Chapter 2 - Molecules Of Life

Question 1

Inorganic substances

Answer 1

Molecules without carbon atoms, such as water and minerals

Question 2

Organic substances

Answer 2

Molecules containing carbon atoms,
Four main groups: carbohydrates, lipids, proteins and nucleus acid

They are known as biomolecules too

Question 3

Importance of water

Answer 3

1. As a solvent to dissolve many substances in the body and act as a medium.

A. for chemical reactions in cells
B. in form of blood to transport nutrients

2. As a reactant

A. React with CO2 to produce sugars in photosynthesis
B. Hydrolyse food into simple forms
C. Activate enzymes

3. As a cooling agent to remove heat by evaporation

A. Sweating to regulate body temp. (Humans)
B. Transpiration to prevent overheating (plants)

4. As a supporting agent

A. Buoyancy (浮力)
B. Turgidity (膨脹度)

5. As a lubricant

A. Mucus
B. Synovial fluid

Question 4

Nitrogen ions

Answer 4

1. Synthesis of proteins in plants

2. Nucleic acids for heredity

Question 5

Magnesium ions

Answer 5

1. Chlorophyll for photosynthesis in plants

2. Biological energy ATP to support many biological processes insides cells, e.g. activation of enzymes

Question 6

Calcium ions

Answer 6

1. Component of bones and teeth
2. Component of cell walls in plants
3. Activator to control blood clotting, sending messages and muscle contraction

Question 7

Iron ions

Answer 7

1. Component of haemoglobin

Question 8

Phosphate

Answer 8

1. A component in teeth and bones

2. A component of phospholipid and nucleic acids for plants and animals

Question 9

Carbohydrates Cx (H2O)y

Ration of H atoms to oxygen atoms is 2 to 1

Answer 9

1. Glucose - main source of energy for cells

2.