The Basics
This is the process by which organisms with favorable traits survive and reproduce more successfully.
What is natural selection?
Darwin noticed the finches on different islands had different shapes of this body part.
What is the beak?
Sickle cell disease is caused by a change in this molecule that carries oxygen in red blood cells.
What is hemoglobin?
If a drought causes only large seeds to remain, finches with this trait will have better survival.
What are large/strong beaks?
These are differences between individuals of the same species.
What is variation?
Finches with large, strong beaks were best adapted for eating these.
What are nuts/seeds?
People who have one normal allele and one sickle cell allele are called this.
What are carriers?
If a mutation gives a finch a slightly longer beak, and it helps the bird survive, the mutation will likely do this in future generations.
What is increase in number?
The idea that more offspring are produced than can survive is known as this.
What is overproduction?
Finches with long, narrow beaks were better adapted for eating these.
What are insects?
Carriers of the sickle cell trait have a survival advantage in areas where this disease is common.
What is malaria?
A student claims “natural selection gives organisms what they need.” Why is this incorrect?
Because natural selection only favors existing traits—organisms don’t “get” traits on purpose.
This term describes a beneficial trait that increases an organism’s chance of survival.
What is an adaptation?
When food sources changed, finch populations with useful traits did this more often.
What is survive and reproduce?
Humans can inherit two normal alleles (SS), two sickle cell alleles (AA), or one of each (AS). Individuals with which allele combination are generally healthy and gain protection from malaria?
What is "AS?"
A finch population becomes split between two islands. Over time they become different species. This process is called ________.
What is speciation?
This is the name for the struggle among organisms to obtain limited resources.
What is competition?
All the different species of Darwin’s finches originated from this single early species that they all evolved from.
What is a common ancestor?
The AS genotype offers malaria resistance but also carries a sickle cell allele, while the AA genotype causes serious disease. This situation—where a trait increases survival in one way but causes harm in another—is an example of a _________.
What is a trade off?
In a population of insects, some individuals survive pesticide spraying because they naturally have a resistant trait. Over several generations, most insects in the population become resistant. This is an example of natural selection caused by this kind of pressure.
What is selective pressure?