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Biology Paper 2
Inheritance, Variation and evolution
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Cards (52)
Meiosis
Cell divides
twice
to produce
4 gametes
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Types of reproduction
Asexual
Sexual
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Fusion
of male and female
gametes
Occurs in animals with sperm and
egg
, and in flowering plants with pollen and egg
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Asexual reproduction
One parent
No fusion of gametes
No mixing of genetic information
Produces clones
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Sexual reproduction
Requires
fusion
of male and female
gametes
Allows mixing of
genetic
information
Creates
variation
Allows
natural selection
to increase the chances of
surviving environmental
changes
Allows
selective breeding
by humans to increase
food production
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Mitosis
Cell
divides by
mitosis
then
differentiates
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DNA Structure
Consists of
2
strands forming a
double helix
Organised into
chromosomes
Four types of repeated nucleotides A to T, G to C
Nucleotides made of
sugar
,
phosphate
, and base (A, T, G, or C)
Sequence of 3 nucleotides codes for an amino acid in a
protein
Change in
structure
may lead to a change in the
protein
Synthesised using a
template
on
ribosomes
Carriers bring
amino acids
to the
template
in
correct order
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Genome
The
entire genetic material
in an organism
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Gene
A section of
DNA
that codes for a sequence of
amino acids
to make a protein
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Non-coding DNA
Controls expression
of
gene
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Allele
Different
form of a
gene
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Sex
Male
(XY)
Female
(XX)
Dominant
Recessive
Genotype
(The alleles of an organism contribute to the
phenotype
)
Altered
shape
or
function
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Variation
Change in
inherited characteristics
over time
Due to
natural selection
Can lead to
formation
of new
species
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Cloning animals
1. Remove
nucleus
from
unfertilised
egg cell
2. Replace with
nucleus
from adult body
cell
(e.g skin cell)
3. Give egg
cell
an electric shock - stimulates
cell division
4. When embryo develops, place in
womb
of adult to develop
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Cloning
animals
Produces
offspring
with
identical genetic
information to parent
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Other cloning methods
1.
tissue culture
/cuttings (
plants
)
2.
embryo transplants
(
animals
)
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Cloning animals
Remove
nucleus
from
unfertilised
egg cell
Replace with
nucleus
from
adult
body cell (e.g skin
cell
)
Give egg
cell
an electric shock - stimulates
cell
division
When embryo develops, place in womb of adult to develop
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Genetic engineering
1.
Desirable gene
isolated using
enzymes
2.
Gene
inserted into
vector
(usually bacterial plasmid/virus)
3.
Gene transferred
to
target organism
early in development
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Genetic engineering
Involves modifying an organism's
genome
to give it
desirable characteristics
Genes from other
organisms
can be added
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Genetic engineering
Desirable gene isolated using
enzymes
Gene inserted into
vector
(usually bacterial
plasmid
/
virus
)
Gene transferred to
target organism
early in
development
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Risks of
genetic engineering
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Benefits of
genetic engineering
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Benefits of genetic engineering
Improve crop yield
Produce materials for
medicines
Less waste
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Benefits of genetic engineering
Bacteria
modified to produce
insulin
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Bacteria
modified to produce
insulin
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Proves that bacteria are evolving
MRSA
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Evidence for evolution
Theory of evolution
Speciation
Genetics
Fossils
Antibiotic resistance
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Ways to combat antibiotic resistance
Only
prescribe
where
needed
/restrict agricultural use
Complete
course
of
antibiotics
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Extinction
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Reasons for extinction
Due to: habitat destruction,
hunting
,
climate change
,
pollution
, competition
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Compare ancient organisms to current organisms
Proof that
characteristics
are passed onto
offspring
in
genes
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A new species is formed when
The groups can
no longer interbreed
to produce
fertile offspring
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Charles Darwin
: 'Proposed theory of evolution by
natural selection'
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Organisms with
beneficial characteristics
Are more likely to
survive
and reproduce so pass them on to their
offspring
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The theory of evolution by
natural selection
was not initially accepted due to
religious beliefs
at the time
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The theory of evolution by
natural selection
is now widely accepted as true due to improvements in technology finding
new evidence
, as well as the science behind it being understood
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Gregor Mendel
: 'Parents pass characteristics to offspring through ‘units’. These are now known as
genes'
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Alfred Russel Wallace
Population
splits and the two groups become isolated for a long time - evolve differently, eventually form
new species
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Chromosomes
were observed during cell division in the
late 19th century
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DNA structure was determined in the
mid 20th century
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