AS Biology Paper 2 AQA 2017

How did everyone find it I found it better than the last paper, but the majority of the people in the exam hall were writing up until the time was over. - Comment what you got and how you found it.

Differences between glycogen and cellulose?

How is starch good for storage?

- Explain water Cohesion- Tension theory in the xylem.

-mRNA Production in plants

I didnt do the paper but those questions sound like a blessing tbh

How did everyone find it I found it better than the last paper, but the majority of the people in the exam hall were writing up until the time was over. - Comment what you got and how you found it.

Differences between glycogen and cellulose? (2)

How is starch good for storage? (2)

Magnification question - I got 40um. (2)

-Mutation questions - (Non disjunction?)

- Explain water Cohesion- Tension theory in the xylem. (6)

-mRNA Production in plants (6)

How did everyone find it I found it better than the last paper, but the majority of the people in the exam hall were writing up until the time was over. - Comment what you got and how you found it.

Differences between glycogen and cellulose? (2)
Glycogen is only in animals, whereas Cellulose is only in plants.
Glycogen a-glucose, Cellulose B-glucose
How is starch good for storage? (2)
Starch is insoluble so does not affect water potential of neighbouring cells.
Magnification question - I got 40um. (2)
I got 2cm for the length of the line
the magnification was x500

- Beetroot - effect of temperature questions.

-Aorta and Pulmonary artery question - disease.

-Mutation questions - (Non disjunction?)

- Adult/ Fetal Haemoglobin

- Explain water Cohesion- Tension theory in the xylem. (6)
Water is a polar molecule, and thus has a propensity to form hydrogen bonds with other water molecules. As water vapour moves out of the stomata via diffusion, this encourages the movement of an unbroken water column due to a diffusion gradient being formed. Water moves out of neighbouring mesophyll cells into the air space, which in turn causes the movement of water up from the roots, where it is being osmotically transported in. This constant movement of water from water vapour leaving the cell puts the xylem under tension, causing an unbroken column to form.


-mRNA Production in plants (6)

Cellulose- beta glucose, hydrogen bonding, microfibrils, unbranched
Glycogen- alpha glucose, branched

Starch good for storage- amylopectin branched ( 1,4 and 1,6) help give it a very compact shape, lot of energy stored, insoluble-doesnt affect osmotic potential

Mutation question- non disjunction is failure of separation of chromosomes in meiosis meaning one cell has an extra copy and one is missing one-can lead to e.g downs and turner respectively

Cohesion tension theory- cohesion between water molecules, delta negative oxygen attracts delta positive hydrogen and drives transpiration stream, adhesion also adds to this effect as cell wall molecules repel water, allows water to travel as a stream, purely passive process, when water removed from leaf by transpiration, osmosis causes water molecule to replace it and cohesion tension causes whole stream to rise from roots to leaves.

mRNA produced when a cistron unwinds exposing bases (unwinds with the help of dna helicase and RNA polymerase) , attracts free complementary bases/ nucleotides which join up to it, Uracil is attracted to adenine,not thymine. Mrna strand then separates and is used as template in translation, 3 bases code for one amino acid, codon on it pairs with anticodon to make proteins.

Ah I see we're both revising for A2s ahaha

How did everyone find it I found it better than the last paper, but the majority of the people in the exam hall were writing up until the time was over. - Comment what you got and how you found it.

Differences between glycogen and cellulose? (2)
Glycogen - Branched - Cellulose - Unbranched
Glycogen alpha glucose. Cellulose beta glucose


How is starch good for storage? (2)
Coiled and compact.
Insoluble, so it can't diffuse out of cells and doesn't effect the water potential

Magnification question - I got 40um. (2)
I got 2cm for the length of the line
the magnification was x500

The chemical test for starch (1)
Potassium Iodine

- Beetroot - effect of temperature questions.

-Aorta and Pulmonary artery question - disease
Oxygenated blood mixes with deoxygenated blood and so less oxygenated blood is delivered to respiring tissues. Cells/Tissues are unable to respire and die. (3)

-Mutation questions - (Non disjunction?)

- Adult/ Fetal Haemoglobin

- Explain water Cohesion- Tension theory in the xylem. (5)
cohesion between water molecules, delta negative oxygen attracts delta positive hydrogen and drives transpiration stream, adhesion also adds to this effect as cell wall molecules repel water, allows water to travel as a stream, purely passive process, when water removed from leaf by transpiration, osmosis causes water molecule to replace it and cohesion tension causes whole stream to rise from roots to leaves.

-mRNA Production in plants (5)
mRNA produced when a cistron unwinds exposing bases (unwinds with the help of dna helicase and RNA polymerase) , attracts free complementary bases/ nucleotides which join up to it, Uracil is attracted to adenine,not thymine. Mrna strand then separates and is used as template in translation, 3 bases code for one amino acid, codon on it pairs with anticodon to make proteins.

Cellulose- beta glucose, hydrogen bonding, microfibrils, unbranched
Glycogen- alpha glucose, branched

Starch good for storage- amylopectin branched ( 1,4 and 1,6) help give it a very compact shape, lot of energy stored, insoluble-doesnt affect osmotic potential

Mutation question- non disjunction is failure of separation of chromosomes in meiosis meaning one cell has an extra copy and one is missing one-can lead to e.g downs and turner respectively

Cohesion tension theory- cohesion between water molecules, delta negative oxygen attracts delta positive hydrogen and drives transpiration stream, adhesion also adds to this effect as cell wall molecules repel water, allows water to travel as a stream, purely passive process, when water removed from leaf by transpiration, osmosis causes water molecule to replace it and cohesion tension causes whole stream to rise from roots to leaves.

mRNA produced when a cistron unwinds exposing bases (unwinds with the help of dna helicase and RNA polymerase) , attracts free complementary bases/ nucleotides which join up to it, Uracil is attracted to adenine,not thymine. Mrna strand then separates and is used as template in translation, 3 bases code for one amino acid, codon on it pairs with anticodon to make proteins.

if the question is asking about the production of mRNA, why would you mention the translation process?