AQA BIOL2~3rd June 2013~AS Biology (Now Closed) Watch
HEPATIC ARTERY- to liver
HEPATIC PORTAL VEIN- away from gut to liver
RENAL VEIN-away from kidney
RENAL ARTERY-to kidney
can someone explain how mutation in base sequence changes a protein to make it non functional???
-Different amino acid sequence gives different tertiary shape of protein
-Different tertiary shape means different shaped active-site
-So substrate cannot bind and cannot form ES-complexes therefore the enzyme becomes non functional
Would someone be happy to go over the ways in water transports in a plant? Like root pressure, etc. I HATE PLANTS
Basically water wants to get from the soil into the xylem vessels. It can do this by 2 methods or 'pathways' called the SYMPLAST PATHWAY or APOPLAST PATHWAY. (Might be useful if you get a labelled diagram showing xylem/root hair cell etc whilst reading this).
In the Symplast pathway, water moves through the CYTOPLASMS of the cells.
Water diffuses along a water potential gradient through PORES between the cells of the Cortex called plasmodesmata. The Cortex is simply all the cells between the Root hair cell and the Xylem vessel.
In the Apoplast pathway, water moves through the CELL WALLS of the cells.
Water stops at the ENDODERMIS as there is a CASPARIAN STRIP which prevents the water from passing further, making the water pass through a membrane by osmosis down a water potential gradient INTO THE SYMPLAST PATHWAY, which is useful as it prevents harmful substances such as toxins or viruses from entering the xylem vessels as the membrane would not let them past.
- Water potential in the root hair cell is lowered by the active transport of mineral ions from the soil, hence water can move from the soil into them down a water potential gradient.
Watch this, if you need more help:
And a sample answer.
I converted the cm and the um into meter, (x10^-2cm) and (x10-6um) but when i measure from X to Y I get 2.2cm, am i measuring it wrong or my ruler is trolling me .
(4.9 x 10^-2) / ( 20 x 10^-6) = x2450
so my units are right but my measurment of the image is not right..
i just measured it again you can get either 4.8 4.9 or 5.0cm i dont know how your getting 2.2cm, oh wait.. is the past paper printed out in the normal size or have you shrunk it down to smaller size? maybe that explains why the size of your image is small when you measure it.. let me know but yeah all your other units are correct