Genetic Organisation
What is a gene?
A section of DNA which codes for a particular trait
What is a mutation?
A permanent change in the base sequence of an individual's DNA
Name 3x processes which create variation.
Crossing Over
Independent Assortment
Fertlisation
Name the reproduction which produces offspring most likely to survive
Sexual reproduction
What is the purpose of mitosis?
Growth and repair
What is the difference between alleles?
Alleles have differences in their DNA base sequence, code for different proteins.
What does a punnett square show?
A prediction of offspring's genotype AND phenotype
What creates new combinations of alleles?
Crossing Over
List 3x advantages of asexual reproduction.
Quick
Requires only 1 parent
Can guarantee favorable characteristics passed on
What occurs before both mitosis and meiosis take place
DNA replication
Order: Gene, DNA, Karyotype, Nucleotide, Chromosome, base
Base>Nucleotide> DNA> Gene> Chromosome> Karyotype
How can white rabbits (W) have a black offspring (w)?
Both parents must have the genotype Ww. They both must have passed on a w allele to offspring. White is a dominant trait which can mask the recessive black trait.
Define independent assortment.
When homologous pairs of chromosomes line up randomly in the center of the cell. The placement of chromosomes along the equator determines which daughter cell the end up in after cell division.
Explain why having cloned plants in an apple orchard may not be ideal.
Cloned means they are genetically identical; therefore, they are all susceptible to the same environmental changes, and any diseases or pests. A drought/flood/disease may kill all apple trees.
A pedigree charts shows colour blindness. A black circle represents what?
A female with colour blindness.
Why must meiosis reduce the chromosome number in a gamete?
Gametes have 1/2 the number of chromosomes as a normal cell, as once they become fertilised they will inherit the other set of chromosomes from the other parent to form a diploid zygote.
A breeder wants to breed white rabbits, describe what must he do first.
The breeder must confirm the genotype of his rabbits. He must do a test cross and breed his rabbits with a recessive rabbit and analyse the phenotype of their offspring to determine the genotype of his breeding rabbit.
Sarah has 2 daughters. Explain her chances of having another daughter.
50/50
each fertilisation even is new and a random event that is not affected by previous outcomes.
Sarah can only provide X chromosomes. Her partner can provide and X or Y
Why do some dominant traits have a low frequency within a population?
Allele frequency is determined by an organism's survival and reproductive success.
If the trait lowers either of these it will have a low frequency.
Define homologous chromosomes
Two chromosomes in a pair with the same gene sequence, loci, length– normally one inherited from the mother and one from the father.
A cat has a new green coat colour. Explain how this occurred and how it might impact the cat population.
New alleles arise by mutations. This must occur in the gametes to be passed to offspring.
Green coat may allow cats to camouflage in grass which allow them to hide from predators and stalk their prey. This will increase their survival. Overtime number of green cat will increase.