inheritance,variation and evolution Flashcards
(146 cards)
1
Q
what are chromosomes
A
they are really long strands of DNA
2
Q
what does DNA stand for
A
deoxyribonucleic acid
3
Q
what is DNA
A
the chemical that all of the genetic material in a cell is made up of and it contains coded information.
4
Q
where is DNA found
A
in the nucleus of animal and plant cells, in really long structures called chromosomes
5
Q
what do chromosomes usually come in
A
pairs
6
Q
DNA is a p
A
polymer
7
Q
what shape is DNA
A
a double helix
8
Q
what is a gene
A
a small section of DNA found on a chromosome
9
Q
How many strands is the helix made up of in DNA?
A
2
10
Q
How many chromosomes are there in a typical human cell?
A
46
23 pairs
11
Q
what is the 23rd pair of chromosomes known as
A
the sex chromosomes
12
Q
what do genes do
A
tells the cell to make a particular sequence of amino acids which are put together to make a specific protein
so tells what order to put the amino acids together
13
Q
what is a genome
A
the entire set of genetic material in a organism
14
Q
what is understanding the human genome useful for
A
for science and medicine
e.g
- identify genes in the genome that are linked to different types of disease
- this helps us understand them better and help develop effective treatments
15
Q
what are gametes
A
sex cells
16
Q
how are gametes produced
A
by meiosis
17
Q
how many chromosomes does a gamete have
A
23
18
Q
how does a human have 46 chromosomes if a gamete has 23
A
the sperm cell (gamete) and the egg (gamete) fuse together to form a cell with the full number of chromosomes
19
Q
what is sexual reproduction
A
sexual reproduction involves the fusion of male and female gametes. Because there are two parents, the offspring contains a mixture of their parents genes
20
Q
how does offspring inherit features from both parents
A
because it receives a mixture of chromosomes from the mum and the dad
21
Q
what is asexual reproduction
A
when there is only one parent so the offspring is genetically identical to that parent
- no fusion of genes
- no genetic variation
22
Q
what does asexual reproduction happen by
A
mitosis
23
Q
what produces asexually
A
bacteria,some plants and some animals
24
Q
Do animals usually reproduce via sexual or asexual reproduction?
A
sexual
25
What do we call the fusion of male of female gametes?
fertilisation
26
During sexual reproduction in plants, which two gametes fuse together?
pollen and egg
27
When bacteria reproduce asexually, which process do they use?
binary fission
28
What does the term 'haploid' mean?
A cell that only has half the normal amount of genetic material
29
what is an example of a haploid cell
gametes
30
when two haploid cells join what do they form
a diploid cell
31
what is the process of meiosis
1. cell duplicates its genetic information forming two armed chromosomes - one arm of each chromosome is an exact copy of the other arm - the chromosomes arrange into pairs
2. line up centre of cell
3. first division - pairs are pulled apart - each cell has one copy of each chromosome - some father some mother
4. lien up in centre of cell
5. the arms of each chromosome are pulled to each side and are pulled apart
6. you get 4 gametes with a single set of chromosome sin them - each gamete is genetically different.
32
During the process of meiosis, how many times does the cell divide?
2
33
As a result of meiosis, how many cells are produced?
4
34
Are the cells produced by meiosis genetically identical to each other, or genetically unique?
genetically unique
35
what are the 23rd pair of chromosomes either labled
XY or XX
36
what type of chromosome do males have
XY
Y - causes male characteristic
37
what type of chromosomes do females have
XX
XX combination allow female characteristic
38
whats the chance that a sperm cells will get a X or Y chromosome
50/50 on which one the sperm will get as they are drawn apart in the first division of meiosis
39
draw a punnet square for male and female gametes
answer is in book page 127
40
what do genes control
what characteristics you develop
41
what is an example of a characteristic being controlled by a single gene
mouse fur colour
42
is the upper case allele dominant or recessive
dominant
43
is the lower case allele dominant or recessive
recessive
44
what is homozygous
if an organism has two alleles for a particular gene that are the same
45
what is heterozygous
if an organism has two alleles for a particular gene that are different
46
for an organism to display a recessive characteristic what do the alleles have to be
both must be recessive e.g cc
47
for an organism to display a dominant characteristic what do the alleles have to be
and why
either Cc or CC because the dominant allele over rules the recessive one
48
what is a genotype
all the alleles and genes an organism has
49
How would you describe the genotype 'AA'?
homozygous dominant
50
How would you describe the genotype 'Hh'?
hetrozygous
51
How would you describe the genotype 'dd'?
homozygous recessive
52
complete the Genetic Diagrams & Punnet Squares quiz on cognito
53
Where are the chromosomes found in the cell?
nucleus
54
what are alleles
different versions of a particular gene
55
Charlie is heterozygous with one dominant allele and one recessive allele.
Which allele will be expressed?
the dominant
56
What is a phenotype?
The characteristics an organism has as a result of their genotype - the characteristics that the organism displays
57
If a mouse has one allele for brown fur, and another allele for black fur, would they be considered homozygous or heterozygous for that gene?
heterozygous
58
what is the difference of a genotype and a phenotype in a example
the genotype of the mouse is a brown fur allele and a black fur allele, whilst the phenotype is brown fur.
59
Is cystic fibrosis a dominant or recessive condition?
recessive
60
Cystic fibrosis is a recessive condition.
Which of the genotypes would result in an individual having cystic fibrosis?
homozygous recessive
61
Cystic fibrosis is a recessive condition.
what genotypes would result in an individual being a carrier for cystic fibrosis?
Heterozygous - as a carrier only carries on copy of a recessive allele
62
do the family trees quiz on cognito
63
what type of disorder is cystic fibrosis
a genetic disorder
64
Which part of a human body cell is affected by cystic fibrosis?
cell membrane
65
what does cystic fibrosis do
it results in the body producing lots of mucus in the air passage ways and the pancreas
66
will someone with one copy of cystic fibrosis have the disorder
and why?
no because it is a recessive allele
67
for a child to get cystic fibrosis what must there parents genotypes be like
they must either both have the disorder themselves or they must be both carriers
68
Is polydactyly a dominant or recessive condition?
dominant
69
what is polydactyly
a genetic disorder where babies are born with extra toes or fingers ( digits)
70
is polydactyly life threatening
no because it usually doesnt come with any other problems
71
Polydactyly is an example of an 'inherited disease', what does this mean?
it is inherited from parents
72
what inherited disorder requires a person to inherit two faulty alleles from their parents
cystic fibrosis
73
what is embryo screening
during IVF before embryos are implanted into a mother womb, it is possible to remove a cell and anaylse its genes
genetic disorders can be detected this way such as cystic fibrosis
its also possible to get DNa from inside the mother womb from a embryo
74
what are the results if embryo screening results in genetic disorders being present
IVF - the embryos with the 'bad' alleles will be terminated
embryos in the womb - there could be the decision to terminate the pregnancy
75
what are the arguments for embryonic screening
- helps people stop suffering
- treating disorders costs government lots of money
- there are laws to stop it going to far
76
what are the arguments against embryonic screening
- implies that people with genetic disorders are undesirable and could increase prejudice
- screening is expensive
- increases the risk of miscarriage
77
what is variation
Differences in the characteristics of individuals within a population
78
what are the two types of variation
genetic variation
environmental variation
79
Which two factors contribute to the variation between organisms?
The genes that individuals inherit
That environment that individuals are exposed to
80
what is a mutation
A change in the DNA code
81
What factor(s) are involved in determining body mass?
both inherited and environmental factors
82
what is the effect of mutations
They generally have no effect, but are occasionally harmful, and very occasionally advantageous
83
what is the theory of evolution
that all of today species have evolved from simple of life forms that first started to develop over 3 billion years go
84
Who is credited with developing and proposing the theory of evolution?
charles darwin
85
what was the theory about evolution Charles Darwin came up with called
evolution by natural selection
86
What does the phrase 'survival of the fittest' mean?
The individuals with the most favourable characteristics are most likely to survive
87
what is evolution by natural selection
- Darwin knew organisms in species had wide variation in characteristic and organisms had to compete for limited resources
- organisms with the most suitable characteristics were more likely to survive.
- the organisms that could survive would reproduce and pass on the genes and less adapted organisms were less likely to survive and reproduce to less likely to pass on genes
88
what provides evidence for the theory of evolution
fossils
antibiotic resistance - how bacteria are able to evolve
89
what is speciation
the development of a new species
90
Describe a series of events that might result in zebras evolving to run more quickly.
- there is a variation among the zebras where some can run faster
- the zebras who can run faster are more likely to survive
- when the reproduce they are likely to pass on their advantageous alleles
- this process keeps happening and is repeated of multiple generation
- this spreads thought o the population until species has evolved to run faster
91
what is extinction
when no individuals of a species remain
92
what is a reason why a species might become extinct
- the environment changes too quickly
- a new predator kills them
- a new disease kills them all
- they cant compete with another species for food
-a catastrophic event happens
93
what is selective breeding
when humans artifically select the plants or animal sthey are going to breed so that the genes for the particular characteristics stay in the population
94
what is an example of a characteristic that humans have selectively bred for?
- horses that run faster
- cows that produce more milk
94
what is an example of characteristics humans selectively breed for in plants?
Increased yield
Better taste
95
What type of variation can be passed on to the next generation?
genetic only
96
What effect does selective breeding usually have on variation within a population?
it decreases variation
97
what is the process involved with selective breeding?
- from existing stock choose which ones have the characteristic your after
- breed them with each other
- select the best offspring and breed them
- continue this process through several generations
98
what is a gene pool
the number of alleles in a population
99
What is the term used to describe the breeding together of closely related individuals?
inbreeding
100
What are the drawbacks of inbreeding?
It reduces that size of the gene pool
The population as a whole will be more at risk of disease
Rare inherited diseases are more likely to appear
101
what does genetic engineering do
transfers genes between organisms
| desierable characteristics from one organism into another so it also has
102
what are the steps in genetic engineering
1) a useful gene is isolated from one organisms genome usuing enzymes and is inserted into a vector
2) the vector is usuallya virus or bacterial plasmid
3) vector is introduced to target,useful gene is inserted into its cells
103
what are example where genetic engineering is used
bacteria to produce human insulin to treat diabetes
genetically modified crops - resistant to disease,improve size and quaility
sheep - produce substances in their milk which cna be used to help treat human diseases
104
What is another name for genetic engineering?
genetic modification
105
what is genetically engineered to produce insulin
bacteria
106
What is gene therapy?
The treatment of an inherited disorder by giving the patient a healthy copy of the faulty gene
107
what disorder could be treated with gene therapy
cystic fibrosis
108
Steps of genetic engineering for human insulin
Isolate the insulin gene from human DNA.
Insert the DNA into a vector, such as a plasmid.
Insert the plasmid into a host bacterium.
Let the bacteria divide and then produce the insulin protein.
109
What is the name of the small circles of DNA that are genetically modified in bacteria?
plasmids
110
what are the worries about the long term affects of Genetic engineering
it could accidentally create unplanned problems which could get passed onto future generations
111
what are the pros of genetically modified crops
- increased yield
- engineered to contain missing nutrients
- gm crops already already being grown without any problems
112
what are the cons of genetically modified crops
- affect the number of wild flowers that live around crops reducing farmland biodiversity
- we might not fully understand the effects of eating them on human health
- transplanted genes might get picked up by environment - weed gets herbicide resistance,creating 'super weed'
113
what are fossils
they are the remains of organisms from many thousands of years ago which are found in rocks and they provide evidence that organisms lived thousands of years ago
114
what can fossils tell us
how much or how little organisms have changed over time
115
what are the three ways fossils form in rocks
from gradual replacement by minerals
from casts and impressions
from preservation in places where no decay happens
116
what are the steps in gradual replacement by minerals in how fossils form in rocks
things like teeth shells and bones dont decay easily so they last a long time when buried
- eventually replaced by minerals as they decay, forming a rock like substance
-the surrounding sediment eventually turns into but the fossil stays distinct until someone digs it up
117
what are the steps in casts and impressions in how fossils form in rock
- when a organism is buried in soft material like clay
- the clay hardens around it and the organism decays leaving cast of itself
118
what are examples of places where no decay happens
- in amber and tar pits there is no oxygen or imposture so decay microbes cant survive
- glaciers its too cold - cant survive
- peat bogs its too acidic - cant survive
119
Why is the fossil record incomplete?
Some fossils formed long ago may have been destroyed since
Some organisms are soft-bodied so do not fossilise well
120
When bacteria evolve to become able to survive exposure to antibiotics, we say that they have developed:
antibiotic resistance
121
To reduce the rise and spread of antibiotic resistance, should we increase or decrease the use of antibiotics?
decrease
122
Describe in detail how antibiotic resistance arises.
A population of a bacteria infect somebody
That person takes antibiotics to kill the bacteria
Some bacteria have (or get) a random mutation that makes them less susceptible to the antibiotic than others (or completely resistant to it)
The antibiotics kill all the bacteria except those that are resistant
The resistance strains of bacteria now have more resources to grow and multiply
More mutations may arise, leading to greater resistance
There is now a strain of bacteria that can't be killed by antibiotics, which we call antibiotic resistance
123
Are antibiotics effective at treating viral diseases?
no Antibiotics only kill bacteria, not viruses.
124
Should you take the whole course of antibiotics, or stop taking them once you feel better?
take the full course to make sure all the bacteria is killed
125
Give 3 reasons antibiotic resistance is becoming more common.
Doctors often prescribe antibiotics in cases where they aren't necessary. For example, mild or viral infections
Many people don't take the full course of antibiotics, so not all the bacteria are killed
Huge amounts of antibiotics are given to farm animals in order to make them grow faster
126
Why is the spread of antibiotic resistance a problem?
f more bacteria are resistant to antibiotics, we won't be able to treat those infections
This means more people will die of bacterial infections
127
why is giving huge amounts of antibiotics to farm animals bad
because the bacteria can develop antibiotic resistance which can then spread to humans through meat consumption.
128
What is the advantage of using a binomial system to name species?
Each species has a unique name
It lets scientists discuss individual species
129
Which 18th Century scientist developed the traditional classification system for classifying living things?
Carl linnaeus
130
What is the correct order of groups in the Linnaean classification system?
kingdom
phylum
class
order
family
genus
species
131
Which international system is commonly used to classify organisms?
The Linnaean classification system
132
Which two groups in the classification system are used in the binomial naming system?
Genus and species
133
What is the binomial name for humans?
Homo sapiens
134
How do we write the binomial name of a species?
in italics and all lower case appart from the first letter of the genus
135
The binomial name for grey wolves is Canis lupus.
What are the species and genus names for the grey wolf?
Genus = Canis
species = lupus
136
Which 20th century scientist used microscopes and modern technology to develop the three domain system to classify organisms?
carl woese
137
Carl Woese developed the three domain system to classify organisms. What are the three domains?
Bacteria
eukaryota
archaea
138
what does the eukaryota domain contain
broad range of organisms like fungi,plants,animals and protists
139
what does the bacteria domain contain
the tiny single celled prokaryotic cells that are found almost everywhere
| true bacteria
140
what does the archaea domain contain
a different type of prokaryotic cell that are found in extreme conditions like hot springs and salt lakes
| primitive bacteria
141
what do evolutionary trees show
the evolutionary relationships between different species or groups
142
how do evolutionary trees work
they show common ancestors between species.
the more recent the ancestor the more closely related the two species are - the more characteristics their likely to share
143
What do the branch points show on an evolutionary tree
The split of a single population/species into two separate populations/species
144
suggest how a mutation can result in the production of a non-functioning enzyme
a mutation is the incorrect sequence of amino acids and that means that the enzyme will not be the right shape which means the substrate will not be able to bind so the complex cant function
145
describe one way a new plant species could be identified as being in the same genus as potatoes
they would have similar characteristics
they would have similar DNA
