Biology Unit 3 Questions Megathread

[WhoTookMyUsername]

Thought we should gather all the kerfuffle (by me) and place it into one continuing post !
For discussion of the finer points of a great subject!

I'll start by posting some starter questions to get deep thinking rolling! (copied from my other thread)


(1) Where are non - essential amino acids synthesized ? In the nucleus? Mitchondria? Specialized cells?
(2) Is Freezing an enzyme so it no longer works at that temperature denaturing? or does denaturing refer to permanent, irreversible change?
(3) Does denaturing an enzyme imply it no longer works? or that it works at way less than optimal rate ( e.g. very cold but still works)
(4) Why does Pyruvate need to be further converted to lactic acid (in animals) in anaerobic respiration as lactic acid is harmful to animals but pyruvate not?
(5) When are plants pronounced 'dead?'
(6) Does anyone know exactly where in a cell hydrolysis of atp occurs to release energy?
(7) If substrate concentration is plotted against rate of reaction and there is a straight line 45 degree angle going north east, and at point Z in the middle,
is the rate of product formation increasing?
( If anyone has neap AOS1 part multiple choice 1.21 and 1.23 o.o
(9) Does anaerobic respiration involve the kreb's cycle ? and if not why not?
(10) Does glycolysis (more accurately) occur in the cytosol or cytoplasm of cells?
(11) Does kreb's cycle require oxygen?
(12) Are C3 plants more efficient in cooler climates because they take greater advantage of moisture and Co2?
(13) What is the difference between ectothermic and heterothermic? (also endothermic and homeothermic)
(14) Are neurotransmitter substances enzymes or hormones or both? (are all proteins?)
Cheers

Have *fun*  :uglystupid2:

[Russ]

Stickied. I also trimmed the title for simplicity's sake.

Please remember, new post for a new question and we'll try to help out as best we can

[WhoTookMyUsername]

Does an enzyme have only 1 active site, if yes, what is the point of some enzymes having more than one secondary coiling?

[Russ]

Enzymes may have more than one active site

[WhoTookMyUsername]

Between the CNS and a receptor, are there many interneurons or 1 sensory neuron or many connected sensory neurons transmitting the one signal to the CNS?

[Russ]

Varies. Sensory information can be sent directly, along a single afferent neuron pathway or can also involve an interneuron. Each pathway has a specific purpose, which escapes me right now, but you probably don't need to know it.

[WhoTookMyUsername]

What are the differences ( and functions of)
glycolipids, glycoproteins, carbohydrate, and proteins involved in facilitated diffusion ( and how do you tell the difference)

[pi]

I think in facilitated diffusion, only proteins are used... The proteins form channels and in fact facilitate the foreign material through the cell membrane. The role glycolipids, glycoproteins and carbohydrates play in facilitated diffusion are very minimal (I don't think they play any role in fact).

Glycoproteins, proteins on the cell membrane which have short carbohydrate chains protruding out from them, are sometimes used as receptor molecules. But this is more for hormones than in facilitated diffusion. Glycoproteins also from H-bonds with H2O molecules to maintain cell shape or something (I don't remember the details). Glycolipids, lipids with an attached carbohydrate, have a similar role as receptor molecules.

In terms of 'telling the difference', that probably depends on how they are drawn, but I doubt you would need to identify them separately on an exam or SAC.

[Kaille]

(4) Why does Pyruvate need to be further converted to lactic acid (in animals) in anaerobic respiration as lactic acid is harmful to animals but pyruvate not?

Correct me if im wrong...which is most likely...

Pyruvate needs to be converted to lactic acid because to continue glycolysis there must be a ready supply of NAD+, but without oxygen this cannot happen. So instead the NADH gives off its electrons to the pyruvate so NAD+ is regenerated and ready for glycolysis again. When the pyruvate receives the electrons from the NADH-> NAD+ it is reduced and lactic acid is formed. 

[HERculina]

i have a question:  What gives carbon the ability to form chains that are almost unlimited in length

[Russ]

It's also the size of the atom. Silicon also has 4 valence electrons but is larger/heavier than carbon, so isn't as adept at forming chains/biomolecules. There have been a few theoretical approaches to constructing a silicon based lifeform but they're all predominantly inefficient and difficult to form.

This is really more of a chemistry question though

[HERculina]

It requires 4 bonds so can form polymers continuosly with a carbon backbone. The other 2 bonds usually are attached to other elements

What are the 4 bonds and why does the backbone have to be carbon in all biomolecules (this is probably a stupid q.)
Where did you get this info from? :O

[HERculina]

Uh the 4 bonds is basic chemistry. Carbon needs to form 4 covalent bonds to get a full outer shell, so it has 4 'bonds available'. Second one is actually a good question wouldn't mind the answer to that

Oh yeaaa. i remember that. So it can bond with any element in groups  15,16,17,18?
So basically it can join with A LOT of elements including other carbon elements, hydrogen, oxygen, sulphur ....

[pi]

Oh yeaaa. i remember that. So it can bond with any element in groups  15,16,17,18?
So basically it can join with A LOT of elements including other carbon elements, hydrogen, oxygen, sulphur ....

For bio, it can bond with other carbons, hydroxyl groups (OH-), oxygens and hydrogens...

Carbon-sulphur bonds are ones that I have not come across before...

AND carbon is able to form chains more easily than atoms of silicon (same group and valency), which tends to crystallise (ie no chains) instead.

[WhoTookMyUsername]

Is a Lipid a Macromolecule? ( i have a definition that does not include lipids as macromolecules??)