AQA AS Unit 2 Biology Exam 1 June 2015

Hope everyone is feeling ok!
Can't wait till it's done!

I for one will be happy when biology is out the way, then i will have to concentrate my attention to chemistry

So just to clarify, root pressure only occurs in the root, not at the base of the xylem?

It starts in the roots, but the fact that it pushes water upwards means that it effects the xylem too
I just looked through my past papers, there was one question in the last 4/5 years that asked "Root pressure moves water through the xylem. Describe what causes root pressure. [3]" and another "Explain how water enters xylem from the endodermis in the root and is then transported to the leaves. [6]" Root pressure wasn't mentioned at all in the mark scheme for this second question. You'd probably expect therefore to have to talk about root pressure on its own rather than how it effects overall water movement, but if it seems relevant and it's a big question, mention it just to be sure.

Does anyone know how a missing base leads to a missing amino acid? 😰 thanks!!


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For the root pressure question - how it's created, does this make sense:
Mineral ions are actively transported into the xylem making the water potential in the xylem low
Water moves down the water potential gradient by osmosis into the xylem
The water potential gradient formed by active transport created a force called root pressure which forces water up the plant

Yeah, that makes sense

Possible 6 markers? Here are my ideas:

Explain how xerophytic plants are adapted to their environment.
Explain how the structures of veins and capillaries are related to their functions.
Explain how the rate of transpiration is affected by various factors.
Explain how water moves from the soil into the xylem.
Compare the gas-exchange systems of insects and plants / fish and mammals / fish and insects.
Compare mitosis and meiosis.

In my opinion, pretty much as bad as unit 1! 😫😫