Digestion and enzymes

Question 1

Define digestion

Answer 1

The breakdown of large insoluble food molecules into small soluble food molecules by chemical and physical means

Question 2

State an enzyme found in saliva

Answer 2

Amylase

Question 3

State two examples of physical digestion

Answer 3

Teeth and churning of food in the stomach

Question 4

Describe how food moves down the oesophagus

Answer 4

Peristalsis occurs. This means that there is muscular contraction behind the bolus of food (and relaxation in front) pushing the food down

Question 5

State the enzyme found in the stomach

Answer 5

Pepsin (a protease which breaks down protein)

Question 6

State the enzyme found in the first part of the small intestine

Answer 6

Amylase (secreted from the pancreas)
Trypsin (secreted from the pancreas)

Question 7

State the role of the small intestine

Answer 7

Digestion of food (in the first part) and then absorption of nutrients into the blood

Question 8

State the role of the liver in digestion.

Answer 8

Produce bile. This is stored in the gall bladder before being secreted into the small intestine to neutralise stomach acid and emulsify fats.

Question 9

State the role of the large intestine

Answer 9

Absorb water by osmosis

Question 10

Define enzyme

Answer 10

Protein biological catalayst that speeds up chemical reactions by lowering the activation energy.

Question 11

Describe the active site of an enzyme

Answer 11

Specific and complementary in terms of shape and charge to the substrate. This means that the substrate can attach and enzyme-substrate complexes can form.

Question 12

Explain why the rate of reaction is low for an enzyme at 5 degrees (very below optimum).

Answer 12

Because the enzyme is inactive.
Then there will be less kinetic energy and successful collisions leading to less enzyme-substrate complexes forming.
Therefore less product produced and a slower rate of reaction.

Question 13

Explain why the rate of reaction is highest for an enzyme at it’s peak.

Answer 13

Because the enzyme is at it’s optimum.
Then there will be the most successful collisions and the most enzyme-substrate complexes forming
Therefore the most products produced and the fastest rate of reaction.

Question 14

Explain why the rate of reaction is lowest for an enzyme way above it’s optimum.

Answer 14

Because the enzyme is denatured.
Then the 3D structure of the active site of the enzyme has changed is no longer specific and complementary in terms of shape and charge to the susbtrate and less enzyme-susbtrate complexes form.
Therefore the least products produced and the lowest rate of reaction.

Question 15

Define absorption

Answer 15

the movement of digested food molecules into the blood or lymph.

Question 16

Define assimilation

Answer 16

the movement of digested food molecules into the cells of the body where they are used or become part of the cell.

Question 17

Define excretion

Answer 17

the process of eliminating or expelling waste matter

Question 18

State the organs of the excretory system

Answer 18

X2 Kidneys
Ureter
Bladder
Urethra

Question 19

Describe the function of the bowman’s capsule

Answer 19

Filters the blood. This means that water and small molecules can pass into the proximal convoluted tubule. Large proteins and blood cells stay behind.

Question 20

Describe the function of the proximal convoluted tubule

Answer 20

Reabsorption of ions. This means that glucose, specific ions, and amino acids are reabsorbed into
capillaries by active transport.

Question 21

Describe the function of the Loop of Henle

Answer 21

Reabsorption of water. This means that the ascending limb actively pumps ions out of the tubule.
This makes the tissue around the descending limb highly concentrated, so water exits.

Question 22

Describe the function of the Distal convoluted tubule

Answer 22

Selective reabsorption. This means that more active transport of ions out, so that water follows based on requirements and water needs.

Question 23

Outline how urine leaves the body from the kidney

Answer 23

The urine goes through the ureter (TO)

which takes the urine TO the bladder.

The urine then leaves the body through the urethra.

Question 24

State the function of bile

Answer 24

Emulsify fats

Question 25

State what the liver produces that is stored in the gall bladder

Answer 25

Bile