural protein

A

Strong proteins in order to form structures, such as collagen

38
Q

The three ways mutations in DNA sequences occur

A
  • A base is inserted
  • A base is deleted
  • A base is substituted
39
Q

Why may mutations alter a protein

A

Shape of protein is changed
So the substrate will no longer fit into the active site
A structural protein may lose its shape

40
Q

What is a gamete

A

An organism’s reproductive cell which has half the numbers of chromosomes

41
Q

What is a chromosome

A

A structure found in the nucleus which is made up of a long strand of DNA

42
Q

What is an allele

A

The different forms of the gene - humans have two alleles for each gene as they inherit one from each parent

43
Q

What is a dominant allele

A

Only one of the two alleles is needed for it to be expressed and for the corresponding phenotype to be observed

44
Q

What is a recessive allele

A

Two copies are needed for it to be expressed and for the corresponding phenotype to be expressed

45
Q

What is homozygous

A

When both inherited alleles are the same (2 dominant or 2 recessive)

46
Q

What is heterozygous

A

When one of the inherited alleles is dominant, and the other is recessive

47
Q

What is a genotype

A

The combination of alleles an individual has (Aa/AA/aa)

48
Q

What is a phenotype

A

The physical characteristics that are observed in the individual (e.g eye colour)

49
Q

What is polydactyly and what causes it

A

Having extra fingers or toes
Caused by a dominant allele

50
Q

What is cystic fibrosis and what causes it

A

Disorder of the cell membranes
Caused by recessive allele, so both parents must be carriers

51
Q

What is embryonic screening

A

When scientists can observe whether a child will have a genetic disorder
- Cells (+DNA) taken from embryos and its analysed

52
Q

Arguments FOR embryonic screening

A
  • Reduces the number of people suffering
  • Treating disorders is very expensive for parents of child
  • there are many regulations in place to stop it getting out of hand
53
Q

Arguments AGAINST embryonic screening

A

Encourages people to pick characteristics
Expensive to carry out
Promote prejudice as it suggests people with genetic disorders are unwanted
Decisions abut terminating a pregnancy have to be made
The procedure can lead to miscarriage

54
Q

What do the 23rd pair of chromosomes carry

A

Sex determining genes

55
Q

What chromosome pair do women have

A

XX
Can only pass on X chromosomes in their egg

56
Q

What chromosome pair do men have

A

XY
Can pass on X or Y chromosomes in their sperm

57
Q

What 2 things affect the phenotype of a plant

A
  • Genotypes
  • Environment
58
Q

Describe the process of natural selection

A
  • Mutations occur which provides variation between organisms
  • If the mutation provides a survival advantage, the organism is more likely to survive to breeding age
    The mutation will then be passed onto offspring
    Over many generations, the frequency of the mutation will increase within the population
59
Q

how can selective breeding lead to problems

A

Inbreeding
Breeding those with similar characteristics meaning you are reducing the gene pool
So if the environment changes or there is a new disease, the species could become extinct
As there is a lower chance of survival advantage as they all have the same genetic make up

60
Q

What is genetic engineering

A

Modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

61
Q

Process of genetic engineering

A

-enzymes are used to isolate the required gene; this gene is inserted into a vector, usually a bacterial plasmid or a virus
- The vector is used to insert the gene into the required cells
- Genes are transferred to the cells of animals, plants or microorganisms at an early stage, so they can develop with those characteristics

62
Q

2 Methods of plant cloning

A
  • Tissue culture
  • Cuttings
63
Q

How is tissue culture carried out

A
  • Plant cells are taken
  • They are placed in a growth medium with nutrients and hormones
  • they grow into new plants, and intoclones as they are genetically identical to the parent
64
Q

How are cuttings carried out

A
  • A section of the meristem is taken from a plant with the desirable feature
  • They are planted and produce clones as they are also genetically identical to the parent
65
Q

How are embryo transplants carried out

A
  • Sperm and egg cells from parents with desirable characteristics are obtained
  • In a lab, embryo divides many times and is then inserted back into the mother
  • The offspring is born genetically identical
66
Q

Benefits of cloning

A

Produces lots of offspring with a specific desirable feature
The study of clones could help research into embryo development
Can help endangered species

67
Q

Risks of cloning

A

The gene pool is reduced, less likely population will survive if there is disease
Clones have low survival rate
It may lead to human cloning

68
Q

Charles Darwin

A

Scientist and naturalist
Put forward the theory of evolution
Supported by experimentation and his knowledge of geology and fossils
Published ‘On the Origin of Species’

69
Q

Detailed theory of evolution

A
  • Variation exists within species as a result of mutations in DNA
  • Organisms with characteristics most suited to the environment are more likely to survive to reproductive age and breed (survival of the fittest)
  • The beneficial characteristics are passed on to offspring
  • Over many generations, the frequency of alleles for this advantageous characteristic increases with the population
70
Q

What is speciation

A

A new species developing through the selection of different alleles, increases genetic variation until the new population cannot breed with those in the old population to produce fertile offspring

71
Q

who developed theory of speciation

A

Alfred Russel Wallace

72
Q

Process of speciation

A
  • Variation exists within population as a result of genetic mutations
  • Alleles which provide a survival advantage are selected for through natural selection
  • Populations of a species become isolated from one another, through a geological barrier
  • Different alleles are advantageous in different environments with different selection pressures
  • Natural selection occurs in different populations, increasing genetic variation between them
  • When they are no longer able to breed together to produce fertile offspring, a new species has been formed
73
Q

Why is theory of evolution now widely accepted

A
  • Fossils
  • Antibiotic resistance
74
Q

What are fossils made up of

A

The remains of organisms from millions of years ago, which are found in rocks

75
Q

Three ways how fossils are formed

A

Parts of an organism have not been decayed because one of more of the conditions needed for decay are absent
When parts of the organism are replaced by minerals
As preserved traces of organisms (footsteps)

76
Q

Why can scientists not be certain about how life began on earth

A
  • Many early forms of life were soft bodied, so they left few traces behind, any traces have been destroyed
77
Q

Explain why sexual reproduction is an advantage for bluebells (4 marks)

A

genetic variation (in offspring)
(so) better adapted survive
(and) colonise new areas by
seed dispersal
many offspring so higher
probability some will survive

Biology paper 2 (3 decks)

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