Genetic Diversity And Adaptation Flashcards
A mutation can lead to the production of a non-functional enzyme. Explain how.
- Change in nucleotide sequence
- Change in primary structure
- Change in hydrogen bonds
- Change in tertiary structure
- Change in active site
- Substrate is not complementary to the enzyme
Scientists investigated the effect of a specific antibiotic on two strains of the same species of bacterium.
• One strain, SR, shows a stringent response in the presence of this antibiotic.
Part of this response involves stopping cell division.
This gives this strain a greater resistance to the effects of this antibiotic.
• The other strain, non-SR, cannot carry out a stringent response.
The scientists grew cultures of the SR strain and the non-SR strain containing the same number of bacterial cells.
They then stopped each strain from dividing and exposed them to different concentrations of the antibiotic.
After a fixed time, the scientists estimated the number of living bacteria remaining in the cultures.
Figure 1 shows their results.
( Figure shows two line graphs labelled SR strain and the other non SR stain, the SR strain levels of at a 10 mirograms per cm^-3 concentration of antibiotic and the non SR strain continues to to decrease at a constant gradient, being higher than it initially was )
( The figure is labelled “ number of living bacteria remaining “ against “ concentration of antibiotic “ )
Describe differences in the effect of increasing the concentration of antibiotic on the SR strain and the non-SR strain.
- Non - SR strain falls more
- Above 10 micrograms per cm^-3, SR strain levels out and non - SR strain continues to decrease
One way in which the stringent response gives resistance to this antibiotic is by stopping cell division.
The scientists concluded that stopping cell division is not the only way in which the stringent response gives resistance to this antibiotic.
Explain how Figure 1 supports this conclusion.
( Figure shows two line graphs labelled SR strain and the other non SR stain, the SR strain levels of at a 10 mirograms per cm^-3 concentration of antibiotic and the non SR strain continues to to decrease at a constant gradient, being higher than it initially was )
( The figure is labelled “ number of living bacteria remaining “ against “ concentration of antibiotic “ )
- Division stopped
- SR strain is still more resistant
The stringent response involves a number of enzyme-catalysed reactions.
Explain how scientists could use this knowledge to design drugs that make the treatment of infections caused by the SR strain more successful.
- Make a non-competitive inhibitor
- Non-competitive inhibitor changes the active site
The antibiotic damages the bacterium by causing the production of substances called free radicals.
The scientists exposed the SR strain and the non-SR strain to the antibiotic.
They then measured the amounts of free radicals and an enzyme called catalase in both strains.
Figure 2 shows their results.
( Figure two shows two sets of bar graphs labelled SR and Non-SR )
( Within these labels, two graphs are present within them, showing the amount of free radicals and the other showing the amount of Catalase )
( For SR strain, there’s a lot of catlase compared to free radicals )
( For non-SR strain, there’s a bit more free radicals than catalase )
( Y-axis is labelled “ Amount of free radicals or catalase / arbitrary units, x-axis is labelled “ Strain of bacterium “ )
Use the information provided and Figure 2 to suggest an explanation for the greater resistance of the SR strain to this antibiotic.
- Fewer free-radicals
- Produces more catalase
- Catalase might be lined to the breaking down of free radicals
The table shows the taxons and the names of the taxons used to classify one species of
otter.
They are not in the correct order.
( Unnamed title ):
1 ) J
2 ) K
3 ) L
4 ) M
5 ) N
6 ) O
7 ) P
8 ) Q
Taxon:
1 ) Family
2 ) Kingdom
3 ) Genus
4 ) Class
5 ) Order
6 ) Phylum
7 ) Domain
8 ) Species
Name of taxon:
1 ) Mustelidae
2 ) Animalia
3 ) Lutra
4 ) Mammalia
5 ) Carnivora
6 ) Chordata
7 ) Eukarya
8 ) lutra
Put letters from the table above into the boxes in the correct order.
Some boxes have been completed for you.
- PKNJ
- ( Fill them in type of question )
Give the scientific name of this otter.
( ( Unnamed title ):
1 ) J
2 ) K
3 ) L
4 ) M
5 ) N
6 ) O
7 ) P
8 ) Q
Taxon:
1 ) Family
2 ) Kingdom
3 ) Genus
4 ) Class
5 ) Order
6 ) Phylum
7 ) Domain
8 ) Species
Name of taxon:
1 ) Mustelidae
2 ) Animalia
3 ) Lutra
4 ) Mammalia
5 ) Carnivora
6 ) Chordata
7 ) Eukarya
8 ) lutra )
- Lutra lutra
Scientists investigated the effect of hunting on the genetic diversity of otters.
Otters are animals that were killed in very large numbers for their fur in the past.
The scientists obtained DNA from otters alive today and otters that were alive before hunting started.
For each sample of DNA, they recorded the number of base pairs in alleles of the same gene.
Mutations change the numbers of base pairs over time.
The figure below shows the scientists’ results.
( Figure shows two sets of bar graphs )
( The darker bar graph is labelled “ Otters alive before hunting started “ and the lighter bar graph is labelled “ Otters alive today )
( Y-axis is labelled “ Allele frequency “ and x-axis is labelled “ Allele size / number of base pairs “ )
( Optimum allele frequencies are in the middle of the graph )
( A lot of “ Otters alive today “ are situated in the middle of the graph )
( “ Otters alive before hunting started “ are optimum around the middle but are a lot less than “ Otters alive today “ )
( “ Otters alive before hunting started “ are more spread out around “ allele size “ ( x-axis ) )
The scientists obtained DNA from otters that were alive before hunting started.
Suggest one source of this DNA.
- Bone
What can you conclude about the effect of hunting on genetic diversity in otters?
Use data from the figure above to support your answer.
( Figure shows two sets of bar graphs )
( The darker bar graph is labelled “ Otters alive before hunting started “ and the lighter bar graph is labelled “ Otters alive today )
( Y-axis is labelled “ Allele frequency “ and x-axis is labelled “ Allele size / number of base pairs “ )
( Optimum allele frequencies are in the middle of the graph )
( A lot of “ Otters alive today “ are situated in the middle of the graph )
( “ Otters alive before hunting started “ are optimum around the middle but are a lot less than “ Otters alive today “ )
( “ Otters alive before hunting started “ are more spread out around “ allele size “ ( x-axis ) )
- Hunting reduced population size
- So only a few alleles left
- Inbreeding
Some populations of animals that have never been hunted show very low levels of genetic diversity.
Other than hunting, suggest two reasons why populations might show very low levels of genetic diversity.
( Figure shows two sets of bar graphs )
( The darker bar graph is labelled “ Otters alive before hunting started “ and the lighter bar graph is labelled “ Otters alive today )
( Y-axis is labelled “ Allele frequency “ and x-axis is labelled “ Allele size / number of base pairs “ )
( Optimum allele frequencies are in the middle of the graph )
( A lot of “ Otters alive today “ are situated in the middle of the graph )
( “ Otters alive before hunting started “ are optimum around the middle but are a lot less than “ Otters alive today “ )
( “ Otters alive before hunting started “ are more spread out around “ allele size “ ( x-axis ) )
- Population might have been very small
- Inbreeding
Malaria is a disease that is spread by insects called mosquitoes.
In Africa, DDT is a pesticide used to kill mosquitoes, to try to control the spread of malaria.
Mosquitoes have a gene called KDR.
Today, some mosquitoes have an allele of this gene, KDR minus, that gives them resistance to DDT.
The other allele, KDR plus, does not give resistance.
Scientists investigated the frequency of the KDR minus allele in a population of mosquitoes in an African country over a period of 10 years.
The figure below shows the scientists’ results.
( Figure shows a line graph which continues to increase staggardly )
( Y-axis is labelled “ Percentage of KDR minus allele in population “ )
( X-axis is labelled “ year “ )
Use the Hardy-Weinberg equation to calculate the frequency of mosquitoes heterozygous for the KDR gene in this population in 2003.
( At 2003, “ Percentage of KDR minus allele in population “ = 20% )
Show your working.
- Q = 0.2
- ( P + Q = 1.0 )
- ( P = Dominant allele )
- ( Q = recessive allele )
- P = 1.0 - 0.2
- P = 0.8
- ( Probability of heterozygous = 2PQ )
- 2 x ( 0.2 ) x ( 0.8 )
- = 0.32
Suggest an explanation for the results in the figure above.
( Figure shows a line graph which continues to increase staggardly )
( Y-axis is labelled “ Percentage of KDR minus allele in population “ )
( X-axis is labelled “ year “ )
( Malaria is a disease that is spread by insects called mosquitoes.
In Africa, DDT is a pesticide used to kill mosquitoes, to try to control the spread of malaria.
Mosquitoes have a gene called KDR.
Today, some mosquitoes have an allele of this gene, KDR minus, that gives them resistance to DDT.
The other allele, KDR plus, does not give resistance.
Scientists investigated the frequency of the KDR minus allele in a population of mosquitoes in an African country over a period of 10 years. )
- Mutation produced resistance allele
- DDT use provides selection pressure
- Mosquitoes with KDR minus allele are more likely to survive and reproduce
- Leading to increase in KDR minus allele in population
The KDR plus allele codes for the sodium ion channels found in neurones.
When DDT binds to a sodium ion channel, the channel remains open all the time.
Use this information to suggest how DDT kills insects.
- Neurones remain depolarised
- So no impulse transmission
Suggest how the KDR minus allele gives resistance to DDT.
- Mutation changes shape of the receptor protein
- DDT is no longer complementary
