AQA Biology Unit one

A random selection of topics from the unit one stuff- just stiff i got wrong in a past paper

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Why is an ice-cold isostonic buffer used in ultrac

(i) ice-cold- minimises any enzyme activity that may take place in the cell

(ii) isostonic- prevent osmosis, so the organelle dont burst or shrivel

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Why can reduced elasticity in the lungs cause brea

The lung capacity is reduced so breathing out is affect as it is no longer a passive process. the concetration gradient is then reduced meaning less oxygen diffuses into the blood.

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How changes of the lung tissue can reduce efficien

-Alveolar walls thicken, meaning that there is a longer diffusion pathway.

-Scarred/fibrous tissue, reduces teh surface area for gaseous exchange

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What are the role of enzymes in the complete break

Amalyse breaks down starch into maltose. maltose is then broken down by maltase into glucose. this is all done by the hydrolisis of glycosidic bonds

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Deescribe the processes involved in the absorption

Sodium ions and glucose move into the epithelial cells via carrier proteins. sodium is then removed fo the epithelial cell by active transport and is absorbed into the blood, maintaing a low concentration of sodium in the cell, which means there is a concentration gradient. Glucose is moved into the blood by facilitated diffusion.

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