# Why are some mitochondria different shapes (e.g circular)

This is what it said in the mark scheme and I don't get it!

(mitochondria) vary in shape ; longer than wide ; cut in different planes / angles / AW ; just divided / growing ; artefact / deformed during preparation of section ;

Can someone explain it to me?

Thanks a lot in advance
Can you show the question: the basic point is that mitochondria themselves are different sizes and or shapes that is because they grow largely independently. Linked to that they divide independently so depending on what stage of mitochondrial development they exhibit they will look different. Finally when you produce a cross section for microscopy you might cut in a particular plane which makes it look like the mitochondria has a circular shape
Original post by DrXavier
Can you show the question: the basic point is that mitochondria themselves are different sizes and or shapes that is because they grow largely independently. Linked to that they divide independently so depending on what stage of mitochondrial development they exhibit they will look different. Finally when you produce a cross section for microscopy you might cut in a particular plane which makes it look like the mitochondria has a circular shape

Q 1ii
What does it mean to cut in a particular plane?

Think of a cucumber. You can cut it in different “planes” e.g. longways or sideways

If you cut it long ways it looks pretty flat. If you cut it sideways it looks circular. Hence in microscopy when we cut the cell we can eexperience something similar ... the mitochondrial might look differently depending on where we cut the cell
Original post by DrXavier
Think of a cucumber. You can cut it in different “planes” e.g. longways or sideways

If you cut it long ways it looks pretty flat. If you cut it sideways it looks circular. Hence in microscopy when we cut the cell we can eexperience something similar ... the mitochondrial might look differently depending on where we cut the cell

Thanks a lot!!
Can I ask two more Q's?
From the same paper.. Question 2 the cell N why is it half open? Just got confused :/
And the last question of the paper 6d
This is what it says in the markscheme:
(sugars) cannot pass the cut / AW ; decrease water potential ; water moves into cells ; (damage triggers) increased cell division ; to produce cells to store sugars ; cut causes, gall / infection ;

The way you look at it, either on the top or the side.

Think of it like a cylinder, cut it in one plane and it looks like a circle. Cut it in another and it looks like a rectangle (kinda).
Original post by RoyalSheepy
The way you look at it, either on the top or the side.

Think of it like a cylinder, cut it in one plane and it looks like a circle. Cut it in another and it looks like a rectangle (kinda).

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Original post by chem11
Thanks a lot!!
Can I ask two more Q's?
From the same paper.. Question 2 the cell N why is it half open? Just got confused :/
And the last question of the paper 6d
This is what it says in the markscheme:
(sugars) cannot pass the cut / AW ; decrease water potential ; water moves into cells ; (damage triggers) increased cell division ; to produce cells to store sugars ; cut causes, gall / infection ;

For question two the cell has burst open (haemolysis) too much water has entered

What is wrong with the answer to question 6d/what don’t you understand ...

Ask whatever you like 😌
Original post by DrXavier
For question two the cell has burst open (haemolysis) too much water has entered

What is wrong with the answer to question 6d/what don’t you understand ...

Ask whatever you like 😌

I don't understand what the markscheme's answer
About the water potential and cell division... And sugars not passing the cut?
Original post by chem11
Thanks a lot!!
Can I ask two more Q's?
From the same paper.. Question 2 the cell N why is it half open? Just got confused :/
And the last question of the paper 6d
This is what it says in the markscheme:
(sugars) cannot pass the cut / AW ; decrease water potential ; water moves into cells ; (damage triggers) increased cell division ; to produce cells to store sugars ; cut causes, gall / infection ;

When you remove the phloem, the vessel used to transport sugars, from that section, the sugars can't pass through. This causes a build up of sugars which decreases water potential, causing water to move in resulting in swelling.
Original post by chem11
I don't understand what the markscheme's answer
About the water potential and cell division... And sugars not passing the cut?

It says in the question the phloem is removed so the sugars moving down from leaves to sink get stuck. That leads to a reduction in water potential so water moves in and causes swelling. The stress of the situation also triggers cell division to try to repair the site and that can lead to a gall.
Original post by Biomed1018
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If you need anything else, feel free to tag me
Original post by RoyalSheepy
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If you need anything else, feel free to tag me

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u should get best tsr member award
Original post by DrXavier
It says in the question the phloem is removed so the sugars moving down from leaves to sink get stuck. That leads to a reduction in water potential so water moves in and causes swelling. The stress of the situation also triggers cell division to try to repair the site and that can lead to a gall.

Thanks a lot!!
Can I ask more questions if I need help? Biology can be so confusing at times!

Can you please help me with question 4b and 4ciii in this paper? These two questions confused me a lot!
I know for 4b, vascular tissue consists of the xylem and phloem, if I'm not mistaken?
(edited 6 years ago)
Original post by chem11
Thanks a lot!!
Can I ask more questions if I need help? Biology can be so confusing at times!

Can you please help me with question 4b and 4ciii in this paper? These two questions confused me a lot!
I know for 4b, vascular tissue consists of the xylem and phloem, if I'm not mistaken?

Just PM me ... but yes that would be correct - xylem and phloem primarily (other than the meristems). For b) just think it though logically: link it back to how water normally goes through the xylem
Original post by DrXavier
For question two the cell has burst open (haemolysis) too much water has entered

What is wrong with the answer to question 6d/what don’t you understand ...

Ask whatever you like 😌

Just to double check..
for question 2 N is an animal cell that has burst open because it is in an hypotonic solution so water has entered the cell by osmosis?
And also would the black dot be the nucleus and the little dots ribosomes?
(edited 6 years ago)
Original post by username3875292
This is what it said in the mark scheme and I don't get it!

(mitochondria) vary in shape ; longer than wide ; cut in different planes / angles / AW ; just divided / growing ; artefact / deformed during preparation of section ;

Can someone explain it to me?

Thanks a lot in advance

When it says cut in different planes, it means that the mithocondria might be vertical to the plane of the stage. Even though they are oval when cut vertically, they would look circular when cut horizontally- or the other way around 😅