practice exam questions thread

[Irving4Prez]

Sometimes. In a monosynaptic reflex arc you'll just have a sensory neuron that synapses with a motor neuron. In a polysynaptic reflex arc there'll be an interneuron between them

Thought so, a few diagrams in past papers depicted an arc with/without an interneuron, thought it was just a misprint. Thanks Scooby

[swagsxcboi]

whats the difference b/w selective agent and pressure?

selective agent applies the selective pressure, eg. the predators apply the selection pressure of predation

[aidana95]

Hi Guys,

Just a quick one,

Q11(MC) of the 2011 Exam 2.

Not too sure how to get the question up here but it says:

"Radioactively labelled nucleotides were incubated with an unlabelled molecule of DNA. Appropriate enzymes were added and the DNA was allowed to replicate for two cycles. Examine the following key:

And it provides Unlabelled DNA, One strand labelled and both strands labelled,

Given that two cycles of DNA replication occurred, the end result would be: ....


It might be really simple but I just cant understand how to get the answer.

Thanks in advance

[SocialRhubarb]

We start off with normal double-stranded DNA. Now what we need is a knowledge of the DNA replication process - PCR.

After denaturing the DNA, we have two single strands. Then nucleotides bind to the single-stranded DNA, to make double stranded DNA again. However, the nucleotides available are all radioactive, so what we'll make is two double-stranded molecules of DNA, but each one will have one strand with normal nucleotides and one strand with radioactive nucleotides.

We repeat this process again, denaturing the DNA to form single-strands of DNA. However, this time we don't just form two strands of normal DNA, we form two strands of normal DNA and two strands formed from radioactive nucleotides. We allow radioactive nucleotides to bind to these again and we have our answer - two strands formed entirely from radioactive nucleotides, and two formed from one strand of normal DNA and one strand of radioactive nucleotides, giving us the answer C.

[Irving4Prez]

What plant hormone is responsible for flowering? Floregen?

[Yacoubb]

What plant hormone is responsible for flowering? Floregen?

Florigen stimulates flowering in plants. But you don't need to know this!

[Irving4Prez]

Florigen stimulates flowering in plants. But you don't need to know this!

Are any other hormones involved? Someone suggested gibberellin

[ellie14]

I feel a bit stupid for not getting this one because it seems like it should be really simple - but then again, only 29% did get it last year.. 

VCAA 2012 exam 1 multi choice Q5

A particular DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases. The number of guanine bases in this DNA double helix would be:
A) 25 (what I thought)
B) 50
C) 75 (correct answer)
D) 100

Why is it 75?

[alondouek]

Recall that "nucleotide pairs" and "nucleotide bases" are not the same thing.

100 pairs = 200 bases

25 adenines = 25 thymines, so we're left with 150 bases that must be either cytosine or guanine.  Recall that # cytosine = # guanine; therefore, 150/2 = 75 guanine bases

[ellie14]

Recall that "nucleotide pairs" and "nucleotide bases" are not the same thing.

100 pairs = 200 bases

25 adenines = 25 thymines, so we're left with 150 bases that must be either cytosine or guanine.  Recall that # cytosine = # guanine; therefore, 150/2 = 75 guanine bases

Ahh thank you! silly me

[FunkyAfrican]

Should i go over the structure of a neuron ?

[Irving4Prez]

Should i go over the structure of a neuron ?

Definitely

[alondouek]

Ahh thank you! silly me

You're welcome! (I made the same mistake last year )

Should i go over the structure of a neuron ?

Sure! Remember the direction of transmission: from dendrites, along the axon, to the axon terminal bud then across the synapse to the next neuron. (Make sure you know aspects of myelination, like Schwann cells - if this isn't still in the course then ignore)