VCE Biology Question Thread

[Chocolatepistachio]

For this question
Meiosis produces gametes which are genetically different to each other and to the parent cell. Two processes are responsible for this and both occur in meiosis 1

Would you just say crossing over and independent assortment and not mention random segregation or could you say crossing over and random segregation.

Why are lipids characteristically hydrophobic aren’t they both hydrophobic and hydrophilic. Amphiphatic

An anabolic reaction requires energy why? Don’t catabolic reactions require energy because breaking bonds requires energy.

Thanks!

[Chocolatepistachio]

hey guys if someone could help with this question that would be great
 would it maybe be d? i'm not sure. idk because it says it depends on what genes were expressed at different times.

[GodNifty]

Hey guys, what are the types of monoclonal antibodies that we need to know? In class, I learnt about conjugated and naked mAbs, but in the textbook, there are 3 types: conjugated, bispecific and humanised. I'm a little confused on which ones we're supposed to know (and the SD doesn't mention which ones either). Any help would be much appreciated!

I don't actually think you need to know the types? At least I didn't last year. You should just know the principles and how it works like it targets cancer cells, marks it, makes it easier to target if its radioisotopic etc.

For this question
Meiosis produces gametes which are genetically different to each other and to the parent cell. Two processes are responsible for this and both occur in meiosis 1

Would you just say crossing over and independent assortment and not mention random segregation or could you say crossing over and random segregation.

Why are lipids characteristically hydrophobic aren’t they both hydrophobic and hydrophilic. Amphiphatic

An anabolic reaction requires energy why? Don’t catabolic reactions require energy because breaking bonds requires energy.

Thanks!

1. Yes, should be crossing over and independent assortment.
2. I would say lipids are amphiphatic. They aren't characteristically hydrophobic as both characteristics are essential.
3. Catabolic reactions are spontaneous which don't require energy. It happens independently (I hope). Anabolic reactions require  energy to create new bonds between the reactants and new atoms.

I haven't done biology in so long... might need to double check with someone else.

[GodNifty]

hey guys if someone could help with this question that would be great
 would it maybe be d? i'm not sure. idk because it says it depends on what genes were expressed at different times.

The answer is D, yes. Every cell has the same genome (one of the cell theory states this) but they produce different proteins due to gene regulation and all that (acetylation and methylation of genes if you're interested in knowing why)

[Chocolatepistachio]

Also can someone help with this question
cant be c or d. Not sure whether its A or B. Maybe b can someone explain

Thanks so much

[Sine]

Also can someone help with this question
cant be c or d. Not sure whether its A or B. Maybe b can someone explain

Thanks so much

my interpretation is 6ml/100ml of oxygen is transported off and 6ml/100ml of Co2 is transported on within a capillary network or a series of a capillary networks within tissues. So A would have to be the answer.

[Chocolatepistachio]

Will all the cells in the embryo have the same form and function and why
- no they each have specialised functions?

Do homologous chromosomes contain the same DNA sequence. Is having the same gene sequence the same as having the same DNA sequence.

[Sine]

Will all the cells in the embryo have the same form and function and why
- no they each have specialised functions?

Do homologous chromosomes contain the same DNA sequence. Is having the same gene sequence the same as having the same DNA sequence.

I think the first question is about how all cells have the same genome but gene expression is different in different groups of cells and that is what dictates cell specialised function.

No, homologous chromosomes have different DNA sequences since one is paternal and one is maternal. Having the same gene sequence is not the same as having the same DNA sequence. Only 1-2% of the genome is actually made of genes so you can have plenty of differences elsewhere which can alter gene expression.

[Chocolatepistachio]

This may be beyond the study design but how does the water move across the root cell into the xylem

[tiredandstressed]

This may be beyond the study design but how does the water move across the root cell into the xylem

I assume you are in Unit 1 Bio?
•   Xylem transports water from roots to the stem and leaves
•   Xylem cells are dead because the perforations at the ends of the cells allowed the removal of all cellular material
•   Transpiration is the evaporation of water from leaves
•   Moisture is carried through plants from the roots to small pores on the underside of leaves, where it changes to vapour and is released into the atmosphere
•   Cohesion: Hydrogen bonding occurs between water molecules
•   Root pressure: Is created by the continuous movement of water from soil into the plants

[Chocolatepistachio]

For this question:
If two chromosomes of a species are the same length and have similar centromere placements and yet are not homologous what is different about them.

- They have different centromere placements?They do not have the same gene sequence?.

Also
Why might different cells of the same organism have cell cycles of different durations.
Could I say
- Different cells have specialised functions in an organism and are therefore needed for different durations.

For the question how does the photolysis of water benefit the biosphere.

Would this be a sufficient answer
Photolysis is necessary for photosynthesis to occur. Water molecules must be broken down so they can react with co2. Photolysis of water releases oxygen as a byproduct.

[Erutepa]

For this question:
If two chromosomes of a species are the same length and have similar centromere placements and yet are not homologous what is different about them.

- They have different centromere placements?They do not have the same gene sequence?.

Homologous chromosomes are chromosomes with the same sequence of genes, thus these chromosomes might not be homologous if they have posses different genes to one another. Note that saying they have different centromere placements is incorrect as this it if specified in the question stem that the chromosomes have similar centromere placements.

Also
Why might different cells of the same organism have cell cycles of different durations.
Could I say
- Different cells have specialised functions in an organism and are therefore needed for different durations.

There a multiple factors that go into cell's lifespans, but a main component is the workload/stress they endure. As you have said, cell's are specialized and carry out different roles - some rolls endure high amounts of stress like those forming the lining of your gastrointestinal tract and those in your skin. These cells experience a fair amount of wear and tear and thus need to be replaced frequently compared to some cells (like some muscle cells) which are exposed to so much stress. As hinted upon though, this isn't the whole story and there are likely other factors at play here - such as the idea that a reason why neurons don't divide much being due to the fact that cell replication may affect the precises wiring of the brain.
Your answer is pretty much correct, although (depending on mark allocation) its probably best to elaborate some more and use some examples if you can.

For the question how does the photolysis of water benefit the biosphere.

Would this be a sufficient answer
Photolysis is necessary for photosynthesis to occur. Water molecules must be broken down so they can react with co2. Photolysis of water releases oxygen as a byproduct.

You have correctly identified that photosynthesis does allow the splitting of water to form oxygen gas, however you have not answered the question by stating how this benefits the biosphere. Why is the production of O2 important?
You might also want to comment on how Photolysis facilitates photosynthesis and thus enables the production of carbohydrates (another very important thing that benefits the biosphere).
While you clearly do have the right idea, its really important to break down the question and actually identify what it wants you to say- in this case it not only wants you to explain what photosynthesis does, but more importantly *how* it benefits other life.

[Chocolatepistachio]

Could I say
The production of o2 is important because it allows organisms to undergo cellular respiration thus benefitting the biosphere.

[Chocolatepistachio]

For the definition of osmosis.

Osmosis is the movement of water molecules across a semi permeable membrane from an area of high concentration to an area of low concentration.

Do you have to say net movement

Does anaerobic respiration occur in the cytoplasm or cytosol and would it be wrong if you said cytoplasm.

Do Only muscle cells undergo lactic acid fermentation ?

[eemmaa]

For an experiment testing the rate of cellular respiration with different concentrations of glucose, where the rate was measured by the volume of bubbles produced, would the dependent variable be the rate of cellular respiration, or the volume of bubbles produced? I'm just a little confused whether it should be the actual biological process or the thing observed.