B3 Organisation

Question 1

What is an Enzyme?

Answer 1

A biological catalyst that speeds up a chemical reaction. They are also proteins

Question 2

What is the lock and key theory?

Answer 2

The substrate binds onto the active site which is complementary in shape. This forms an “enzyme-substrate complex”. The enzyme then breaks down the substrate into the products. Enzymes are specific to certain substrates

Question 2

Where are proteases found?

Answer 2

In the pancreas, stomach and the small intestine

Question 3

Where is amylase found?

Answer 3

In the salivary glands and the pancreatic fluid

Question 4

Where are lipases found?

Answer 4

In the pancreatic fluid and the small intestine

Question 5

Where is bile made and stored?

Answer 5

Bile is made in the liver and stored in the gall bladder

Question 6

Explain the role bile plays in the digestion of lipids

Answer 6

Bile emulsifies lipids, breaking down large insoluble lipid molecules into smaller ones, increasing their surface area, and the rate of lipid breakdown by lipase. Bile also provides the optimum pH for lipase to act

Question 7

Describe the role of bile in the small intestine

Answer 7

Bile is alkaline and neutralises stomach acid, creating alkaline conditions inside the small intestine, increasing the rate of lipid digestion by lipase

Question 8

What is a tissue?

Answer 8

A group of cells working together to perform a specific function

Question 9

What is an organ?

Answer 9

A group of tissue working together to perform a specific function

e.g. The stomach contains muscular and glandular
tissue

Question 9

What is an organ?

Answer 9

A group of tissue working together to perform a specific function

e.g. The stomach contains muscular and glandular
tissue

Question 10

What is digestion?

Answer 10

Large, insoluble molecules, being broken down into smaller, soluble molecules that can be absorbed into the bloodstream

Question 11

Describe and adaptation of the stomach

Answer 11

It contains HCL which helps to digest proteins

(idk if its an adaptation)

Question 12

How do muscles in the stomach aid digestion

Answer 12

The churning action of the muscles (peristalsis), turns the food into a fluid, increasing the surface area for enzymes to digest

Question 13

Describe and explain how the small intestine is adapted for digestion

Answer 13

• It’s around 5m and has a very large surface area for absorption of molecules produced by digestion
• The interior of the small intestine is covered in villi,
  which increases the surface area for absorption

Question 14

Describe how the villi are adapted for increasing the rate of diffusion and active transport of food molecules into the bloodstream

Answer 14

• Villi have a good blood supply, so the products of
  digestion are quickly removed by the bloodstream, maintaining a steep concentration gradient
• The villi have a thin membrane, ensuring that
  there is a short diffusion path
• Microvilli are located on the surface of each villus,
  further increasing the surface area, increasing the
  rate of absorption of food molecules

Question 15

How do enzymes function as biological catalysts?

Answer 15

• They lower the activation energy required to start
  the chemical reaction
• They destabilise bonds in the substrate making it
  more reactive

Question 16

What makes experiments repeatable?

Answer 16

If the original experimenter repeats the investigation using same method and equipment and obtains the same results

Question 17

Suggest why eating too much sugar can cause someone to become overweight

Answer 17

More sugar/energy is provided than used
(Stored as fat)

Question 18

Describe 2 adaptations that help the lungs to exchange O2

Answer 18

• Many alveoli
• large surface / area
• thin (exchange) surface or short diffusion pathway
• good blood supply / many capillaries

Question 19

Why is it necessary to break down proteins in the digestive system? (3)

Answer 19

• Proteins are large / product is small
• Proteins (may be) insoluble / product is soluble
• Cannot be absorbed / cannot enter blood or cannot pass
  through gut lining

Question 20

Describe the role of the Liver and the Pancreas in the digestion of fats

Answer 20

• Pancreas produces lipase
• Which breaks down / digests fats into fatty acids and
  glycerol
• Liver produces bile / hydrogen carbonate
• Which neutralises acids / makes alkaline
  provides optimum / best / most effective pH for lipase /
  enzyme action
• Bile emulsifies fats / description
  increasing the surface area for lipase / enzyme to act on