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Ocr A level biology paper 2 EXAM QUESTIONS AND ANSWERS UPDATED 2024/2025 ALL ANSWERS 100 CORRECT VERIFIED BEST EXAM SOLUTION TOP RANKED TO SCORE A+$11.99
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Ocr A level biology paper 2 EXAM QUESTIONS AND ANSWERS
UPDATED 2024/2025 ALL ANSWERS 100% CORRECT VERIFIED
BEST EXAM SOLUTION TOP RANKED TO SCORE A+
Phenotype - CORRECT ANSWERS Characteristics of an organism as a result
of the expression of its genotype and the environment.
Gene - CORRECT ANSWERS Section of a chromosome that codes for a
polypeptide.
Allele - CORRECT ANSWERS Alternative version of the same gene.
Gene locus - CORRECT ANSWERS Location of a gene on a chromosome.
Dominant allele - CORRECT ANSWERS Allele that is always expressed in
the phenotype.
Recessive allele - CORRECT ANSWERS Allele that is only expressed in the
phenotype when there are two of them i.e. in a homozygote.
Codominant allele - CORRECT ANSWERS Both alleles are expressed in the
phenotype.
Multiple alleles - CORRECT ANSWERS More than 2 alleles for a particular
gene.
Sex linkage - CORRECT ANSWERS Characteristic or trait controlled by a
gene found on the sex chromosomes.
Homologous chromosomes - CORRECT ANSWERS Pair of chromosomes
that carry genes for the same characteristics, at the same gene loci.
,Ocr A level biology paper 2 EXAM QUESTIONS AND ANSWERS
UPDATED 2024/2025 ALL ANSWERS 100% CORRECT VERIFIED
BEST EXAM SOLUTION TOP RANKED TO SCORE A+
Homozygous - CORRECT ANSWERS When an organism carries two copies
of the same alleles.
Heterozygous - CORRECT ANSWERS When an organism has two different
alleles of the same gene.
Genotype - CORRECT ANSWERS Description of an organism's alleles.
Autosome - CORRECT ANSWERS Any chromosome that is NOT a sex
chromosome.
Autosomal linkage - CORRECT ANSWERS Genes coding for different
characteristics, found on the same non-sex chromosome, are said to be
linked.
Independent assortment - CORRECT ANSWERS During metaphase I of
meiosis, the arrangement of one pair of homologous chromosomes on the
equator of the spindle is independent of the arrangement of any other pair
of chromosomes. A key event that produces GENETIC VARIATION in
gametes.
Crossing over - CORRECT ANSWERS Where chromatids twist around each
other and exchange genetic material. Happens during prophase I of meiosis
which increases the amount of GENETIC VARIATION in gametes by
producing new combination of alleles.
Carrier - CORRECT ANSWERS Individual who has an allele, often for a
disease, which is not expressed in the phenotype i.e. they are heterozygous.
True breeding - CORRECT ANSWERS Individuals that are true breeding are
homozygous for a particular characteristic or trait.
,Ocr A level biology paper 2 EXAM QUESTIONS AND ANSWERS
UPDATED 2024/2025 ALL ANSWERS 100% CORRECT VERIFIED
BEST EXAM SOLUTION TOP RANKED TO SCORE A+
Epistasis - CORRECT ANSWERS A type of gene interaction, where the allele
of one gene masks the effect of the allele of a different gene.
Hemizygous - CORRECT ANSWERS Having a single copy of a gene instead
of the normal two. For example, if there is heterozygous inheritance of the
sex chromosomes, XY.
Variation - CORRECT ANSWERS The range of differences in characteristics
between organisms
Phencopy - CORRECT ANSWERS When environmental conditions alter the
phenotype to resemble the effects of genotypic change
Discontinuous variation - CORRECT ANSWERS Variation where there are 2
or more distinct categories with no intermediates. Determined by a small
number of genes with little or no environmental influence.
Continuous variation - CORRECT ANSWERS Variation where there are two
extremes and all possible intermediate forms. Determined by many genes
(polygenic) and influenced by the environment.
Etiolation - CORRECT ANSWERS When plants grow abnormally long and
spindly because they are not getting enough light.
Chlorosis - CORRECT ANSWERS When plants don't produce enough
chlorophyll and turn yellow eg due to lack of magnesium in the soil.
Artificial selection - CORRECT ANSWERS When humans select which
individuals in a population to breed together in order to get desirable traits.
, Ocr A level biology paper 2 EXAM QUESTIONS AND ANSWERS
UPDATED 2024/2025 ALL ANSWERS 100% CORRECT VERIFIED
BEST EXAM SOLUTION TOP RANKED TO SCORE A+
Stabilising selection pressure - CORRECT ANSWERS Factor that reduces
the range of phenotypes by selecting against individuals with the extreme
phenotype.
Selection pressure - CORRECT ANSWERS A factor that gives a greater
chance of surviving to some members of the population than others e.g.
moth camouflage
Stabilising selection - CORRECT ANSWERS Types of selection that operates
against the extremes of the range of phenotypes so the population remains
the same over time.
Directional selection - CORRECT ANSWERS Factor that selects individuals
with an extreme phenotype of a range of phenotypes so the population
changes over time.
Genetic drift - CORRECT ANSWERS The increase or decrease in the
frequency of alleles as a result of chance events.
Carrying capacity - CORRECT ANSWERS The maximum population size of a
species that a particular habitat can support over time.
Gene pool - CORRECT ANSWERS The sum of all the alleles in a population
at a given time.
Genetic bottleneck - CORRECT ANSWERS An event, such as a natural
disaster, that causes a large reduction in the size of a population.
Founder effect - CORRECT ANSWERS What happens when a small number
of individuals start a new population and there is only a small number of
alleles.
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