BY5: Environment, Genetics and Evolution

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  • Created by: GGB2016
  • Created on: 22-06-16 13:24
What is semi-conservative replication?
When each DNA molecule produced contains one strand of the original parent DNA and one strand of newly formed DNA
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During which part of the cell cycle does DNA replication take place?
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Where are proteins synthesised?
In the nucleus
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How many codons can a ribosome accommodate at any time?
2 codons (6 bases)
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What type of bond links two amino acids together?
Peptide bond
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What is meiosis for?
To produce genetically varied haploid cells
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What can cause variation during meiosis?
Crossing over and random assortment
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What is the sequence of the stages in meiosis?
Interphase > Prophase> Metaphase > Anaphase > Telophase (Cytokinesis)
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What is a gene?
A portion of a chromosome that codes for one polypeptide
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What is an allele?
An alternate form of the gene
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What is complete dominance?
Where one allele is dominant over the other producing a 3:1 ratio
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What is incomplete dominance?
When neither allele is dominant or recessive but instead there is codominance, giving a 1:2:1 ratio
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What is sex linkage?
Where genes occur on the X/Y chromosome
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What are unlinked genes?
Where multiple factors are observed but are not found on the same chromosome, giving a 9:3:3:1 ratio
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What are linked genes?
Where both genes are on the same chromosome so alleles will be inherited together unless crossing over occurs
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What is the null hypothesis?
There is no significant difference between expected and observed ratios
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What is the difference between continuous and discontinuous variation?
Discontinuous is controlled by one gene, continuous is controlled by multiple genes and the environment
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What is population?
The total number of individuals of a species in a given area at a given time
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What is gene pool?
The sum of all individual alleles within a population
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What is genetic drift?
Variations in allele frequency caused by chance
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What is the difference between allopatric and sympatric speciation?
Allopatric is when demes become geographically separated, sympatric is when demes are reproductively separated
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Where are leydig cells found and found do they produce?
In the seminiferous tubule - produce testosterone
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Where are sertoli cells and what is their function?
In the seminiferous tubule - protect spermatocytes from immune response and provide nutrients
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What is capacitation?
Changes that occur to the acrosome membrane after fertilisation
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What is the cortical reaction?
An influx of Ca2+ causes cortical granules to fuse and form a fertilisation membrane
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What is a blastocyst
A hollow ball of undifferentiated cells
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What hormone is produced by the embryo and what does it do?
hCG - prevents the breakdown of the corpus luteum
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How do blocked fallopian tubes prevent conception?
The oocyte cannot be passed down and fertilised
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Which parts of the flower make up the carpel?
Stigma, style, ovary, ovule
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Which parts of the flower make up the stamen
Anther and filament
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What becomes the seed, fruit and testa?
Seed = ovule, fruit = ovary, testa = outer integument
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What is the function of the generative nucleus?
It divides by mitosis to form two sperm nuclei. One fertilises the egg and the other fuses with 2 ovary nuclei to form the endosperm
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What is the function of the tube nucleus
Controls the growth of the pollen tube
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What does totipotent mean?
Has the ability to produce all types of tissue
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What are stem cells?
Undifferentiated totipotent cells can become specialised
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What is germ line therapy?
Replacing genes in gametes, therefore it is inheritable
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What is somatic cell therapy?
Targeting cells in affected tissues, therefore it is not inheritable
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What is PCR
Polymerase Chain Reaction - amplifies a sample of DNA by causing it to replicate in an artificial situation
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What is gel electrophoresis?
Where fragments of DNA are separated to give a visual comparison
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What is carbon footprint?
The total release of carbon dioxide due to the actions of an individual
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What is Net primary productivity?
The remainder of light energy that is converted to biomass
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What is Gross primary productivity?
The rate of conversion of light energy to chemical energy
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What is photosynthetic efficiency?
A measure of how well a plant captures light energy
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What is an autotroph?
An organism that produces organic materials from inorganic ones
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What is primary succession?
The introduction of a species to an area not previously colonised
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What is a pioneer species?
The first species to colonise an area from spores/seeds
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What is the climax community?
The final and most stable community within an area
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Card 2


During which part of the cell cycle does DNA replication take place?



Card 3


Where are proteins synthesised?


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Card 4


How many codons can a ribosome accommodate at any time?


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Card 5


What type of bond links two amino acids together?


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