HSC Biology Question Thread

[Annie657]

Hi,
So I just have a quick question for action potentials in communication,
Do the sodium channels open as soon as stimulus is detected to begin depolarisation? Also, is it ok to say -50mv for the threshold p, not -55,v?

[Daniyahasan]

Hi,
So I just have a quick question for action potentials in communication,
Do the sodium channels open as soon as stimulus is detected to begin depolarisation? Also, is it ok to say -50mv for the threshold p, not -55,v?

i think you'll be safer saying -55v

[pikachu975]

Hi,
So I just have a quick question for action potentials in communication,
Do the sodium channels open as soon as stimulus is detected to begin depolarisation? Also, is it ok to say -50mv for the threshold p, not -55,v?

Yep stimulus opens voltage-gated sodium ion channels which causes them to rush in. However, if the stimulus is too weak it doesn't open enough so it doesn't depolarise enough to reach an action potential.

Threshold is anywhere between -50 and -60 mV but best to use -55 mV.

[Annie657]

Yep stimulus opens voltage-gated sodium ion channels which causes them to rush in. However, if the stimulus is too weak it doesn't open enough so it doesn't depolarise enough to reach an action potential.

Threshold is anywhere between -50 and -60 mV but best to use -55 mV.

Thankyou so much! Makes sense now

[Becky234]

Hey, Guys
Does anyone understand what refraction of light has to do with myopia and hyperopia

[pikachu975]

Hey, Guys
Does anyone understand what refraction of light has to do with myopia and hyperopia

Myopia is shortsightedness that can result from an eyeball being too long or the lens/cornea's refractive power isn't correct. Refraction relates because the parallel rays are refracted TOO MUCH so the light converges IN FRONT of the retina, meaning distant objects are blurred.

Hyperopia is longsightedness that can result from an eyeball being too short or the lens/cornea's refractive power isn't correct. Refraction relates because the diverging rays are refracted TOO LITTLE so the light converges AFTER the retina, meaning close objects are blurred.

[Daniyahasan]

Hey, Guys
Does anyone understand what refraction of light has to do with myopia and hyperopia

myopia (short sightedness) – close objects can be seen clearly but distant objects (more than about 5 meters away) appear blurred and out of focus
   A common cause is the eyeball being too long
   This makes the image position to not lie on the retina, but in front of it

Hyperopia (long sightedness) – distant objects can be see clearly, but close objects appear blurred and out of focus
   A common cause is the lens using its flexibility
   So that it is unable to become thick enough to clearly focus images of objects which are close
   Another cause is the eyeball being too short
   This makes the focus position to lie behind the retina

[Potatohater]

Hi, the biology syllabus printed for us by our teacher has extra parts to the syllabus that I can't seem to find any notes on and a lot of people just seem to ignore, so I'm a bit confused by this. What I can't find is

• Outline the role of rhodopsin in rods and cones
• describe rods as containing a form of rhodopsin that is sensitive to blue green light

[Natasha.97]

Hi, the biology syllabus printed for us by our teacher has extra parts to the syllabus that I can't seem to find any notes on and a lot of people just seem to ignore, so I'm a bit confused by this. What I can't find is

• Outline the role of rhodopsin in rods and cones
• describe rods as containing a form of rhodopsin that is sensitive to blue green light

Hi!

- Cones don't contain rhodopsin; they contain iodopsin. They are the type of photoreceptor cells that are sensitive to colour
        - Blue = 455 nm (Short wavelength)
        - Green = 530nm (Medium wavelength)
        - Red = 625 (Long wavelength)
        - Wavelengths either side of these values can stimulate more than one Iodopsin type to create secondary colours (Magenta: Blue/Red, Cyan: Green/Blue, Yellow: Red, Green)
        - The brain can perceive colours and shades depending on the number and combination of iodopsins stimulated

Hope this helps

[Daniyahasan]

Hi, the biology syllabus printed for us by our teacher has extra parts to the syllabus that I can't seem to find any notes on and a lot of people just seem to ignore, so I'm a bit confused by this. What I can't find is

• Outline the role of rhodopsin in rods and cones
• describe rods as containing a form of rhodopsin that is sensitive to blue green light

i just looked at the syllabus and i agree i dont really see those dotpoints (iv linked the syllabus below if you wanna look again)
https://www.boardofstudies.nsw.edu.au/syllabus_hsc/pdf_doc/biology-st6-syl.pdf
BUT maybe your teacher just wants you guys to have extra understanding of the topic or it may be an old syllabus...

[Daniyahasan]

Hi!

- Cones don't contain rhodopsin; they contain iodopsin. They are the type of photoreceptor cells that are sensitive to colour
        - Blue = 455 nm (Short wavelength)
        - Green = 530nm (Medium wavelength)
        - Red = 625 (Long wavelength)
        - Wavelengths either side of these values can stimulate more than one Iodopsin type to create secondary colours (Magenta: Blue/Red, Cyan: Green/Blue, Yellow: Red, Green)
        - The brain can perceive colours and shades depending on the number and combination of iodopsins stimulated

Hope this helps

why is their school giving them a dotpoint to study if it isnt even correct......?

[Potatohater]

why is their school giving them a dotpoint to study if it isnt even correct......?

Maybe it's an old syllabus and hence why that part has been taken out (because it's supposedly incorrect), cause knowing my school it wouldn't have been on purpose, my teacher has been teaching for aggggeees (at this point he looks like Santa Claus) and probably gave us the old one by mistake

[pikachu975]

Maybe it's an old syllabus and hence why that part has been taken out (because it's supposedly incorrect), cause knowing my school it wouldn't have been on purpose, my teacher has been teaching for aggggeees (at this point he looks like Santa Claus) and probably gave us the old one by mistake

The bottom part of your question is good to know. Rhodopsin is more sensitive to blue-green light which are at the lower end of the wavelength spectrum.

[Daniyahasan]

Maybe it's an old syllabus and hence why that part has been taken out (because it's supposedly incorrect), cause knowing my school it wouldn't have been on purpose, my teacher has been teaching for aggggeees (at this point he looks like Santa Claus) and probably gave us the old one by mistake

oh yeah probably! luckily you asked so thats cleared up for you know. My maths teacher is like that to HAHAHAHA, shes been teaching for 40 years damn

[justwannawish]

Could anyone offer a summary of the different types of bio options? Our school usually does communication but our teacher is willing to change it seeing as it's the final year and he really likes the genetics option (which he said was like an extension of the things we did in year 10, like dihybrid). Which topics are more conceptual and which ones are more equation-y?