Psyxwar's Biology 3/4 Question Thread

[Implore01]

discrete is subjective and objective at the same time, if you're classifying in terms of colour, then it has to be one or the other, so it's discrete, however if you're pedantic and want to talk about it in terms of the colour spectrum, then no doubt it is continuous

[psyxwar]

I guess it depends how you classified it. If you're classifying the phenotype of the plants according to whether the petals are "red" or "blue", then it's definitely discrete. If you're actually considering all the different shades of those colours, I'd argue that it's continuous

Thanks.

Why can igneous rock be dated but sedimentary rock cannot?

[slothpomba]

Why can igneous rock be dated but sedimentary rock cannot?

Is this is in the study design now? This might help (http://science.howstuffworks.com/environmental/earth/geology/dinosaur-bone-age1.htm).

Obviously, fossils cant form in igneous (think like ignite, lava/magma/volcano) because the bones would just vaporise. Sedimentary rock is actually composed of bits of eroded igneous rock that has redeposited; try focus on the world sediment here to help you remember as well. For me, it's whats left over, its whats the dregs, sort of like whats left at the bottom of a coffee cup or something. The sedimentary rock could include eroded and redeposited rock from differing time periods making it hard to date. You'll wind up with the age of the original igneous rock rather than the layer of sediment where the fossil was found.

[psyxwar]

Thanks, I'll check it out. Nah, it's something my teacher mentioned briefly in class today

[psyxwar]

What are some adaptations you'd expect to find in multicellular parasites living in humans?

[Yacoubb]

What are some adaptations you'd expect to find in multicellular parasites living in humans?

Structural adaptations like hookers to attach to the inside of the host organism, large surface area to volume ratio to be able to move quickly through the inside of the organism.

Other adaptations like the ability to reproduce quickly.

[vox nihili]

What are some adaptations you'd expect to find in multicellular parasites living in humans?

Also, a variety of mechanisms to avoid the immune system. There are quite a few, some of which are pretty cool.
A stronger tegument that is able to deal with hostile environments, particularly if they're living in the gut.
Structures that help them invade cells (eg. apical complex in the Apicomplexa).

[psyxwar]

Thanks.

Do we actually need to know the distinction between gram positive and negative bacteria? I haven't seen this come up at all

[Yacoubb]

Thanks.

Do we actually need to know the distinction between gram positive and negative bacteria? I haven't seen this come up at all

I don't think you need to know about the difference! I've never seen it!

[vox nihili]

Thanks.

Do we actually need to know the distinction between gram positive and negative bacteria? I haven't seen this come up at all

I think you might. I knew it last year, and I had a habit of only knowing the bare minimum....

It's easy to remember if you understand how it works. Gram negative means two membranes, because there's not enough wall for the gram stain to get. Gram positive means one membrane, because in the absence of another membrane, the wall is much thicker.

[psyxwar]

It's easy to remember if you understand how it works. Gram negative means two membranes, because there's not enough wall for the gram stain to get. Gram positive means one membrane, because in the absence of another membrane, the wall is much thicker.

WOAH. Mindblown.

The electron transport chain generally produces 32 ATP, but in certain cells with
a high energy requirement (e.g. heart muscle cells) 34 ATP can be produced. The reason D is wrong is
that when it is written as 32-34 ATP this implies that 33 ATP can be produced, which is impossible.

This is wrong, right?

[vox nihili]

WOAH. Mindblown.

The electron transport chain generally produces 32 ATP, but in certain cells with
a high energy requirement (e.g. heart muscle cells) 34 ATP can be produced. The reason D is wrong is
that when it is written as 32-34 ATP this implies that 33 ATP can be produced, which is impossible.

This is wrong, right?

It's certainly true that certain cells have better outputs. And it could very well be possible that only 32 or 34 is produced, though I couldn't explain why that's the case. Even after first year biol and first year chem at Uni, I still haven't encountered that...

[psyxwar]

It's certainly true that certain cells have better outputs. And it could very well be possible that only 32 or 34 is produced, though I couldn't explain why that's the case. Even after first year biol and first year chem at Uni, I still haven't encountered that...

I looked through a first year text and the 32-34 ATP output is wrong in itself. The amount isn't concrete and varies due to a lot of factors apparently, and it certainly isn't a 32 or 34 scenario. But even in the context of 3/4 bio I've never seen something like this (where they flat out say it's not a range between 32-34, but just 32 OR 34) before.

[alondouek]

Oddly enough, it's true. Like any other chemical reaction, the ETC has its clear inputs and outputs. Due to the Laws of Conservation (e.g. energy, mass etc), it would be chemically impossible - under current understanding, anyway - for the electron transport chain to produce 33 units of ATP. Due to the ETC's reactants, only 32 or 34 units can be produced, not anything in-between.

[Yacoubb]

I looked through a first year text and the 32-34 ATP output is wrong in itself. The amount isn't concrete and varies due to a lot of factors apparently, and it certainly isn't a 32 or 34 scenario. But even in the context of 3/4 bio I've never seen something like this (where they flat out say it's not a range between 32-34, but just 32 OR 34) before.

In that case wouldn't it just be safe to mention the total energy yield for aerobic cellular respiration is 36 ATP molecules/glucose molecule or 38 ATP molecules/ glucose molecule, and correspondingly, 32 ATP molecules/glucose molecules for ETC or 34 ATP molecules/glucose molecule.

I'd just stick with 32 ATPs for ETC and 36 for aerobic cellular respiration (overall).