VCE Biology Question Thread

[bts]

1) whats the difference between zygote and embryo? How do I know when to use each term?
For eg. when two gametes unite do they form a zygote or embryo?

2) whats the difference between centrosomes and centrioles?

3) whats the difference between microtubules and spinal fibres?

thanks

[CarterGray12]

What is the function of a nucleus? In a test,I said "to contain the genetic information of a cell" and received half a mark out of one.
Does anyone have a full mark answer?

[cosine]

Is this a good hypothesis for the osmosis sac:

It is hypothesised that when an egg is submerged into differing concentrations of NaCl solutions, the mass of the egg will change accordingly through osmosis.

[MagicGecko]

Is this a good hypothesis for the osmosis sac:

It is hypothesised that when an egg is submerged into differing concentrations of NaCl solutions, the mass of the egg will change accordingly through osmosis.

hmmm it seems a bit vague, I mean your hypothesis would still be valid even if the mass of your egg increases in a hypertonic  solution, which shouldnt happen.
I'd say something along the lines of:

It is hypothesised that the mass of the eggs placed in the hypotonic, isotonic, and hypertonic  solutions will increase, stay the same, and decrease respectively via osmosis.

This way you have something to compare to in your discussion. 

[paper-back]

Thanks nickjparkinson
I was thinking of it this way;
As the enzyme concentration=substrate concentration, all substrates proceed merge to enzymes hence after a period of time reaction rate drop as there are no longer substrate compounds available to bind to enzyme's

[Dkontro]

I have a sac tomorrow on enzymes more specifically how amylase breaks down starch in different conditions. Did anyone have a sac like this and give me an idea of sample questions

[mondray]

Hey Guys,
I have a SAC on Factors affecting Enzyme activity soon and I'm a little stuck on the wording of the Hypothesis.
I was wondering if anyone could give me some samples of what's considered a well structured Hypothesis is possible.
In the experiment we utilized Catalase (Yeast) and Hydrogen Peroxide as Substrate. We tested Enzyme concentration, temperature and pH levels as factors.

Any response will be greatly appreciated, thanks

[paper-back]

Does increasing substrate concentration overcome both types of inhibition?

[Dkontro]

Does increasing substrate concentration overcome both types of inhibition?

Nope. Only overcomes competitive inhibition. Noncompetitive inhibition changes the active site so it doesn't matter how many substrates there are

[Jay.C]

Why is the enzyme "lock and key" model considered to be inaccurate?

[Jay.C]

Also why when catalase reacted with hydrogen Perioxide did we here a pop sound when a flame was inserted into the test tube??

[mondray]

Is Catalase in Yeast an Intracellular Enzyme?

[grannysmith]

Why is the enzyme "lock and key" model considered to be inaccurate?

I think studies have shown that the induced fit model is more accurate (or perhaps the accurate) model. It's rather hard to imagine enzymes being extremely rigid entities like a 'lock and key'.
You don't need to know why though.

Also why when catalase reacted with hydrogen Perioxide did we here a pop sound when a flame was inserted into the test tube??

If you do chem, think of the chemical reaction that would have taken place. hydrogen peroxide is being decomposed into oxygen gas and water, with catalase acting as a catalyst. Now, if a glowing splint is inserted into the test tube the presence of extra oxygen gas would actually ignite the glowing splint. So I don't think a 'pop' sound would occur (this is actually the test for hydrogen gas).

[cosine]

Can someone please explain to me the inhibition process with enzymes. Thanks

[kimmytaaa]

I got my first sac back and the mark that I got was unexpected. The sac was said to contribute 40% of the study sac what does that mean? My second sac is worth 30%.