VCE Biology Question Thread

[Damo23]

How to describe what happens when the impulse generated along a motor neuron reaches a muscle fiver resulting in it's contraction?
This is about neuromuscular junctions. Neurotransmitter diffuses across the synapse between the pre-synaptic neuron and muscle fibre, and binds to muscle cell receptors, which promotes an intracellular response eventually resulting in the contraction of the muscle.

Why inhibitory neurons necessary for functioning of the nervous system? Idk but has this got to do with feeling no pain?
Inhibitory neurons ensure that cells respond to only the most potent stimuli.
 
How inhibitory neurons prevent excitation of the next neuron? Do they like produce inhibitory neurotransmitter that block receptors so like competitive enzymes?
I don't think we need to know this (not explained in NOB in detail...however the textbook has some really nice visuals! Pg. 178)

Are lipids made from condensation polymersairion?

NO! lipids are not polymers because they have no monomer (fatty acids and glycerol are building blocks, not monomers). Lipids are formed via condensation reactions, however they don't polymerise. 

After the synthesis stage in mitosis does dna have 92 molecules of dna or 92 chromosomes?

What do you mean by synthesis stage in mitosis? Do you mean DNA replication in the cell cycle? Because if so, then 46 chromosomes that have two sister chromatids. (# of chromosomes is relative to the # of centromeres in a cell)

What are benefits if signal transduction? I know about amplification is there any others?
It's how a cell responds to any extracellular message. VITAL in homeostasis, among many other important processes.

In signal transduction, the original signalling molecule does not pass along the pathway but rather is changed into a different form? Give an example.
This is a question about hydophilic ligands/signalling molecules. So secondary messengers are used. An example would be the signal transduction of glycagon.

Thanks so much

[anat0my]

Can someone please explain MC question 6 & 7 of unit 4 2003? Thanks!

[katiesaliba]

Can someone please explain MC question 6 & 7 of unit 4 2003? Thanks!

Okay, so for Q.6 both parents are heterozygous, therefore there's a 1/4 chance that their child will be affected. HOWEVER, the question also wants to know what the chance is that their affected child will be a male (1/2 chance that the child is a male). Therefore, 1/4 x 1/2= 1/8 (A)

Q.7: IV-2 is unaffected, therefore there's a 2/3 chance that he's heterozygous as both parents are carriers of the condition and thus produce offspring in the ratio of 3 unaffected: 1 affected.

Hope that helps

[katiesaliba]

For tRNA, would be accurate to say that 'tRNA carries specific amino acids which are complementary to its anticodon to the ribosomes for use in translation.' ??
Thanks

[Reus]

For tRNA, would be accurate to say that 'tRNA carries specific amino acids which are complementary to its anticodon to the ribosomes for use in translation.' ??
Thanks

the tRNA possesses the anticodon which is complementary to the codon of a mRNA strand.

[psyxwar]

If asked to describe the structure of a tRNA molecule, would it suffice to say that on one end there is an anticodon, and on the other end there is a corresponding amino acid? Or does extra information have to be given, and if so can  someone explain what extra information please?

Thanks

I doubt they'd ever ask this. The most you would probably have to know is to be able to identify a tRNA molecule (think this has come up in the past) if they give you a diagram.

[jessica666]

Do we need to know about rhesus incompatibility? 

[RazzMeTazz]

Do we need to know about rhesus incompatibility? 

Yes

[RazzMeTazz]

Would this be sufficient definition for cultural evolution: Change in skills, ideas and customs over time which is transmitted by communication.

I'm kind of having difficult summing up what constitutes 'culture' and I don't really want to say "Change in culture over time" in my definition since definitions technically shouldn't have the word itself in it :p

[Reus]

Do we need to know about rhesus incompatibility? 

Never heard of this? :/ Someone keen to explain please! 

[jessica666]

Never heard of this? :/ Someone keen to explain please! 

Do you have NOB? If so check out page 270

[katiesaliba]

Do we need to know about rhesus incompatibility? 

Somewhat. You need to know that rhesus negative individuals cannot receive rhesus positive blood, however rhesus positive can receive rhesus negative blood.

[katiesaliba]

the tRNA possesses the anticodon which is complementary to the codon of a mRNA strand.

Yes I know, but isn't the amino acid complementary to the tRNA's anticodon? Perhaps I just forget tRNA structure ahah.

So it'll suffice to just say that: tRNA carries specific amino acids to the ribosomes, where its anticodons are complementary to the codons of the mRNA.

I seriously hate how there's like actual exam technique now to master on top of everything else! I wish the whole bio exam was multiple choice <3 ahaha So annoying 

[vox nihili]

Yes I know, but isn't the amino acid complementary to the tRNA's anticodon? Perhaps I just forget tRNA structure ahah.

So it'll suffice to just say that: tRNA carries specific amino acids to the ribosomes, where its anticodons are complementary to the codons of the mRNA.

I seriously hate how there's like actual exam technique now to master on top of everything else! I wish the whole bio exam was multiple choice <3 ahaha So annoying 

It's not exactly complimentary per se, it's just the fact that a tRNA with anticodon XXX will take amino acid X

Do we need to know about rhesus incompatibility? 

No, any questions about blood groups should contain the info you need.

[shivaji]

Is this ok for the definition and benefit of studying the genome

definition: The genome is all the genes (including alleles) present in a cell of an organism.
Benefit of Studying: It allows to pinpoint certain alleles which cause hereditary conditions, and hence allows better treatment of such conditions.

thanks