biology - chp 3 - the biosphere - powerpoint

Chapter 3

The Biosphere

Chapter 3

The Biosphere

Chapter 3

The Biosphere

3-1 What is Ecology

Objectives• Identify the levels of organization

that ecologists study

• Describe the methods used to study ecology

Ecology• The scientific study of interactions

among organisms and between their environment

Biosphere• The portion of the planet which all

life exists

Levels of Organization • To understand relationships within

the biosphere ecologists ask questions about events and organisms that range in complexity from single individuals to the entire biosphere

• Studies can focus on…

Species• A group of organisms similar to

one another that can breed together

Populations• Groups of individuals that belong

to the same species and live in the same area

Communities• Assemblages of different

populations that live in a particular place together with their non-living physical environment

Ecosystem• Collection of all the organisms

that live in a particular place, together with their non-living environment

Biome• A group of ecosystems that have

the same climate and similar dominant communities

Ecological Methods1. Observing

2. Experimentation

3. Modeling

3 – 2 Energy Flow

Objectives• Identify the source of energy for

life processes

• Trace the flow of energy through living systems

• Evaluate the efficiency of energy transfer among organisms in an ecosystem

Producers• Sunlight is the main energy

source for life on Earth

• Some types of organisms rely on the energy stored in organic chemical compounds

Producers (autotrophs)• Use energy from the environment

to make their own food

Ex.) plants, some algae, certain types of bacteria

Photosynthesis• Process that converts light

energy, carbon dioxide and water into oxygen, sugars and starches

Chemosynthesis• The process that converts

chemical energy into carbohydrates

Consumers (heterotrophs)• Organisms that rely on other

organisms for their energy and food supply

Herbivores• Eat plants

Carnivores• Eat animals

Detritivores• Feed on plant and animal remains

and other dead matter

Ex.) mites, earthworms, snails, crabs

Decomposers• Break down organic matter

• Ex.) fungi, bacteria

Feeding Relationships• Energy flows through an

ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers)

Food Chain• A series of steps in which

organisms transfer energy by eating or being eaten

Food Web• A network of complex interactions

formed by the feeding relationships among the various organisms in an ecosystem

Trophic Levels

• Each step in a food chain or food web

1st – Producers

2nd – 3rd or higher – consumers

• Each consumer depends on the trophic level below it for energy

Ecological Pyramid• A diagram that shows the relative

amounts of energy or matter contained within each trophic level in a food chain or food web

Energy Pyramid• A diagram that shows the relative

amounts of energy available of each level

• Only about 10% of energy available within one trophic level is transferred to organisms at the next trophic level

Biomass Pyramid• Represent the amount of food

available for each trophic level

biomass• The total amount of living tissue

within a given trophic level

Pyramid of numbers• Shows the relative number of

individual organisms at each trophic level

3 – 3 Cycles of Matter

Objectives• Describe how matter cycles among

the living and nonliving parts of an ecosystem

• Explain why nutrients are important in living systems

• Describe how the availability of nutrients affects the productivity of ecosystems

• Energy is crucial to an ecosystem, but organisms need more than that to survive

• They also need

• Water

• Minerals/nutrients

• Oxygen

• Carbon

• Nitrogen

• Phosphorus

Recycling in the Biosphere

• Unlike the one way flow of energy, matter is recycled within and between ecosystems

Evaporation• The process by which water

changes from liquid form to an atmospheric gas

Transpiration• The process by which water can

enter the atmosphere by evaporating from leaves of plants

Condensation• Forming Clouds

Precipitation• When water returns to the earths

surface

Nutrients• All the chemical substances that an

organism needs to live• Every living organism needs

nutrients to grow and carry out essential life functions. Like water; nutrients are passed between organisms and the environment through cycles

The Carbon cycle• There are 4 different kinds of

processes involved in the carbon cycle:

1. Biological processes

2. Geochemical processes

3. Mixed biogeochemical processes

4. Human activity

The Nitrogen Cycle• All organisms require nitrogen to

make amino acids, which in turn are used to build proteins

• Many different forms of nitrogen occur naturally in the biosphere

• Although nitrogen gas is the most abundant form of nitrogen on Earth, only certain types of bacteria can use this form directly

Nitrogen fixation• Process of converting nitrogen

gas into useful forms

The Phosphorus Cycle• Phosphorus is essential to living

organisms because it forms part of important life sustaining molecules such as DNA and RNA

• Unlike carbon, oxygen and nitrogen, phosphorus does not enter the atmosphere

• Phosphorus remains mostly on land in rock and soil minerals, and in ocean sediments

• As the rocks and sediments gradually wear down, phosphate is released

• Plants absorb phosphate then it moves to the rest of the ecosystem

Nutrient Limitation• Ecologists are often interested in

the primary productivity of an ecosystem

Primary Productivity• The rate at which organic matter

is created by producers

• If a nutrient is in short supply, it will limit an organisms growth

Limiting Nutrient• Single nutrient that either is

scarce or cycles very slowly, limiting the growth of organisms in an ecosystem