VCE Biology Question Thread

[alondouek]

Is it possible for a monosaccharide to have one carbon atom --> CH₂0

CH2O is formaldehyde (an aldehyde), which is definitely not a monosaccharide

[nerdmmb]

CH2O is formaldehyde (an aldehyde), which is definitely not a monosaccharide

Thanks alondouek!
So even if a carbon-hydrogen-oxygen compound is proportional to that of a carbohydrate, it's not always a sugar?

[vox nihili]

Thanks alondouek!
So even if a carbon-hydrogen-oxygen compound is proportional to that of a carbohydrate, it's not always a sugar?

It depends on which definition you look at. Carbohydrates are often actually given the formula C_x(H₂O)_y, where x≥3. Though some chemists disagree with this definition and let x be equal to 2, making a diose the smallest kind of which only one, glycoaldehyde, exists.

[alondouek]

Thanks alondouek!
So even if a carbon-hydrogen-oxygen compound is proportional to that of a carbohydrate, it's not always a sugar?

What T-Rav said^

Keep in mind that the ubiquitous components of most - if not all - biomacromolecules and their monomeric components are carbon, hydrogen and oxygen. Given this, a lot of compounds will have a general formula derivative of C_nH_nO_n, but they can be wildly different in grouping, structure and function!

[nerdmmb]

Thank-you! That makes much more sense now!

[MM1]

Do plants have specific immunity? If yes, can someone please explain the concept? Thanks!

[Yacoubb]

Do plants have specific immunity? If yes, can someone please explain the concept? Thanks!

No. Plants only have physical and chemical barriers to stop pathogenic agents from entering the internal environment of the plant organism. This includes things like the formation of galls to trap and prevent the spread of a pathogen, etc. No specific attacks are made against specific strains of pathogens, and no memory is involved.

[MM1]

No. Plants only have physical and chemical barriers to stop pathogenic agents from entering the internal environment of the plant organism. This includes things like the formation of galls to trap and prevent the spread of a pathogen, etc. No specific attacks are made against specific strains of pathogens, and no memory is involved.

Thanks Yacoubb! So if a pathogen does manage to enter into the internal environment, does the plant have no other choice but to essentially die? Do plants possess anything similar to the mechanisms of a white blood cell?

[Yacoubb]

Thanks Yacoubb! So if a pathogen does manage to enter into the internal environment, does the plant have no other choice but to essentially die? Do plants possess anything similar to the mechanisms of a white blood cell?

There are different means by which the plant can try to protect itself. For instance, the formation of a gall. This gall is just a mass of tissue that forms around the site where the pathogen enters, which traps the pathogen, and prevents it from spreading to other parts of the plant.

However, its more than likely the plant will die if it is infected by a pathogen, because of its limited immunity to pathogenic agents.

[nerdmmb]

I just wanted to clarify, glucose is found in the form of glycogen in animals and as starch in plants.
I know that excess glycogen is stored as fat in animals but is it possible for a plant to have 'excess' starch? If so, in what form does it exist?
Thanks!

[Yacoubb]

I just wanted to clarify, glucose is found in the form of glycogen in animals and as starch in plants.
I know that excess glycogen is stored as fat in animals but is it possible for a plant to have 'excess' starch? If so, in what form does it exist?
Thanks!

Starch is found as starch granules within plant cells. The starch molecules are hydrolysed when required, to provide a source of glucose.

[Chang Feng]

I was just reading the nature of biology and Nelson of biology unit 4 genes, genomics, genetic code, cell division and stuff, an have noticed quite a lot of stuff that is only said in nature of biology. So I was just wondering if we needed to know the below stuff: downstream/upstream flanking region, hybridization, dissociation, re-association, chargaff's rule, gene duplication, horizontal gene transfer. Finding it hard to tell what relevant here cause its all over the place. Thanks.

[vox nihili]

I just wanted to clarify, glucose is found in the form of glycogen in animals and as starch in plants.
I know that excess glycogen is stored as fat in animals but is it possible for a plant to have 'excess' starch? If so, in what form does it exist?
Thanks!

I wouldn't say that glucose is stored as glycogen. It's nitpicking, but it's not really. It's more or less the major complex carbohydrate is glycogen.

[nerdmmb]

This question has actually been on my mind for a long time...
Why do we refer to chemical reactions in the body as cellular reactions?

[alondouek]

This question has actually been on my mind for a long time...
Why do we refer to chemical reactions in the body as cellular reactions?

Because the cells are where the vast majority of biochemical processes are carried out