Genetic Crosses and Heredity Mock Questions Flashcards
Explain the term genotype
Genotype means the genetic make-up of an organism i.e. the genes that are present
Explain the difference between alleles and genes
Alleles are different/alternative forms of the same gene
A gene is a section of DNA that causes the production of a protein
Give an example of an allele
Eye colour
Explain what is meant by the term linkage
Linkage means that genes are located on the same chromosome
Explain why Mendel’s Law of Independent Assortment does not generally hold true for linked genes
As linked genes tend to be passed together to the next generation which means they don’t show independent assortment
Explain what is meant by non-nuclear inheritance
4
DNA inherited only from the mother
Non-nuclear DNA is present as small circles of DNA in mitochondria and chloroplasts
These organelles reproduce by themselves and pass on their genes to the resulting organelle
Mitochondrial DNA (mtDNA) is inherited only from the mother as the mitochondria from the sperm tail do not enter the egg during fertilisation
Explain what is meant by sex linkage
Sex linkage means that a characteristic is controlled by a gene on a sex (or X) chromosome
Why is the incidence of colour blindness more common in men than women?
Men only need one copy of the recessive allele to be colour blind while women need two copies of the recessive allele
Name the scientist whose work with pea plants led him to propose the basic rule of genetics
Gregor Mendel
Explain the basic principle behind the law of Segregation
(definition)
(2)
Inherited characteristics are controlled by pairs of alleles
These alleles are segregate or separate from each other at gamete formation, with only one member of the pair being found in each gamete
Explain what is meant by “pure-breeding”
Homozygous recessive or homozygous dominant
From which parent is non-nuclear DNA inherited from?
The mother
Explain what is meant by the term allele
Alleles are different or alternative forms of the same gene
What term is used to describe alleles that lie on the same chromosome?
Linked
What is the significance of non-linked alleles?
This allows for independent assortment and allows for more variation in offspring
