VCE Biology Question Thread

[Sine]

For this question would this answer be fine
Describe the directions in which oxygenated and deoxygenated blood flows through the circulatory system.

Blood enters the heart through the inferior and superior vena cava. Deoxygenated blood enters the superior vena cava and passes through the right atrium. It then flows through the tricuspid valve until it is full and then the right ventricle pumps the blood through the pulmonary arteries to the lungs. The left atrium receives oxygenated blood from the lungs via the pulmonary veins. Blood passes through the bicuspid valve to the left ventricle and is pumped to the rest of the body.

Broadly correct, just a few notes.

SVC and IVC both empty into the right atrium.
"until it is full" what are you referring to by this? I don't think the ventricles completely fill. The opening of the pulmonary valve for blood to pass through depend more on pressure differences.

[homeworkisapotato]

Hi! In the study design it says "sources and mode of transmission of various signalling molecules to their target cell"
What do sources refer to? I understand that mode refers to autocrine, paracrine, endocrine, and exocrine, but I was wondering if there's something specific we have to learn about 'sources.'
Also how much of the exam is drawing diagrams? I'm wondering if drawing diagrams of a lot of the processes is an efficient and effective way to study
Thank you so much!

[SS1314]

Hi! In the study design it says "sources and mode of transmission of various signalling molecules to their target cell"
What do sources refer to? I understand that mode refers to autocrine, paracrine, endocrine, and exocrine, but I was wondering if there's something specific we have to learn about 'sources.'
Also how much of the exam is drawing diagrams? I'm wondering if drawing diagrams of a lot of the processes is an efficient and effective way to study
Thank you so much!

As far as I know 'sources' refers to the cell's that secrete the signalling molecules, e.g. cytokines are generally secreted by immune cells in order to coordinate an immune response, neurotransmitters are secreted by neurons and hormones are secreted by ductless endocrine glands.

[homeworkisapotato]

Oh! That makes so much sense ahaha thank you! So for plants is it enough to know that for example auxins are usually secreted by cells in the shoot tips, or do we need to know like how they travel in the tissues and all?
Thank you!

[miyukiaura]

Is it correct to state that:
Reliability is when you get similar results when the experiment is repeated and reproduced. While repeating the experiment tests reliability, it does not improve it. To improve reliability, you must reduce the effect of random errors by increasing the number of trials and taking the mean, and using more sophisticated measuring equipment.
Are there any other ways to increase reliability?

[homeworkisapotato]

Hi! Just to be sure, in steps of natural selection and allopatric speciation do I say there is genetic variation or phenotypic variation?
Thank you so much!

[Owlbird83]

Hi! Just to be sure, in steps of natural selection and allopatric speciation do I say there is genetic variation or phenotypic variation?
Thank you so much!

I would say genetic variation 

Edit: ^this is when you mention at the beginning about genetic variation existing in the population
-(but the environmental/selective pressures act on the phenotypic traits.)

[homeworkisapotato]

Thank you Owlbird!! So to mention genetic variation and still be specific to the scenario, how would you phrase the first dot point regarding genetic variation?
So for example would you say something like
- there is genetic variation in rat population with both short and long tails

Thank you!

[whys]

Thank you Owlbird!! So to mention genetic variation and still be specific to the scenario, how would you phrase the first dot point regarding genetic variation?
So for example would you say something like
- there is genetic variation in rat population with both short and long tails

Thank you!

That looks fine to me. The way I phrase it (applied to your scenario) is 'there is pre-existing genetic variation within a rat population, resulting in phenotypes with short or long tails'.

[homeworkisapotato]

That looks fine to me. The way I phrase it (applied to your scenario) is 'there is pre-existing genetic variation within a rat population, resulting in phenotypes with short or long tails'.

Thank you! That's a great way to phrase it so now I'm going to steal it

[Bri MT]

Thank you Owlbird!! So to mention genetic variation and still be specific to the scenario, how would you phrase the first dot point regarding genetic variation?
So for example would you say something like
- there is genetic variation in rat population with both short and long tails

Thank you!

I would probably say something like "the rat population had pre-existing heritable variation in tail length"

Whys' answer is also good.

I wouldn't go with the answer you had because it doesn't clearly link the genetic variation to the phenotypic variation. If you swapped out "with" for "resulting in" then it would be stronger.

[Moonblossom]

Is it correct to state that:
Reliability is when you get similar results when the experiment is repeated and reproduced. While repeating the experiment tests reliability, it does not improve it. To improve reliability, you must reduce the effect of random errors by increasing the number of trials and taking the mean, and using more sophisticated measuring equipment.
Are there any other ways to increase reliability?

I think this is a pretty good answer but I'm not sure what you mean by sophisticated measuring equipment. Maybe say more precise? I don't think there are any other ways other than repeating trials to improve reliability

[miyukiaura]

I think this is a pretty good answer but I'm not sure what you mean by sophisticated measuring equipment. Maybe say more precise? I don't think there are any other ways other than repeating trials to improve reliability

Thanks for sophisticated measuring equipment I was referring to those that can give a more precise reading.

Completely unrelated but is anyone going to bother memorising the names and roles of plant hormones?

[PhoenixxFire]

Completely unrelated but is anyone going to bother memorising the names and roles of plant hormones?

Definitely not needed for the exam

[thenuttyprofessor]

Definitely not needed for the exam

wait so does that mean like we don't have to know about auxins, GA, cytokinins, abcisic acid and ethylene and functions? or does that mean more specific hormones fitting under the banner of these categories?