The Only Prep You Need

# Chapter 13: The Skin as an Organ System

### Chapter 13: The Skin as an Organ System

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### Re: Chapter 13: The Skin as an Organ System

This is regarding Biology Chapter 13 Worked solution for Q5 (BIO-243):

Why are you choosing answer A randomly to incorporate in your calculations if we don't know which one is correct and why are you converting it all to cm per year and then cm per year? All question answers are all in m/s...
horbowiec.7527

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Joined: Mon Mar 08, 2021 11:35 am

### Re: Chapter 13: The Skin as an Organ System

This is regarding Biology Chapter 13 Worked solution for Q6 (BIO-243):

I am a bit confused with the answer here as I though charged molecules like electrolyte ions cant freely diffuse through PM? So only option was active transport?

Regards,
Ania
horbowiec.7527

Posts: 71
Joined: Mon Mar 08, 2021 11:35 am

### Re: Chapter 13: The Skin as an Organ System

horbowiec.7527 wrote:This is regarding Biology Chapter 13 Worked solution for Q5 (BIO-243):

Why are you choosing answer A randomly to incorporate in your calculations if we don't know which one is correct

Only because we can choose any number to try but Answer choice A happens to be first! I would choose a different letter if it seemed something else might make the calculation easier.

horbowiec.7527 wrote:why are you converting it all to cm per year and then cm per year? All question answers are all in m/s...

"Since we can’t relate to the numbers provided, convert to either a month or a year so that you can have some context. "

A student is not expected to know how many m or cm their nails or hair grows in one second. But, you might be able to have a 'educated' guess if the growth was over a more relatable time period. You can choose month or year or anything that you personally can relate to. We chose year.

Later we converted 0.18 m, which some students might not relate to, to 18 cm which might be more clear.
goldstanda3269

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Joined: Wed Aug 25, 2010 10:59 pm

### Re: Chapter 13: The Skin as an Organ System

horbowiec.7527 wrote:This is regarding Biology Chapter 13 Worked solution for Q6 (BIO-243):

I am a bit confused with the answer here as I though charged molecules like electrolyte ions cant freely diffuse through PM?

Largely correct.

horbowiec.7527 wrote:So only option was active transport?

No, because there is no such thing as active transport down a concentration gradient: it must be the opposite. So, the worked solution alluded to the possibility that the answer may be diffusion via facilitated transport (BIO 1.1.1, 1.1.2).
goldstanda3269

Posts: 1719
Joined: Wed Aug 25, 2010 10:59 pm

### Re: Chapter 13: The Skin as an Organ System

So just to confirm electrolyte ions such as Na+ or K+ are transported through active transport with the use of ATP ONLY if its against their concentration gradient like in sodium potassium pump? And if they go with concentration gradient (from higher to lower concentration) then the movement is ALWAYS passive transport via facilitated diffusion?

Regards,
Ania
horbowiec.7527

Posts: 71
Joined: Mon Mar 08, 2021 11:35 am

### Re: Chapter 13: The Skin as an Organ System

horbowiec.7527 wrote:So just to confirm electrolyte ions such as Na+ or K+ are transported through active transport with the use of ATP ONLY if its against their concentration gradient like in sodium potassium pump?

Correct!

horbowiec.7527 wrote:And if they go with concentration gradient (from higher to lower concentration) then the movement is ALWAYS passive transport via facilitated diffusion?

That is largely, but not always, correct. In advanced courses, they may calculate the very small degree to which simple diffusion occurs across the plasma membrane but that is not GAMSAT-assumed knowledge.
goldstanda3269

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Joined: Wed Aug 25, 2010 10:59 pm