9.3 - Genetic diversity and adaptation

Question 1

what determines the variation of proteins that make up each organism

Answer 1

DNA

Question 2

what causes the vast genetic diversity we find within organisms

Answer 2

genetic similarities/differences is due to variation in DNA

Question 3

do all members of the same species have the same genes

Answer 3

yes
- all humans have a gene for blood group
- which blood group humans have depends on which 2 alleles of the gene they posses
—-> therefore organisms of the same species differ in their combination of alleles, not their genes

Question 4

define genetic diversity

Answer 4

the total number of different alleles in a population

Question 5

what is a population

Answer 5

• a group of individuals of the same species that live in the same place and can interbreed. A species consists of one, or more, populations

Question 6

what increases genetic diversity

Answer 6

• the greater the number of different alleles that all members of a species possess = the greater the genetic diversity
• therefore genetic diversity is reduced by a species having fewer different alleles.

Question 7

what is the advantage to genetic diversity, explain why

Answer 7

• the greater the genetic diversity = the more likely some individuals in a population will survive an environmental change
• this is because of a wider range of alleles and therefore a wider range of characteristics
• This gives a greater probability that some individual will posses a characteristic that suits it to the new environmental conditions
• Therefore genetic diversity is a factor that enables natural selection to occur

Question 8

what is natural selection in the evolution of populations

Answer 8

• Not all alleles of a population are equally likely to be passed to the next generation.
• This is because only certain individuals are reproductively successful and so pass on their alleles

Question 9

what does differences between the reproductive success of individuals affect

Answer 9

allele frequency in populations

Question 10

describe the process of how differences between the reproductive success of individuals affect allele frequency in populations

Answer 10

• Within any population of a species there will be a gene pool containing a wide variety of alleles
• Random mutation of alleles within this gene pool may result in a new allele of a gene which in most cases will be harmful
• However in certain environments, the new allele of agene might give its possessor an advantage over other individuals in the population
• these individuals will be better adapted and therefore more likely to survive in their competition with others
• These individuals are more likely to obtain the available resources and so grow more rapidly and live longer. As a result, they will have a better chance of breeding successfully and producing more offspring
• only those individuals that reproduce successfully will pass on their alleles to the next generation
• As these new individuals also have the new, ‘advantageous’ allele, they in turn are more likely to survive and so reproduce successfully
• Over many generations, the number of individuals with the new, ‘advantageous’ allele will increase at the expense of the individuals with the ‘less advantageous’ alleles
• Over time, the frequency of the new, ‘advantageous’ allele in the population increases while that of the ‘non-advantageous’ ones decreases