A2 Biology OCR June 2015 Revision Thread

Is the coursework not included?

Not too sure tbh, don't want to mislead you but I remember someone telling me it was over the 2 main A2 units, anyone feel free to correct me

Reply 1461

maisie__x

2

Original post by cinderella25

Yeah I am doing the same thing. Good luck

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Good luck to you too :smile:

Reply 1462

baffledchick

6

What years are the hardest papers for f214? So I can leave them to last to try and gain experience through the rest aha, also are all the past papers on biotutor?

Reply 1463

Maham88

2

can someone please explain gluconeogenesis, glycogenolysis and glycogenesis

Reply 1464

ellyphhant

7

Original post by E_149

Do we need to know anything about relay neurones? e.g. their stucture

nope

Reply 1465

maisie__x

2

Original post by domcandrews

Not too sure tbh, don't want to mislead you but I remember someone telling me it was over the 2 main A2 units, anyone feel free to correct me

I got told the same thing as you :smile:

Reply 1466

ellyphhant

7

Original post by Maham88

can someone please explain gluconeogenesis, glycogenolysis and glycogenesis

gluconeogenesis: conversion of fats and amino acids to glucose (BSL too low)

glycogenolysis: conversion of glycogen to glucose (BSL too low)

glycogenesis: conversion of glucose to glycogen (BSL too high)

Reply 1467

domcandrews

2

Original post by Maham88

can someone please explain gluconeogenesis, glycogenolysis and glycogenesis

Gluconeogenesis - conversion of amino acids and fats to glucose, Glycogenolysis is conversion of glycogen to glucose and glycogenesis is the conversion of glucose to glycogen

Reply 1468

Maham88

2

Original post by ellyphhant

gluconeogenesis: conversion of fats and amino acids to glucose (BSL too low)

glycogenolysis: conversion of glycogen to glucose (BSL too low)

glycogenesis: conversion of glucose to glycogen (BSL too high)

thanks

Reply 1469

E_149

2

Original post by Maham88

can someone please explain gluconeogenesis, glycogenolysis and glycogenesis

Gluconeogenesis and glycogenolysis both increase blood glucose levels (caused by glucagon from alpha cells) while glycogenesis reduces it (insulin from beta cells).
Gluconeogenesis converts amino acids and fats to glucose.
Glycogenolysis converts glycogen to glucose.
Glycogenesis converts glucose to glycogen for storage.

Reply 1470

Maham88

2

Original post by domcandrews

Gluconeogenesis - conversion of amino acids and fats to glucose, Glycogenolysis is conversion of glycogen to glucose and glycogenesis is the conversion of glucose to glycogen

thanks

Reply 1471

cinderella25

11

Original post by Maham88

can someone please explain gluconeogenesis, glycogenolysis and glycogenesis

Just remember lysis means breaking so breaking glycogen into glucose. Genesis means making so making glycogen to glucose and neo means new so making glucose with new products like amino acids. That's how I remember it

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(edited 8 years ago)

Reply 1472

E_149

2

Can anybody try and explain the Loop of Henle to me in the simplest way possible please. After being taught it, reading textbooks and watching youtube videos it's the main thing I can't seem to get my head around.

Reply 1473

Maham88

2

what detects low and high glucose levels in the blood ?

Reply 1474

shardatarini

s it possible to get an A/B by memorising the textbook????????

Reply 1475

domcandrews

2

Original post by Maham88

what detects low and high glucose levels in the blood ?

Alpha cells detect low, Beta cells detect high (both in the Islets of Langerhans)

Reply 1476

Maham88

2

Original post by E_149

Can anybody try and explain the Loop of Henle to me in the simplest way possible please. After being taught it, reading textbooks and watching youtube videos it's the main thing I can't seem to get my head around.

It is where re absorption of water and sodium and chloride ions from the filtrate takes place
Desert animals have longer loop of henle so more re absorption therefore they produce a concentrated urine called hypertonic urine

(edited 8 years ago)

Reply 1477

RichBitch

2

Original post by Cara_rose

Chemiosmosis drives oxidative phosphorylation.

Chemiosmosis is the flow of protons and oxidate phosphorylation is the synthesis of ATP from ADP and Pi in the presence of oxygen. Oxidative phosphorylation can only occur because of the flow of protons through the channels associated with the ATP synthase enzyme, which drives the rotational part of the enzyme allowing the ADP and Pi to joing together.

The kinetic energy that is lost by electrons being passed down the ETC is what allows protons (H+) to be pumped across the membrane, which in turn ultimately aids chemiosmosis.

Do this help?

Yes yes thank you so much!!!

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Reply 1478

maisie__x

2

Original post by E_149

Can anybody try and explain the Loop of Henle to me in the simplest way possible please. After being taught it, reading textbooks and watching youtube videos it's the main thing I can't seem to get my head around.

1. The asending limb is permeable to sodium chloride ions, these leave the tubule by diffusion at the bottom and further up by active transport and are reabsorbed into the tissue fluid.

2.Because there is now a higher concentration of sodium and chloride in the tissue fluid than in the tubule this creates a concentration gradient between the tissue fluid and tubule fluid.

3. The descending limb is permeable to water but impermeable to sodium chloride. Because of the created concentration gradient, water diffuses out of the descending limb by osmosis and is reabsorbed into the tissue fluid.

4.This creates a concentrated tubule fluid so minimize water loss. As the fluid flows through the collecting duct, more water can be reabsorbed into the tissue fluid and then into blood capillaries by altering the walls permeability to water (this is osmoregulation)

Reply 1479

kell123

hi guys, is it worth learning the method for measuring the rate of respiration even though its not included in the spec. many thanks

A2 Biology OCR June 2015 Revision Thread

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