VCE Biology 2021 Exam Solutions

[darkz]

Hi all,

Here are my 'sample' solutions for the 2021 Biology Exam. However, please note that these are not exemplar responses - i.e. they are not perfect, fully comprehensive solutions, but rather reflect the ideas you should have included in your response. Also, they don't represent the only thing you could have written - some questions sometimes have multiple different accepted solutions, and note that there may be mistakes here and there as well (these are unproofed/corrected). Also, unfortunately it is not possible to distribute the exam.

MULTIPLE CHOICE

Spoiler

1.   B
2.   C
3.   A
4.   D
5.   D
6.   C
7.   B
8.   C
9.   A
10.   D
11.   A D
12.   A
13.   C
14.   B
15.   B
16.   C
17.   C
18.   A
19.   B
20.   B
21.   D
22.   C
23.   A
24.   D
25.   C
26.   D
27.   B
28.   A
29.   D
30.   D
31.   A
32.   A ? C
33.   B
34.   B
35.   D
36.   A
37.   B
38.   C
39.   B or D? A
40.   A D

SHORT ANSWER

Spoiler

1.   
a. Hydrophilic = glucose, glucose enters cells for the generation of energy (ATP) water, for use in metabolic rxns
Hydrophobic = carbon dioxide, carbon dioxide diffuses into a plant cell for photosynthesis
b. Outline the process of endocytosis or exocytosis. e.g. exocytosis is the energy dependent mode of bulk transport out of a cell, involving the fusing of a secretory vesicle with the plasma membrane and the subsequent release of its contents into the extracellular environment.

2.   
a. Note that this question asks us to give an example of a type of protein, so I assume anything such as transport, enzyme etc would be accepted. If you did have a specific example that would be even better. One suggested response could simply be – enzymes are proteins that reduce the activation energy required for reactions, thereby increasing their rate. Enzymes, such as those responsible for anaerobic respiration, may increase in environments requiring high energy use (during replication) or stress to increase the production of energy or ATP. 
b. Pre-mRNA, mRNA, Polypeptide chain, Amino acid
c. Regulatory genes influence the expression of other genes, therefore they will be ADR1 which acts as a transcription factor influencing the transcription of that particular gene, and GCN4 which controls the activity of RNA polymerase, influencing transcription of that gene.
d.Exons, coding regions of DNA.

3.   
a. Glucose is an input of cellular respiration to produce ATP, therefore, by measuring the change in glucose we are essentially measuring the rate of cellular respiration, allowing us to measure metabolic activity.
b. Higher, increased demand for glucose if you decrease oxygen. i.e. you decrease oxygen = decrease ATP output, cell needs to compensate by using more glucose via anaerobic respiration.

4.   
a. Talk about the entire immune response. Phagocytosis, antigen presentation, T helper cell, activation of B cells, clonal selection differentiation into plasma B and memory B cells, which persist in the body. Plasma B cells = antibodies. On subsequent exposure to the pathogen, activation of memory B cells provides a rapid, large response against the pathogen before it can cause disease, allowing long-term protection.
b. Second dose can increase memory B cells present. On subsequent exposure, even greater, more rapid response.
c. Different = active involves generation of an immune response by the body (e.g. production of memory, antibodies), passive = immunity received from an external source (e.g. antibodies injected). Active = long lasting, passive = short lasting. Similarities = both can potentially involve the use of antibodies.

5.   
a. Cell signalling involves the use of a cell signalling molecule that binds to a complementary receptor on a target cell to initiate signal transduction, which involves the conversion of an external stimulus into a response within the cell via the use of secondary messengers that amplify the signal.
b. X = cytokine, macrophage, Y = neurotransmitter = muscle cell, neuron
c. Pheromones, fan their wings to spread it further into the air

6.   
a. Standard speciation question here. Introduce geographical barrier, preventing gene flow (here can be distance between the two populations), populations are subjected to different environmental selection pressures, genetic differences allowed to accumulate. New species are formed when they can no longer interbreed to form viable and fertile offspring.
b. This question tells us that the two populations are basically genetically similar. This can be achieved through the presence of gene flow – the idea that the populations are still migrating with one another and interbreeding with each other, preventing the accumulation of genetic differences. Another way could be through having similar environmental selection pressures/ living in similar environments.

7.   
a. Opposable thumb, forward facing eyes
b. Fast mutation rate, not subjected to recombination
c. Most recent common ancestor between L. catta, E. coronatus, E. flavifrons was around 21mya, most recent common ancestor between E. coronatus, E. flavifrons was around 7.5mya.
d. DNA hybridisation involving denature, mixing and anneal, then reheat and measure the melting temperature. Higher melting = high degree of similarity as more bonding needs to be broken. Lower melting = less degree of similarity. Temperature of hybrid DNA between E. coronatus, E. flavifrons will be higher than that between L. catta, E. coronatus and L catta and E. flavifrons.

8.   
a. Cave paintings showing that passage of knowledge down between generations, showing customs and traditions etc with differences in paintings between generations also illustrating that cultural evolution.
b. Drawings going to be older than the dated deposits (65,000yrs), as the deposits covered the drawings i.e. drawings came first, and then the mineral deposit formed over the top.
c. First appearance of sapiens was 45,000 yrs ago which is too early for the cave paintings, which in the previous question we said arose later than 65,000 years ago.

9.   
a. GM cotton, GM canola both transgenic = contain DNA from external source (bacteria). GM safflower not transgenic – only silencing no external DNA.
b. Dig it up? lol Use a different insecticide?
c. Social = increase health of wider population; biological = is it safe for consumption.

10.   
a. The idea of forming DNA from different sources or something along these lines
b. Knew the amino acid sequence = can reverse engineer and determine a DNA sequence that codes for the amino acid sequence. Differences with the natural gene is that it won’t contain introns (non coding regions), it will only contain exons.
c. Standard outline how to use recombinant plasmids question. Restriction enzymes to produce complementary sticky ends in both plasmid and gene of interest, DNA ligase joins them together, chuck plasmid back into bacteria (e.g. through electroporation or some other method), then grow the bacteria.
d. Ethical response? Wat…? Ensure safety before human use? Share research with others to advance medical care? Such a broad question….

11.   
a. Type of bacteria – E coli, Temperature, time of incubation
b. If the bacteria were cultured on 0 ug/mL of ampicillin on day 0 then there will be less bacteria at the end of day 3 on 6ug/mL of ampicillin? Something along the lines of that or anything that relates IV and DV. IV = antibiotic concentration of day 0, DV = bacterial growth.
c. Analyse the results, you’ve got 3 marks, so just systematically talk about the results. E.g. identify trends, did growth go down? Did growth go up? support your answer. Comparisons between the two groups would’ve been good as well.
d. Results of the experiment don’t support the predicted. Students predicted that in the control group you got no bacterial for 6ug/mL of ampicillin but you still have colonies in the actual experiment. Then for experimental group, you have that initial increase in bacterial growth between day 0 and day 1 which they did not draw. Something else could’ve been the idea that they only predicted the presence of distinct colonies, but in day 1 you had a bacterial lawn for the control group in the experiment.

[darkz]

Brief responses for short answer added. Haven't finished Q10, Q11 but if you have any questions about them lmk.

[specimen]

Wouldn't question 2D be structural genes rather than exons?

[theo111]

Wouldn't question 2D be structural genes rather than exons?

Pretty sure they would be exons because the question told us that section B was an intron.

[SaladPimp]

Would you be able to do 10 and 11 too please?

[neth2005key]

Hiii for 1a) I said water for the hydrophilic and said that it moves through membrane via osmosis lol is ok?
  and for 2c) did we have to mention both ADR1 and GCN4 bc I only mentioned ADR1??
for 5a) did we need to talk about the secondary messenger bc the question only talked about cell signalling overall so io didn't mention it - I mentioned the other stuff however
for 5b) I said X= interferons and Target cell = cells nearby virally infected cells in order to increase their viral defences - is this ok or were they like most likely looking for cytokines?? I mean interferons is like a type of cytokine?? so would it be okay?? coz I'm ranting lol...
 also could u pls pls put up q10 and q11 - im had a few questions with q10 🥲
thx!!

[RaspberryTau]

Q1: Doesn't glucose pass through a carrier protein though... I thought it was after molecules that diffused through.... could be wrong though. I said water (and my example was a guard cell in the stomata), and then CO2 (from an aerobically respirating animal cell).

[specimen]

Yeah it was simple diffusion im pretty sure. I put water for hydrophilic and carbon dioxide for hydrophobic.

[bluebird]

Yeah I said glucose for hydrophilic and changed it to water because the question specified small molecules that diffuse through and an example as diffusing through for photosynthesis?

[darkz]

Hiii for 1a) I said water for the hydrophilic and said that it moves through membrane via osmosis lol is ok?
  and for 2c) did we have to mention both ADR1 and GCN4 bc I only mentioned ADR1??
for 5a) did we need to talk about the secondary messenger bc the question only talked about cell signalling overall so io didn't mention it - I mentioned the other stuff however
for 5b) I said X= interferons and Target cell = cells nearby virally infected cells in order to increase their viral defences - is this ok or were they like most likely looking for cytokines?? I mean interferons is like a type of cytokine?? so would it be okay?? coz I'm ranting lol...
 also could u pls pls put up q10 and q11 - im had a few questions with q10 🥲
thx!!

1a) water would be fine, 2c) question asked to identify regulatory genes so I assume both needed to be identified. 5a) no you probably won't need to talk about secondary messengers. 5b) interferons should be fine.

Yeah I said glucose for hydrophilic and changed it to water because the question specified small molecules that diffuse through and an example as diffusing through for photosynthesis?

Ah yep! Thanks for picking this up - this has been corrected. Water would be a better answer.

Q10, Q11 added.

[neth2005key]

hiii its me again... low-key stressing over here 😅but for 10b) I didn't really know what to put down so I wrote smth along the lines of how the insulin protein structure and amino acid chain are needed to be known as they are important for the correct functioning of the insulin protein and so if the insulin gene in the plasmid produced  insulin protein that had an amino acid chain and a protein shape different from that which would be coded for by an normal human insulin gene, the function would be impaired or it wouldn't function properly. would this be ok cuz I'm not very sure??

also for my 11d) I said that the results of the experiment did support the predicted -( I described how they had the same overall trend) like on Day 0 in both predicted and experiment results, there was more bacteria growing on the plate of the control group  compared to the experimental group and on the final day (Day 3) I said that there was less bacteria growing on the plate of the control group and more bacteria growing on the plate of the experimental group. would this still be okay bc I'm not too sure??

[bluebird]

Thank you so much for creating this darkz! It is extremely helpful 

[SaladPimp]

Thanks so much!

[Ollied]

With the recombinant plasmid q it asked about how the gene would be cloned and the gene would be expressed in the bacteria. U spoke about restriction enzyme and all that which is to do with uptake and formation of the plasmid. I spoke about how it would be left to replicate on the nutrient agar plate after they were exposed to an antibiotic such as ampicillin and those not transformed would die and transformed would survive. Then the scientists would induce these transformed bacteria to express the human insulin gene. I might be wrong but that’s how I interpreted the q.

[Stormbreaker-X]

Thank you so much, I wished I had my answers here. For some reason, I feel like I messed up the first 2 questions of short answers.