AQA BIOL2 Biology Unit 2 Exam - 26th May 2011

I think it'll either be structure/function of blood vessels (maybe comparisons), ventilation in fish and/or insects or movement of water through plants.

i just hope it'll be an easy question.

Starch
-Made from alpha glucose
-Joined by condensation [forms glycosidic bonds]

Features:
-Compact - able to store a large amount in a small space
-Insoluble - no effect on water potential
-Has branches which can be hydrolysed to release glucose

Cellulose
-Made from Beta-Glucose
-Joined by condensation
-Carbons 1 & 4, 1 & 6
-Flipping over of alternate molecules

Features:
-Unbranched chains lie side by side
-To form microfibrils
-Hydrogen bonds link the cross-linkages of chains to give tensile strength

Starch - Plants
Glycogen - Animals [Muscles/Liver]

Nope, in cells, the chromosome is just one chromatid, it's when the DNA replicates that another sister chromatid is formed.

thats amazing!! is there any chance you could summarise variation topic,the stuff we need to knw. thank you in advance..

I think I've seen this question, I think it was an oxygen dissociation curve and the curve was shifted to the right, to show higher affinity for oxygen. At higher altitudes the partial pressure of oxygen is low and therefore if the people have many haemoglobin that have higher affinity for oxygen the haemoglobin can become fully saturated at lower partial pressures?

Why is MRSA transmission more prevalent in hospitals?

Thanks seriously! Makes much more sense now to me about meiosis, because I was wondering before why there meiosis occurs twice.

I think it was just more red blood cells, means more haemoglobin, so can carry a larger amount of oxygen to respiring cells?

Hmm.. because there are many people in small area (easier transmission), sick and elderly people, have weaker immune systems so more likely to be effected. Not sure what else - can you think of anything?

I think it was just more red blood cells, means more haemoglobin, so can carry a larger amount of oxygen to respiring cells?

Hmm.. because there are many people in small area (easier transmission), sick and elderly people, have weaker immune systems so more likely to be effected. Not sure what else - can you think of anything?

Possibly tissue fluid formation or movement of water thriugh roots ( apoplast/symplastic pathway) transpiration, antibiotic resistance

Erm aside from what you have I don't think there is much more, I guess you could say that there is increased doctor-patient contact and therefore increased transmission if there is a lack of hygiene i.e doctor not washing hands after patient contact or something along those lines.. I guess they would only ask for max 2 reasons so we're okay

Doctors moving from patient to patient as vehicles for the disease?

Once again, just checking my knowledge. Hope I'm not being annoying.

Comparisons between blood vessels:

Arteries: More elastic (to expand and recoil to even out blood pressure) and muscle fibres (to contract and relax to help push blood along) than veins, smaller lumen, no valves, carries oxygenated blood (except pulmonary artery which carries deoxygenated blood). Also has more muscle fibres/less elastic fibres than arterioles.

Veins: Less elastic and muscle fibres than arteries, larger lumen, valves (to prevent back-flow of blood), carries deoxygenated blood (except pulmonary vein which carries oxygenated blood)

Capillaries: One cell thick (for short diffusion pathway), flat cells (to reduce friction), smallest of the blood vessels, closer to tissues/cells so exchange occurs in capillaries, many branching capillaries increase surface area, small lumen

Arterioles: More elastic fibres than arteries (for vasoconstricion/vasodilation), less muscle fibres than arteries

Venules: I actually don't know that much about these. Don't really remember any past questions on venules.

All blood vessels: Have an layer, one cell thick, called the endothelium to prevent the blood from sticking to the sides of the vessel and reduces friction. surrounded by a layer of protein called collagen to protect the vessel from pressure

Hmm this question was in a paper:

The elephant is a very large animal. It has adaptations to increase heat loss from its
body surface. A mouse is a very small animal and it has adaptations to reduce heat
loss from its body surface. Explain why these animals have different adaptations for
heat loss.

The markscheme said:

-Elephant has smaller surface area to volume ratio
-Elephant generates more heat - wouldn't it be less heat, as they loose heat more slowly?

Out of interest, what UMS did everyone get in Unit 1? Quote me

Might be worth noting that arteries have thicker walls to prevent them from bursting. And, about venules, they don't really come up. It's not in the NT textbook anyway.