Topic 6 p2 Flashcards
(26 cards)
What is the allele that causes cystic fibrosis
Recessive allele f
Because it is recessive people with only 1 copy of the allele won’t have the disorder. What r they known as
Carriers
What must the parents have for their child to get cystic fibrosis
They must be either carriers Or have the disorder themselves
What is polydactyly
It is a genetic disorder where a baby is born with extra fingers or toes and it isn’t life-threatening
What is polydactyly caused by
A dominant Allele D so you can be inherited if just one parent carries the defective allele. The parent who has the defective allele will also have the condition because the allele is dominant
What can embryos be screened for
To find any genetic disorders
Why did people not understand Mendels work until after his death
His workers need to scientists and they had no idea about genes DNA and chromosomes
What is the theory of evolution
All of today’s species have evolved from simple life forms first started developing over 3 billion years ago
What was Charles Darwin’s theory of evolution
The successful organisms that survive are more likely to reproduce and pass on their genes. Overtime beneficial characteristics become more common in the population and the species changes (it evolves)
Why do new phenotypic variations arise
Because genetic variants produced by mutations
What is specification
Development of a new species
How does specification happen
When populations of the same species change enough to become reproductively isolated, this means that they can’t interbreed to produce fertile offspring
What is extinction
When no individuals of a species remain
How do species become extinct
Environmental changes, a new predator kills them all, a new disease kills them all, they can’t compete with another species for food, a catastrophic event happens that kills them all like a volcano
Why didn’t everyone agree with Darwin’s theory
It went against religious beliefs Darwin couldn’t explain why these new useful characteristics appeared or how they were passed on and he didn’t know anything about genes or mutations there wasn’t enough evidence to convince scientists
What scientist had a different idea to Darwin
Lamarck and he argued that changes that an organism acquires during its lifetime will be passed on to its offspring
Why was Lamarck’s hypotheses rejected
Because experiments didn’t support his hypotheses
Why was Darwin’s theory accepted
The discovery of genetics supported his idea because it provided an explanation of how organisms born with beneficial characteristics can pass them on
What is the main drawback to selective breeding
It’s reduces the gene pool
What is a gene pool
The number of different alleles in a population
What is inbreeding
When a farmer keeps breeding from the best animals or plants which are closely related
What can inbreeding cause
Health problems because there’s more chance of the organisms inheriting harmful genetic defects when the gene pool is limited. There can also be serious problems if a new disease appears because there’s not much variation in the population so if one is killed by a new disease the others are also likely to die
What is selective breeding
When humans artificially select plants or animals that are going to breed so that the genes for particular characteristics remain in the population
What can selective breeding be used for in agriculture
To improve yields for example to improve meat yields a farmer could bring together cows and bulls with the best characteristics for producing meat and after doing this for several generations the farmer would get cows with a very high meat yield
