Selection Flashcards
How does natural selection work?
If an organism has an allele that codes for a characteristic that increases their chance of survival they are more likely to survive, reproduce and pass on those genes. Their offspring is then more likely to survive, reproduce and pass on those genes to the next generation. Over time the frequency of that allele increases until almost all the organisms of that population have it and that leads to evolution.
What is evolution?
A change in a species over time.
What are behavioural adaptations?
The way an organism acts increases its chance of survival.
What are physiological adaptations?
When the processes within an organism increase its chance of survival.
What are structural adaptations?
The structural features of an organism that increase its chance of survival.
What is directional selection?
When organisms have an allele that codes for an extreme characteristic.
What is an example of directional selection?
Some bacteria have an allele that codes for antibiotic resistance. These bacteria are more likely to survive reproduce and pass on those genes to their offspring. After some time most of the bacteria will carry that antibiotic resistance.
What is stabilising selection?
When organisms have an allele that codes for a characteristic in the middle of two extremes.
What is an example of stabilising selection?
Human babies are more likely to be born with medium weight because small babies are less likely to survive as they can’t thermoregulate and large babies are also less likely to survive because they are hard to give birth to and that can cause complications for the baby and mother.
