B14 - Variation + Evolution Flashcards
B14 - what is variation?
Differences between living organisms
Genotype variation - caused by the genetic material you inherit from your parents
Phenotype variation - caused by environmental factors such as where you live, what you eat etc.
B14 - apply the theory of evolution to explain how a specific species evolved.
Variation within a population.
This will mean that some animals better adapted than others.
These organisms survive and their favourable alleles are inherited by their offspring.
Poorly adapted organisms die - their unfavourable alleles are bred out of the population.
This process happens repeatedly over millions of years causing a species to evolve.
B14 - What is a mutation?
A random change in the genetic code.
Can happen whenever cells divide.
Some can be advantageous.
Some can have negative effects.
B14 - Explain the process of selective breeding.
Choose parents with the desired characteristics.
Breed these two organisms together.
From the offspring, identify those who possess the desired characteristic.
Breed these together.
Continues the process over many generations.
Eventually, all of the offspring will show the desired characteristic.
B14 - Explain the problems involved with selective breeding.
Reduced variation.
Only organisms with desired alleles allowed to breed.
Lack of variation reduces a population’s ability to cope with environmental change.
Increased risk of extinction
B14 - Explain the process of genetic engineering
Enzymes used to cut out the required gene.
This gene is inserted into a bacterial plasmid.
The plasmid, which now contains our required gene is inserted into the required cells.
The gene is transferred to the cells at an early stage of their development.
As the organism grows, it develops with the new, desired characteristics from that gene.
B14 - What are the benefits of genetic engineering?
Pros:
GM crops provide the best way to solve the world’s hunger crisis.
Improved growth rates of plants and animals.
Increased food value of crops, GM crops produce much bigger yields than normal crops.
Crops can be designed to grow well in all conditions.
Crops can be designed to produce their own pesticide or are resistant to herbicides used to control weeds
B14 - What are the risks of genetic engineering?
Cons:
Effects of eating GM produced food are unknown.
Genes from GM plants and animals might spread into the wildlife of the countryside.
GM organisms can affect populations of wild flowers and insects.
GM crops were originally made infertile - farmers in poor countries had to buy new seed
each year.
The spreading of infertility genes could cause major problems in the environment.
