Inheritance, Variation and Evoloution Flashcards

1
Q

Meiosis

A

A special type of cell division producing gametes
Happens in sex organs
Ovaries and testes
Gametes contain half the number of chromosomes 23. This is called haploid.
Normal body cells contain 46 chromosomes. This is called diploid.
Meiosis results in variation

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2
Q

Diploid cells have pairs of chromosomes- Why?

A

One maternal and one paternal
In this pair the chromosomes are said to be homologous

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3
Q

what does sexual reproduction involve

A

fusion of male and female gametes, bc there are 2 parents the offspring contain a mixture of their parents genes

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4
Q

the mixture of genetic information produces what?

A

variation

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5
Q

what happens in asexual reproduction?

A

only one parent
no fusion of gametes
no mixing of chromosomes
no genetic variation between parent and offspring
the offspring are genetically identical to the parent
clones

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6
Q

what are the stages of meosis?

A

1) genetic information duplicates forming 2 armed chromosomes - one arm of each chromosome is an exact copy of the other arm. after replication the chromosomes arrange themselves into pairs

2) in the first division the chromosome pairs line up at the centre of the cell

3) pairs pulled apart so each new cell has one copy of each chromosome. some of mothers and fathers chromosomes go into each new cell

4) in the second division, the chromosome line up again at the centre of the cell. the arms of the chromosomes are pulled apart

5) four gametes are made each with only a single set of chromosomes in it. each gamete is genetically different from the others because the chromosomes all get shuffled up during meiosis each gamete only gets half of them, at random

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7
Q

what happens in mitosis that makes up a whole organism?

A

after 2 gametes have fused during fertilisation, mitosis , means the new cell divided to make a copy of itself, this keeps happening to produce lots of cells in an embryo. as the embryo develops these cells then start to differentiate into different types of specialised cells that make up an entire organism

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8
Q

what happens in sexual reproduction?

A

male and female gametes fuse. offspring have two parents so the offspring genes are a mix of mum and dads genes

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9
Q

how many chromosomes are in every human cell?

A

23 pairs

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10
Q

22 are matched pair of chromosomes that control…..

A

characteristics

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11
Q

the 23 pair are labelled…..

A

XX or XY

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12
Q

what do the XX and XY chromosomes decide?

A

your sex

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13
Q

males have ………. chromosme

A

XY

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14
Q

females have an ,,,,,,,,,,,,,,,,,,,,,,,,,,, chromsome

A

XX

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15
Q

punnet square for a boy

A

50 % chance

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16
Q

what genes you inherit contol what ………………..

A

characteristics you develop

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17
Q

what is a homozygous gene

A

when an organism has 2 alleles for a particular gene that are the same

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18
Q

what is a heterozygous

A

when 2 alleles for a particular gene are different

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19
Q

what is the dominant allele

A

When displayed the characteristic is always shown

Can be heterozygous or homozygous
E.g BB or Bb

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20
Q

Recessive alleles:

A

Only shown when the alleles are the same (homozygous)

E.g bb - blue eyes

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21
Q

phenotype

A

normal

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22
Q

what is cystic fibrosis caused by

A

a recessive allele

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23
Q

what is polydactyly caused by

A

a dominal allele

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24
Q

GENOTYPE

A

The alleles the person has

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25
PHENOTYPE
The characteristic displayed by the alleles
26
DOMINANT
The stronger allele, always shown in the phenotype
27
RECESSIVE
The weaker allele, only shown in the phenotype if homozygous
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HOMOZYGOUS
Both alleles are the same
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HETEROZYGOUS
One dominant and one recessive allele present
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ALLELE
An alternative copy of a gene
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CHROMOSOME
A thread –like structure containing DNA and protein that you inherit from your parents
32
GENE
A small section of DNA that codes for a particular characteristic
33
DNA
Stands for Deoxyribonucleic Acid.
34
Huntington’s Disease
Very rare but very serious. Nerve cells in brain degenerate. Incurable and fatal
35
what is embryo screening
Tests are now available to show if people carry a faulty allele. People can test for these alleles before they start trying for a baby. Embryos can be screening before implantation in IVF Also the fetus during pregnancy can be screened Both of these carry ethical issues Both can risk miscarriage.
36
what are the 3 types of embryo screening?
Amniocentesis Chorionic Villus Sampling Pre-implantation genetics
36
what are the 3 types of embryo screening?
Amniocentesis Chorionic Villus Sampling Pre-implantation genetics
37
Amniocentesis:
Carried out at 15-16 week pregnancy. Involves taking some fluid around the fetus. This fluid will contain fetal cells for screening. amniotic fluid draw with a needle under ultrasound guidance
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Amniocentesis:
Carried out at 15-16 week pregnancy. Involves taking some fluid around the fetus. This fluid will contain fetal cells for screening. amniotic fluid draw with a needle under ultrasound guidance
39
Chorionic Villus Sampling:
Taking cells from a part of the placenta whilst mother is pregnant It is analysed for genetic disorders If they are found to have genetic disorders the pregnancy can be terminated sampling villi of placenta
40
what are the two methods of Chorionic Villus Sampling:
transcervical method - catheta through vagina into uterus transabdominal method - needle into uterus
41
Pre-implantation genetics:
Diagnosis during IVF Embryos are screened for genetic disorders Prevents a pregnancy affected by a genetic condition Only healthy embryos are placed into the uterus of the mother, the others are discarded.
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pros of genetic screening
treating the disorders costs the gov money there are laws to stop it going too far stop people from suffering from genetic disorders
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cons of genetic screening
Risk of miscarriage of a healthy fetus Always a risk of a false positive/negative Expensive testing Does not take into account future cures for disease designer babies people may want to pick the most desire able one
44
what are the 2 types of variation?
Genetic variation Environment variation
45
what are 4 examples of genetic variation?
Eye colour Natural hair colour Blood group Some inherited diseases
46
why do children look like their parents?
Children look like their parents because of genetic information passed on in gametes (sex cells).
47
what is the order of largest to smallest for gene, chromosome, nucleus and DNA?
(largest) nucleus.chromosomes genes.DNA. (smallest)
48
WHat would be the best way to test whether a trait is inherited or if it has been affected by your environment?
scientists study twins adopted by different families compared to identical twins brought up together and non-identical twins
49
what are some examples of environmental variation
Scars, accents, drinking when pregnant, tattoos
50
what are some examples of combined variation?
Height, weight, skin colour
51
what are the two types of variation on a graph?
continuous and discontinuous
52
continuous:
wide range on values between two extremes Continuous variation is represented as a line graph or histogram. eg height no distinct categories controlled by a lot of genes strongly influenced by environment
53
discontinuous:
there are distinct groups Discontinuous variation is represented as a Bar Graph. Example: Blood groups (A, B, AB or O) controlled by few genes unaffected by enviroment
54
what are some examples of continuous variation?
Human body mass Human hand span Human heart rate Human neck size Human shoe size Human height Body length in a specific species of fish Number of leaves on a specific species of tree Number of petals on a daisy Bean seed mass Number of fruits on an apple tree
55
what are some examples of discontinuous variation?
Human fingerprint types Attached or unattached earlobes in humans Human blood group types Ability or inability to roll tongue Eye colour Smooth or wrinkled seed coats in a pea seed White or red eye in a fruit fly Green or variegated leaf in a spider plant White or coloured flower in a pea plant
56
what is the theory of evolution?
all of today species have evolved from simple life forms that first started to develop over 3 billion years ago.
57
What was Darwin’s theory?
Organisms evolve due to natural selection Only the best suited organism to the environment will survive Those that survive will reproduce and pass on their genes (and characteristics) onto their offspring Gradually, a species will change over time.
58
Darwin’s work
From his travels, Darwin noticed that animals had similarities on different islands in the Galapagos. He observed finches on these islands and noticed that their beaks were different due to the food that was available.
59
what is speciation?
over a long period of time the phenotype of organisms can change so much because of natural selection, that a completely new species is formed.
60
when does speciation happen?
when populations of the same species change enough to become reproductivley isolated - this means they cant interbreed to produce fertile offspring.
61
survival of the fittest:
darwin concluded that the organisms with the most suitable characteristics for the environment would be more successful competitors and would be more likely to survive
62
species become extinct for these reasons:
the environment changes too quickly (eg destruction of a habitat) a new predator kills them all (eg humans hunting them) a new disease kills them all they cant compete with another new species for food a catastrophic event happens that kills them all (eg volcanic eruption)
63
what is an example of an extinct species
dodos humans hunted them and introduced other animals which ate all their eggs and we destroyed the forest where they lived.
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Natural Selection
Mechanism for evolution Organisms best adapted to their environments more likely to survive to reproductive age Favourable characteristics are passed on Produces organisms that are well adapted to their environment
65
what is selective breeding?
when humans breed plants and animals for particular genetic characteristics.
66
what features or characteristics are selectivity bred
animals that produce more meat or milk crops with disease resistance dogs with a good, gentle temperament decorative plants with big or unusual flowers
67
what is the process of selective breeding?
1) from your existing stock select the ones which have the characteristics you desire 2) breed them with each other 3) select the best of the offspring and breed them together 4) continue this process over several generations and the desirable trait gets stronger. eventually all the offspring will have the characteristic.
68
how is selective breeding used in agriculture?
it can be used to improve yields for example: to improve meat yields a farmer could breed together the cows and bulls with the best characteristics for producing meat eg large size. after doing this for several generations the framer should get cows with a very high meat yield.
69
what is the main problem with selective breeding?
it reduces the gene pool: the number of different alleles in a population decreases this is because of inbreeding inbreeding causes health problems because there is more chance of the organisms inheriting harmful genetic defects
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example of a problem with inbreeding in dogs
some dog breeds are susceptible to certain defects because of inbreeding - eg pugs often have breathing problems
71
what is another problem with selective breeding?
is a new disease appears because there is not much variation in the populations if one organism is susceptible to the disease then the rest of the stock will be
72
how does genetic engineering work?
1) a useful gene is isolated from one organisms genome using enzymes and is inserted into a vector 2) the vector is usually a virus or a bacteria plasmid, depending on the type of organism that the gene is being transferred to. 3) when the vector is introduced to the target organism, the useful gene is inserted into its cells
73
what can genetic engineering be used for?
manufacturing insulin crops which produce a greater yield finding out where genes are expressed in the body crops resistant to disease
74
GM disadvantages
Genetically modified organisms may be expensive Need for long term studies Effects may be passed on to other crops, e.g. weed resistance spreading from crops to weeds Ethical issues about abortion Risk of miscarriage or “false positives” with amniocentesis
75
GM advantages
Improving crop yield Improving resistance to pesticides Extend shelf-life Manufacture a certain chemical (e.g. insulin) Convenience Current medical research into using genetic modification to overcome inherited disorders
76
what are fossils?
the remains of organisms from many thousands of years ago which are found in rocks
77
fossils form in rocks in one of 3 ways:
1) from gradual replacement by minerals 2) from casts and impressions 3) from preservation in places where no decay happens
78
fossils from gradual replacement by minerals:
1) teeth, shells, bones which don't decay easily can last a long time when buries. 2) they are replaced by minerals as they decay, forming a rock like substance shaped like the original hard part. 3) the surround sediments also turn to rock but the fossil stays distinct inside the rock and eventually some digs it up
79
fossils from casts and impressions:
1) fossil are formed when an organism is buried in a soft material like clay. the clay hardens around it and the organism decays, leaving a cast of itself. an animals burrow or a plants roots can be preserved as casts 2) footprints can also be pressed into these materials when soft, leaving an impression when it hardens
80
fossils from preservation in places where no decay happens:
1) in amber and tar pits there's no oxygen or moisture so decay microbes cant survive 2) in glaciers its too cold for the decay microbes to work 3) peat bogs are too acidic for decay microbes
81
How do bacteria become resistant to antibiotics?
1) in bacteria there is genetic variation due to mutations 2) a mutation can make a bacterium resistant to antibiotics 3) if an antibiotic is used, all of the bacteria are killed, apart from the bacterium that is resistant to antibiotics 4) the antibiotic stain survives and reproduces, without any competition form other bacteria 5) over time the population of the resistant stain increases 6) the resistant stain now spreads, because people are not immune to it, and there is no effective treatment
82
How can antibiotic resistance be prevented?
Prevent overuse of antibiotics Finish the course of antibiotics Restrict the use of antibiotics in agriculture
83
Prevent overuse of antibiotics:
If they are over used it gives bacteria more chance to mutate and form an antibiotic resistant strain. Antibiotics can also kill some of the harmless bacteria which can create more resources and space for the harmful bacteria to grow.
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Finish the course of antibiotics:
To ensure that all bacteria are killed by the antibiotic, therefore none survive to mutate and form resistant strains.
85
Restrict the use of antibiotics in agriculture:
Antibiotic resistant strains can often arise in animal pathogens which can then be transferred to human pathogens
86
MRSA
MRSA can spread from person to person by skin-to-skin contact or someone who is infected or is a carrier, by contaminated wound dressings or bed sheets. Hospital staff can ensure a reduction in the spread of MRSA by ensuring very strict hygiene and hand-washing protocols amongst hospital staff, visitors and patients. Patients should be regularly screened for the bacteria and isolated if they are infected. Try and limit transfer of patients between hospitals, especially if infected with MRSA.
87
why has antibiotic resistance increase nowadays?
Antibiotic resistance has increased over recent years because doctors have been prescribing antibiotics regularly over the past few decades. People have also been going to the doctors more when they are only a little bit ill or have a virus. Antibiotics have also been used in agriculture and passed down in the food chain.
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Carl Linnaeus
living things are divided into kingdoms and then subdivided into smaller and smaller groups : kingdom, phylum, class, order, family, genus, species. according to their characteristics and the structures that make them up
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species defintion:
A species is a group of organisms that can breed together to produce fertile offspring.
90
what are the 7 taxa:
kingdom king phylum Phillip class came order over family for genus good species soup
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what are the 3 domains?
archaea - primitive bacteria, found in extreme places eg hot springs or salt lakes bacteria - true bacteria eg E.coli eukaryota - eg fungi, plants animals and protists
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what are the 5 kingdoms
Animalia Plantae Fungi Protoctista Prokaryotae
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Animalia kingdom
Multicellular (made of many cells) Heterotrophic (can’t make their own food, so no chlorophyll) Cells do not have cell walls Cells have complex structure Cells have a nucleus
94
Plantae kingdom
Multicellular (made of many cells) Autotrophic (make their own food using chlorophyll) Cells have cell walls made of cellulose Cells have complex structure Cells have a nucleus
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Fungi kingdom
Multicellular (made of many cells) Saprophytic (leech food from other things, so no chlorophyll) Cells have cell walls, but are not made of cellulose Cells have complex structure Cells have a nucleus
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Protoctista kingdom
Mostly Unicellular (made of single cells) Cells have complex structure Cells have a nucleus Eg Algae, Amoebas,
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Prokaryotae kingdom
Unicellular (made of single cells) Cells have simple structure Cells have no nucleus Eg bacteria, salmonella
98
How does the structure of a prokaryotic cell differ from a eukaryotic cell?
Prokaryote No nucleus Loop of DNA – no chromosomes No membrane-bound organelles Eukaryote Has a nucleus Nucleus contain chromosomes Has membrane-bound organelles
99
what are the 3 domains called?
archaea bacteria eukaryota
100
archaea domain:
organisms in this domain are primitive bacteria. they are often found in extreme places such as hot springs and salt lakes
101
bacteria domain:
true bacteria like E. coli and Staphylococcus.
102
eukaryota domain:
broad range of organisms including fungi, plants, animals and protists