VCE Biology Question Thread

[Sine]

Thank you so much!! 

Another question - I know that in a karyotype, the X and Y chromosomes are obviously not homologous, since they are of different lengths and have different banding patterns. But what if the karyotype was of a female, and there were XX chromosomes? Would they be considered homologous, since they are both X chromosomes? Or are they non-homologous since they may have different banding patterns? (leading on to my next question - in a female karyotype, does the X and the other X have different banding patterns at all? Or do they have the same banding patterns?)

Thank you!!

X and X chromosomes are homologous chromosomes as they have the same size, same gene loci (same or different alleles) and same position of centromere.

[Butterflygirl]

What's gene regulation? Can someone please give me a summary of what I need to know? So far, I only know that there's an operator next to the promoter region which a repressor protein can bind to. If it does bind, mRNA can't be transcribed and therefore, the protein cannot be synthesised. If another molecule binds to the repressor protein, it will release the operator region as it will undergo a conformational change. This will allow RNA polymerase to transcribe the mRNA.

Is this the only way? and what information have I missed above?


Thankyou so much

[anotherworld2b]

Consumption of caffeine increases rate of human urine production.
But I was wondering about why this happens and the processes that are involved?

[solution]

A few questions. thanks

1. What is the difference between crossing over and recombination?
2. Does crossing over occur before metaphase I (during prophase I) or during metaphase I?
3. How much do we need to know about mitochondrial DNA (haven't seen this topic until doing past exams)?

[m.mawas]

Hi Guys, does anyone know when will receive the images from the atarnotes biology book?

[vox nihili]

Consumption of caffeine increases rate of human urine production.
But I was wondering about why this happens and the processes that are involved?

Google it and tell us what you found then we can perhaps suggest any changes, not that you actually need to know

A few questions. thanks

1. What is the difference between crossing over and recombination?
2. Does crossing over occur before metaphase I (during prophase I) or during metaphase I?
3. How much do we need to know about mitochondrial DNA (haven't seen this topic until doing past exams)?

1. There is none
2. During prophase I (you absolutely need to remember this)
3. Not very much. Just that it exists really and contains some mitochondrial genes.

[anotherworld2b]

We have been assigned an assignment to investigate
'what effect does the intake of caffeine (iced tea) have on the rate of human urine production?'
Our hypothesis is that Consumption of caffeine increases rate of human urine production.
I've tried to explain how this happens in my introduction but I am not sure what I should and need to
search up to find the information I need.

Abstract: Individual* - summary of investigation
The hypothesis is that the consumption of caffeine increases rate of human urine production over time. The results were an evident increase in urine production over the course of two hours. This was because due to increase of caffeine in the body the body’s natural response is to increase the amount of water expelled by the body.The hypothesis was supported in this experiment.

Introduction: Individual* - research...
The kidneys are efficient and important organs in the excretory system that filters the blood. Two kidneys receive ¼ total of total output (1.2L blood/min). Blood is filtered within the kidney due to nephrons: a functional unit of kidney where urine is formed, there is more than 1.2 million nephrons. In the nephron 99% of water entering the nephron is reabsorbed through obligatory reabsorption by osmosis in the proximal convoluted tubule and loop of Henle. Facultative reabsorption is active where the remainder is due to hormonal control depends on body’s needs. Antidiuretic hormone controls the permeability Distal convoluted tubule of the plasma of the cells making up parts of the tubules according to the body’s needs.

[vox nihili]

We have been assigned an assignment to investigate
'what effect does the intake of caffeine (iced tea) have on the rate of human urine production?'
Our hypothesis is that Consumption of caffeine increases rate of human urine production.
I've tried to explain how this happens in my introduction but I am not sure what I should and need to
search up to find the information I need.

Abstract: Individual* - summary of investigation
The hypothesis is that the consumption of caffeine increases rate of human urine production over time. The results were an evident increase in urine production over the course of two hours. This was because due to increase of caffeine in the body the body’s natural response is to increase the amount of water expelled by the body.The hypothesis was supported in this experiment.

Introduction: Individual* - research...
The kidneys are efficient and important organs in the excretory system that filters the blood. Two kidneys receive ¼ total of total output (1.2L blood/min). Blood is filtered within the kidney due to nephrons: a functional unit of kidney where urine is formed, there is more than 1.2 million nephrons. In the nephron 99% of water entering the nephron is reabsorbed through obligatory reabsorption by osmosis in the proximal convoluted tubule and loop of Henle. Facultative reabsorption is active where the remainder is due to hormonal control depends on body’s needs. Antidiuretic hormone controls the permeability Distal convoluted tubule of the plasma of the cells making up parts of the tubules according to the body’s needs.

This should give you some answers to your question.

[mtDNA]

Just wanted to know - is every base sequence of a recognition site for a restriction enzyme palindromic?
Thanks

[HighTide]

Just wanted to know - is every base sequence of a recognition site for a restriction enzyme palindromic?
Thanks

Not all are, just the majority. It's simpler to cut when it's palindromic.

[anotherworld2b]

I've looked at many sites but they do not explain the processes that are involved :___;

[vox nihili]

I've looked at many sites but they do not explain the processes that are involved :___;

It's pretty complicated. Basically just go with the fact that caffeine increases the rate of filtration of blood by the kidneys, thereby causing more urine to be produced.
Caffeine is a fairly "general" drug, in that it has a wide range of effects on the normal physiology, so it can be tricky to tease those away from each other sometimes.

[solution]

Need a little clarification on gene translation:

Genes are segments of DNA that code for a particular protein. DNA is composed of two strands, each with complementary base sequences. When mRNA copies one strand, it becomes identical to the other strand (with U replacing T). When tRNA brings an amino acid, the amino acid corresponds to the mRNA codon. Therefore, does this mean the protein that is made corresponds to the strand that was not copied? Similarly, will a different protein be made if the other strand is copied (in that case, how does mRNA know which strand to copy?)? I thought a gene only calls for one particular protein...

Thanks

[anotherworld2b]

Would this be a good explanation of the effect of caffeine on the rate of human urine production?
What else could I explain? It is hard to find the information I need due to them being vague and brief.

The kidneys are efficient and important organs in the excretory system that filters the blood. Two kidneys receive ¼ total of total output (1.2L blood/min). Blood is filtered within the kidney due to nephrons: a functional unit of kidney where urine is formed, there is more than 1.2 million nephrons. In the nephron 99% of water entering the nephron is reabsorbed through obligatory reabsorption by osmosis in the proximal convoluted tubule and loop of Henle. Caffeine present in the ice tea increases the rate of filtration of blood by the kidneys, thereby causing more urine to be produced. Caffeine stimulates the action of the Antidiuretic hormone controlling the permeability Distal convoluted tubule of the plasma of the cells making up parts of the tubules according to the body’s needs. This process is known as selective reabsorption. Caffeine from the ice tea will cause this response from the body increasing the rate of human urine production.

[solution]

A particular protein has 100 amino acids.
a. How many codons would there be in the mRNA strand that codes for this?
I wrote 102, 100 for the 100 amino acids, 1 for the start codon and 1 for the stop codon. But the answer is 100?