HSC Biology Marathon 2015 (1 Viewer)

[BlueGas]

Describe how genes assist in the maintenance of health 3 MARKS.

Genes are hereditary units that control the production of polypeptides that make up proteins need in the body for growth, repair and normal cell functioning. A malfunction in a particular gene can result in the inability of the cell to function properly, which may lead to a disease. Through the production of proteins (especially enzymes), genes ensure that the correct cell processes occur need to maintain metabolism and homeostasis.

 

[BlueGas]

Coagulation, Sedimentation, Filtration and Disinfection are methods used to treat water to make it suitable for drinking.

Select ONE of the four processes and explain how this process reduces the risk of infection from pathogens. (3 marks)

 

[Flop21]

Coagulation, Sedimentation, Filtration and Disinfection are methods used to treat water to make it suitable for drinking.

Select ONE of the four processes and explain how this process reduces the risk of infection from pathogens. (3 marks)

is this actually a HSC question? I didn't know those 4 processes were in the syllabus.

I suppose you could talk about disinfection > chlorine.

 

[BlueGas]

is this actually a HSC question? I didn't know those 4 processes were in the syllabus.

I suppose you could talk about disinfection > chlorine.

It all depends on what notes/book you use really, that's why they included 4 processes so it can be a generic question and you have the option of choosing whichever process you want.

 

[Chris_S]

Describe the historical role that models play in determining the structure of DNA as the "chemical of life" (4 marks)

 

[Queenroot]

Here: I'll start it off:

The interaction between B cells and T cells, as per MacFarlene Burenett's clonal selection theory, plays an integral part in the immune response to maintain health, because it is these interactions which lead to the destruction of specific antigens (produced by a pathogen) invading the body.

Someone continue. I've never learnt this before. I didn't even see the dotpoints on this before you posted this question and made me check.

I guess you could say that it leads to the destruction of the pathogen itself rather than the antigen. The antigen is really a medium by which the pathogen is identified and destroyed.
You pretty much were on point as to why it was important, but it's probably a good idea to be more specific in terms of which immune response it allows to be executed (aka the anti-body mediated immune response).

Genes are hereditary units that control the production of polypeptides that make up proteins need in the body for growth, repair and normal cell functioning. A malfunction in a particular gene can result in the inability of the cell to function properly, which may lead to a disease. Through the production of proteins (especially enzymes), genes ensure that the correct cell processes occur need to maintain metabolism and homeostasis.

Good answer tbh

I like your answers, I've seen a couple of them on this site.

 

[Queenroot]

How does the amino acid attached to the tRNA gets accumulated onto another amino acid (attached to another tRNA) during translation? Is it through an enzyme? If so, anyone knows the name of it?

This is like uni biochemistry. But if you understand chem, hopefully this will help. The amino acids have a carboxyl group attached on to them. When both of these are joined together by the ribosome (the ribosome is kind of split into two so one of these "subunits" clamps the amino acids shut) it produces I guess what you could call a condensation reaction (water extracted). Then you get a formation of a peptide bond.

So essentially you know that translation takes place at a ribosome, and the role of the ribosome is kind of like an enzyme joining the amino acids together.

 

[Flop21]

This is like uni biochemistry. But if you understand chem, hopefully this will help. The amino acids have a carboxyl group attached on to them. When both of these are joined together by the ribosome (the ribosome is kind of split into two so one of these "subunits" clamps the amino acids shut) it produces I guess what you could call a condensation reaction (water extracted). Then you get a formation of a peptide bond.

So essentially you know that translation takes place at a ribosome, and the role of the ribosome is kind of like an enzyme joining the amino acids together.

tRNA also have an anticodon which is complementary to a codon on mRNA. The ribosome has 3 binding sites to hold mRNA strands and 2 tRNA molecules together temporarily. The ribosome moves along the mRNA strand one codon at a time. The amino acids are linked by a peptide bond.

When a 'stop' codon is reached the polypeptide chain is released into the cytoplasm.

 

[Queenroot]

tRNA also have an anticodon which is complementary to a codon on mRNA. The ribosome has 3 binding sites to hold mRNA strands and 2 tRNA molecules together temporarily. The ribosome moves along the mRNA strand one codon at a time. The amino acids are linked by a peptide bond.

When a 'stop' codon is reached the polypeptide chain is released into the cytoplasm.

yes that's the process of translation but not directly related to how amino acids are joined together

 

[Flop21]

yes that's the process of translation but not directly related to how amino acids are joined together

I was just adding information that might be helpful to fellow biology students. I know it helped me.

"The two amino acids link by a peptide bond" is really all you need to know about amino acids joining together though for HSC biology.

 

[Flop21]

ANOTHER QUESTION:


"Identify the 3 forms carbon dioxide is carried in mammalian blood"

 

[BlueGas]

ANOTHER QUESTION:


"Identify the 3 forms carbon dioxide is carried in mammalian blood"

Such a simple question yet it can catch people off-guard haha, it's a really good question.

Answer: Carbonic acid, hydogen carbonate ions and carboxyhemogloblin

 

[FlyingKanga]

I am finding Blueprint of Life Topics 3, 4 and 5 extremely difficult to understand. Stuck on these two dotpoints at the moment.


explain the role of gamete formation and sexual reproduction in variability of offspring
describe the inheritance of sex-linked genes, and alleles that exhibit co-dominance and explain why these do not produce simple Mendelian ratios

 

[Queenroot]

I am finding Blueprint of Life Topics 3, 4 and 5 extremely difficult to understand. Stuck on these two dotpoints at the moment.


explain the role of gamete formation and sexual reproduction in variability of offspring
describe the inheritance of sex-linked genes, and alleles that exhibit co-dominance and explain why these do not produce simple Mendelian ratios

Have you done punnet squares relating to sex-linked inheritance yet? It's a good way to visualise how the process works.

 

[Flop21]

I am finding Blueprint of Life Topics 3, 4 and 5 extremely difficult to understand. Stuck on these two dotpoints at the moment.


explain the role of gamete formation and sexual reproduction in variability of offspring
describe the inheritance of sex-linked genes, and alleles that exhibit co-dominance and explain why these do not produce simple Mendelian ratios

explain the role of gamete formation and sexual reproduction in variability of offspring:

Gamete formation = meiosis > how does meiosis create variety in genes?? 2 things, random segregation, and crossing over. 2 things you should know and should be in any good set of notes.

Sexual reproduction creates variety due to fertilisation of gametes being random. I.e. the two gametes are randomly drawn rom the huge group of gamete possibilities from each parent due to the variety created in meiosis.

describe the inheritance of sex-linked genes, and alleles that exhibit co-dominance and explain why these do not produce simple Mendelian ratios:

Here it requires you to know what sex-linked genes are and how they are inherited, same for co-dominant alleles.

Sex-linked genes are carried on the sex chromosomes. Remember males have XY sex chromosomes (1 x chromosome), females have XX sex chromosomes (2 x chromosomes).

Co-dominance is where two alleles are dominant, so both are expressed in the phenotype. Imagine a chicken, parent 1 is black, parent 2 is white, offspring is black and white (e.g. spotted/speckled).

Both these do not produce Mendelian ratios because Mendel did not account for sex-linked genes or co-dominance, and only tested dominance and recessiveness in his pea plants (someone else could word this better probably).



Let me know if out of this you don't understand something specifically, I'll try and explain.

 

[Flop21]

Such a simple question yet it can catch people off-guard haha, it's a really good question.

Answer: Carbonic acid, hydogen carbonate ions and carboxyhemogloblin

Yeah definitely, caught me out in the trials, I only knew 2 not all 3 forms!

 

[BlueGas]

Here's another question: Describe how lipids are transported in the mammalian blood. (2 marks)

 

[DepressedPenguino]

explain the role of gamete formation and sexual reproduction in variability of offspring:

Gamete formation = meiosis > how does meiosis create variety in genes?? 2 things, random segregation, and crossing over. 2 things you should know and should be in any good set of notes.

Sexual reproduction creates variety due to fertilisation of gametes being random. I.e. the two gametes are randomly drawn rom the huge group of gamete possibilities from each parent due to the variety created in meiosis.

describe the inheritance of sex-linked genes, and alleles that exhibit co-dominance and explain why these do not produce simple Mendelian ratios:

Here it requires you to know what sex-linked genes are and how they are inherited, same for co-dominant alleles.

Sex-linked genes are carried on the sex chromosomes. Remember males have XY sex chromosomes (1 x chromosome), females have XX sex chromosomes (2 x chromosomes).

Co-dominance is where two alleles are dominant, so both are expressed in the phenotype. Imagine a chicken, parent 1 is black, parent 2 is white, offspring is black and white (e.g. spotted/speckled).

Both these do not produce Mendelian ratios because Mendel did not account for sex-linked genes or co-dominance, and only tested dominance and recessiveness in his pea plants (someone else could word this better probably).



Let me know if out of this you don't understand something specifically, I'll try and explain.

Also independent assortment.

 

[DepressedPenguino]

Such a simple question yet it can catch people off-guard haha, it's a really good question.

Answer: Carbonic acid, hydogen carbonate ions and carboxyhemogloblin

Actually carbaminohaemoglobin

 

[Mr_Kap]

Here's another question: Describe how lipids are transported in the mammalian blood. (2 marks)

Lipids are transported in the mammaliam blood as chylomicrons (which are clusters of phospholipids, triglycerides, and cholesterol), which are wrapped in a coat of protein, released in the lymph, and end up passing into the veins.