Key Area 1.7 Flashcards
How can genetic material be inherited
- vertical gene transfer
- horizontal gene transfer
Definition of vertical gene transfer and explain the different types of vertical gene transfer
PVertical gene transfer is when gene are transferred from parents down to offspring
It’s can happen by:
- sexual reproduction
- asexual reproduction
Sexual:
•two parent that differ from one another genetically
•The parents pass a combination of their gene to offspring
Asexual:
•this is the reproduction from one single parent
•parent pass gene to offspring causing offspring to be genetically identical
What is the disadvantage of asexual reproduction
Disease that affects one individual will affect whole clone population
Define the term evolution
Evolution is the gradual change in the characteristics of a population of organisms over successive generations as a result of variation within the population
Describe horizontal gene transfer
Only occurs in prokaryotes
Genetic information passed from one cell to another
Name the different types of horizontal gene transfer
Transformation
Transduction
Conjunction
What is the advantage of horizontal gene transfer
Obtaining a gene from a neighbour is much faster than waiting for one to evolve, which may confer better chances of survival
Disadvantage of horizontal gene transfe
No guarantee transfer led gene will confer an advantage
How has resistance to anti-biotic a been caused
Horizontal gene transfer
Give an account of natural selection
1) organism produce more offspring than the environment can’t support
2) all members of the species show variation from one another
3) a struggle for survival occurs and many offspring die before they can reproduce
4) only those who are better adapted to the environment (the fittest) will survive and breed,
Passing on their advantageous adaptation to their offspring
5) this process is repeated for generations causing a change in the characteristics of a population
What is sexual selection
Selection is driven by the organisms ability to get a mate
Name and describe the mechanisms that sexual selection operate through
Make to make competition:
Makes compete aggressively to defend territory and get access to females
Female choice:
Female select makes which they consider high quality to breed with
Describe the difference between stabilising, directional and disruptive selection
Stabilising:
•Selection pressure goes against extreme versions and favours intermediate versions of a trait
•This leads to a decrease in genetic diversity
Directional:
•selection pressure favours a version which was initially less common
•this leads to a progressive shift in mean value
Disruptive:
•selection pressure favours extreme versions of a trait at the expense of the intermediate version
- can result in population being split into two distinct groups
- this is the force behind sympatric speciation
What is a species and what is speciation
Species: group of organism that can interbreed with one another to produce viable offspring
Speciation: the formation of a new biological species brought about by evolutionary change
Name the 2 types of speciation and describe the difference between them
Allopatric speciation:
Flow between populations is prevented by a GEOLOGICAL barrier
Sympatric speciation:
Populations that live in close proximity of each still become genetically isolated because of BEHAVIOURAL, ECOLOGICAL barriers or the occurrence of polyploidy (in plants only)
