genetic diversity pack 9

Question 1

the greater the variety of genotypes

Answer 1

the more genetically diverse

Question 2

genetic diversity allows

Answer 2

the population to adapt to changing conditions

Question 3

how may genetic diversity of a species decline?

Answer 3

some alleles may be lost and the genetic diversity decreases

Question 4

how does genetic diversity (variation) arise?

Answer 4

• crossing over which takes place in meiosis
• independant assortment of chromosomes in meiosis
• random fertilisation
• mutations which change the DNA base sequence

Question 5

how can we measure genetic diversity?

Answer 5

• can be observed in the external phenotype
• DNA sequencing can determine which alleles are present
• Gel electrophoresis can be used to produce DNA fragments and a heterozygosity index can be calculated

Question 6

gene pool

Answer 6

all the alleles of all the genes present in a population of a species

Question 7

genetic diversity

Answer 7

the number of different alleles in a population / gene pool, and the frequency of different alleles in a particular species

Question 8

heterozygosity index =

Answer 8

number of heterozygotes / number of individuals in the population

Question 9

the more genetically diverse the population is the more likely the

Answer 9

population can adapt to changing conditions therefore be able to survive and reproduce

Question 10

it is more likely that an advantageous allele will

Answer 10

exist in the gene pool that could code for a characteristic that gives the organisms a selective advantage in the new environmental conditions

Question 11

genetic variation diagram

Answer 11

genotype -> mutations: there are the source of new genetic material -> altered genotypes -> preparation for sexual reproduction -> gamete - carrying the genetic contribution from one parent -> gamete from another individual carrying a different combination -> fertilisation: fusion of genetic material from 2 individuals -> individual with new genotype -> expression of genotype dominant alleles mark recessive ones -> phenotype

Question 12

genetic variation diagram annotations for: mutations there are the source of new genetic material

Answer 12

• gene point mutations -> these are alterations of the dna base sequence. they may arise during dna replication of more rarely at another stage of the cell cycle
• chromosome mutation -> small sections of chromosomes may be rearranged during meiosis: they may be inverted, moved from one chromosome to another or even lost altogether

Question 13

genetic variation diagram annotations for: preparation for sexual reproduction

Answer 13

• independent assortment -> each homologous pair of chromosomes is sorted independently of the others during meiosis and the process is random
• crossing over -> new combinations of alleles result when pieces of genetic material are exchanged between homologous chromosomes during meiosis

Question 14

genetic variation diagram annotations for: fertilisation- fusion of genetic material from 2 individuals

Answer 14

• mate selection -> different combinations of alleles will come together in the offspring depending on which two parents mate together, conservations can increase genetic diversity by selecting which pairs of animals (or plants) will mate
• random fertilisation -> different combinations of alleles will come together in the offspring depending on the sperm and egg involved in fertilisation

Question 15

genetic variation diagram annotations for: phenotype

Answer 15

conservation management can be thought of as a successful if an endangered species retain enough genetic diversity to provide phenotypes so that the population is able to adapt to minor environmental changes in the natural habitat