Biol unit 2

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  • Created by: Rachel
  • Created on: 03-06-13 07:42
What is interspecific variation?
Variation across different species.
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What is intraspecific variation?
Variation that occurs within the same species.
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What is genotype?
The alleles an organism has.
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What is phenotype?
It is the characteristics displayed by an organism.
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How do you study variation?
You use a sample of the population which has to be RANDOM.
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Why does the sample need to be random?
To ensure any patterns are observed and tested to make sure they are not due to chance. To make sure the sample is not biased.
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What does standard deviation tell you?
The spread of values about the mean within a sample.
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What is DNA?
Deoxyribose nucleic acid. Polynucleotide. Made up of the bases ACTG.
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What are the components of each nucleotide?
Phosphate group (round), pentose sugar which is deoxyribose and the base (A C T or G)
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What do the nucleotides join to make?
Sugar phosphate backbone.
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What is the bonding between the bases?
Hydrogen.
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What is it called when the bases can only join with one particular partner?
Specific base pairing.
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How is DNA adapted to contain alot of genetic information?
It is very long and coiled up very tightly so alot of genetic info can fit into the nucleus.
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How is DNA adapted to self-replicate?
Double stranded.
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How is DNA adapted to be stable?
Double helix structure.
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How is DNA found in eukaryotes?
It is linear molecules which exist as chromosomes. Wound up.
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What is wrapped around DNA is eukaryotes which make it supported?
Proteins called histones.
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How is DNA found in prokaryotes?
Also chromosomes but molecules are shorter and circular.
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How does prokaryotic DNA fit in the cell?
Supercoiling.
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What are sections of DNA called that DONT code for amino acids?
Introns.
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What are sections of DNA that DO code for amino acids?
Exons.
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When are introns removed?
Protein synthesis.
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What 3 things to genes determine?
Nature, development and phenotype.
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How do genes determine out nature, development and phenotype?
They contain the information to produce all of our proteins and enzymes.
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What do enzymes do in order to determine how we grow and develop?
Speed up most of our metabolic pathways - chemical reactions in the body.
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What are alleles?
Different versions of the same gene.
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What are homologous chromosomes?
Chromosomes that are a matching pair.
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How do gene mutations result in a non functional protein?
Mutations change base sequence which codes for different amino acids, causing a different or non functional proteins to be developed.
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How do mutations cause a non functional enzyme?
Change in amino acids causes a change in ionic bonds this alters the tertiary structure of the active site so the enzyme can not form e-s complex.
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What is diploid chromosomes?
Each cell has two of each chromosome (2n).
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What is haploid chromosomes?
Each cell has only one copy of each chromosome (n).
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What happens if meiosis I ?
Chromosome arrange themself into homologous pairs which are then separated halvig
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Which two factors cause cells to be genetically different in meiosis?
Crossing over and Independent segregation.
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What is crossing over?
This is when the homologous pairs twist around eachother in meiosis I and bits of chromatids swap over.
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What is independent segregation?
This is the when the gametes are formed different combinations of maternal and paternal chromosomes go into each cell.
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Does genetic diversity happen within or across a species?
Within a species.
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How do organisms within a species vary?
They have the same genes but different alleles.
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How is genetic diversity increased?
Mutations in DNA forming new alleles. Different alleles being introduced when individuals from another population migrate - gene flow.
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What is genetic bottle neck?
Causes a big reduction in genetic diversity. E.g when a large number of the population die before they reproduce so the number of alleles in the gene pool is reduced.
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What is the founder effect?
This is when a few organisms from a species start a new colony. Only a small number number of alleles are contributed to the gene pool.
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What is selective breeding?
This is when humans select certain strains of animals and plants to reproduce to produce high yielding or desirable breeds.
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Give an argument for selective breeding.
It can produce animals and plants that are resistant from disease.
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Give an argument against selective breeding.
Can cause health problems and make the organism lame or have a short life expectancy.
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What is the main energy store in plants?
Starch.
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What is starch a mixture of?
Amylose and amylopectin both polysaccharides of alpha-glucose.
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Describe amylose.
It is a linear molecule. The angles of the glycosidic bonds give it a helical structure. Makes it compact.
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Describe amylopectin.
Branched molecule. Branches allow enzymes to hydrolyse the molecule quickly into glucose.
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What is the main energy store in animals?
Glycogen, also a polysaccharide of alpha-glucose.
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Describe glycogen.
Many branches coming off it so it can be quickly hydrolysed into glucose.
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What is the major component of plant cell walls?
Cellulose, made up of beta-glucose.
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Describe cellulose.
Linear molecule. Chains linked together by hydrogen bonds to form microfibrils. Structural support.
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What plant cells have that animals cells dont?
Cell wall, chloroplasts and vacuole.
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What are the membranes called inside chloroplasts?
Thylakoids.
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What do thylakoids stack to make?
Grana.
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What is stroma?
Thick fluid.
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Where does photosynthesis occur in the chloroplast?
Grana or stroma.
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How is DNA replicated?
DNA helicase breaks hydrogen bonds between two strands. Original strand acts as template. Free floating nucleotides join to exposed base. Joined together by DNA polymerase. H bonds reform. Each new strand of DNA contains one strand from original.
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How does chemotherapy affect the cell cycle?
Prevents synthesis of enzymes needed for DNA replication. If these arnt produced the cell cannot enter S phase and kills itself.
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How does radiotherapy affect the cell cycle?
It damages DNA. If the cell detects any damaged DNA it will kill itself.
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Give ways you can reduce damage to normal cells.
Remove tumour surgically first- increase access to any nutrients and oxygen, triggers them to enter cell cycle. Repeated treatments with breaks to allow body to recover.
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What is a tissue?
A collection of similar cells that work together to perform a particular function.
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What is an organ?
A group of different tissues that work together to perform a particular function.
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What is a system?
A group of different organs that work together to perform a particular function.
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Other cards in this set

Card 2

Front

What is intraspecific variation?

Back

Variation that occurs within the same species.

Card 3

Front

What is genotype?

Back

Preview of the front of card 3

Card 4

Front

What is phenotype?

Back

Preview of the front of card 4

Card 5

Front

How do you study variation?

Back

Preview of the front of card 5
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