B3 - Principles of Organisation

Question 1

1. What are cells? ( 1 mark)

Answer 1

Cells are the basic building blocks of all living organisms

Question 2

1. What is a tissue? (1 mark)

Answer 2

A group of cells with similar structure and function

Question 3

1. What are organs? ( 1mark)

Answer 3

A group of tissues performing specific functions and working together

Question 4

1. What are organ systems? ( 1 mark)

Answer 4

A group of organs working together

Question 5

1. Put these in size order: (1 mark)

Answer 5

• Cell (smallest)
• Tissues
• Organ
• Organ System
• Organism (largest)

Question 6

6. What is the digestive system? (2 marks)

Answer 6

• It is an example of an organ system. It digests and absorb large molecules of food into smaller molecules of food.
• It is made of several organs which work together to digest and absorb food: mouth, salivary glands, oesophagus, stomach, small intestines, large intestines, rectum, anus, pancreas, liver and gall bladder.

Question 7

7. Name three digestive enzymes (3 marks)

Answer 7

• Amylase
• Protease
• Lipase

Question 8

. State where each of these enzymes are made, what they break down and the product made (14 marks)

Answer 8

Question 9

9. What is the role of digestive enzymes? (2 marks)

Answer 9

• To break down large molecules into smaller, soluble molecules
• That can be absorbed into the bloodstream

Question 10

How does the ‘lock and key’ model show how enzymes work? ( 3 marks)

Answer 10

• Substrate molecules are specific to the enzyme
• Like a key only fits one type of lock
• The substrate fits the active site of an enzyme as its shape fits perfectly

Question 11

What can the products of digestion be used for? ( 2 marks)

Answer 11

• Build new carbohydrates, lipids and proteins
• Some glucose is used in respiration

Question 12

List two factors that could change the shape of an enzyme (2 marks)

Answer 12

• High temperature
• High/Low pH

Question 13

. What does denatured mean?

Answer 13

Denatured is the change of the shape of the active site of an enzyme.

Question 14

. Describe the effect of a denatured enzyme on the rate of reaction.

Answer 14

When an enzyme is denatured, the rate of the reaction decreases and may eventually decrease to zero.

Question 15

15. What can the products of digestion be used for? (2 marks)

Answer 15

• Build new carbohydrates, lipids and proteins
• Some glucose is used in respiration

Question 16

. What is bile? (1 mark)

Answer 16

A green-yellow alkaline liquid

Question 17

17. Where is bile made? (1 mark)

Answer 17

In the liver

Question 18

. Where is bile stored? (1 mark)

Answer 18

In the gall bladder

Question 19

19. Describe the roles of bile in digestion? (4 marks)

Answer 19

• It neutralises hydrochloric acid coming from the stomach
• Emulsifies fat (breaks it up) to form small fat droplets
• This increases the surface area of the fat
• The alkaline conditions and large surface area speed up the breakdown of fat by lipase

Question 20

20. What is the main function of the digestive enzymes?

Answer 20

The digestive enzymes if to convert large food molecules like starch, lipids and proteins into small soluble substances

Question 21

21. Why does food need to be digested (broken down into small molecules)?

Answer 21

Food molecules are digested to allow absorption into the blood stream.

Question 22

. What is the pH of bile?

Answer 22

Bile is alkaline (a pH greater than pH7).

Question 23

25. What are the two functions of bile in digestive system?

Answer 23

Bile neutralises hydrochloric acid from the stomach.

Bile also emulsifies fat to form small droplets which increases the surface area.

Question 24

26. What is the effect of the large surface area and alkaline conditions created by bile?

Answer 24

The rate of lipid (fat) digestion by lipase is increased as a result of the large surface area and alkaline conditions created by bile.