Digestive System.

Question 1

What is a tissue?

Answer 1

A group of cells with a similar structure and function.

Question 2

What is an organ?

Answer 2

A group of tissues working together for a specific function.

Question 3

What is an organ system?

Answer 3

Organs are grouped into organ systems which work together to form organisms.

Question 4

What are the three main nutrients that food contains?

Answer 4

Carbohydrase
Protein
Lipase

Question 5

Why cant large molecules be absorbed into the bloodstream?

Answer 5

They are too large, so they need to be digested.

Question 6

What breaks down larger food molecules into smaller food molecules?

Answer 6

Enzymes.

Question 7

Process of Digestion? (10 steps)

Answer 7

1.First food is chewed in the mouth and enzymes in the saliva begin to digest the starch into smaller sugar molecules.
2.The food passes down the oesophagus into the stomach. In the stomach enzymes begin the digestion of proteins.
3.The churning action of the stomach muscles turn the food into a fluid increasing the surface are for enzymes to digest. (Fluid passes into the small intestine)
4.Chemicals are released into the small intestine from the liver and pancreas.
5.Pancreas releases enzymes to continue the digestion of starch and protein. They also start the digestion of lipids.
6.The liver releases bile which helps speed up the digestion of lipids. Bile neutralises the stomach acid.
7.The walls of the small intestine release enzymes to continue the digestion of proteins and lipids.
8.In the small intestine the small food molecules produced by digestion are absorbed into the bloodstream by diffusion or active transport.
9.Now the fluid makes its way to the large intestine where water is absorbed into the bloodstream.
10.Finally the faeces are released from the body.

Question 8

What is Hydrochloric acid? Where is it found?

Answer 8

It is stomach acid found in the stomach and it helps enzymes to digest proteins.

Question 9

Function of bile and where its found.

Answer 9

Found in the liver.
Neutralises the stomach acid.
Speeds up the digestion of lipids.

Question 10

The small food molecules are absorbed into the bloodstream by which two processes?

Answer 10

Active transport
Diffusion

Question 11

What is the glucose used in?

Answer 11

Respiration

Question 12

What is a catalyst?

Answer 12

It is an enzyme, and it speeds up chemical reactions.

Question 13

Where is the active site found?

Answer 13

On the surface of the enzyme.

Question 14

Where does the substrate attach to?

Answer 14

The active site.

Question 15

What breaks down proteins?

Answer 15

The enzymes called protease.

Question 16

Where are protease found?

Answer 16

In the stomach, pancreas and small intestine.

Question 17

What are proteins?

Answer 17

Long chains of chemicals called amino acids.

Question 18

What does starch contain?

Answer 18

A chain of glucose molecules.

Question 19

What breaks down carbohydrates?

Answer 19

Carbohydrase and in the case of starch it is called amylase.

Question 20

What is produced when carbohydrates are digestes?

Answer 20

Simple sugars.

Question 21

Where is amylase found?

Answer 21

The saliva and pancreatic fluid.

Question 22

What are lipid molecules digested by?

Answer 22

Lipase

Question 23

Where is lipase found?

Answer 23

The pancreatic fluid and small intestine

Question 24

What happens to enzymes when the temperature is increased?

Answer 24

The activity of the enzyme increases. (Reaction gets faster)
The enzyme and substrate are moving faster so there are more collisions per second between the substrate and the active site.

Question 25

What is the optimum temperature?

Answer 25

Where the enzyme is working at the fastest possible rate.

Question 26

What is the optimum temperature for most human enzymes?

Answer 26

37 degrees Celsius.

Question 27

What happens if we increase the temperature past the optimum?

Answer 27

The activity of the enzyme decreases to zero.

Question 28

What happens to the enzyme when the substrate no longer fits into the active site perfectly?

Answer 28

It denatures.

Question 29

What happens if we make the pH more acidic/alkaline?

Answer 29

The activity drops to zero.

Question 30

What pH do protease enzymes work better at?

Answer 30

An acidic pH

Question 31

What pH do lipase enzymes work better at?

Answer 31

An alkaline pH.

Question 32

What does amylase break starch molecules into?

Answer 32

Simple sugars.

Question 33

Practical Enzymes pH/Temperature

Answer 33

1.Place one drop of iodine solution into each well of a spotting tile. 2.Get three test tubes and in the first one add 2cm^3 of starch solution. In the second test tube add 2cm^3 of amylase solution. In the third tube add 2cm^3 pH 5 buffer solution. 3.Place all three test tubes in a water bath at 30 degrees Celsius. Leave for 10 minutes to allow the solutions to reach the correct temperature. 4.Now combine the three solutions into one test tube and mix with a stirring rod to transfer one drop of solution to a well in the spotting tile which contains iodine. 5.After 30 seconds use the stirring rod to transfer one drop of solution to a well in the spotting tile which contains iodine. 6.The iodine should turn blue/black if starch is present. 7.Now take the sample every 30 seconds until the iodine remains orange. 8.When the iodine remains orange this means that starch is no longer present and the reaction has completed. 9.We now repeat the experiment several times using different pH buffers.

Question 34

Adaptation of the small intestine?

Answer 34

Large surface area for the absorption of the products of digestion.

Question 35

What is the interior of the small intestine covered with?

Answer 35

Villi.

Question 36

What does villi do?

Answer 36

Increases the surface area for the absorption of molecules.

Question 37

What do microvilli do?

Answer 37

They increase the surface area even further.

Question 38

Adaptation of the villi?

Answer 38

1.Good blood supply so the bloodstream rapidly removes the product of digestion. This increases the concentration gradient. 2.Thin membrane which ensures a short diffusion path.

Question 39

What are molecules that cant be absorbed by diffusion absorbed by?

Answer 39

Active transport.