VCE Biology Question Thread

[StupidProdigy]

Perform a dihybrid cross between the parents: HHGG x hhgg

Sorry I forgot to mention that they're linked genes, but thanks

[StupidProdigy]

Also why is it that the electron transport chain can NOT produce 33 atp? Is it due to one of the molecules missing a partner or something haha?

anddddd in the attachment, the solutions say the answer is x linked dominant. How can that be since ii-1 must be affected then mustn't they?

and another..There was a multi-choice question I did about a nerve cell and it listed it's features. One of the options said that the membrane of the nerve cell prevents the entry of water. Logically I thought this made sense because don't nerve cells pass messages which literally are electrical, hence I thought that having water in the cell would be a bad mix if it comes into contact with an electrical current. What logic am I missing haha? 

[paper-back]

What's the difference between divergent and branching evolution?

[Jay.C]

Could someone please tell me the time frame that each absolute dating technique is valid for.
1. Carbon 14
2. Potassium argon
3. Electron spin resonance

Thanks 

[sunshine98]

Could someone please tell me the time frame that each absolute dating technique is valid for.
1. Carbon 14
2. Potassium argon
3. Electron spin resonance

Thanks 

1. 100-50, 000 years
2. Over 500, 000 years
3. not sure ,soz

[tashhhaaa]

hey guys,

if organisms are phenotypically similar, does that mean they have a recent common ancestor? eg. because of convergent evolution?

[HighTide]

hey guys,

if organisms are phenotypically similar, does that mean they have a recent common ancestor? eg. because of convergent evolution?

Na, if they are phenotypically similar it usually means they have environments which share selection pressures.
i.e. The streamlined body of all fish is because they share the need for such a shape in the water as it allows them to move much more efficiently. Hence, its an adaptation to a selection pressure.
From what I remember, recent common ancestor is usually in reference to divergent evolution. But recent divergence would probably result in some physical characteristics being shared.

[tashhhaaa]

Na, if they are phenotypically similar it usually means they have environments which share selection pressures.
i.e. The streamlined body of all fish is because they share the need for such a shape in the water as it allows them to move much more efficiently. Hence, its an adaptation to a selection pressure.
From what I remember, recent common ancestor is usually in reference to divergent evolution. But recent divergence would probably result in some physical characteristics being shared.

thank you for clearing it up!

[vox nihili]

hey guys,

if organisms are phenotypically similar, does that mean they have a recent common ancestor? eg. because of convergent evolution?

It can mean either. Normally if two organisms are phenotypically similar they will be related via a recent common ancestor; however, in some cases they can converge on the same phenotype via convergent evolution as HighTide explained.

[Biology24123]

The number of chromosomes in a diploid cell of a red kangaroo is 20

The number of molecules of DNA in the nucleus of such a cell is?

Can someone explain why the answer isn't 40, 20 chromosomes and each is made up of 2 chromatids, so 40 DNA molecules???

[Sine]

The number of chromosomes in a diploid cell of a red kangaroo is 20

The number of molecules of DNA in the nucleus of such a cell is?

Can someone explain why the answer isn't 40, 20 chromosomes and each is made up of 2 chromatids, so 40 DNA molecules???

A chromosome is only two pieces of DNA (two chromatids) after the S phase of the cell cycle(DNA replication) and before the before Anaphase of Mitosis
With exception to this time 20 chromosomes means 20 strands of DNA

[StupidProdigy]

Are the two antigen binding sites on an antibody always the exact same (for that antibody)? Thankya

[heids]

Are the two antigen binding sites on an antibody always the exact same (for that antibody)? Thankya

Yes.  (100% sure at VCE level, but I never feel certain making dogmatic statements which will always be wrong once you get into the complex chemistry of things...)  So yes.

[vox nihili]

Yes.  (100% sure at VCE level, but I never feel certain making dogmatic statements which will always be wrong once you get into the complex chemistry of things...)  So yes.

They can be engineered to be different, but in nature they are always the same

[heids]

They can be engineered to be different, but in nature they are always the same

Thanks

> States X.
> Does research.
> Finds that, above VCE level, X is actually quite often wrong and it should be Q.
> Next time, scared to state Y.