B2- Organisation

Digestive System

Q: Order the following from smallest to largest: Tissue, Organ System, Cell, Organ        

A: Cell, Tissue, Organ, Organ System

Q: Explain the origin and role of bile in digestion

A: Bile is made in the liver and stored in the gall bladder. Bile is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase. 

Q: How do you test for sugar?

A: Mix the substance into a solution and add benedicts solution before heating. If it turns orange/brick red then it indicates the prescense of sugar.

Q: What's Amalyse?

A: Amalyse is an enzyme that breaks down starch. It is produced in the pancreas but also in the saliva, where it breaks down it's substrate into glucose.

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Enzymes and Metabolsim

Q; Explain the Lock and Key analogy

A: Enzymes act as locks. Their active sites have a specific shape that only a specific subrate, the key, can fit into for the reaction to occour.

Q: What is denaturing and why does it happen?

A: When an enzyme passes it's optimum temperature (usually 37 degrees) it will lose it's shape, so the active site will no longer fit the substate. This means it cannot digest the substrate.

Q: Explain why an enzyme at 10 degrees will be slow to digest?

A: It will have less kinetic energy, so collisions between it and the substrate will be less common

Q: What is metabolism

A: The sum of all reactions in the body

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Circularity System

Q: How are the lungs adapted for gaseous exchange?

A: Each aveoli is close to an individual capililary, reducing the distance gasses must diffuse to reach the bloodstream. This is further reduced by the fact aveoli walls are extremely thin.

Q: What is the differance between the left and right ventricle?

A: The right pumps blood to the lungs to recieve oxygen, the left pumps blood to the rest of the body.

Q: Describe the role of plasma

A: Plasma transports dissolved substances around the body, such as hormones, nutrients (water, glucose, minerals) and waste substances (carbon dioxide, urea).

Q: What is a valve?

A: A valve is a tissue in veins that can open and close to prevent backflow of blood.

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Responses to Exercise

Q: Name three things the body does during exersize to supply extra oxygen to muscles.

A: Increase heart rate, breathing rate and breathing volume

Q: What is anaerobic respiration and when would the body do it?

A: If the body can not supply sufficient oxygen to the muscles then the muscles may start to convert glucose into lactic acid to produce energy.

Q: What is oxygen debt?

A: Anaerobic respiration produces an oxygen debt. This is the amount of oxygen needed to oxidise lactic acid to carbon dioxide and water. The existence of an oxygen debt explains why we continue to breathe deeply and quickly for a while after exercise.

Q: Where and how is lactic acid turned to water and carbon dioxide?

A: Blood flowing through the muscles takes it back to the liver.

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