Biology 2013ers MARATHONN (4 Viewers)

[fionarykim]

Okay i know it is early, but the earlier we start constantly revising the better stuff will stay in our heads
and the more we'll know for HSC

so lets start having a marathon now?
im pretty sure the rules are real easy, answer the last question posted by someone, then post your own question
if anyone sees an answer that could have more detail or depth we can help improve it!
lets try to do the topics in order? im pretty sure we're all starting with maintaining a balance yeah??


OKAYY first question

a.Explain why homeostasis is important in organisms.
b.Describe the two stages of homeostasis.

 

[HKspec009]

1..Homeostasis is the regulation/maintenance of an organism's internal environment regardless of the changes in the external environment. This is important since cellular activities that take place within the body, operate at their highest when conditions are optimum. This includes maintaining Temp,pH,Osmotic balance,toxicity,metabolite etc. This is directly linked to the action of enzymes. Enzymes are temperature and pH sensitive and are substrate specific. (Make sure you say they are proteins that can denature at high temperatures). Enzymes are needed for metabolic activities as they lower the activation energy required for certain activities. Therefore, homeostasis is important in organisms especially for metabolic efficiency
Depends how many marks this Question is worth, the more detail you can add. This is the bare minimum though.

2. Homeostasis consists of two stages--> Detecting the change (Since everything has a set point)
and counteracting that change to bring it back to the set point. As an example you can do thermoregulation (cbf)
Either through negative or positive feedback system.

Source: I had my Bio HSC on Friday LOL
No question for me to ask, i just answered this because i couldn't be bothered studying for maths tomorrow.

 

[ayeplus_]

This thread is brilliant A chemistry thread would be awesome too~

a) Homeostasis is important in organisms as it allows for a relatively stable and constant internal environment which is critical for enzymes to operate most efficiently within its optimum pH and temperature range. Homeostasis regulates an organism's internal environment to ensure that enzymes do not change shape at slight temperatues and pH variations or denature, which has a significant impact on the enzyme's rate of reaction; a slow rate of reaction would be detrimental.

b) I haven't covered this in class, so here goes:
Homeostasis is comprised of two stages: detecting changes and counteracting changes.
The first stage involves an effector e.g. thermoreceptor receiving a stimulus and transmitting the stimulus to the control centre of an organism e.g. hypothalamus
The second stage involves the initiation of a response by an effector e.g. sweat gland to retain balance within an organism.

Question: Explain how the lock and key model illustrates the specificity of enzymes on substrates.

 

[superSAIyan2]

Lock and key model illustrates the substrate specific nature of enzymes as it shows how the active site is reciprocally shaped to bind with a specific substrate molecule. This model is simplistic and demonstrates that only a specific molecule is able to attach to the enzyme at the active site.
I'd probably draw a diagram just in case.

Question: Describe the role of the nervous and endocrine system in maintaining a stable internal environment

 

[hayabusaboston]

Okay i know it is early, but the earlier we start constantly revising the better stuff will stay in our heads
and the more we'll know for HSC

so lets start having a marathon now?
im pretty sure the rules are real easy, answer the last question posted by someone, then post your own question
if anyone sees an answer that could have more detail or depth we can help improve it!
lets try to do the topics in order? im pretty sure we're all starting with maintaining a balance yeah??


OKAYY first question

a.Explain why homeostasis is important in organisms.
b.Describe the two stages of homeostasis.

erm tbh I dont think you need like, a whole YEAR, to rote memorize bio syllabus haha. 9 months is more than enough I think. The risk you take, is getting bored of the constant and constant repetition of stuff, before your actual HSC. If you won't get bored though, by all means go for it. Good to go for dem state ranks

My personal recommendation is simply finish the bio course in 6 week holidays. THEN you can revise over and over and over every single day till ur HSC. Starting this early in term 4 is only a tad too early imo.

 

[LoveHateSchool]

Haha this is certainly a marathon! As with haya, make sure you don't get too bored of it too fast!

 

[hayabusaboston]

Haha this is certainly a marathon! As with haya, make sure you don't get too bored of it too fast!

I started studying for 2012 chemistry national qualifying exams a few days after the 2011 ones finished. I did shitloads of study EVERY DAY and repeated it over and over and over and over again, and doing all these problems and stuff, and after 7 months I just got so bored and thought "fuck it I aint wasting my time on this when ive got my HSC on" and stopped altogether. Just thought, why bother with olympiads. Just focus on good ATAR.
\
Even though its outside of HSC, just thought it fits well with what I said, doing something for too long will bore you eventually. THOUGH i suppose, since it ur HSC, you'll be constantly motivated for repetition, cos u wanna get good ATAR.

Okay I guess I take what I said back. It depends on person.
\I'll just stick with original plan of mine, finish phys and chem course in 6 week holidays, revise and past papers till HSC.

 

[fionarykim]

The nervous system is an integral element in the process of homeostasis as it enables the detection of changes in body conditions and co ordinates the responses to counteract them.
Dunno bout endocrine system.Someone answer that one?

 

[fionarykim]

I started studying for 2012 chemistry national qualifying exams a few days after the 2011 ones finished. I did shitloads of study EVERY DAY and repeated it over and over and over and over again, and doing all these problems and stuff, and after 7 months I just got so bored and thought "fuck it I aint wasting my time on this when ive got my HSC on" and stopped altogether. Just thought, why bother with olympiads. Just focus on good ATAR.
\
Even though its outside of HSC, just thought it fits well with what I said, doing something for too long will bore you eventually. THOUGH i suppose, since it ur HSC, you'll be constantly motivated for repetition, cos u wanna get good ATAR.

Okay I guess I take what I said back. It depends on person.
\I'll just stick with original plan of mine, finish phys and chem course in 6 week holidays, revise and past papers till HSC.

Hhahaa i know what you mean, but i think if we know our stuff nows, by the hsc i dun really need to study much
also, its proven if u simply revise something uve learnt 6 times a year, then, u know it back to front already
so yeahh D ahha

 

[Aysce]

The nervous system is an integral element in the process of homeostasis as it enables the detection of changes in body conditions and co ordinates the responses to counteract them.
Dunno bout endocrine system.Someone answer that one?

The endocrine system partakes in a major role since it refers to the system responsible for glands ie effectors. For example, when the core body temperature is higher, the hypothalamus will detect this and refer to the endocrine system where sweat glands release sweat. This will provide evaporative cooling and help bring back the temperature to the original state.

Hope that helps.

 

[HKspec009]

SO is the effector the glands or the blood vessels and skin that dilate?

 

[Aysce]

SO is the effector the glands or the blood vessels and skin that dilate?

Effectors incorporate muscles and glands, but in the case of vasodilation, I think the blood vessels are also considered as effectors.

 

[Dan895]

Hahahaha, I would love to write a biological anwser to what homeostasis is. Oh wait our biology class is still doing the first prac :/

 

[superSAIyan2]

You could also say that the endocrine system is involved in the secretion of hormones which enables organisms to react to stimuli appropriately - i.e. adrenalin is secreted by adrenal glands for quick response to stimuli. Also controls the internal chemical composition - e.g. glucagon insulin

 

[fionarykim]

Hahahaha, I would love to write a biological anwser to what homeostasis is. Oh wait our biology class is still doing the first prac :/

Homeostasis is the process in which organisms maintain a stable internal environment

Question: explain the negative feedback mechanism

 

[ayeplus_]

The negative feedback mechanism involves opposing or negating a stimuli by instigating a new response in the opposite direction.
This type of feedback mechanism results in relatively constant stability and maintenance of optimum levels within the body by constant repetition of the system.
e.g. when the body heats up and increases in temperature, the nerves send messages to the control centre in order for the sweat glands to perspire to cool down the body.

Question: Identify the broad range of temperatures over which life is found compared with the narrow limits for individual species

 

[fionarykim]

Some life forms can be found at extreme temperatures, ranging from -400 0C + 120oC, however the majority of living organisms are found in the -20C + 40oC range and for each individual specie the range is even narrower, Below 0oC, cells risk ice crystals forming in them and above 45oC, proteins within cells may denature.

Explain why Haemoglobin may be considered an adaptive advantage

 

[TheOptimist]

Some life forms can be found at extreme temperatures, ranging from -400 0C + 120oC, however the majority of living organisms are found in the -20C + 40oC range and for each individual specie the range is even narrower, Below 0oC, cells risk ice crystals forming in them and above 45oC, proteins within cells may denature.

Explain why Haemoglobin may be considered an adaptive advantage

Couple of things:
-Haemaglobin boosts the bloods oxygen carrying capacity by 100 times, as oxygen usually has very low solubility in the water of the blood plasma.
-Haemaglobin consists of 4 haem groups, and thus is able to carry 4 molecules of oxygen for every haemaglobin molecule --> boosts oxygen carrying capacity of blood
-Haemaglobin has a special affinity for oxygen being able to release it where it is required in the body and maintain it when it is not needed.
-Haemaglobin in a Red Bloood Cell is exposed, thus it allows for a larger SA:V ratio whereby oxygen can diffuse quickly when it is needed. --Haemaglobin can alter the shape of its haem grouups to appropriate the shape of oxygen molecules --> faster binding ---> greater oxygen concentration in a relatively short period of time
-At different altitudes Haemaglobin can alter its affinity for oxygen, i.e. in higher altitudes Hb alows for oxygen to readily bind to it, whereas in lower altitudes Hb can readily release oxygen.

Overall these adaptative advantages of haemaglobin allows for the organism to maintain its health and grow (as oxygen is required by the mitochondria of all cells for aerobic respiration).

 

[fionarykim]

Couple of things:
-Haemaglobin boosts the bloods oxygen carrying capacity by 100 times, as oxygen usually has very low solubility in the water of the blood plasma.
-Haemaglobin consists of 4 haem groups, and thus is able to carry 4 molecules of oxygen for every haemaglobin molecule --> boosts oxygen carrying capacity of blood
-Haemaglobin has a special affinity for oxygen being able to release it where it is required in the body and maintain it when it is not needed.
-Haemaglobin in a Red Bloood Cell is exposed, thus it allows for a larger SA:V ratio whereby oxygen can diffuse quickly when it is needed. --Haemaglobin can alter the shape of its haem grouups to appropriate the shape of oxygen molecules --> faster binding ---> greater oxygen concentration in a relatively short period of time
-At different altitudes Haemaglobin can alter its affinity for oxygen, i.e. in higher altitudes Hb alows for oxygen to readily bind to it, whereas in lower altitudes Hb can readily release oxygen.

Overall these adaptative advantages of haemaglobin allows for the organism to maintain its health and grow (as oxygen is required by the mitochondria of all cells for aerobic respiration).

Wow amazing answer! but now ur meant to ask a Q!!
i'll ask it for u xP

Use one example of an ectotherm and one example of an endotherm to compare an organism’s responses to change in environmental temperature. In each case explain how the responses help the organism regulate body temperature.

 

[fionarykim]

Describe active transport and reabsorption as alternative methods of removing nitrogenous wastes