Genetic diversity

Question 1

What is genetic diversity?

Answer 1

the number of different alleles of genes in a population
difference in DNA

Question 2

How does mutation contribute to genetic diversity?

Answer 2

results in the generation of new alleles and contributes to genetic diversity or the size of gene pool

Question 3

How does meiosis cause genetic diversity?

Answer 3

independent segregation - chromosomes separated in random formation
crossing over - non-sister chromatids randomly join at multiple points, mixing alleles

Question 4

What is random fertilisation?

Answer 4

any sperm fertilises any egg
range of different alleles in population increases genetic variation

Question 5

What is non-disjunction?

Answer 5

failure to separate during anaphase

Question 6

What does non-disjunction result in?

Answer 6

chromosomes aren’t evenly split

Question 7

What is a mutation?

Answer 7

change in base sequence of DNA

Question 8

What are chromosomal mutations?

Answer 8

changes in whole set of chromosomes leading to polyploidy

Question 9

What is worse: tetraploid or triploid?

Answer 9

triploid as can’t split/line up evenly

Question 10

Why is genetic diversity important?

Answer 10

contributes to biodiversity as wider range of phenotypes increases likelihood of species surviving in a changing environment
important for variation within gene pool

Question 11

What types of populations have high genetic diversity?

Answer 11

large
higher adaptive capacity
potential for long term survival
high resilience

Question 12

What types of populations have low genetic diversity?

Answer 12

small, isolated
lower adaptive capacity
weak potential for long term survival
low resiliance

Question 13

How is genetic diversity measured in a popultaion?

Answer 13

sequence the DNA and count the number of different alleles

Question 14

How does genetic diversity enable natural selection to occur?

Answer 14

range of alleles so selection can occur and more advantageous alleles can be selected

Question 15

Why might a population with low genetic diversity struggle to survive environmental changes?

Answer 15

haven’t got allele required to survive if environment changes
smaller range of phenotypes

Question 16

What prevents the possibility of population size exceeding carrying capacity of environment?

Answer 16

environmental resistance

Question 17

What are the possible abiotic factors contributing to environmental resistance?

Answer 17

water availability, mineral ions, number of habitats

Question 18

What is carrying capacity?

Answer 18

max size a population can be

Question 19

What are the possible biotic factors contributing to environmental resistance?

Answer 19

predation/food availability, disease

Question 20

What is natural selection?

Answer 20

genetic diversity in population
new alleles arise due to random mutation
population experiences selection pressure
individuals with advantageous allele survive to reproduce
advantageous allele is inherited by offspring
passed over many generations, increasing in frequency in population

Question 21

What is selection pressure?

Answer 21

an environmental factor which reduces the organisms ability to survive

Question 22

What is the advantageous allele?

Answer 22

coding for the phenotype which increase survival

Question 23

What are the different types of adaptations?

Answer 23

anatomical e.g. fur colour, neck length

physiological e.g. rate of gas exchange

behavioural e.g. courtship displays

Question 24

What is a polygenic trait?

Answer 24

controlled by more than 1 allele
several genes contribute to final phenotype of a given trait

Question 25

What are the types of selection?

Answer 25

stabilising directional disruptive

Question 26

What is stabilising slection?

Answer 26

intermediate phenotypes are best adapted to survival in environment -> these alleles are advantageous intermediate become more common, extreme phenotypes may disappear e.g. birth mass in humans

Question 27

What is directional selection?

Answer 27

an extreme phenotype is best adapted to survival in environment so a particular allele is more advantageous extreme becomes more common e.g. antibiotic resistance in bacteria

Question 28

How do antibiotics work?

Answer 28

inhibition of cell wall synthesis inhibition of protein synthesis inhibition of nucleic acid replication and transcription injury to plasma membrane inhibition of synthesis of essential metabolites

Question 29

How does the bacteria destroy / avoid effects of antiobiotic?

Answer 29

mutations e.g. increasing strength of cell wall

Question 30

How does antibiotic resistance occur?

Answer 30

mutation vertical gene transfer - binary fission horizontal gene transfer - conjugation (exchange of plasmids), transduction (viral infection)

Question 31

What is the nutrient media?

Answer 31

contain biological molecules needed for growth: sugar, lipids, amino acids, nucleotides, vitamins and minerals e.g. agar plate, broth culture

Question 32

Why is the agar plate sterilised?

Answer 32

so no unwanted bacteria / species grown on agar