Key Area 4: Variation and Inheritance Flashcards
Combining genes from two parents contribute to
Variation within a species
When one gene controls a characteristic?
It produces a different number of different phenotypes
A discrete variation is where
Measurements fall into distinct groups
A discrete variation is usually represented on?
Bar charts
Most features on individual phenotypes are?
Polygenic (controlled by many genes) and show continuous variation
Continuous variation shows a range of values between a
Minium and a maximum
Continuous variation is usually represented on?
Histograms
Discrete variation are characteristics that
Characteristics controlled by a single gene (one copy inherited from each parent) tend to have phenotypes that fall into separate categories
A phenotype is an
an individual’s observable traits, such as height, eye color and blood type
Genotype is
a statement of the alleles it has for a characteristic
The final appearance of an organism (phenotype) is the result of?
It’s genes (genotype) and the effect of the environment
If organisms form identical genotypes are subject to different environmental condition they can?
Show considerable variation
Environmentally influenced changes have minor
Evolutionary significance as they are not passed from one generation to another
Gene is
A strand of DNA coding for a protein
A gene will
Affect the organisms appearance
Allele is
The forms a gene can take
eg. Pea height gene has alleles for tall and dwarf
Dominant alleles will?
Always show in the phenotype, it hide other allele(s) of the same gene
Recessive alleles are
Hidden by the dominant allele
The genotype is
The list of actual alleles present in an organism
Eg. AA or aa
Homozygous are?
Alleles that are the same
Eg. AA or aa
Heterozygous are
Alleles that are different
Eg. Aa or Bb
Phenotype is
The visible/detectable effect of the genotype
Eg. Tall or dwarf peas
an individual’s observable traits, such as height, eye color and blood type
The parental genotypes is the?
P generation
You can work out the p generations offspring by reading questions carefully. The offspring are referred to as
The F1 generation
The grandchildren or offspring of F1 are referred to as the
F2 generation
The crosses can be worked out using a
Punett square
The predicted phenotype ratio among offspring are not always
Achieved
The ratio is not always achieved because fertilisation is
A random process
polygenic inheritance?
where a characteristic is controlled by more than one gene
Most features of an individual pheotype are?
Polygenic and show continuous variation
Discrete variation is?
when a characteristic can only fall into a certain number of distinct categories, with no intermediate forms. eg. You either have detached earlobes or attached ones.
Continuous variation is?
Continuous variation is a gradual change in a characteristic across a population. For example, a person’s height is a continuous variation because it can be any value between the shortest and tallest person in the world
