VCE Biology Question Thread

[katiesaliba]

Does the rough endoplasmic reticulum synthesise proteins that are then secreted from the cell? Do proteins exit the cell via exocytosis? Is exocytosis (and cytosis in general) a form of passive transport? Are a protein's secondary, tertiary and quaternary structures determined in the endoplasmic reticulum?

[khatem]

I just did a prac for homeostasis where we had agar plates and bacteria in them, then we put different antibiotics and household antiseptics into the plates. Tomorrow we will measure the clear zone around the antibiotic to measure its effectiveness, I don't really understand how this relates to homeostasis though. my teacher said it was a good idea to focus on signal transaction. I'm so lost at how this relates to homeostasis 

[swagsxcboi]

Does the rough endoplasmic reticulum synthesise proteins that are then secreted from the cell? Do proteins exit the cell via exocytosis? Is exocytosis (and cytosis in general) a form of passive transport? Are a protein's secondary, tertiary and quaternary structures determined in the endoplasmic reticulum?

Yes, the rough endoplasmic reticulum synthesises proteins that are secreted from the cell.

Yes, the proteins are packaged into vesicles at the golgi complex and the vesicle fuses with the cell membrane depositing the protein into the extracellular fluid (via exocytosis). This process does require energy (ATP) and is NOT passive transport.

Both endocytosis and exocytosis require energy.

the protein's primary structure is determined at the rough endoplasmic reticulum (or ribosome)

the secondary, tertiary and quaternary structure is determined by various interactions,
learn these definitions (post your definitions of primary, secondary, tertiary and quaternary structures ITT)
we had to explain them in last years exam!

btw, not all proteins will have a quaternary structure

[vox nihili]

Just a heads up guys. If you're going to bombard with questions, you may like to start your own post. You're more likely to get answered that way!

[katiesaliba]

How do large lipid-soluble molecules diffuse across membranes?

[Tyleralp1]

Despite it being lipid soluble, I believe the majority of large molecules will move through a plasma membrane via facilitated diffusion. If however, there is an excess quantity, it may most likely move via endo/exo cytosis.

[jessica666]

Is this a good definition for a hormone?

An organic molecule produced and secreted by cells that act on specific target cells, causing profound effects in tiny quantities.

Any tips would be much appreciated

[MM1]

Are hormones recycled or degraded?
Also, gibberellins and cytokinins both promote cell division, so what is the difference between the two. Why do both with the same function need be secreted? Thanks!

[popoy111]

Hey everybody so i have just completed the cellular respiration sac. The exercise involved was running up and down the oval a few times. So now as part of my discussion questions i have been asked to answers the discussion questions but am not to sure about these 2. do any of you guys have an answer?


1. A slight rise in heart rate (pulse) may occur just prior to the start of the period of exercise?  Try to explain why this may be the case.

2. The same experimental procedure was performed for two anonymous individuals.   Individual A had an increase in heart rate of 58% while individual B had an increase in heart rate of 34%. 

[Scooby]

Hey everybody so i have just completed the cellular respiration sac. The exercise involved was running up and down the oval a few times. So now as part of my discussion questions i have been asked to answers the discussion questions but am not to sure about these 2. do any of you guys have an answer?


1. A slight rise in heart rate (pulse) may occur just prior to the start of the period of exercise?  Try to explain why this may be the case.

The adrenal glands could be releasing adrenaline (increasing heart rate) in anticipation for exercise

[grannysmith]

Is this a good definition for a hormone?

An organic molecule produced and secreted by cells that act on specific target cells, causing profound effects in tiny quantities.

Any tips would be much appreciated

Yes, that sounds good

Are hormones recycled or degraded?
Also, gibberellins and cytokinins both promote cell division, so what is the difference between the two. Why do both with the same function need be secreted? Thanks!

Well, the degradation of hormones can, in a way, be interpreted as recycling them.
Gibberellins:

• Stimulate cell elongation and mitosis in stems and leaves
• Promote seed germination

Cytokinins:

• Stimulate cell division in shoots, roots and fruits
• Increase rate of cellular respiration in fruits as they ripen

As you can see, although this isn't a complete list, there are slight variances in their functions.

Hey everybody so i have just completed the cellular respiration sac. The exercise involved was running up and down the oval a few times. So now as part of my discussion questions i have been asked to answers the discussion questions but am not to sure about these 2. do any of you guys have an answer?


1. A slight rise in heart rate (pulse) may occur just prior to the start of the period of exercise?  Try to explain why this may be the case.

2. The same experimental procedure was performed for two anonymous individuals.   Individual A had an increase in heart rate of 58% while individual B had an increase in heart rate of 34%. 

1. Release of adrenaline increases heart rate
2. Don't really know what this is referring to - care to elaborate?

[Rishi97]

Why does a plant undergo cellular respiration and photosynthesis?
In photosynthesis, the plant makes glucose yeah? So does it then use some of the glucose to undergo cellular respiration?
I seriously do not understand photosynthesis at all
Urgent help needed before sac
Thanks

[rhinwarr]

Why does a plant undergo cellular respiration and photosynthesis?
In photosynthesis, the plant makes glucose yeah? So does it then use some of the glucose to undergo cellular respiration?

Yes, you're right. Plants are autotrophs so they make their own food (glucose) by photosynthesis in order to be used to produce energy (ATP) in cellular respiration. Glucose in itself does not provide the energy so it needs to be broken down in cellular respiration to release the energy held in its bonds.

[Rishi97]

oh ok so cellular respiration occurs just to break down the bonds of glucose into what? Monosaccarides?

[grannysmith]

oh ok so cellular respiration occurs just to break down the bonds of glucose into what? Monosaccarides?

Remember that there are several stages of cellular respiration (glycolysis, Krebs cycle and electron transport chain). Essentially, the breakdown of glucose releases energy, and this energy is used to synthesise ATP molecules, which in turn can be used for the plant's metabolism. Glucose itself is a monosaccharide.

Plants still need to undergo cellular respiration as this is necessary for all living organisms.