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OCR Biology F211 Exam - Tues 11'th January 2011

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how are cells produced in meiosis different from mitosis apart from have half as many chromosomes?? (it was a 3marker)???

also haploid and diploid definitions and homologous chromosomes????

Don't know about the first one, sorry. Haploid and diploid is just 23 chromosomes versus 23 pairs. Homologous is where they code for the same thing but can vary in what they actually say eg. genes for eye colour from your mum or dad.

Anybody know if we have to learn the sizes of the different organelles?

Reply 341

taunt

Original post by levantine

how are cells produced in meiosis different from mitosis apart from have half as many chromosomes?? (it was a 3marker)???

also haploid and diploid definitions and homologous chromosomes????

haploid- half
diploid-full

meiosis produces gametes oh and in that question you basically have to compare mitosis and meiosis.

to be quite honest with you i havnt gota clue what hell homoglous pairs r lol urmmm mabye a pair that have similar DNA..urm i duno sorry : :confused:

Reply 342

levantine

Original post by Wish I Could Change This

ive seen it come up but they are normally leanient on the mark scheme.eg width of cell surface membrane is 7nm but on mark schem said 'accept5nm to 20nm

Reply 343

Wish I Could Change This

How about the organelles themselves, apart from the cell membranes? there are so many to learn :dong:

Reply 344

CullenLoverX

does anyone know the grade boundaries for june 2010? or have they not been released yet?

edit: nvm i found it... only 41/60 for an A! thats just 68%! wow i guess i wasnt the only one that found the paper tough :biggrin:

(edited 13 years ago)

Reply 345

Konshi

All aboard the fail train woop woop

Reply 346

taunt

we did this Question paper in school before holidays and the teacher said that

41-A
36-B

and i cant remember the others lol

hope that helped :smile:

Reply 347

emmaD96

I actually thought the june '10 paper was rather easy (got 52/60) so I'm pretty confident about the exam tomorrow

Reply 348

levantine

mitochondria 2-5um (micro metres)
chloroplasts 4-10um

although i doubt you would have to know them

Reply 349

taunt

Original post by emmaD96

I actually thought the june '10 paper was rather easy (got 52/60) so I'm pretty confident about the exam tomorrow

Im gona do a late nighter lol
Im not very confident , im finding it really difficult lol

Reply 350

CullenLoverX

well i'm off guys...
good luck to everyone!
(now wish me luck :P )

can't wait for the discussion that'll follow tomorrow lol

Reply 351

abu125

Confused with the functions of a glycoprotein, the role of the cytoskeleton and how translocation occurs.

Reply 352

Zay18

Original post by levantine

how are cells produced in meiosis different from mitosis apart from have half as many chromosomes?? (it was a 3marker)???

also haploid and diploid definitions and homologous chromosomes????

Meiosis differs from mitosis because it produces cells that contain half the number of chromosomes and meiosis produces cells that are genetically different to each other and different to the parent cell.

Hope that answers your question. :smile:

Good luck for tomorrow!!

Reply 353

Konshi

Got blood, tissue fluid & lymphatic system on a lock. Onto the carriage of oxygen SON

Reply 354

taunt

Original post by Konshi

Got blood, tissue fluid & lymphatic system on a lock. Onto the carriage of oxygen SON

Hi i was just wondering if you could explain blood, tissue fluid & lymphatic system to me pls, i honestly dont get it :confused:

thnx

Reply 355

Zay18

Original post by abu125

Confused with the functions of a glycoprotein, the role of the cytoskeleton and how translocation occurs.

Functions of Glycoproteins:

Allow hormones to bind with cells so that a cell response can be carried out.

The cell membrane receptor allows drugs to bind.

Glycoproteins they are involved in cell signalling they are the 'self'.

They allow recognition by the immune system.

They form hydrogen bonds with water molecules and stabilise the membrane.

Act as a receptor for hormones and neurotransmitters.

Fibres keep cells shape stable by providing an internal framework called cytoskeleton. They contain fibres that are able to move against each other. They also move organelles around inside of the cell. Microtubles are fibres made up of protein called tubulin. They move microorganisms through a liquid or waft a liquid past the cell.

Translocation is movement of assimilates. Sugars are transported into the phloem in the form of sucrose. A part of the plant releases sucrose into the phloem which is called the source. A part of the plant removes sucrose from phloem which is called sink.

Good luck!! :smile:

Reply 356

undertaker1

anyone pullin a late nighter

how many past paper has everyone done

Reply 357

taunt

Original post by undertaker1

anyone pullin a late nighter

how many past paper has everyone done

yep im pullin a late nighter lol

iv left my revision till last minute...so im paying for it now lol :s-smilie:

what bwt you, hows revisionnn

Reply 358

Konshi

Original post by taunt

yep im pullin a late nighter lol

iv left my revision till last minute...so im paying for it now lol :s-smilie:

what bwt you, hows revisionnn

Couple of pages back a guy posted a pretty good explanation. Here's mine that I've just written up based off of him and textbook:

Blood enters the tissue through the arteries, with a high hydrostatic pressure as it has just been pumped by the contraction of the heart (ventricular systole). These arteries branch off into a network of arterioles and capillaries, which will eventually link up with venules to carry the blood back to the heart.
The high hydrostatic pressure forces fluid out of the capillaries through tiny pores in the capillary wall. There is a net loss of fluid from the upstream end of the capillary near the arteriole. The fluid that leaves is called TISSUE FLUID.

Blood – Erythrocytes, leucocytes, platelets. Hormones and plasma proteins. Some lipoproteins.
Tissue Fluid – Some phagocytic white blood cells. Some hormones. No fats.

Plasma proteins are not able to cross through the pores in the capillary wall. Neither are erythrocytes, platelets, leucocytes. Therefore the tissue fluid has a higher water potential. The tissue fluid transports substances such as oxygen to the tissue cells. It now has a lower hydrostatic pressure, and has a higher water potential due to lacking the bigger solutes, so the fluid returns to the blood via osmosis down a water potential gradient.

Lymphatic system returns lost fluid and proteins to the blood. Fluid enters by diffusing into tiny lymph capillaries, where the fluid is called LYMPH. Composition is near similar to tissue fluid, except lymph has a higher concentration of lymphocytes, produced by the lymph nodes. Lymphatic system drains into the bloodstream near the junction of the venae cavae and the right atrium.

Hope that helps mate. Not sure whether I should go for the all nighter. Never done an exam with 0 hrs sleep lol.