Chapter 2.3

Question 1

What is productivity?

Answer 1

The rate at which an ecosystems producers capture and store energy with organic compounds over a certain length of time

Question 2

What is productivity measured in?

Answer 2

Energy per area, per year (J/m2/a)

Question 3

What does the rate of productivity depend on?

Answer 3

• The number of producers in an ecosystem
• the amount of light and ehat available
• The amount of rainfall a system recieves

Question 4

What is homeostasis?

Answer 4

Maintaining a state of balance or equilibrium

Question 5

How does a grizzly bear maintain homeostasis?

Answer 5

The cells of a grizzly bear converts ingested food into usable energy and ride the body of waste

Question 6

What is the Gaia Hypothesis?

Answer 6

A way of thinking about homeostasis that considers it on a global level. According to it the biosphere acts like an organism that self regulates itself. It needs constant input of energy and cycling of nutrients to keep balance

Question 7

What holds clues about the composition of the earths atmosphere?

Answer 7

Deposits of ancient microorganisms

Question 8

What was oxygen like in the ancient past?

Answer 8

Atmosphere lacked free oxygen and bacteria grew forming thick mounds in shallow bodies of water

Question 9

How did stromatolites form?

Answer 9

They formed in the past as microorganisms like bacteria died and the cells piled up and trapped sediments

Question 10

What is a characteristic of stromatolites?

Answer 10

They show bands of iron oxides that formed when iron ions combined with dissolved oxygen in oceans. These suggest that during this time oxygen levels in the ocean began to rise

Question 11

Why do some stromatolites not have iron bands?

Answer 11

They are less than 1.8 billion years old. This is because most of the iron ions in the ocean were already bound with iron oxide.

Question 12

What caused a sudden increase in atmospheric oxygen?

Answer 12

This was due to the activity of photosynthetic organisms

Question 13

What are dead zones?

Answer 13

Regions of lakes or oceans in which aquatic life has suffocated due to algal blooms

Question 14

What types of pollution can contribute to algal blooms?

Answer 14

• Nutrients in soil exposed by deforestation can be washed into rivers by rain
• Sewage that contains significant amounts of phosphate and nitrate
• Surface Runoff and snow melt carrying manure can add phosphate and nitrate to streams and rivers
• Runoff from fertilized agricultural fields