VCE Biology Question Thread

[tiff_tiff]

The organelles that have double membranes are; Mitochondria, Chloroplasts, Endoplasmic Reticulum, Golgi Body, and Nucleus.
Vacuoles have a singular membrane, ribosomes can be free and without a membrane or can be attached to the ER and have a singular membrane and lysosomes have singular membranes.
 

thank u ~

 do plants cells NOT have centrioles?

[Jay.C]

How does the nucleus have a double membrane?

It was born that way!  Jks
The nucleus consists of two lipid bilayers, the inner nuclear membrane and the outer nuclear membrane. The space in-between the membranes is called the perinuclear space and nuclear pores run through both the membranes.

[Jay.C]

thank u ~

 do plants cells NOT have centrioles?

No problem 
And yes plant cells do not contain centrioles.

[tiff_tiff]

how do plant cells divide then?

[Jay.C]

how do plant cells divide then?

Plant cells contain centrosomes, so as to what produces the spindle fibres is different between plant and animal mitosis. The phases of mitosis is the same except when it comes to cytokinesis. Plant cells divide the cytoplasm between the two new nuclei by forming a new cell wall. Animal cells do this by forming a pinch in at the middle of the cell until two new cells have been formed with cytoplasm and organelles for each new nuclei.

[tiff_tiff]

aren't the centrioles in the centrosomes,and from which the spindle fibres radiate from during metaphase to connect with the kinetochores of the chromosomes?

[Jay.C]

aren't the centrioles in the centrosomes,and from which the spindle fibres radiate from during metaphase to connect with the kinetochores of the chromosomes?

Plants have microtubules, they are able to form a circular loop of microtubules around the future plane of division prior to prophase, rather then centrosome.

[cosine]

It was born that way!  Jks
The nucleus consists of two lipid bilayers, the inner nuclear membrane and the outer nuclear membrane. The space in-between the membranes is called the perinuclear space and nuclear pores run through both the membranes.

Is the outer membrane the one which forms the rough ER?

[Jay.C]

Is the outer membrane the one which forms the rough ER?

Yes! The membranes of the ER are continuous with the outer membrane of the nuclear envelope.

[Arithmetic]

In the experiment of photosynthesis, why does the leaf disc float when it photosynthesises?

[cosine]

In the experiment of photosynthesis, why does the leaf disc float when it photosynthesises?

The leaf disc is initially sunk because the oxygen was sucked out of it, making it more dense than the solution in which is sits in. So when it's placed in a beaker, and as it photosynthesises, oxygen is produced as the H20 is broken down by chlorophyll. When this oxygen is produced, it is either released in the atmosphere or stored in the spongy mesophyll of the leaf discs, hence the discs start to float again as they become less dense than the solution in the beaker.

Hope it helped

[KingDrogba]

Out of 200 marks for sacs what would you need to get to obtain a 40? Also, for the exam what kind of mark would you need to get that 40+?

cheers

[Reus]

Out of 200 marks for sacs what would you need to get to obtain a 40? Also, for the exam what kind of mark would you need to get that 40+?

cheers

Give or take 180/200 depending on how your SACs will scale after your exam. You need an A+ on the exam for a 40+ SS. The A+ range changes every year depending on the state's performance however if I recall correctly, you needed around 95/120 last year for a 40+.

[wobblywobbly]

Out of 200 marks for sacs what would you need to get to obtain a 40? Also, for the exam what kind of mark would you need to get that 40+?

cheers

An A+ is required for all graded assessments for a 40+. You would require 184/200 in your SACs to get an A+ (Around 94 for Unit 3, 90 for Unit 4). Note scaling, of course.

In the exams, last year's exam required 96/110 for an A+, whereas the year before required 93. If you ace the multiple choice (or get close), then it should definitely be achievable.

[Sine]

An A+ is required for all graded assessments for a 40+. You would require 184/200 in your SACs to get an A+ (Around 94 for Unit 3, 90 for Unit 4). Note scaling, of course.

In the exams, last year's exam required 96/110 for an A+, whereas the year before required 93. If you ace the multiple choice (or get close), then it should definitely be achievable.

What score on the exam would you require for a study score of 45, given A+ SACs