Biology by2 revision

No further reactions on carbon Ethanol and lactic acid can be broken down dioxide and water. A lot of energy is produced.

Biology by2 revision

Gas exchange in advanced multicellular organisms For efficient gas exchange, advanced organisms require A ventilation mechanism An internal transport system often a blood circulation system to move gases from respiratory surface to respiring cells and vice versa A respiratory pigment in the blood — to increase the oxygen carrying capacity Gas exchange in fish Water contains far less oxygen than air The rate of diffusion in water is slower Water is a dense medium compared to air so does not flow as freely, meaning it has to be pumped over the respiratory surface.

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In fish, gas exchange takes place across the gill, over which a one-way current of water is kept flowing by a specialised pumping mechanism. The density of water prevents the gill from collapsing which is why fish suffocate on land — their gill plates all stick together as there is no water to support them, so the surface area is greatly reduced.

Gills are made up of many folds, providing a large surface area for exchange. Fish are divided into two main groups Cartilaginous fish — eg sharks. They have skeletons made entirely of cartilage.

Five gill clefts, located just behind the head, have water forced over them when water is taken into the mouth and the floor of the mouth raised. A parallel flow arrangement operates, where the blood flows in the same direction as the water. This is not very efficient.

Bony fish — These fish have a skeleton made of bone and a flap called the operculum covering the gills. Gas exchange involves a counter current flow, where blood in the gill capillaries flows in the opposite direction to the water. There are four pairs of gills in the pharynx, with each gill supported by a gill arch.

Along each of these gill arches are many thin plates called gill lamellae or gill filaments which in turn hold the gas exchange surface, the gill plates. Gills provide: A specialised area for gas exchange as opposed to using the whole body surface A large surface area extended by the gill filaments An extensive network of blood capillaries to allow efficient diffusion and haemoglobin for oxygen carriage.

Ventilation mechanism:GCSE Biology revision covering Cell Activity, Genetics and DNA, Green Plants as Organisms, Humans as Organisms, Living Things in their Environment, Polymerisation of Amino Acids, The .

Biology WJEC BY2 Notes for Evolution. Got given some notes at college, decided to edit them a tad, making them a bit easier to read and getting rid of the irrelevant stuff and highlighted the main points. I found actually making these notes, (and the rest which are still to come) good revision, so if you don't know what to do with them.

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Biology by2 revision

Go to first unread XenoDoublade23 Badges: 1. Rep:? #1 Report Thread starter 2 years ago #1 Hi, I'm currently revising for my AS biology exam and I'm in middle of revising Unit Evolution.

There is a lot to learn so could someone give me some useful revision tips. Jan 08,  · BY2 revision Page 2 Digestion 21 May = the break down of large insoluble molecules into smaller soluble molecules.

Physical & chemical. Food passes through alimentary canal where it is digested & absorbed into the body. Apr 07,  · I am at a loss. I have revised so much for Biology but it is not working anymore I got an A (/ which is 88 UMS) in January for BY1 (WJEC) and in BY2 all I can muster seems to be B grades What should I do?

I know that getting a low B (72 UMS) would still be enough for an A overall but I want to apply for Cambridge and their minimum is 90 UMS across AS Resolved.

revision notes for form 2. Trending: Maranda High Form 1, Form 2, Form 3 & Form 4 End Term 1 Past Papers revision notes biology form 2. TRANSPORT IN PLANTS AND ANIMALS. Introduction. Transport is the movement of substances within an organism.

All living cells require oxygen and food for various metabolic processes.

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