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Control, Genome and Environment
Cellular Control & Variation
Cellular Control
(a) state that genes code for polypeptides, including enzymes;
(b) explain the meaning of the term genetic code;
The sequence of the bases on a gene is a code with instructions for the construction of proteins. It
has a number…

Page 2

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Control, Genome and Environment
(h) explain genetic control of protein production in a prokaryote using the lac operon;
E. coli grown in a culture medium with no lactose can be placed in a growth medium with lactose.
At first they cannot metabolise the lactose because they only have tiny amounts…

Page 3

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Control, Genome and Environment
Meiosis and Variation
(a) describe, with the aid of diagrams and photographs, the behaviour of chromosomes during meiosis, and
the associated behaviour of the nuclear envelope, cell membrane and centrioles. (Names of the main
stages are expected, but not the subdivisions of prophase);
Meiosis I

Page 4

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Control, Genome and Environment
(b) explain the terms
An alternative version of a gene
Specific position on a chromosome, occupied by a specific gene
Observable characteristics of an organism
Alleles present within cells of an individual, for a particular trait/characteristic
Characteristic in which the allele…

Page 5

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Control, Genome and Environment
(e) use genetic diagrams to solve problems involving sex linkage and codominance;
Sex linkage
e.g. Haemophilia

Parental Phenotypes Carrier Mother Normal Father
H h H
Parental Genotypes X X X Y
H h H
Gametes X X X Y

Male Gametes
Female Gametes X Y…

Page 6

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Control, Genome and Environment
(h) use the chi-squared ( ) test to test the significance of the difference between observed and expected
results. (The formula for the chi-squared test will be provided);
( - )

O is observed
E is expected
The smaller the value of , the…

Page 7

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Control, Genome and Environment
(n) explain, with examples, how environmental factors can act as stabilising or evolutionary forces of natural
In unchanging conditions, stabilising selection maintains existing adaptations and so maintains
existing allele frequencies.
In changing conditions, directional selection alters allele frequencies.
A mutation may be disadvantageous in existing…

Page 8

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Control, Genome and Environment
(s) describe how artificial selection has been used to produce the modern dairy cow and to produce bread
wheat (Triticum aestivum)
Dairy cow
Each cow's milk yield is measured and recorded
The progeny of bulls is tested to find out which bulls have produced daughters with…

Page 9

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Control, Genome and Environment
Biotechnology and Gene Technologies
Cloning in Plants and Animals
(a) outline the differences between reproductive and non-reproductive cloning;
Reproductive cloning is the production of offspring which are genetically identical to either the
mother (nuclear transfer), or the other offspring (splitting embryos)
Non-reproductive cloning is the use…

Page 10

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Control, Genome and Environment
(a) state that biotechnology is the industrial use of living organisms (or parts of living organisms) to produce
food, drugs or other products;
(b) explain why microorganisms are often used in biotechnological processes;
Grow rapidly in favourable conditions, with a generation time of as little…


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