VCE Biology Question Thread

[vox nihili]

So there isn't much of a difference? Just that a chromatid is single duplicate whereas a chromosome can be both single or composed of two sister chromatids?

So a chromosome contains chromatids.

It's kind of like a house. Most houses only have one storey. Some have two storeys. You just can't have a storey by itself, that doesn't make sense.

Likewise with chromosomes. The chromatid is technically the whole chromosome like the first storey technically is the whole house, but it can't stand alone.

[Rachelle]

In human females, only 1 of 4 haploid daughter cells will result after meiosis has proceeded. Does that mean that only 1 daughter cell will result, or on top of that 3 daughter cells that aren't haploid daughter cells?

(oogenesis)

[vox nihili]

In human females, only 1 of 4 haploid daughter cells will result after meiosis has proceeded. Does that mean that only 1 daughter cell will result, or on top of that 3 daughter cells that aren't haploid daughter cells?

(oogenesis)

It's a quirk that you don't need to know. But in meiosis I, only one of the daughter cells goes onto meiosis II. At the end of meiosis II, only one of the daughter cells makes an ovum. The other two are lost as polar bodies.

[Rachelle]

It's a quirk that you don't need to know. But in meiosis I, only one of the daughter cells goes onto meiosis II. At the end of meiosis II, only one of the daughter cells makes an ovum. The other two are lost as polar bodies.

That makes sense! Thankyou

[grannysmith]

Independent assortment happens during metaphase I & II right? As there is a 50% chance of each chromosome of each homologous pair lining up on either side of the cell equator.

[vox nihili]

Independent assortment happens during metaphase I & II right? As there is a 50% chance of each chromosome of each homologous pair lining up on either side of the cell equator.

Yeah, pretty much, it's kind of the whole process that makes independent assortment occur. So it would "start" in prometaphase and "finish" in anaphase.

[RazzMeTazz]

Can the term 'nuclear division' be used to refer to either mitosis or meiosis?

[Rishi97]

When writing the steps of mitosis and meiosis, would I include interphase and cytokinesis?

[alondouek]

When writing the steps of mitosis and meiosis, would I include interphase and cytokinesis?

Strictly speaking, interphase - no; cytokinesis - yes

The cell cycle can be divided broadly into interphase and mitosis/meiosis (so interphase cannot logically be a part of the actual division). Interphase is, generally speaking, a cell's preparations for mitotic/meiotic division

[vox nihili]

When writing the steps of mitosis and meiosis, would I include interphase and cytokinesis?

Most cell cycles view cytokinesis and interphase as separate processes. Sometimes cytokinesis is incorporated in telophase. Depend on which text book you look at. Interphase is definitely not a part of cell division though.

[Jason12]

what is the chiasma and independent assortment? What stage(s) of Meiosis do these occur in?

[RazzMeTazz]

What is the difference between centrioles and the spindle?

[grannysmith]

what is the chiasma and independent assortment? What stage(s) of Meiosis do these occur in?

The chiasma is the point at which two homologous pairs of chromosome synapse i.e. come into contact. Non sister chromatids of a homologous pair exchange segments of their DNA, resulting in genetic variation. This is called cruising (edit: lol, damn Swype. *crossing) over or recombination. It occurs during prophase I.

Independent assortment is also another means of genetic variation which occurs during metaphase I and II. This is because there is an equal chance of the chromosomes in a homologous pair lining up on either side of the cell equator. So there is equal chance that each chromosome of each homologous pair end up in either of the daughter cells.

[grannysmith]

What is the difference between centrioles and the spindle?

Centrioles are organelles which produce spindle fibres

[dankfrank420]

How does linkage reduce variety?

Can recombination only occur in linked genes?

How does recombination increase variety?