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March 29, 2024, 02:06:41 am

Author Topic: VCE Biology Question Thread  (Read 3570626 times)  Share 

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Emily24566:

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Re: VCE Biology Question Thread
« Reply #12525 on: June 02, 2020, 12:57:32 am »
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Haemoglobin transports oxygen in the blood and consists of a chain of 146 amino acids  . How many different types of amino acids are used to contract proteins

Why is the answer for this question 20 and is it just something you need to know or do you need to do calculations

darkz

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Re: VCE Biology Question Thread
« Reply #12526 on: June 02, 2020, 08:50:25 am »
+1
An individual is constipated. They take magnesium salts to help loosen the stool why does this work?
Water moves from the blood to the intestines because the blood is hypotonic.
Can someone please explain why this is the answer. Don’t really understand

I would assume that when taking magnesium salts i.e. increasing the concentration of magnesium ions, they enter (via diffusion/facilitated diffusion/active transport - don't know which one) intestinal cells thereby increasing the concentration of magnesium ions inside the cells. Therefore, the concentration of magnesium ions inside the intestinal cells will be higher (hypertonic) than the concentration of magnesium ions in the blood (hypotonic), causing water to move into the intestinal cells (osmosis).
Edit: see below for right ans! hehe

Haemoglobin transports oxygen in the blood and consists of a chain of 146 amino acids  . How many different types of amino acids are used to contract proteins
Why is the answer for this question 20 and is it just something you need to know or do you need to do calculations

This question is simply asking for how many amino acids exist in the world, which is 20. For U3&4, this is not something I'd expect students to memorise.
« Last Edit: June 02, 2020, 11:13:47 am by darkz »
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vox nihili

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Re: VCE Biology Question Thread
« Reply #12527 on: June 02, 2020, 11:09:26 am »
+3
I would assume that when taking magnesium salts i.e. increasing the concentration of magnesium ions, they enter (via diffusion/facilitated diffusion/active transport - don't know which one) intestinal cells thereby increasing the concentration of magnesium ions inside the cells. Therefore, the concentration of magnesium ions inside the intestinal cells will be higher (hypertonic) than the concentration of magnesium ions in the blood (hypotonic), causing water to move into the intestinal cells (osmosis).

This is close but not entirely correct.

There are three compartments: the inside of the intestines, the intestinal cells that make up the wall of the intestines, blood vessels that sit under this wall.

Magnesium salts make the inside of the intestines hypertonic. They can't really pass the membrane of intestinal cells, to balance out the tonicity water moves into the inside of the intestine from the intestinal cells by osmosis. This then makes the intestinal cells hypertonic to blood, because water has moved out of the intestinal cells into the intestine. Therefore, osmosis happens between the blood and the intestinal cells too.

It's a bit of a tricky question and one that probably assumes an unreasonable understanding of the basic anatomy of the intestines. Suffice to say, from blood to the intestines is a two-step process.

On the original question of why this works: if there's more water in your poo it's looser.
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Anna254.

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Re: VCE Biology Question Thread
« Reply #12528 on: June 02, 2020, 12:17:45 pm »
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Where and why is water produced during the process of photosynthesis?
Is it because of the dehydration synthesis / condensation reaction

Some resources include water as a product in the equation whereas others do not. Is it supposed to be included as a product in the equation

GodNifty

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Re: VCE Biology Question Thread
« Reply #12529 on: June 02, 2020, 12:30:37 pm »
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Where and why is water produced during the process of photosynthesis?
Is it because of the dehydration synthesis / condensation reaction

Some resources include water as a product in the equation whereas others do not. Is it supposed to be included as a product in the equation
Water is taken up by plant's xylem.
You're looking at the non-simplified photosynthesis reaction, where water (on the right hand side) is produced in the calvin cycle.

The reaction is saying that 12H2O molecules are used in the light dependent, then 6H2O are made in the calvin cycle. So overall 6 H2O molecules are used in the light dependent.

Anna254.

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Re: VCE Biology Question Thread
« Reply #12530 on: June 02, 2020, 12:33:52 pm »
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A particular DNA double helix is 100 nucleotide pairs long and contains 25adenine bases.the number of guanine bases in this DNA double helix would be
A.25
B50
C.75
D. 100

Why is the answer for this question C and not A ?

Thanks

Coolmate

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Re: VCE Biology Question Thread
« Reply #12531 on: June 02, 2020, 01:07:48 pm »
+1
A particular DNA double helix is 100 nucleotide pairs long and contains 25adenine bases.the number of guanine bases in this DNA double helix would be
A.25
B50
C.75
D. 100

Why is the answer for this question C and not A ?

Thanks

Hey Anna254.! :)

This question looks like it could trip up a lot of students, as the wording of the question is quite confusing.

The answer is 75 (C).
This is because in the question it says there are 100 Nucleotide Pairs (for a particular DNA strand), but because of base pairings (x2), there are 200 separate nucleotides (A, T, G, C). For Example, if Adenine has 25 bases, Thymine must have 25 bases as well. This leaves us with the two bases, Cytosine and Guanine, which mathematically looks like this: 200 - 50 = 150 bases left (for C and T).

Thus, we can conclude that Cytosine has 75 bases and Guanine has 75 bases.

I hope this makes sense and helps!
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s110820

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Re: VCE Biology Question Thread
« Reply #12532 on: June 02, 2020, 01:19:29 pm »
+2
Hi Anna!

I think I would be able to help you with this question, but of course, if I do make any errors, please don't hesitate to correct me as Biology isn't exactly my strongest subject. Anyway, it is important to note that the question asks you to find the number of guanine bases from a DNA strand of 100 nucleotides long.

In terms of the nucleotide pairings, I use the mnemonic of ATGC, which I remember it by saying "At The Gold Coast" which suggests that each of the beginning letters of each word pairs with each other. For example, "A" or "Adenine" pairs with "T" or "Thymine" and "G" or "Guanine" pairs with "C" or "Cytosine".

The reason why you got the question wrong is that adenine does not pair with guanine, and thus, the number of adenine bases would not be equivalent to the number of guanine bases.

However, to solve this problem, I would recommend using several methods of basic mathematics. For example, you are given two variables -- the number of nucleotide pairs (100) and the number of adenine bases (25). To solve this problem and get the correct answer of 75 guanine bases, you would subtract the number of nucleotide pairs from the number of adenine pairs. See below if you need to provide evidence of how you worked it out for the question:

Guanine bases = number of nucleotide pairs - number of adenine bases
                          = 100 - 25
                          = 75.

Hence, you would get the answer of C (75) rather than the answer of A (25). However, I would personally recommend revising the concept of nucleotide bases/pairings, by using the mnemonic I provided to enhance your understanding of the concept when you do more similar questions whether it may be for practice or in an actual exam setting.

Hopefully, this helps but of course, if you do have any questions, queries or concerns about how I worked out the answer or about biology in general, please don't hesitate to message me or use the forums to your advantage, as the Biology forums are extremely helpful to use in your studies.

Have a great week and kind regards,

Darcy Dillon.
QUT 2021 - Bachelor of Education (Primary).

Emily24.

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Re: VCE Biology Question Thread
« Reply #12533 on: June 02, 2020, 01:23:45 pm »
0
Can someone explain this question and why is the answer for this question b

In pea plants the allele for green pods (G) is dominant over that for yellow pods (g). A plant breeder crosses 2 pea plants and obtains the following my offspring
424 plants with green pods:399 plants with yellow pods

What are the most likely genotypes of the parent plants
A GG x gg
b Gg x gg
C Gg x Gg
D gg x gg

Plants grown in light were supplied with water containing radioactive oxygen atoms. After four hours,an analysis of the chemicals in and around the plants were undertaken. Which of the following would contain the radioactive oxygen atoms after four hours?

A protein
b glucose
C Oxygen gas
D carbon dioxide gas

Why is the answer for this question C??

A plant cell can be distinguished from an animal cell due to the presence of
A cytosol
B a cell wall
C A nucleus
D Chloroplasts

Why is the answer for this question b and not D

Thanks!!

Mod edit(PF): Merged posts :)
« Last Edit: June 05, 2020, 08:05:31 pm by PhoenixxFire »

s110820

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Re: VCE Biology Question Thread
« Reply #12534 on: June 02, 2020, 01:42:48 pm »
0
Hi Emily,

I think I would be able to help you with this question, but of course, if I do make any errors, please don't hesitate to correct me as Biology isn't exactly my strongest subject. Anyway, I think that the best way to help you through this question and hopefully, enable you to solve these questions in the future is to use a Punnett Square. More specifically, a 2x2 Punnett Square since the trait is "monohybrid" meaning that you are only analysing one trait at a time. I have attached an example of a Punnett Square for your question, to the forum post for reference.

When you analyse the inheritance of monohybrid alleles, you will always result in the ratio of a 50% chance of the offspring inheriting the recessive trait or 50% chance of the offspring inheriting the dominant trait. To effectively answer your question, you do not need to think about the ratio of 424 green: 399 yellow, rather you need to use a Punnett Square to deduce the possibilities of the genotypes, not the phenotypes.

Hence, using the image attached as a guide of a monohybrid Punnet Square, it would be deduced that there is a 50/50% chance of the offspring inheriting the recessive or the dominant trait, which would thus, enable you to eliminate the option of "A" as the question mentions that the trait of G is dominant over the trait of Y (which would suggest that the genotypes would be Gg rather than GG which would suggest that the trait is entirely dominant) as well as the options of "C" and "D" as the question asks you to find the genotype of both the dominant and recessive trait, not just one or the other.

However, I would recommend revising the topic of "inheritance" and the methods of determining "inheritance" such as through pedigrees and Punnett Squares to enhance your understanding of the concept when you do more similar questions whether it may be for practice or in an actual exam setting.

Hopefully, this helps but of course, if you do have any questions, queries or concerns about how I worked out the answer or about biology in general, please don't hesitate to message me or use the forums to your advantage, as the Biology forums are extremely helpful to use in your studies.

Have a great week and kind regards,

Darcy Dillon.



« Last Edit: June 02, 2020, 01:49:12 pm by s110820 »
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Emily24.

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Re: VCE Biology Question Thread
« Reply #12535 on: June 02, 2020, 02:41:03 pm »
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What is polyploidy and aneuploidy ?

Also what’s aptosis and necrosis

Thanks!!

Sine

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Re: VCE Biology Question Thread
« Reply #12536 on: June 02, 2020, 02:53:14 pm »
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What is polyploidy and aneuploidy ?

Also what’s aptosis and necrosis

Thanks!!
What aspects are you not sure about?

Generally when people posts questions they include what they have thought about already and what area they need help with rather than just posting the question.

s110820

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Re: VCE Biology Question Thread
« Reply #12537 on: June 02, 2020, 02:53:55 pm »
+1
What is polyploidy and aneuploidy ?

Also what’s aptosis and necrosis

Thanks!!

Hi Emily,

Polyploidy refers to a condition in which the cells of an organism have more than two paired (homologous) sets of chromosomes whereas aneuploidy refers to the presence of an abnormal number of chromosomes in a cell, for example, a human cell having 45 or 47 chromosomes instead of the usual 46.

Apoptosis refers to a form of programmed cell death, or “cellular suicide.” It is different from necrosis, in which cells die due to injury whereas necrosis refers to a form of cell injury which results in the premature death of cells in living tissue, as caused by factors external to the cell or tissue, such as infection, toxins, or trauma which result in the unregulated digestion of cell components.

Hopefully, this helps :)

Have a great week and kind regards,

Darcy Dillon.
QUT 2021 - Bachelor of Education (Primary).

Amelia257

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Re: VCE Biology Question Thread
« Reply #12538 on: June 02, 2020, 03:11:41 pm »
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Hello

Coat colour inheritance in certain cats is sex linked and codominant
Male cats can have yellow or black coat colours . Female cats may be yellow, black or tortoiseshell in colour. What would be the probability of having yellow female offspring if a tortoiseshell  female is crossed with a yellow male?
A 0%
B 25%
C 50%
D 75%

Why is the answer for this question B
Can’t work it out

Thank you

Amelia257

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Re: VCE Biology Question Thread
« Reply #12539 on: June 02, 2020, 03:16:53 pm »
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If a red flowered snap dragon is crossed with a white flowered one, the progeny will all be pink flowered. Which of the following is the most correct prediction of the ratios of offspring when a red snapdragon is crossed with a pink snapdragon ?
A 1 red:1pink
B. 1pink :3 white
C. 1red:2pink:1 white
D. 1 red: 1 pink: 2 white

Not sure how to do this question and why the answer is A. Also what does progeny mean

Thanks in advance