VCE Biology Questions Thread

Can someone please help me with this question? It is from the 2023 Northern Hemisphere exam, so there are no answers available.
DNA evidence from present-day humans shows that Homo neanderthalensis interbred with
H. sapiens while the two species coexisted in Europe. Fossil discoveries show that H. erectus
and H. sapiens coexisted in Indonesia about 143000 years ago.
Explain whether you would expect scientists to find DNA evidence to support the view that
H. erectus and H. sapiens interbred?

thanks

abbey1234321

maybe modern day humans living in indonesia would have higher percentages of homo erectus dna than compared to other modern day human populations living in other countries- this would prove that homo sapiens and homo erectus coexisted and interbred in indonesia 143000 yrs ago.

I'm not sure if my answers correct but that's what I would say, hope it helps!

prettypink1881
Thanks so much I really appreciate it!

Hey guys, could someone please explain to me why this answer wouldn't be allowed:
question: " Over the weekend, Morgan went to the movies with Alex and PAT. They all sat together and shared a drink. The next day Morgan had symptoms of the flu virus and the Doctor told Morgan that Morgan had been infectious when at the movies. Describe a component of the immune systems first line of defence that the virus overcame:"
answer: "The virus had to have overcome the intact skin barrier on Morgan"
On the answers, it doesn't mention anything about skin, only mucous, nose hairs and stomach acid.
Thanks in advance

All good

I need help with this question:

A scientist wishes to make a recombinant plasmid into which they are going to insert gene X.
(I summarised what's Important from the table they showed):
EcoRI (sticky ends)
HindIII (sticky ends)
BamHI (sticky ends)
BalI (blunt ends)
HaelI (blunt ends)
SmaI (blunt ends)
The best option to do this is to
A. use BamHI to cut around the gene and through the plasmid.
B. cut around gene X with SmaI and cut the plasmid with SmaI.
C. cut around gene X with EcoRI and cut the plasmid with BamHI.
D. cut around gene X with HaeIII and cut the plasmid with HindIII.

The answer is A but I don't understand how. Can someone explain?

I need help with another question:
Which one of the following is a correct statement about monoclonal antibodies?
A. They facilitate a specific immune response.
B. They provide protection against a wide variety of pathogens.
C. They can help reduce swelling caused by rheumatoid arthritis.
D. They are produced by the cells of organisms that have strong immune systems.

The answer is C but I don't understand how

I need help with yet another question:

Many laboratories around the world have been sequencing influenza viruses since the 1980s. The results are available in databases so that researchers can compare genetic sequences in a process called genetic characterisation. Which one of the following would a researcher be interested in if their aim is to control the emergence of a new strain of virus that can infect humans?
A. if a current virus has caused infections in the past
B. the extent of genetic similarity between different strains
C. how effective vaccines are against different strains of virus
D. genetic changes in viruses that circulate in animal populations

The answer is D and the explanation is :The aim of studying the viruses is to attempt to control the emergence of new strains. This can only be accomplished by monitoring genetic changes.
It doesn't make sense??

_sophiestudies_ I understand that they do not initiate the specific immune response, but they do help with it right? When the question says facilitate do they mean the antibodies start it or help it>

Taaaa76 Remember that recombination works best with sticky end restriction endonucleases. This is because they create a specific overhang in the gene that can match the overhang created in the plasmid (blunt ends aren't specific enough, and any nucleotides could insert themselves. There's no hydrogen bonding between the complementary nucleotide overhangs to stabilize the formation of the vector/insert structure (i.e. the overhangs of the gene and plasmid can form hydrogen bonds, whereas that doesn't work with blunt ends). Therefore, B and D are incorrect (they're blunt end restriction endonucleases). C isn't correct either because you need to use the same restriction endonuclease for both the gene and plasmid, as they'll make a cut at the same base code (means they'll be complementary and can bind). A is correct because BamHI is a sticky end restriction endonuclease and is used to cut around the gene and through the plasmid (used for both).

Taaaa76 They don't facilitate, they activate or supress. It is kind of confusing, and in a way, it's somewhat correct because they play a role in it, but C is the most correct.

_sophiestudies_
So monoclonal antibodies suppress or activate the specific immune response?

_sophiestudies_ I still don't understand why it needs to be same restriction enzyme.
And I don't understand another thing: why does it need to make two cuts? one through the gene and through the plasmid? Can't it just cut at one point, end up with two ends and then the gene can bind there?

Taaaa76 yes. They specifically supress or activate a specific immune response, depending on the application. They're not the same as regular antibodies. This MCQ answer is correct to a degree, but not specific enough compared to answer C.

Taaaa76 Restriction enzymes all make cuts at different DNA sequences. It ensures the cuts made in the gene and the plasmid match and can bind via complementary base pairing. Also, it doesn't make two cuts. It makes one cut in the plasmid, creating an opening for the gene, and two cuts in the gene (basically at either end of the gene to ensure the hanging indents will be able to bind with those on the plasmid).

_sophiestudies_
_sophiestudies_
Ohhh I understand now. Thanks for explaining!