HSC Biology Question Thread

[Rachelh7]

Hi can anyone answer this biology question i found in a trial. Describe the historical role that models played in determining the structure of DNA as the 'chemical of life'. (4 MARKS). Not sure where to start....

[pikachu975]

Hi,
I am wondering when to use a line of best fit in biology, all the teachers tell something different.
On a practise exam the questions asks to graph the data from an experiment comparing pH to enzyme reaction rates. Obviously, the graph becomes almost like an upright triangle, so it isn't linear.
So, do you do a line of best fit here, or connect the dots?

For pH vs enzyme activity it should be 1/clotting time vs pH which would be a bell curve, so either join the dots or do a curve of best fit! Make sure you label it 'line of best fit' or 'curve of best fit'. Usually do a line or curve of best fit if you EXPECT a perfect line or curve but some points are a bit off.

[AimeeO]

For pH vs enzyme activity it should be 1/clotting time vs pH which would be a bell curve, so either join the dots or do a curve of best fit! Make sure you label it 'line of best fit' or 'curve of best fit'. Usually do a line or curve of best fit if you EXPECT a perfect line or curve but some points are a bit off.

Thank you, I wasn't sure what to do but I will give it a go!

[bimberfairy]

Hey, I'm struggling with this question on my assignment;
Produce a table for both the disease and the microflora imbalance using the following headings:
- name
- pathogen
- cause
- symptoms
- treatment

What I'm understanding is that a microflora imbalance causes a disease, so then how do I answer this question?

I did something similar to this recently, so I'll try to put in my two cents + contribute to the previous reply to your question!

Microflora's all over your body and covers surfaces that are exposed to the outside. So basically, it prevents and protects your body from disease, but if the conditions of your body changes, the environment that the microflora is in can also change, therefore affecting the effectiveness of your microflora in doing what it's meant to do. As a result, diseases can be generated from it.

A really good example that you can use in your table for your assignment is "Candidiasis" which, in everyday lingo, is thrush, and it results from this microflora imbalance (generated from an environmental change in your body!)

An imbalance of microflora allows the fungus to grow out of control, causing "Candidiasis" (Candida albicans is the fungus that causes this) and the cause of this is usually through the intake of antibiotics which destroy harmful AND beneficial bacteria in the body, allowing more of the candida albicans fungus to grow and multiply, resulting in..... badum tiss! THRUUUSHHHH

I hope this helps!! I tried my best to explain how microflora imbalance relates to a particular disease, and the rest of the table can be filled out through some research online for the particular disease you plan to use (:

[maddiewainwright]

Hi can anyone answer this biology question i found in a trial. Describe the historical role that models played in determining the structure of DNA as the 'chemical of life'. (4 MARKS). Not sure where to start....

Hi Rachelh7,

For a 4m question, probably start off with a definition, so explain what DNA is and what it does:
'Deoxyribose Nucleic Acid is the molecule which carries genetic information within organisms. It is composed of nucleotides, arranged in a specific order to generate a 'code', telling the body which proteins to produce, and therefore influencing phenotype.'
Then, I think what the question wants you to talk about is the Watson and Crick discovery of DNA structure, and how they used models to test their hypothesis:
'Watson and Crick were responsible for proposing the now commonly accepted model of how DNA is structured. By collating findings of Chargaff (complementary nature of nitrogen bases) and Franklin/Wilkins (x-ray crystallography images of DNA strands), they proposed that DNA had a double helix structure, with a sugar-phosphate backbone on the outside, and nucleotide bases facing inwards to bind purine - pyrimidine (A-T, G-C). They came up with this hypothesis without conducting any formal experiments, but by constructing a 3D metal model, they measured the dimensions, and compared them to Franklin's 'photograph 51', to ultimately determine DNA structure.'

This would probably be a good place to begin, however potentially worth conducting a little more research into whether other models were proposed (as the question asks for models, plural), but is was the main one that you're likely to have a question on for the HSC.

[maddiewainwright]

Hi,
I am wondering when to use a line of best fit in biology, all the teachers tell something different.
On a practise exam the questions asks to graph the data from an experiment comparing pH to enzyme reaction rates. Obviously, the graph becomes almost like an upright triangle, so it isn't linear.
So, do you do a line of best fit here, or connect the dots?

Hi AimeeO,
For Bio it's best to connect your data points in a smooth curve (always do this for the enzyme rate of reaction questions), unless they explicitly ask for a line of best fit. For comparing pH, your line should look like a bell curve if plotted correctly.

[maddiewainwright]

For anyone doing the option Genetics Code Broken could you explain the outcome: identify the role of genes in embryonic development. I'm finding it really difficult to understand

Hi bethr,
When talking about embryonic development they specifically want you to understand that genes are switched on in a 'cascade'. So firstly, our homeobox genes are switched on to generate differentiation of cells, allowing development of bodily structures. For example, to develop an arm, first the genes which encode development of an arm 'bud' are translated, and then those which extend the arm, and so on so forth.

[mixel]

Hi all, just wondering if there's a quick way to draw tables?

I often hear suggestions to answer compare questions with a table, but I feel like it takes me too long to rule out a table that's neat enough to justify the amount of time it takes. Are there any ways I can cut corners?

[pikachu975]

Hi all, just wondering if there's a quick way to draw tables?

I often hear suggestions to answer compare questions with a table, but I feel like it takes me too long to rule out a table that's neat enough to justify the amount of time it takes. Are there any ways I can cut corners?

Pretty simple for compare just draw a line down the middle and rule a horizontal line for the headings of each column. Once done, just quickly rule lines that enclose the box or just don't even close it.

[olr1999]

Hi! Can I please have some help with this question?:
Some people believe that transgenic organisms may play a large part in food production in the future.
Describe the genetic make-up of ONE transgenic organism you have studied. 1m
It's probably straightforward but I don't understand what it means by 'genetic make-up'
Thank you in advance

[maddiewainwright]

Hi! Can I please have some help with this question?:
Some people believe that transgenic organisms may play a large part in food production in the future.
Describe the genetic make-up of ONE transgenic organism you have studied. 1m
It's probably straightforward but I don't understand what it means by 'genetic make-up'
Thank you in advance

Hi orl1999!
An example of a transgenic organism which would be great for this question would be BT Wheat. This is a genetically modified wheat crop which has a bacterium gene (from the Bacillus thuringiensis) encoding a toxin inserted into its genome. This makes it naturally resistant to pests, so that farmers don't need to use pesticides/insecticides.
Basically when the question asks for 'genetic make-up', it's just asking what genes are added, encoding what specific characteristics.

[olr1999]

Hi orl1999!
An example of a transgenic organism which would be great for this question would be BT Wheat. This is a genetically modified wheat crop which has a bacterium gene (from the Bacillus thuringiensis) encoding a toxin inserted into its genome. This makes it naturally resistant to pests, so that farmers don't need to use pesticides/insecticides.
Basically when the question asks for 'genetic make-up', it's just asking what genes are added, encoding what specific characteristics.

That's an amazing help, thank you so much!

[michelleh]

Help!

There was a particular question in my Biology test paper that was marked down. The question was: 'Link the structure and function of a feature of the mammalian eye'.

My answer was this: 'The choroid is a layer of the eye that consists of blood vessels near the outer surface of the layer. The blood vessels transports oxygenated blood around to the choroid layer which maintains the functioning of the eye as the eye requires cellular respiration and thus the need for oxygen to carry out the functioning of the eye'.

The feedback was simply that it did not link the structure to the function... but I'm not convinced since I did state the feature ('choroid') with its function ('blood vessels near the outer surface layer') and the function ('transports oxygenated blood to mantain functioning of eye')?

Would like to know your opinion on this, please!

Thank you!

[mixel]

Help!

There was a particular question in my Biology test paper that was marked down. The question was: 'Link the structure and function of a feature of the mammalian eye'.

My answer was this: 'The choroid is a layer of the eye that consists of blood vessels near the outer surface of the layer. The blood vessels transports oxygenated blood around to the choroid layer which maintains the functioning of the eye as the eye requires cellular respiration and thus the need for oxygen to carry out the functioning of the eye'.

The feedback was simply that it did not link the structure to the function... but I'm not convinced since I did state the feature ('choroid') with its function ('blood vessels near the outer surface layer') and the function ('transports oxygenated blood to mantain functioning of eye')?

Would like to know your opinion on this, please!

Thank you!

Hey, I don't have my textbook on me so I'm not sure, but iirc what you described is the function of the sclera. I think the choroid layer is more specifically a darkly pigmented layer between the retina and the sclera (structure) that's meant to reduce reflections of incoming light to prevent internal scattering and outward reflection of light, which would interfere with detection of light by the retina (function). I'm not sure though, and from your teacher's explanation it sounds like they pinged you for something else.

[pikachu975]

Help!

There was a particular question in my Biology test paper that was marked down. The question was: 'Link the structure and function of a feature of the mammalian eye'.

My answer was this: 'The choroid is a layer of the eye that consists of blood vessels near the outer surface of the layer. The blood vessels transports oxygenated blood around to the choroid layer which maintains the functioning of the eye as the eye requires cellular respiration and thus the need for oxygen to carry out the functioning of the eye'.

The feedback was simply that it did not link the structure to the function... but I'm not convinced since I did state the feature ('choroid') with its function ('blood vessels near the outer surface layer') and the function ('transports oxygenated blood to mantain functioning of eye')?

Would like to know your opinion on this, please!

Thank you!

The structure of the choroid is a thin sheet of densely packed blood vessels. The function is to prevent stray light from hitting the retina to prevent stray images from being seen, which is possible as the blood vessels cause a dark pigment to absorb the stray light.