Chapter 1 - Conditions for Life on Earth

Question 1

Define: Physiological Function

Answer 1

Any substance that is involved in chemical reactions in a living organism has a physiological function.

Question 2

Define: Specific Heat Capacity

Answer 2

The measure of the amount of heat energy needed to heat up a particular mass of a material through a particular temperature rise. Water has a high specific heat capacity so it heats up and cools down slowly and has an important role in moderating climatic fluctuations.

Question 3

Define: Thermophilic

Answer 3

Heat-loving, such as the bacteria that live around hot volcanic vents and springs.

Question 4

Define: Ambient Gases

Answer 4

The surrounding environmental gases that are available to organisms.

Question 5

Define: Atmosphere

Answer 5

The gases surrounding the Earth. Different layers are characterised by their temperature, density, turbulence and composition.

Question 6

Define: Photolysis

Answer 6

The splitting of molecules by light, including the splitting of water molecules in the early atmosphere, producing oxygen.

Question 7

Define: Greenhouse Gas

Answer 7

A gas that absorbs infrared radiation and causes atmospheric heating.

Question 8

Define: Transpiration

Answer 8

The loss of water by evaporation from the stomata of leaves.

Question 9

Define: Biosphere

Answer 9

All the living organisms on Earth.

Question 10

Define: Hydrosphere

Answer 10

All the water on Earth, found solid, liquid or gaseous form in a variety of reservoirs, including the oceans, ice caps, rivers and lakes, soil, groundwater, atmosphere and living organisms.

Question 11

Define: Lithosphere

Answer 11

The relatively hard outer layer of the Earth, consisting of the crust and upper layer of the mantle.

Question 12

What are the main functions and processes of large amounts of water for living organisms?

Answer 12

Physiological Solvent (Chemical reactions in cells)
Transport (Oxygen, Carbon Dioxide, Sugars, Amino Acids, Waste Products, Mineral Nutrients etc.)
Temperature Control (Sweat cools the body)
Anomalous Expansion (Ice prevents cold air separate from water)
High Specific Heat Capacity (warm up and cool down slowly)
Provision of Aquatic Habitats (Rivers, lakes and oceans)

Question 13

Why is the temperature range found on Earth suitable for the survival of living organisms?

Answer 13

• Most areas have temperatures above zero degrees allowing liquid water to be present. (0 - 40 degrees)
• Thermophilic Bacteria can withstand higher temperatures. (Above 80 degrees)

Question 14

State two suitable ambient gases for developing and sustaining life.

Answer 14

Carbon Dioxide (Photosynthesis, climate control)
Nitrogen (Protein synthesis)

Question 15

What conditions are the result of the position of the Earth in the Solar System?

Answer 15

Distance from the Sun (Controls light levels and temperatures)
Daily Rotation (Controls the duration of day and night)
Tilted Axis (Produces seasonal variations)
Molten layers beneath the crust (Produce the Earth’s magnetic field)

Question 16

What conditions are the result of features of the Earth itself?

Answer 16

Sunlight (Provides the energy for photosynthesis)
Heat production when absorbed (Source of energy for the water cycle)
Little harmful Ultraviolet (UV) and ionising radiation