HSC Biology Question Thread

[amelia20181]

would an organism with a 14:1 ratio be more suited to a desert environment than the organism with 4:1

can you say that a lizard lies in the shade so that its body temperature is cooler than the air

would respiratory tract infections or diarrhoeal diseases be caused by untreated drinking water


can you say that something is negative feedback because it returns to the stable state


when you are evaluating a statement should you first say the statement is correct

[KT Nyunt]

For the syllabus dotpoint:

•   LT: explain how one of the following strategies has controlled and/or prevented disease:
-   public health programs
-   pesticides
-   genetic engineering to produce disease-resistant plants and animals

Can we still be asked about any of the 3 in an exam question??

Yes I think so. I would have an idea of how each generally help control the spread and occurrence of disease and know an example for each.
I just had my trials and it included a question a stimulus with a public health program. So I would suggest not just learning one (even though that's what the syllabus says)

- note: it may just be something my school does but it's safer to just learn an example for each. You most likely already know an example for all of them through points in the search for better health or other core topics

[KT Nyunt]

would an organism with a 14:1 ratio be more suited to a desert environment than the organism with 4:1

what's the ratio? Solute/water concentration in urine vs blood?
Remember, to be more suited for a desert environment, it needs to conserve water by excreting very small amounts of highly concentrated urine (as it removed wastes but not a lot water as it is reabsorbed at the nephron, hence blood would have a higher amount of water) - use this to answer your question

can you say that a lizard lies in the shade so that its body temperature is cooler than the air

I think it's more accurate to say that since the lizard is an ectotherm, meaning that it cannot control internal body temperatures as it fluctuates with ambient temperature, in hot temperatures, it stays in the sheltered areas to avoid the hot sun.

would respiratory tract infections or diarrhoeal diseases be caused by untreated drinking water

Diarrhoeal illnesses - for example cholera, typhoid, and dysentery.

can you say that something is negative feedback because it returns to the stable state

Yeah, I'd also add that it's negative feedback because it counteracts changes from the stable state

when you are evaluating a statement should you first say the statement is correct

Yes, I think it's good to start by immediately answering the question and then breaking it down why you believe a statement is correct/incorrect/correct to some degree.
If it feels too robotic to say "The statement [insert statement here] is correct because" I would normally paraphrase the statement and then say "to a great extent/to some extent etc."

 

[amelia20181]

would you get a mark if you say bees can see in infrared

would you get a mark if you say humans can see in the visible spectrum but get the range wrong

how would you write an epidemiological study

[amelia20181]

Thanks KT Nyunt!

[KT Nyunt]

would you get a mark if you say bees can see in infrared

No, because I believe that it's incorrect unfortunately. Bees can see ultraviolet, which allows them to see special patterns on flowers, allowing it to spot foot easily. If you need an animal that can see infrared, the snake is a good example. It has pits between each eye and nostril and can detect infrared. As heat is a form of infrared, this allows the snake to detect body heat emitted from their prey, allowing them to detect pray easily.

would you get a mark if you say humans can see in the visible spectrum but get the range wrong

mmm idk, maybe if it was out of 2 you'd get 1 mark?

how would you write an epidemiological study

A good epidemiological study (the study of diseases - which helps to explain the cause and effect relationship between a risk factor and a disease) always has these 5 features:
1) collects data from a wide range of people - age, sex, occupation, geographical location, ethnicities etc. - improves validity as it considers anything that might skew results
2) collects data from a large number of people (a couple hundred thousands) - this improves reliability
3) Shows the effect of an increased dosage of a risk factor (a proportional relationship should be seen - ie. people who smoke 40 packs a day had an higher number of cases of lung cancer than those who smoke 10 packs a day)
4) Has a control group - ie. people who don't smoke at all - improves validity
5) The study is conducted over a long period of time (as for cases like lung cancer, the number of years between the occurrence of lung cancer and the onset of smoking for an individual is ~40 years)

Thanks KT Nyunt!

No problem!   

[BrittyG]

Omg if anyone saw that... I am so so sorry lmao

[amelia20181]

whats the difference between convergent and divergent evolution and punctuated equilibrium

and how would you draw a diagram to show punctuated evolution

[BrittyG]

Convergent evolution: when species in living in develop similar adaptations despite not sharing a recent common ancestor.
→ For example; sharks and dolphins. They both live in the open ocean (similar environment), similarities are flippers, strong swimmers and tails. Dolphins are mammals and Sharks are fish. The common ancestor is ichthyosaur (reptile).

Divergent evolution: when groups of a single species are geographically separated into isolated populations in different environments, and develop different adaptations as a result.
→ For example; Darwin found 14 different species of finches on the Galapagos and Coco islands. They all had grey/black feathers, similar calls, nests, eggs and courtship displays (indicating a common ancestor. But their habitats, diets, body sizes and beaks were all different (indicating divergence).

Punctuated Equilibrium is the theory by Eldrige and Gould which states that there are periods in which little or no evolution is taking place, followed by extreme amounts of change in a short space of time, usually as a product of high environmental pressures.
→ For Example; The apparent ‘sudden’ appearance of new species of dinosaurs in the Judith river area - there had been environmental pressures that caused a small group to move away and evolve quickly, then move back.

So the difference between these two would be the fact that Convergent involves species living in the same environment developing similar traits whereas Divergent involves the adaptation of a species due to its movement from an environment in order to survive.

Not too sure about that diagram though.

[Mate2425]

Hi everyone, i have been stirring on this syllabus dot point in the Biology option of Communication  - Define the term threshold and explain why not all stimuli generate an action potential. ...... I am unsure what the last part of the question means "explain why not all stimuli generate an action potential". Any helps as soon as possible would be of great appreciation.

Thanks, Mate2425.

[amelia20181]

A neurone and a neuron are the same thing but why is there different spelling

[BrittyG]

Hi everyone, i have been stirring on this syllabus dot point in the Biology option of Communication  - Define the term threshold and explain why not all stimuli generate an action potential. ...... I am unsure what the last part of the question means "explain why not all stimuli generate an action potential". Any helps as soon as possible would be of great appreciation.

Thanks, Mate2425.

- Threshold refers to the minimum voltage required to generate an action potential in a neurone.
- The action potential is an ‘all-or-none’ response either the level of stimulation is below the threshold > nothing happens or it reaches threshold and > action potential is generated.
- THRESHOLD FOR ACTION POTENTIAL IS -55mV.
- Small stimulus still depolarises membrane but not enough to reach threshold > action potential. IF STIMULUS IS NOT INTENSE ENOUGH > DOESN’T REACH THRESHOLD > NO ACTION POTENTIAL!!

E.g. A weak stimulus like dim light might only produce 5 action potentials per second in the photoreceptor cells of the eye, whereas a strong stimulus like a flash of bright light might produce 150 action potentials, however for an action potential to occur both stimuli must reach the required threshold.

[Mate2425]

A neurone and a neuron are the same thing but why is there different spelling

Hi, Amelia20181
Like you said they are the same thing, and the reason for the different spelling stems from the phrase neurone = restricted to non-technical concepts ... whereas in stark contrast neuron is reserved for the standard scientific spelling.
Hope this helps 
Mate2425.

[amelia20181]

Can you say Down syndrome is caused by a mutation

[kauac]

Can you say Down syndrome is caused by a mutation

Hi,
Down syndrome is caused by the inheritance of an extra chromosome, as a result of incomplete separation during meiosis.

So to say that it is a 'mutation' could be a bit of a stretch, because the word can have connotations that the condition can be acquired at any given time, rather then being present at birth. And we know that it is definitely a condition inherited by genetics.

Hope this clarifies things.