HSC Biology Question Thread

[sophiegmaher]

This is from a trial paper I found online

Does my answer make sense, like how would you have answered it/how did the sample answers go about it?

[archie33]

They together determined that Chromosome Theory of Inheritance: that patterns of inheritance in mammals matched those established by Mendel and his pea plants. So, they found that the law of random segregation, the law of independent assortment, and the law of simple dominance applied in mammals by testing sea urchin eggs, in relation to Boveri, and grasshopper testes, in Sutton's case. It is important to note that each of them were observing the process of meiosis in each of these two different organisms, hence the fact that these same laws applied to them enhances the reliability of the theory. This theory also includes that chromosomes are found in the nucleus, where previously it was thought to be found in the cytoplasm AND the nucleus, and that fertilisation allows new pairs of chromosomes to form as those that randomly segregate/independently assort come together.

And to answer the latter part of your question, they found out slightly different things that all contributed to the one theory explained above!
There are heaps of youtube videos on them if you need further clarification.
Hope that makes sense

@sophiegmaher  Thank you so much! Makes sense now.

[vanessalouiseee]

Can anyone explain the functions of DNA helicase and DNA polymerase??

[pvee123]

Hey guys, just a quick question, does the fluid inside the cochlea pass through the Reissner and Basiler membrane into each canal, or does it just provoke other fluids located in different canals to transfer mechanical energy?

[caitlinlddouglas]

hey guys would someone mind describing the lung cancer dot point for epidemiology? Do we have to know the names of specific studies?
Thanks!!

[sidzeman]

Can anyone explain the functions of DNA helicase and DNA polymerase??

DNA Helicase is responsible for the "unzipping" of DNA during RNA replication - this creates the exposed strand where new, complementary nucleotide bases are then added - DNA Polymerase is what catalyses the addition of these new bases. Both are enzymes

[sidzeman]

What exactly do we have to know about the structures of xylem and phloem?

[ellybubble]

hey guys would someone mind describing the lung cancer dot point for epidemiology? Do we have to know the names of specific studies?
Thanks!!

I think just know a brief outline of the epidemiological study by Hill and Doll from the 50's in the UK
so like the case study: by collecting data on the occurrence of the disease to identify the impacts of age, race, geographic specificity
e.g. lung cancer incidence was higher in UK than Japan and try to form a hypothesis for the etiology of the disease (E.g. could be due to increased smoking since WW2 or from increased construction of roads etc)
then they did a case control by determining the frequency of the determinant (smoking) in diseased and non diseased individuals
e.g. they asked 650 lung cancer sufferers and only 2 didn't smoke --> so there is a correlation b/w smoking and lung cancer
but this sample size was too small so they did a cohort study following 40,000 doctors for like 40 years or something where they one group is exposed to the determinant whereas the other isn't (analytical study)

and then Doll found the odds ratio b/w smoking and lung cancer to be like 9.01 and anything above 1 suggests there is a causal relationship

hope this is right lol
not sure if u needa know that much detail

[left right gn]

Can i use down syndrome as an example of an inherited disease?

[ellybubble]

What exactly do we have to know about the structures of xylem and phloem?

Maybe the differences and similarities in structure and purpose and the associated theories of movement of substances?
like xylem is dead tissue and supported by lignin and passively transports water and mineral ions upwards only (unidirectionally) via the cohesion- adhesion- transpiration theory or whatever

and phloem is alive, has sieve plates and companion cells, sugars, bidirectionally, active transport... bleh
and xylem is larger than phloem i think (which is weird considering phloem transports sugar?)

[ellybubble]

Can i use down syndrome as an example of an inherited disease?

yeah i think so, since it is a genetic disease?

[Mathew587]

Can i use down syndrome as an example of an inherited disease?

No down syndrome isn't generally inherited as it's a mutation of the 21 chromosome and cos most peeps with down syndrome don't reproduce.

[angelahchan]

Can anyone explain the functions of DNA helicase and DNA polymerase??

I know there's a genetics elective or something, so bear in mind this is just info from blueprint. DNA helicase is an enzyme that catalyses the unwinding of the double helix. DNA polymerase breaks the bonds between the bases of nucleotides, and it also checks to see whether the new bonds (during DNA replication) match (e.g. A with T, G with C)

Hey guys, just a quick question, does the fluid inside the cochlea pass through the Reissner and Basiler membrane into each canal, or does it just provoke other fluids located in different canals to transfer mechanical energy?

The latter- the fluid (perilymph and endolymph depending on which chambers)  in the different chambers don't actually mix because of the membranes separating them. instead, like you said, they push on each other from pressure from round window, transferring mechanical energy

[ellybubble]

No down syndrome isn't generally inherited as it's a mutation of the 21 chromosome and cos most peeps with down syndrome don't reproduce.

Translocation Down syndrome is sometimes hereditary apparently but i think in most cases it is not inherited (ur right). i think i would use another example like cystic fibrosis?

[itssona]

Hii wondering what type of adaptation sunbaking is? e.g. central netted dragon sunbake during the morning to absorb heat which activates their daily body functions.

also during day their skin becomes lighter? what type of adaptation is this too?