Human Digestion Y9

Question 1

What is the role of the mouth in the digestive system?

Answer 1

Mechanically breaks down food increasing the SA: Vol

Forms food into a bolus which can easily be swallowed

Question 2

What is the role of the salivary glands?

Answer 2

Produces saliva which is a mixture of the enzyme amylase, mucus and water.
(Amylase converts starch into maltose)

Question 3

What is the role of the Oesophagus?

Answer 3

Moves food down into the stomach by peristalsis

(The process which involves the rhythmic contraction of muscles to push food through the gut in one direction0

Question 4

What is the role of the Stomach?

Answer 4

Contains Pepsin which breaks down large proteins into small polypeptide chains
HCl which is produced is pH 2 which is the optimum pH for the enzyme pepsin
HCL also kills bacteria
The muscular wall of contracts, churning food ( a type of mechanical digestion) forming chyme

Question 5

What is the role of the Liver?

Answer 5

Produces Bile which has 2 functions
.Bile is alkaline which neutralises the acid chyme allowing the enzymes in the ileum to work at their optimum pH.
. Bile also emulsifies lipids to increase their SA: V. This increases the rate at which lipase can break down liquids

Question 6

What is the role of the Gall Bladder?

Answer 6

Where the Bile is stored

The Bile then passed down the Bile Duct to the food

Question 7

What is the role of the Pancreas?

Answer 7

Produces enzymes which then helps food digest in the duodenum (Optimum pH around 7)
Protease: Proteins and Polypeptides –> amino acids
Amylase: starch  maltose  Lipase: lipids  fatty acids and glycerol

Question 8

What is the role of the Ileum?

Answer 8

This is where digested food is absorbed via diffusion and active transport

Question 9

What is the role of the Colon?

Answer 9

Reabsorbs water via Osmosis

Question 10

What is the role of the Rectum?

Answer 10

Store faeces before expulsion

Question 11

What is the role of the Anus?

Answer 11

A muscle which regulates the release of faeces (egestion- this is the removal of undigested food)

Question 12

Adaptions of the ileum to digest food?

Answer 12

The small intestine is well adapted for absorption of small, soluble molecules into the blood  It is long (the ileum is 4m and the whole small intestine is about 7m)  Inner wall is covered with millions of tiny projections called villi which themselves are covered in microvilli. This increases the surface area  The wall of the villus is 1 cell thick to create a short diffusion pathway  The villi have are supplied with tiny blood vessels called capillaries. This helps maintain a steep concentration gradient.  This all helps increase the rate of diffusion  Each villus also contains a lacteal which allows large fat molecules to be absorbed into the lymphatic system.

Question 13

What is an enzyme an example of?

Answer 13

A protein

Question 14

What are enzymes known as and what does that mean?

Answer 14

They are known as biological catalysts. This means that they reduce the activation energy required for a reaction to take place which allows them to increase the rate of chemical reactions

Question 15

What is the region of an enzyme which contains a specific shape?

Answer 15

Active Site

Question 16

Why can one enzyme catalyse one specific reaction?

Answer 16

as the substrate must bind the active site for the reaction to take place.

Question 17

What are the 5 processes which take place in the digestive system?

Answer 17

Egestion
Ingestion
Digestion
Absorption
Assimilation

Question 18

What is Ingestion and how does it work?

Answer 18

When Food particles pass through the gut wall, by diffusion and active transport into the blood and lacteal.

Question 19

What is Digestion and how does it work?

Answer 19

The removal of undigested food

Question 20

What is absorption?

Answer 20

The intake of food

Question 21

What is Assimilation?

Answer 21

The chemical breakdown of food using enzymes from breaking large particles into smaller particles

Question 22

What is Egestion?

Answer 22

Using the food for the synthesis of new molecules for growth

Question 23

What parts of the body is involved for Ingestion?

Answer 23

Mouth, Stomach and Ileum

Question 24

What parts of the body is involved for Digestion?

Answer 24

Mouth

Question 25

What parts of the body is involved for Absorption?

Answer 25

All parts of the body

Question 26

What parts of the body involve Assimilation?

Answer 26

Anus

Question 27

What parts of the body involve Egestion?

Answer 27

Ileum and colon

Question 28

What are the four factors that affect the rate of Enzyme activity?

Answer 28

Temp, pH, enzyme conc and substrate conc