Inheritance, Variation and Evolution Flashcards
(132 cards)
1
Q
How is genetic variation created?
A
through mutations
2
Q
What is a mutation?
A
change in the DNA code
3
Q
What is natural selection?
A
fittest individual due to mutation is more likely to survive and reproduce
4
Q
Which two factors contribute to the variation between organisms?
A
mutations and natural selection
5
Q
What is speciation?
A
the process in which a species evolves to become another species
6
Q
What was Lamarck’s theory?
A
an organism could acquire new traits during their lifetime, and these traits would be passed onto their offspring
7
Q
What was Darwin and Wallace’s theory?
A
the variation in species means that the more favourable traits allow the organisms to survive and reproduce more, spreading throughout the population
8
Q
What were 3 reasons people didn’t accept Darwin and Wallace’s theory?
A
religious reasons, lack of evidence, DNA hadn’t been discovered yet
9
Q
According to Darwin and Wallace’s theory, why do giraffes have long necks?
A
Giraffes with longer necks were better adapted to their environment
10
Q
According to Lamarck’s theory, why do giraffes have long necks?
A
Giraffes acquired longer necks during their lifetime and passed this trait to their offspring.
11
Q
What is selective breeding?
A
taking the best plants or animals and breeding them together in hopes to get a better offspring
12
Q
What is a drawback of selective breeding?
A
reduces the gene pool of the population
13
Q
What type of variation can be passed on to the next generation?
A
Genetic variation
14
Q
What effect does selective breeding usually have on variation within a population?
A
It decreases variation
15
Q
What is the term used to describe all the genes and their alleles found in a population?
A
genepool
16
Q
What is the term used to describe the breeding together of closely related individuals?
A
inbreeding
17
Q
What is genetic engineering?
A
modifying an organism by changing their genome for a benefit
18
Q
What is gene therapy?
A
giving a person a healthy version of the gene that is causing the illness
19
Q
What is one reason gene therapy is very difficult?
A
the faulty gene is in every cell of the body so we would have to transfer the healthy gene into every cell in the body.
20
Q
How do you trasfer a gene from one organism to another?
A
1) you isolate the gene you want from the organism using restriction enzymes
2) you put it in a vector (virus of bacterial plasmid)
3) you make the other organism take up the vector and with it the gene.
21
Q
What is the Human Genome Project (HGP)?
A
a major international research effort aimed to map out the entire human genetic code
22
Q
When did the HGP map out the entire human genome?
A
2022
23
Q
How many human genes have been found to be linked to diseases?
A
2,000
24
Q
How do you clone an organism?
A
1)take an egg cell of the donor female and remove its nucleus
2) take an adult body cell and remove its nucleus
3)Put the body cell nucleus into the egg cell
4)Stimulate the cell to start dividing and forming an embryo.
5)Implant the embryo into a surrogate mother and wait for it to be born like normal.
25
What do you call a cell with its nucleus taken out?
enucleated cell
26
what is a clone?
an individual which is genetically identical to another individual
27
What is a transgenic organism?
an organism with DNA from another organism
28
How do you clone an embryo?
1) Pick the two organisms (of the same species) that have the most desirable traits
2)take sperm and use it to fertilise the egg.
3) let the zygote develop into an embryo
4) Separate the embryo into smaller embryos
5) Implant each embryo into a surrogate mother and the offspring will all be clones`
29
How do you clone a plant through cuttings?
1) find a plant you want to clone
2) Cut off a small part (ideally a growing shoot or branch)
3) Place the cutting in soil with nutrients and rooting powder
4) the cutting will grow into a clone of the original plant
30
What is another way to clone plants other than cuttings?
micropropagation (tissue culture)
31
How does micropropagation work?
1) find a plant you want to clone
2) take a small piece of plant tissue from the tips of the stems
3) sterilise it to remove microorganisms
4) Place the explants in a nutrient medium (agar) and let them grow into small masses of cells called calluses. The nutrient medium should also contain growth hormones.
5) Transfer the calluses to soil where they can grow into plantlets (basically baby plants).
6) The plantlets can then be transferred to their own pots to develop into genetically identical adult plants.
32
What are explants?
very small pieces of plant tissue from the tips of stems
33
What are calluses?
small masses of cells grown from explants
34
What are plantlets?
small baby plants
35
Give two benefits of cloning via cuttings rather than micropropagation.
Cuttings is quicker
Cuttings is cheaper
Cuttings requires less technical expertise/equipment
Don't have to worry about sterilisation so much for cuttings
36
What are 3 types of fossils?
skeletons made of rock
impressions in the ground
organisms that havent decayed yet
37
Why do we study fossils?
to see how organisms have changed over millennia and give proof for evolution
38
What are the 3 main ways fossils form?
gradual replacement by minerals
casts and impressions
preservation
39
How do fossils form by gradual replacement by minerals?
body parts like bones teeth and shells decay slowly so as they decay they can be replaced by minerals to form rock like substances in the exact same shape and size as original structures.
40
How are casts made?
when an organism is buried in a soft material (e.g clay) and it hardens whilst the organism decay.
41
How are impressions made?
often footprints or marks in the ground around which the material has hardened
42
Why is it difficult to find out how life first began on the earth through fossils?
early life forms were soft bodied so decayed too quickly.
Fossils formed so long ago may have been destroyed
43
When can we say a species has gone extinct?
no individuals of that species remain
44
What is the most common reason a species goes extinct?
sudden environmental change
45
What are 3 reasons for extinctions?
rapid environmental change
new predator kills all
new species out competes them
new disease kills all
catastrophic event kills all
46
Who was Wallace?
a scientist who presented the theory of evolution by natural selection along with Darwin.
47
What 2 things is Wallace best known for?`
1) studying warning colouration in animals
2) his theory of speciation
48
What is speciation?
the formation of a new species
49
What is isolation?
A physical barrier (river, mountains etc.) which separates the population
50
How does isolation cause speciation?
The populations live in different environments, so different traits are more favourable making the populations' evolution different and eventually creating a new population
51
What is antibiotic resistance?
when bacteria develop to be able to survive antibiotics
52
Give 3 reasons antibiotic resistance is becoming more common.
antibiotics are being overused
many people dont take the full course
huge amounts of antibiotics are given to farm animals
53
What did Linnaeus do?
in the 1700s, he classified animals by their characteristics and bone structures
54
What is the order of the Linnean system?
kingdom, phylum, class, order, family, genus, species.
55
What is the binomial naming system?
a way to identify an organisms using their genus and species.
56
What did Woese introduce?
the 3 domain system
57
What are the 3 domains?
bacteria, eukaryota, archaea
58
Where do the domains fit in in the Linnean system?
above kindoms
59
What are 2 advantages of the binomial naming system?
each species has a unique name
it lets scientists discuss individual species
60
What 4 types of organisms are considered eukaryotes?
fungi, plants, animals, protists
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62
Where does protein synthesis take place?
ribosome
63
What is a chromosome?
a tight coil of genetic material that make up part of the DNA
64
What is special about the 23rd pair of chromosomes?
they are the sex chromosomes
65
What are the chromosomes for male and female?
male - XY
female - XX
66
What is a gene?
a small section of a chromosome that codes for a protein
67
What is a genome?
entire set of genetic material in an organism
68
What does knowing the entire human genome help with?
* search for genes linked to different types of disease
* understanding and treatment of inherited disorders
* use in tracing human migration patterns from the past.
69
What is an allele?
a different version of the same gene
70
What does heterozygous mean?
you have different alleles for the same characteristic from your parents
71
What does homozygous mean?
you have the same allele for the characteristic from your parents
72
What does dominant mean?
if present, the allele will be expressed
73
What does recessive mean?
only if both alleles are the recessive one, they will be expressed
74
What is genotype?
the two alleles present for a particular gene, e.g. heterozygous, homozygous recessive, homozygous dominant
75
What is phenotype?
the characteristics you get from your genotype, e.g. eye colour
you can have the same phenotype with different genotypes
76
What is the structure of DNA?
2 polymer strands (of nucleotides) that are wrapped around each other to form a double helix
77
What is the structure of a nucleotide?
a phosphate
a sugar
a base
78
What are the 4 bases?
Adenine
Thymine
Cytosine
Guanine
79
What are the complimentary base pairings?
A - T
C - G
80
How does a polymer form from nucleotides?
the phosphate of one nucleotide binds to the sugar of another, and this creates a long chain
81
What is the outside of the DNA called?
the sugar-phosphate backbone
82
What holds the 2 strands together?
the bases pairing up in the middle
83
What is genetic code?
sequence of bases
84
What is a triplet?
3 bases that code for a single amino acid
85
What are the main uses of proteins?
in enzymes
in hormones to send messages around the body
in strengthening our muscles and tissues
86
What is a chain of amino acids called?
polypeptide
87
How are proteins of different shapes made?
different sequences of amino acids
88
What do the different shapes of proteins allow them to do?
carry out different specific functions
89
How does protein synthesis work?
a copy of the gene is made by the mRNA
the mRNA travels to a ribosome in the cytoplasm
the ribosome joins amino acids together in an order determined by the mRNA
90
What is a mutation?
change in the sequence of bases in the DNA
91
What increases the risk of mutations?
carcinogens
certain types of radiation (e.g. x-rays, gamma rays)
92
What does a mutation do?
it changes the sequence of amino acids and therefore the protein which could lead to the protein not able to function correctly
93
Where do most mutation occur?
non-coding DNA
94
What is a role of the non-coding DNA?
whether certain genes are turned on or off
e.g., nerve cells will not make haemoglobin
95
Describe how a change of one of the bases in the gene for an enzyme could affect the functioning of that enzyme.
Change in a base changes the triplet/codon
This changes the amino acid it codes for
So there will be a different sequence of amino acids
This means the polypeptide will fold into a differently shaped protein/enzyme
The protein/enzyme may have a differently shaped active site
So it may no longer be complementary to the substrate
Which would mean it couldn't form an enzyme-substrate complex
So it couldn't catalyse the reaction as well / the rate would be lower
96
What are the 2 main ways organisms can reproduce?
sexual and asexual
97
What 2 organisms can sexually reproduce?
animals and plants
98
What 2 organisms can asexually reproduce?
bacteria and plants
99
Which organism reproduces both ways?
plants
100
What are characteristics of sexual reproduction?
fusion of male and female gametes
offspring genetically different
inherit characteristics
lots of variation
101
What are gametes?
sex cells that only have half the chromosomes so when they fuse together they have complete genetic material
102
How are gametes produced?
by meiosis
103
What are characteristics of asexual reproduction?
only one parent
no gametes
no mixing of genetic material
achieved through mitosis
offspring are clones
104
What is asexual reproduction in bacteria called?
binary fission
105
What are pros of sexual reproduction?
lots of genetic variation so less likely to be wiped out by a single event
allows for evolution to take place, so population can adapt to changing conditions
106
What are cons of sexual reproduction?
takes a lot more time and energy
animals have to find a potential mate
they need to impress their mate
107
What are pros of asexual reproduction?
only one parent needed
process is very quick
108
What are cons of asexual reproduction?
all offspring are clones so less genetic variations
if a new disease comes along it could wipe out the entire population
less chance of adapting to new conditions, e.g. change of climate, new predator
109
What is a cell with half the genetic material called?
haploid
110
What is a cell with all the genetic material called?
diploid
111
Give an overview of meiosis.
a cell duplicates its genetic material so it has double the chromosomes
the cell then splits so there are 2 cells with 23 pairs of random chromosomes
then these cells split into 4 genetical different haploid cells which are gametes
112
What is polydactyly?
born with extra fingers or toes
dominant allele
113
What is cystic fibrosis?
disorder of cell membranes
stick mucus released in airways and pancreas
recessive allele
114
What is embryo screening?
in IVF, before the embryo is implanted into the uterus, the doctors can check its genes for any genetic disorders, and the parents can decide to discard that embryo and use another
115
What are pros of embryo screening?
reduce suffering
save money from treating disorders
116
What are cons of embryo screening?
implies that people with genetic disorders are undesirable
ethical issues
religious issues
designer babies as people may screen for other traits
117
Who was Gregor Mendel?
austrian scientist and monk
lived in the mid 1800s
118
What did Gregor Mendel do?
he studied how traits were passed onto offspring in pea plants
119
What was one of Mendel's experiments?
1) took a green pea plant and a yellow pea plant and cross bred them
2) all the offspring were yellow pea plants
3) then he took 2 of these yellow pea plants and cross bred them
4) 3/4 of the offspring were yellow and the rest were green
120
What was Mendel's conclusion?
hereditary units were being passed down from parents to offspring
these could be recessive or dominant
121
Why did people not realise how important Medel's discoveries were?
nobody knew anything about DNA or genes
122
What is continuous variation?
differences between individuals of a species where the differences are measurable and can take any value within a range, e.g. height, shoe size
123
What is discontinuous variation?
differences between individuals where the characteristics are categorised and distinct, e.g. blood type, eye colour
124
What are the gametes in flowering plants?
pollen and egg
125
How does the malarial parasite reproduce?
asexually in human host
sexually in mosquito
126
How do fungi reproduce?
many fungi reproduce asexually by spores but also sexually to give variation
127
What have plants been genetically engineered for?
resistant to disease
produce larger fruits
128
What have bacteria been genetically engineered for?
producing useful substances such as insulin which humans can harvest
129
When are organisms genetically engineered?
at early stages of development so they can develop with desired characteristics
130
What is a brief history of DNA?
mid 19th century - Mendel's experiments
late 19th century - behaviour of chromosomes during cell division was observed
early 20th century - Mendel's units and chromosomes behaved similarly, led to idea that the units (now called genes) were located on chromosomes
mid-20th century - the structure of DNA was determined and the mechanism of gene function worked out
131
What is an example of bacteria that is resistant to antibiotics?
MRSA
132
What are 2 pieces of evidence for evolution?
fossils
antibiotic resistance
