Chapter 3: Ecosystems: What are they and how do they work?

Question 1

Atmosphere (Air)

Answer 1

Envelopes the Earth, primarily made of nitrogen (78%) and oxygen (21%)

Question 2

Hydrosphere (Water)

Answer 2

All water on or near Earth’s surface. Only 2.5% is freshwater, with most being ice

Question 3

Geosphere (Earth)

Answer 3

Consists of rocks, minerals, and soil. It is the source of fossil fuels and essential minerals

Question 4

Biosphere (Life)

Answer 4

Parts of the atmosphere, hydrosphere, and geosphere where life exists

Question 5

Life on earth depends on three interconnected factors

Answer 5

1. Solar energy flow through biosphere (Greenhouse effect)
2. Nutrient cycling within the biosphere (Chemical cycling)
3. Gravity, which holds the atmosphere and enables nutrient cycling

Question 6

Ecosystems have 3 things

Answer 6

1. Producers (Autotrophs): Organisms like plants that produce their own nutrients through photosynthesis
2. Consumers (Heterotrophs): Organisms that consume other organisms for nutrients. They range from herbivores to carnivores
3. Decomposers: Break down waste and dead organisms, recycling nutrients

Question 7

Soil

Answer 7

A renewable resource, vital for plant growth, water purification and climate control. It is a mix of rock, mineral, organic matter, water, and living organisms. Can be unrenewable when used to much

Question 8

Food Chain

Answer 8

Energy flows through ecosystems from one feeding level to another

Question 9

Pyramid of Energy Flow

Answer 9

Every use and transfer of energy involves a loss of some high quality energy

Question 10

Trophic Levels

Answer 10

Each feeding level in an ecosystem

Question 11

Food web

Answer 11

Organisms in most ecosystem form a complex network or interconnected food chains

Question 12

Gross Primary Productivity (GPP)

Answer 12

Rate of energy conversion by producers

Question 13

Net Primary Productivity (NPP)

Answer 13

Energy stored by producers after accounting for energy used in respiration. Limits the number of consumers that can survive on earth

Question 14

Water Cycle

Answer 14

Driven by the sun, it involves evaporation, precipitation and groundwater flow

Question 15

Humans alter the water cycle in three ways

Answer 15

1. Withdrawing freshwater from rivers, lakes and aquifers at rates faster than the natural process can replace it
2. Clear vegetation from land for agriculture, mining and road building
3. We drain and fill wetlands for farming and urban development

Question 16

Carbon Cycle

Answer 16

Balances carbon dioxide together with water vapor from the water cycle through photosynthesis and respiration

Question 17

Nitrogen Cycle

Answer 17

Converts atmospheric nitrogen into usable forms for plants

Question 18

Phosphorus Cylce

Answer 18

Slow cycle where phosphorus moves from rocks to soil to living organisms. Phosphorus is a nutrient

Question 19

To learn about ecosystems, scientists use a combination of 3 things

Answer 19

1. Field Research: Direct observation and study in natural environments
2. Laboratory Research: Controlled experiments in lab settings
3. Models: Mathematical and other simulations to predict ecosystem behavior