Chapter 20-patterns Of Inheritance Flashcards
Define chlorolsis
When leaves look pale or yellow. This occurs because the cells aren’t producing enough chlorophyll. The lack of chlorophyll reduces the ability of the plant to make food by photosynthesis.
Environmental factors which cause chlrosis
Lack of light- in the absence of light, plants will turn of their chlorophyll production to conserve resources.
Mineral deficiencies - for example, a lack of iron or magnesium. Iron is needed as a cofactors by some of the enzymes that’s make chlorophyll, and magnesium is found at the heart of the chlorophyll molecule. If eithier of these elements are lacking plants can’t make chlorophyll therefor go yellow.
Virus infections- when viruses infect plants, they interfere with the metabolism of cells. A common symptom is the yellowing in the infected tissue. A common symptom is yellowing in the infected tissue.
Genetic contributions
Sexual reproduction involving meiosis, and the random fusion of gametes at fertilisation.
Definition of continuous variation
A characteristic that can take any value within a range
Causes of continuous variation
Genetic and environmental
Genetic control of continuous variation
Polygenes - controlled by a number of genes
Definition of discontinuous variation
A characteristic that can only appear in specific discrete values
Causes of variation of discontinuous variation
Mostly genetic
Genetic control of discontinuous variation
One or two genes
Define monogenetic inheritance
The inheritance of a single gene
Define codominance
Occurs when two different alleles occur for a gene- both of which are equally dominant. Usually meet in the middle and form a different colour
Define sex linkage
Some charactersics are determined by genes carried on the sex chromosomes
Define multiple alleles
Have more than two versions of a gene
Define dihybrid inheritance
Used to show the inheritance of two genes
Chi squared test
X2=sum of (observed - expected) squared divided by expected
