Classification And Evolution PPQs

Question 1

Use information from figure 3 to suggest why the two females did not attempt to mate (2)

Answer 1

Mp1 - Peaks occur at the same time because they are both female (aka. They don’t hear the three peaks of the male)
Mp2 - So no male song to stimulate

Question 2

Differences in the primary structure of haemoglobin molecules can provide evidence of phylogenetic evolution relationships between species. Explain how (5)

Answer 2

mp1 - mutations cause change in base sequence
mp2 - so change in AA sequence
Mp 3 - mutations build up over time
Mp 4 - more mutations = more distantly related species
Mp 5 - closely related species have a more recent common ancestor. Distantly related species have an early common ancestor

NOTES
‘Differences’ = aka mutations
First 4mps = explaining how mutations cause diff relations
5th mp - like summary idek AQA is disgusting

Question 3

Explain the purpose of transferring the same volume of liquid culture onto each agar plate (1)

Answer 3

So same number of bacteria transferred to allow for comparison.

Question 4

Explain the purpose of boiling the agar. (1)

Answer 4

No contamination

Question 5

Describe how you would obtain a more accurate estimate of the minimum concentration of antibiotic needed to stop the growth of the bacterium? (2)

Answer 5

Mp1 - Use values (of concentration of antibiotic) between 10 and 15
Mp2 - repeat (using) each value

Question 6

Calculate the percentage difference in actual numbers of bacteria in group A compared with group R (2)

XXXX

Answer 6

97-97.8%

Question 7

Scientists said to use the current antibiotic and the new antibiotic.

Use the graph and your knowledge of evolution of antibiotic resistance in bacteria to explain your answer. (3)

Answer 7

Mp1 - The new antibiotic doesn’t kill all of the bacteria

Mp2 - (Some bacteria will be resistant to the new antibiotic) these will reproduce to produce more resistant bacteria

Mp3 - Using both antibiotics means one antibiotic will kill the bacteria resistant to the other antibiotic

Question 8

Write the letter M on the diagram to show where meiosis occurs (1)

Answer 8

Meiosis occurs during sexual reproduction when the chromosome number halves (2n —> n)

Eg. Zygote —> zygospore

Question 9

Explain one advantage of a sexual reproduction and one advantage of sexual reproduction. (2)

Answer 9

Mp1- asexual: fewer stages so quicker/only one parent involved so can colonise new environment/produces clone so successful genotype maintained

Mp2- sexual: increases genetic diversity so more chance of survival

Question 10

Suggest one advantage of the hypha being vertical. (1)

Answer 10

Allows spores to spread/disperse further

Question 11

Describe how scientists could calculate the mean volume of spores (3)

XXXX

Answer 11

Measure diameter of a large number of spores

Divide measured valleys by 700 (to find true diameter)

(Add and divide true diameters by number of spores to find mean?)

Use volume of a sphere

Question 12

Binomial naming system

Answer 12

Homo sapiens

Genus species

Question 13

What does the phylogenetic tree show about the relationship between the fungi and insects? (2)

Answer 13

Common ancestor

Diverged a long time ago (DON’T SAY EARLY ON)

Question 14

What can you conclude about the effect of hunting on genetic diversity in otters? (2)

Answer 14

Hunting reduced population size so only a few alleles left

Otters today from one of the surviving populations

Inbreeding

Question 15

Two reasons why populations might show very low levels of genetic diversity other than hunting (2)

Answer 15

Genetic bottleneck

Founder affect

Question 16

Explain the principles which biologists used to classify organisms into groups (3)

Answer 16

Large groups divided into smaller groups

Members of groups have features in common based on anatomy

Reflects evolutionary history

Question 17

Suggest how information on amino acid sequences is used to construct a phylogenetic tree (2)

Answer 17

Closely related species have similar amino acid sequences

Greater/more differences in amino acid sequence = longer ago the groups diverged

*LONGER AGO GROUPS DIVERGED
NOT
‘More differences means more distantly related’ - say answer in terms of time.

Question 18

Suggest one advantage and one disadvantage of using cytochrome C to construct a phylogenetic tree (2)

Answer 18

Adv - Present in all eukaryotic species of organisms/quantifiable

Dis - Extinct species can’t be considered/ prokaryotic species can’t be included/ only a limited number of amino acid sequences

Question 19

Scientist want to confirm a relationship between three species.

They made samples of hyper DNA using a gene that was found in all three species.

Explain why it is important that they make samples of hybrid you know from the same gene (2)

Answer 19

The base sequence will be similar (related species will have some bases in common)

So complimentary base pairing and formation of hydrogen bonds can occur

Question 20

DNA hybridisation

Explain what caused the DNA to separate a high temperature (2)

Answer 20

Two organisms have closer relationships so more complimentary bases

So more hydrogen bonds which require more heat energy to be separated

Question 21

Explain how these results suggest the animal is the most closely related to humans (2)

*A only has one difference in amino acid sequence compared to cytochrome C in humans

Answer 21

A has the LEAST (smallest) number of differences

So base sequence must be more similar

Question 22

Suggest one reason why be and say might not be more closely related to each other than any of the other animals (1)

B and C have 12 differences in am in o acids compared to cytochrome C

Answer 22

Differences in B and C are compared with number of differences in humans. Not compared with each other.

(Even if B and C had the same number of differences) the differences may be at different positions (hence not as closely related)

Question 23

Suggest why cytochrome C is more useful than haemoglobin for studying how closely related different organisms are. (1)

Answer 23

All organisms respire and have cytochrome C

Cytochrome C structure is more conserved/less varied between organisms

Question 24

Explain why biologists could use calls to investigate relationships between different species of crane. (2)

Answer 24

Calls are species specific (and allow recognition of the same species)

Greater similarity in calls the more closely related the species are

Question 25

Biologist can also use protein structure to investigate the relationship between different species of crane. Explain why. (2)

Answer 25

Similar species have a similar response to a protein

More closely related species produce more antibody-antigen complexes

//

More closely related species have more similar similarities in the primary structure

In the same protein

Question 26

Use the information to explain how a very high diversity of bird species has developed an Amazonian forest. (5)

Answer 26

Geographical isolation / no interbreeding

(Individual has a) mutation

Different selection pressures

Adapted organisms survive and breed (reproduce)

(So) Change in allele frequencies

Question 27

Speciation is far less frequent in the reformed Amazonian forest. It’s just one reason why (1)

Answer 27

No isolation

Same selection pressures

Question 28

Explain which of these levels of classification could not be

a genus

a phylum

XXXX DONT GET

Answer 28

A - genus only has species

C - kingdom only has phylum