Chapter 17 Flashcards
Variation & selection (25 cards)
what is variation?
differences between the individuals of the same species
Name the 2 types of variation?
- discontinous
2.continuous
What is discontinous variation?
variation in which there are distinct caregories of phenotypes(ex.blood groups)
Name the 4 blood groups?
1.A
2.B
3.AB
4.O
What is population?
a group of organisms of 1 species living in the same area at the same time
what is continuous variation?
variation in which there is a continuous range of phenotypes(eg.height in humans)
What are the causes of variation?
1.difference in genotypes
2.difference between the envirment between indivuduals
What causes genetic variation?
mutation
What is mutation?
a random change in a gene,which can produce new alleles
When does mutation often happen?
no apparent reason,can happen at anytime
What can radiation do?
damage the bases in DNA molecules
name the different chemicals that can increase the risk of mutation happening?
heavy metals(lead & murcury)
What is the chemicals called that can cause mutation?
mutagens
what is a adaptive feature?
an inherited feature that helps an organism to survive & reproduce in its environment
What are adaptive features causes by?
genes
What is natural selection?
a process in which indivuduals with advantageous feautes are more likely to survive & reproduce
Name the 4 points of natural selection?
1.variation
2.overproduction(more offspring can be produced)
3.best-adapted individuals more likely to survive & reproducde
4.alleles that confer useful adaptions are more likely to be passed on
Name 2 reasons why natural selection can cause a change in population?
1.a new alleles could arise
2.the envirment can change
What is selection pressure?
something in the envirmoent that affects the chance that iduviduals with different feautures will survive & reproduce
What is adaption?
the process,resulting from natural selection,by which populations become more suited to their envirment
What is a drug?
any substance taken into the body that modifies/affects chemical reactions in the body
What is a antibiotic?
substance taken into the body,which kills bacteria but does not affect humans cells
What is artifical selection/selective breeding?
choosing particular organisms with desired characteristics to breed together
Name the 5 steps a farmer can use to improve her herd?
- choose only cows that produce large volumes of high quality milk
2.Choose a bull whose mother/sister/daughter produce llarge volumes of quality milk
3.breed the chosen cow whith the chosen bull
4.allow calves to grow into adults
5.repeat for many generations
