HSC Biology Marathon 2015 (1 Viewer)

[Mr_Kap]

Describe Morgan's findings involving his experiments with fruit flies.

 

[obliviousninja]

Sex linked genes

 

[obliviousninja]

10/10

 

[Queenroot]

do we have to know about the sodium channel shit? Or just the graph.

Good idea to know what's going on, especially if they ask you to explain the graph.

 

[obliviousninja]

do we have to know about the sodium channel shit? Or just the graph.

ez bro. r0te learn that shit

 

[Mr_Kap]

ez bro. r0te learn that shit

all day erry day

 

[Mr_Kap]

Help with this Multiple Choice question. I don't get how the graph shows Homeostasis. I guessed the answer was homeostasis because the question says a "student" and a student is human, and humans use homeostasis. But what's the real reasoning for this.

 

[Hatem EB]

Its homeostasis because regardless of the external conditions (cold air or hot air), the skin's temperature remains fairly constant (within 3-4 degrees).

Homeostasis is the process by which organisms maintain a relatively stable internal environment.

You could also do it by elimination. Its obviously not A or D, and its not B because enantiostasis is for estuarine conditions.

Next question:
Organisms living in an estuary experience large changes in salt concentrations in their surroundings over a very short time. Discuss the importance of enantiostasis to estuarine organisms in maintaining appropriate salt concentrations.

 

[youix]

Its homeostasis because regardless of the external conditions (cold air or hot air), the skin's temperature remains fairly constant (within 3-4 degrees).

Homeostasis is the process by which organisms maintain a relatively stable internal environment.

You could also do it by elimination. Its obviously not A or D, and its not B because enantiostasis is for estuarine conditions.

Next question:
Organisms living in an estuary experience large changes in salt concentrations in their surroundings over a very short time. Discuss the importance of enantiostasis to estuarine organisms in maintaining appropriate salt concentrations.

Enantiostasis is the maintenance of metabolic and physiological function in the face of a fluctuating external environment. For estuarine organisms, there is a daily fluctuation in salt concentration due to tidal factors. Osmoconformers attain enantiostasis by allowing the bodys osmotic pressure to vary with that of the environment. Osmoconformers are the opposite of osmoregulators, who attempt to maintain their salt concentration regardless of the external environment - difficult task in estuarine environemnts.

Osmoconformers must deal with changing body fluid salt concentration, which can adversely affect body function. E.g if enzyme activity was affected by a changing salt concentration, another body function must be changed in a way that compensates for the change in enzyme activity.

Enantiostasis could have arisen in estuarine organisms through natural selection. It is possible to hypothesize that an ancestral population of estuarine organisms were restricted to the fringes of the estuarine habitat that did not exhibit large fluctuations in salt concentration. It is possible that some members of the population were not effective osmoregulators and allowed their body's osmotic pressure to vary with that of the environment. Eventually, they reproduced more often than their counterparts leading to a population of osmoconformers.

I think that's right.

 

[Mr_Kap]

Next question:
Organisms living in an estuary experience large changes in salt concentrations in their surroundings over a very short time. Discuss the importance of enantiostasis to estuarine organisms in maintaining appropriate salt concentrations.

Enantiosasis in the maintenece of physiological and metabolic functioning in response to changes in the external environment. Wwhen salt concentration is changed in the body fluid, this results in the reduced efficiency of an enzyme. To compensate for this change, pH is increased to boost the efficiecy of the enzyme. An estuary is formed when a river meets the sea. In this environment, fresh water draining from the land mixes with saline water from the sea. This results in the change of salinity -> during the daily cycle of tides brining salt water in and out.
Estuarine organisms must be able to respond to the daily changes in salinty - or they die.
Specific ways to deal with the daily change in salinity include varying the body's osmotic pressure with that of the environment (osmoconformers). then talk abt Osmoregultors ...

 

[Mr_Kap]

Explain the importance of using controls in microbial experiments. 3 MARKS

 

[Khan.Paki]

Controls allow for the comparison of results, in such that they can be validated. It ensures the results are a product of the experimental conditions rather than any random condition that could have occurred.

 

[Khan.Paki]

Now for a question which I hate the most:

A new non-infectious disease has been discovered in people in some aged care homes.
Outline at least FOUR features of an epidemiological study that could be used to identify the cause of this disease. [4 marks]

 

[Flop21]

Help with this Multiple Choice question. I don't get how the graph shows Homeostasis. I guessed the answer was homeostasis because the question says a "student" and a student is human, and humans use homeostasis. But what's the real reasoning for this.

It's homeostatis because look at the other answers, they're ridiculous lol. Not diffusion, not inflammation, I suppose maybe enantiostatis - but like you said this is a human and they use homeostasis.

I don't think this is a good question, it's dumb and doesn't really show homeostasis. They are measuring skin temperature, which is not actually measuring INTERNAL body temperature (which is what homeostasis maintains).

 

[Mr_Kap]

Now for a question which I hate the most:

A new non-infectious disease has been discovered in people in some aged care homes.
Outline at least FOUR features of an epidemiological study that could be used to identify the cause of this disease. [4 marks]

Large Sample Size
Large period of time the epidemiological study is conducted over.
Data analysis showing link between the cause and the disease: Comparing people with and without the disease, and looking for common data on people with the disease.
Data collection over a variety of possible factors: Diet, Ethnicity, Hygeine, Smoking Status.

 

[Mr_Kap]

Aldosterone is a hormone which results in the control of body fluids in the kidney by acting on the distal tubes and collecting ducts of the nephron to increase the reabsorption of salt ions and hence water (by osmotic balance) back into the body. In blood containing high salt concentration, there are low levels of aldosterone as it is not needed. However, in blood of low salt concentration Aldosterone levels increase.

is this correct on "Outline the effect of aldosterone on the control of body fluids"

 

[BlueGas]

is this correct on "Outline the effect of aldosterone on the control of body fluids"

Your answer would sound more better if you wrote "In blood containing high salt concentrations, levels of aldosterone are decreased" rather than "it is not needed". But overall the answer is pretty good.

 

[Mr_Kap]

how do 3d glasses work. I've seen a question asking this in Communication HSC.

 

[moonshoes]

how do 3d glasses work. I've seen a question asking this in Communication HSC.

If I remember from what my teacher said:

It's just an example of how our brain creates depth perception by combining the two images our left and right eyes send to the brain. By manipulating the colour of the image (through the blue and red coloured lenses of the glasses), our brain interprets the different wavelengths of these colour images to perceive depth.

Is this on the right track?

 

[Mr_Kap]

If I remember from what my teacher said:

It's just an example of how our brain creates depth perception by combining the two images our left and right eyes send to the brain. By manipulating the colour of the image (through the blue and red coloured lenses of the glasses), our brain interprets the different wavelengths of these colour images to perceive depth.

Is this on the right track?

Yeh, something like that. It was talking about our left eye can see a different image to the right eye (because thats how the movie is created so that the through the red you see differently than through the blue), and then depth perception.