VCE Biology Question Thread

[MLGityaJ^A]

Hey vox, for Question 11.c. in your suggested solutions for the Biology Exam this year, you said that Matthew measured the O2, CO2 concentration and temperature for four minutes to record more data and reduce the effect of random errors. However, wouldn't it be because he wanted to find out what point the values being recorded stopped changing? In the last three entries of Matthew's recordings, the values stayed the same. In addition, if Matthew wanted more precise values, wouldn't he simply take recording repeated times rather than just waiting for a period of time? My answer was that Matthew took four minutes to record so that he could obtain more ACCURATE values, rather than precise ones, by waiting long enough for the recordings taken every minute to stop changing, allowing for the true amount of O2, CO2 and level of temperature present in the container to be recorded.

[PhoenixxFire]

well for the first question about potentcy, i my pretty sure that somatic cells are multipotent and induced pluripotent cells are pluripotent, but im unsure of what embryonic and parthenotes are.

and for the second question, "State three ways that meiosis enables variation in the resulting cells, and give a brief explanation of each.", ive got this so far but i dont know the third way it causes variation:
Crossing Over
Chromatids can cross over with others and exchange segments of their genetic information. This creates combinations of genes not found in the parents, creating diversity.
Independent Assortment
Chromosomes assort into gametes independently, meaning there are many different possible kinds of gamtes that can result from meiosis.
Third way
?

thanks

I think the third way mighty be that meiosis created a haploid cell, meaning there is input from 2 parents, whereas mitosis creates a diploid fell, where there is only input from 1 parent

[MLGityaJ^A]

Phoenix, wouldn't that still be independent assortment?

[PhoenixxFire]

No. Independent assortment refers to how we have 2 copies of each chromosome, and which one ends up in each cell is random. Whereas haploid cells mean that there is only one copy of each chromosome in each cell.

[MLGityaJ^A]

Ahhh, having more than one parent means that different sets of chromosomes can be produced, thanks

[peachxmh]

Hi guys, would really appreciate if someone helped me out with this haha It's a pretty simple question but I'm still getting really confused with it.

A cell in G1 of interphase has 24 chromosomes. How many chromatids will be found in a cell during metaphase II of meiosis?

The answer says that there will be 12 chromatids but I keep getting 24 chromatids. Would someone be able to walk me through this question? Thanks so much in advance

[vox nihili]

Hi guys, would really appreciate if someone helped me out with this haha It's a pretty simple question but I'm still getting really confused with it.

A cell in G1 of interphase has 24 chromosomes. How many chromatids will be found in a cell during metaphase II of meiosis?

The answer says that there will be 12 chromatids but I keep getting 24 chromatids. Would someone be able to walk me through this question? Thanks so much in advance

It's 24. You're right.

[peachxmh]

It's 24. You're right.

Thank you so much haha I've been sitting here for a while trying to figure this thing out xD really appreciate it!

[Sunset.T]

Ayo, so i am officially picking up 3/4 bio next year for year 12 and i recently realised that i really only need/want a studay score of 40 in bio.
But as i did 3/4 hhd this year and i was basically competing against one of my friends to get a 50 raw, my mind is now skewed on how well you need to do to achieve a 40 study score in other subjects.
i feel like i need a near perfect score for all my sacs and the exam to achieve 40 in Bio but perhaps i'm wrong? maybe i should be letting a little more leeway with my scores. So if i got 88% on one SAC or even two, could that blow my chances? plus apparently no one from my school that my bio teacherr has taught has ever gotten 40+ in bio. the highest out of her students is 39.

I also have some concerns that i am just realising;
1. What type of SACs does bio use? Are most SACs like a question and answer type thing or are there lots of research investigation type things? I looked at the study design but honestly still dont know what type of SAC to expect. My worst SAC results in my year 11 subjects (only PE & Psychology) were from research tasks. I still managed an A, but my best is normaly A+ and research things drive me insane because i never could figure out if i had enough info to cover everything.

2. The Unit 3 content i think i'm concerned about, Looking at the study design and seeing the fancy terms and stuff looked so alien to me, i don't understand any of it but i'm hoping that maybe that's just because i've never learnt any of that stuff before? A friend of mine who did 1/2 bio this year said that she reckons i'll be fine because of how easily i pick up the biology aspects of PE. Which is true, i pick up those aspects almost immediately, but i'm pretty sure Bio goes into way more cellular depth and all that crazy stuff.

3. Is bio really as straight forward as i've heard people say it is? I have done limited biology stuff in school. I had compulsory biology class for the first semester of year 10 last year but i actually did close to nothing and mucked around and slept in class because i was sick and i hated the teacher. However some how i have managed to remember the structure of DNA including the names of the bases and stuff and some how i actually have a small amount of knowledge about RNA and i know how genetics work pretty well despite not actually really learning about it in school. Not sure how or where i retained that stuff from. But i dont even think its necessary knowledge for 3/4 bio. I also have a lot of knowledge about the immune system and all that stuff, i've barely learnt any real deep details about it but i still know more than the vast majority of people in my year level. And evolution should be super easy tbh. but yeah.
I've heard loads of people say its straight forward and loads of people say its ridiculously hard and its really messing with me and now i'm really getting worried about doing it next year. but i am only doing 4 subjects next year so i'll have extra study sessions to help myself i guess

[Bri MT]

This numbers are for my organising my response, they don't match the numbers you used.

1. Previous performance in your school doesn't define how you will go (no one in my teacher's bio class had gotten an A in the exam since it they stopped doing 1 per unit until me, so trust me when I say it shouldn't dictate you)
2. Be prepared for the fact that your scores are highly likely to drop in year 12 compared to what you are used to
3. VCAA doesn't actually care about what percentages you get on the SACs, SACs  are important for ranking
4. You are wayyy over stressing yourself. You do not need to already be familiar with the terminology of the course, and you can lose several marks in the exam and still get 40+.
5. People are giving conflicting messages because they are different people and experienced the course differently. I wouldn't stress over it.
6. There is some flexibility in SACs, and the study design lists what they can be. You will do a research poster, and you can expect test format

You are really over stressing yourself without good cause, and I wish you luck in calming down

[K888]

+1 to miniturtle

Noone getting a 40+ previously won't restrict you from achieving well - like, realistically, the teacher you have shouldn't dictate your study score, because you shouldn't be expecting your teacher to spoon-feed you the whole year and hold your hand haha. If you have the drive to succeed - you will.

The content in Bio isn't particularly complex or anything - and tbh you should understand some of it already from PE and perhaps even some stuff from HHD. I found it to be a pretty straightforward subject personally, although I recognise that everyone has different experiences. If you're struggling, you can always ask your teacher for help and you can watch videos from places like Khan Academy and Crash Course. Often all it takes is just spending a bit of extra time to go over something you don't understand fully and it'll click. But yeah, like miniturtle said - you shouldn't expect yourself to know or understand all the content or terminology just yet!

For what it's worth, I got a 39 in Bio, and although SAC difficulties and structures are different from school to school, I consistenly got SAC scores in the high 80s/low 90s with maybe a few high 90s from time to time. Think I got an A in the exam. But yeah, like, I didn't spend that much time on Bio, and still got a score that I was pretty happy with. Definitely possible to do 40+ with losing marks across SACs and the exam (ranking is what matters for SACs, anyway).

I reckon it'd probably be helpful if you sat down and had a chat to your Bio teacher at your school about your concerns - because a) they'll be able to keep your concerns in mind during the year and b) they will easily know more about you as a student than we do so can probably give some more personalised advice.

[Sunset.T]

Thanks guys, i'm totally over thinking it, i should just wait until i get into the subject before i worry.

[Hiea]

In endocytosis, where does the coating of the resulting vesicle come from? My understanding of it only covers how the plasma membrane sort of pinches around the molecule, but I don't quite have a grasp on how the vesicle is actually formed (do the bits of the plasma membrane pinching around it just . . .  break off? Wouldn't that make the cell smaller?), or what it's made out of (as in, where does the bilayer come from?).

Sorry if my wording is confusing 

[PhoenixxFire]

So to understand this you need to know that the plasma membrane is made out of a bilayer of phospholipids (and some other things). These phospholipids are polar so they naturally form bilayer spheres (they are not held in place by anything, they just 'float' there).

 When a molecule presses into the bilayer, the section of phospholipids being pushed against moves inwards. eventually the phosphoplipids on either side of the indent break, and rejoin. This leaves a sphere of them inside the cell, containing whatever is entering.

Yes this takes some out of the cell membrane, making it smaller, however it is not much, and more is added when molecules leave through exocytosis.

[vox nihili]

So to understand this you need to know that the plasma membrane is made out of a bilayer of phospholipids (and some other things). These phospholipids are polar so they naturally form bilayer spheres (they are not held in place by anything, they just 'float' there).

 When a molecule presses into the bilayer, the section of phospholipids being pushed against moves inwards. eventually the phosphoplipids on either side of the indent break, and rejoin. This leaves a sphere of them inside the cell, containing whatever is entering.

Yes this takes some out of the cell membrane, making it smaller, however it is not much, and more is added when molecules leave through exocytosis.

Just adding, but directed at OP:

It’s actually a really good point to ask about making the cell smaller, shows you’re really thinking about things

For interest, the cell actually has mechanisms for controlling organelle size. It’s an active process that is closely monitored by the cell.