VCE Biology Question Thread

[marangutan]

Can anyone explain how many chromosomes are in the two daughter cells after telophase 1?

[PopcornTime]

Please correct me if I’m wrong...
Hominoids are apes (so humans, gorillas, chimpanzees, orangutans, gibbons and Neanderthals)

Hominids are great apes (humans and all of the above... except for gibbons...?)

And homo are Homo sapiens, erectus and Neanderthal, I think?

Not homo but hominins, which compromise extinct and modern human species

Should I know anything else??

Somebody else would need to clarify above.

Also...true or false

Anabolic reactions build up organic molecules
-and an example includes synthesising glucose so photosynthesis???

Yup

Catabolic break down
-breaking down glucose in glycolysis

Endergonic use ATP and are non spontaneous (does that mean it takes a while to occur?)
Photosynthesis.

Not sure if you need to know about spontaneous but yes, endergonic reactions require energy as an input.

Exergonic release ATP and are spontaneous.
Cellular respiration.

Yup, exergonic reactions release energy

Wait... so is cellular respiration exergonic and catabolic
And photosynthesis anabolic and endergonic??

Yes for both. Exergonic and catabolic are the same, except exergonic refers more to release of energy and catabolic refers to breakdown of large molecules to smaller molecules.

[Bri MT]

Can anyone explain how many chromosomes are in the two daughter cells after telophase 1?

In the first "stages" of meiosis you go from having homologous pairs to double-stranded DNA. The second  "stages" take you from doble stranded chromosomes to single stranded chromosomes (seperation of sister chromatids)


After telophase 1 you have n chromosomes in each of the two nuclei, where n is the haploid number of chromosomes (23 for humans)

[marangutan]

In the first "stages" of meiosis you go from having homologous pairs to double-stranded DNA. The second  "stages" take you from doble stranded chromosomes to single stranded chromosomes (seperation of sister chromatids)


After telophase 1 you have n chromosomes in each of the two nuclei, where n is the haploid number of chromosomes (23 for humans)

But meiosis starts with a germ cell that has 46 chromosomes, then during interphase it doubles to 92 chromosomes. After all the steps of meiosis 1, telophase splits into two, so how does both daughter cells not have 46 chromosomes when the original amount was 92?

[PhoenixxFire]

But meiosis starts with a germ cell that has 46 chromosomes, then during interphase it doubles to 92 chromosomes. After all the steps of meiosis 1, telophase splits into two, so how does both daughter cells not have 46 chromosomes when the original amount was 92?

There isn't actually 92 chromosomes, there's still 46 chromosome, they just replicate so that each chromosome has a sister chromatid (the two chromatids are joined together into one chromosome - you'll probably have seen these drawn as X's. So you have two homologous chromosomes, which is a total of 4 chromtids. During meiosis one the chromosomes separate into the haploid daughter cells. Each daughter cell has one copy of each chromosome, but it has 2 chromatids which are still attached. Then during meiosis 2 the sister chromatids separate into each of the daughter cells.

Please correct me if I’m wrong...
Hominoids are greater and lesser apes monkeys, and promisians (so humans, gorillas, chimpanzees, orangutans, gibbons and Neanderthals No need to include neanderthals here, they come under the broader definition of 'human')

Hominids are great apes (humans and all of the above... except for gibbons...?) Yep
And homo are Homo sapiens, erectus and Neanderthal, I think?

Not homo but hominins, which compromise extinct and modern human species

The genus homo are part of what we call hominins, hominins also includes other genus' like paranthropus and australopithicus.

Should I know anything else??

Nah you probably don't need to. You need to know evolutionary trends though (so increased cranium capacity, shorter arms, reduced brow ridges, etc)

[Sine]

But meiosis starts with a germ cell that has 46 chromosomes, then during interphase it doubles to 92 chromosomes. After all the steps of meiosis 1, telophase splits into two, so how does both daughter cells not have 46 chromosomes when the original amount was 92?

The number of chromosomes = the number of centromeres

As PhoenixFire has said, when the chromosomes are replicated each chromosome is now made up of 2 sister chromatids.

[PhoenixxFire]

1. VCAA 2005 exam 2, question 5 b). little confused about this experiment. if there is growth of the fungus in tube 12, then how could the answer be that the fungus cannot produce histidine (the amino acid in tube 12)?

2. what innate immune response does not involve cells/chemicals? coughing,vomiting?

3. VCAA 2017 northern hemisphere exam. I know the mice in group 2 were not treated with bacteria, which is why the growth of pathogenic fungus was large, but why would the levels of APCs and Tc cells be low? Also, in group 1, why would the levels of APCs and levels of Tc cells be high if the bacteria played a role in reducing pathogenic fungus growth.

4. Function of primer: to act as a site for Taq polymerase to bind to and to select the region of DNA to be amplified.

5. Why s-shaped spine is important? acts as a spring to facilitate bipedalism.

6. How does following indicate cultural evolution: presence of art, stone tools, burials? I'm more so struggling with how to word my answer for this.

7. With NADH, what do we say happens after it reaches ETC. Does it offload or donate the hydrogen ions to the cytochromes?

1. Histidine was added to tube 12. That's what they were testing. The fungus did not need to make it's own histine (because it was present in the tube) which meant the the fungus could grow.

2. also intact skin

3. I'm not entirely sure - and I don't think the question requires you to know why, but I think the high levels of of APC's and Tc cells are supposed to be due to the bacteria being present, like maybe the bacteria caused the immune reaction. The question kind of skims over that bit - so I don't think you need to know why, it's just assumed to be caused by the bacteria and thought to help prevent fungus growth.

4. Depending on the context, you should probably include something about taq polymerase extending the strand of DNA from that point

5. Yeah. Probably should include something about it making bipedalism more efficient

6. They're sophisticated actions and indicate that learning occured. Cultural evolution is essentially attributable to learning being possible. The development of rituals like burial is an example of cultural evolution.

7. Doesn't really matter. I've heard 'donate' used more commonly.

[marangutan]

There isn't actually 92 chromosomes, there's still 46 chromosome, they just replicate so that each chromosome has a sister chromatid (the two chromatids are joined together into one chromosome - you'll probably have seen these drawn as X's. So you have two homologous chromosomes, which is a total of 4 chromtids. During meiosis one the chromosomes separate into the haploid daughter cells. Each daughter cell has one copy of each chromosome, but it has 2 chromatids which are still attached. Then during meiosis 2 the sister chromatids separate into each of the daughter cells.

So what's the X structure called? Is it called a chromosome or sister chromatids? From what I'm reading from your post, you said that the X structure is called a chromosome (I probably misconstrued). Please see link attached on what I mean (dunno how to attach a picture) https://teaching.ncl.ac.uk/bms/wiki/index.php/Chromatids

[PhoenixxFire]

So what's the X structure called? Is it called a chromosome or sister chromatids? From what I'm reading from your post, you said that the X structure is called a chromosome (I probably misconstrued). Please see link attached on what I mean (dunno how to attach a picture) https://teaching.ncl.ac.uk/bms/wiki/index.php/Chromatids

They're called sister chromatids, but it's also 1 chromosome (because it only has one centromere) which is why the cell is haploid not diploid.

[marangutan]

They're called sister chromatids, but it's also 1 chromosome (because it only has one centromere) which is why the cell is haploid not diploid.

So pretty much sister chromatids and chromosomes are exactly the same thing? Then what's it called when there's half of a chromosome?

[PhoenixxFire]

So pretty much sister chromatids and chromosomes are exactly the same thing? Then what's it called when there's half of a chromosome?

Most chromosomes are just one copy - so there's no sister chromatids. Chromosome normally refers to just one copy, and sister chromatids refers to when there's two copies. That's what they'll normally be called, but sister chromatids are still just one chromosome, not 2, because they're joined. So it would be correct to call it a chromosome, but generally they're called chromatids. (If it helps, sister chromatids are one sort of chromosome)

[M-D]

Are we required to know specific names of plant signalling molecules such as gibberellins, ethylene, abscisic acid etc. and their functions?

See VCAA 2007 Exam 1 MCQ Question 22 (attached)

[PhoenixxFire]

No. You’re no longer required to know specific molecules. If they give you a question on it they’ll also give you the information you need to answer it.

[marangutan]

Can anyone tell me what the symbol is for carriers on pedigree charts? Is it a dot in the middle or is it half-shaded?
Thank you!!!

[AngelWings]

Can anyone tell me what the symbol is for carriers on pedigree charts? Is it a dot in the middle or is it half-shaded?
Thank you!!!

Both are generally accepted. (Although, I’m speaking in general genetics and not the VCE Biology curriculum. I didn’t do VCE Biology, but I assume they’d say both too.)