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July 09, 2020, 11:09:37 am

Author Topic: HSC Biology Question Thread  (Read 166258 times)  Share 

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Annasimon

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Re: HSC Biology Question Thread
« Reply #1365 on: June 03, 2020, 02:49:33 pm »
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Why does a small cube have a higher surface area to volume ratio

Einstein_Reborn_97

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Re: HSC Biology Question Thread
« Reply #1366 on: June 03, 2020, 05:09:49 pm »
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Why are white blood cells bigger and fewer in number compared to red blood cells
Hey Annasimon,

Um...well, I think this has to do with their respective functions. Red blood cells facilitate gaseous transport around the body; they carry oxygen from the lungs to all body tissues and carbon dioxide away from the tissues back to the lungs. White blood cells are mainly responsible for defending the body against infection. I'd say red blood cells are more frequently needed over the entire life span of a human than white blood cells. Oxygen, from the red blood cells, is used to produce energy which the body needs.

As for why white blood cells are bigger than red blood cells, I think it has to do with the nature of their roles. Red blood cells have to be really small to squeeze through the capillaries (which are tiny). White blood cells, however, contain several substances that they release at the site of infections and they also perform phagocytosis and have to produce antibodies.

Hope that answers your questions ;)
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Einstein_Reborn_97

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Re: HSC Biology Question Thread
« Reply #1367 on: June 03, 2020, 06:26:35 pm »
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Why does a small cube have a higher surface area to volume ratio
This video should help...


If you need anything to be clarified, ask away ;)
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Annasimon

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Re: HSC Biology Question Thread
« Reply #1368 on: June 03, 2020, 06:54:08 pm »
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Ok . Also why does the Y chromosome not undergo crossing over

And would the definition of homologous chromosomes be chromosomes that have the exact same genes but different versions of the gene-alleles

Thanks!!

Annasimon

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Re: HSC Biology Question Thread
« Reply #1369 on: June 03, 2020, 06:54:46 pm »
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I canít see the video . It says playback error...

Annasimon

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Re: HSC Biology Question Thread
« Reply #1370 on: June 03, 2020, 07:00:52 pm »
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Independent assortment and crossing over both occur in meiosis and not mitosis right?

Also what stage do they occur

Einstein_Reborn_97

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Re: HSC Biology Question Thread
« Reply #1371 on: June 03, 2020, 07:09:22 pm »
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I canít see the video . It says playback error...
Try this: https://youtu.be/uu9eHX6Tu8Q
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Einstein_Reborn_97

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Re: HSC Biology Question Thread
« Reply #1372 on: June 03, 2020, 08:58:35 pm »
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Ok . Also why does the Y chromosome not undergo crossing over

And would the definition of homologous chromosomes be chromosomes that have the exact same genes but different versions of the gene-alleles

Thanks!!
Homologous chromosomes are a pair of chromosomes with the same genes, one originating from the mother and the other from the father in sexual reproduction (And yes, they have different of the same genes).

Crossing over can only occur between homologous chromosomes. The X and Y chromosomes are not homologous and so crossing over doesn't occur. However, the X and Y chromosomes have homologous sequences (sections that contain the same genes), called pseudoautosomal regions, and crossing over is restricted to these regions. I doubt we'll need to know this for the HSC, it's not included in any HSC resource I'm aware of.

Hope that helps ;)
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Annasimon

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Re: HSC Biology Question Thread
« Reply #1373 on: June 03, 2020, 11:14:23 pm »
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Is random segregation the same thing as independent assortment??

How would you draw a diagram to show DNA replication


Coolmate

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Re: HSC Biology Question Thread
« Reply #1374 on: June 04, 2020, 01:07:14 pm »
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Independent assortment and crossing over both occur in meiosis and not mitosis right?

Also what stage do they occur

Hey Annasimon!

Yes, you are correct --> Independent assortment and crossing over only occur in meiosis

🧬Independent Assortment occurs during Metaphase 1
🧬Crossing Over occurs during Prophase 1

I hope this helps!
Coolmate 8)
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Coolmate

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Re: HSC Biology Question Thread
« Reply #1375 on: June 04, 2020, 01:42:23 pm »
+1
Is random segregation the same thing as independent assortment??

How would you draw a diagram to show DNA replication

Random segregation is not the same thing as independent assortment. This is because:

🔹Random Segregation = Occurs during gamete formation and alleles that are responsible for the same trait are separated from each other
🔹Independent Assortment = Alleles for different traits are lined up and are independently separated from each other when gametes form

Here is a YouTube video for further explanation:
https://www.youtube.com/watch?v=9yTgUvLORkA

To draw a diagram to show DNA Replication, I have attached an image that goes through the various steps of DNA Replication succinctly for an exam question response. (accessed from Google Images)

I hope this helps!
Coolmate 8)
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Annasimon

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Re: HSC Biology Question Thread
« Reply #1376 on: June 04, 2020, 02:21:54 pm »
+1
Thank you!

Annasimon

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Re: HSC Biology Question Thread
« Reply #1377 on: June 04, 2020, 02:26:25 pm »
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For this question:
During protein synthesis the nucleic acids DNA and rna act in which of the following orders?
A messenger rna, transfer rna, dna
B DNA , transfer rna, messenger rna

C DNA, messenger RNA, transfer rna

D transfer rna, messenger rna, dna


Would the answer be c??

Thanks!

Annasimon

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Re: HSC Biology Question Thread
« Reply #1378 on: June 04, 2020, 02:32:30 pm »
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Also for this question I think the answer is b am I correct?

All of the following plant transport processes are directly driven by osmosis , except one .which one does not directly involve osmosis?
A guard cells losing turgor pressure
B oxygen diffusion into leaves
C transpiration
D translocation

Coolmate

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Re: HSC Biology Question Thread
« Reply #1379 on: June 04, 2020, 03:43:07 pm »
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For this question:
During protein synthesis the nucleic acids DNA and rna act in which of the following orders?
A messenger rna, transfer rna, dna
B DNA , transfer rna, messenger rna

C DNA, messenger RNA, transfer rna

D transfer rna, messenger rna, dna


Would the answer be c??

Thanks!

Hey!

The answer would be C.
(DNA --> mRNA --> tRNA)

This is because DNA is untwisted by the enzyme, Helicase, then the order of bases of the DNA are transcribed onto messenger RNA (mRNA). This mRNA, travels out of the nucleic pores into the cytoplasm, by which it binds to a ribosome, then transfer RNA (tRNA), carrying a correct respective amino acid begins to create a polypeptide chain.
Thus, the answer is C, the other answers are out of the correct order.

Hope this helps,
Coolmate 8)
« Last Edit: June 04, 2020, 03:44:56 pm by Coolmate »
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