The

Biosphere

What is the Biosphere?

• Combined portions of

the planet in which all

of life exists,

including land, water

and atmosphere

• Extends from 8-km

above Earth’s surface

to 11-km below the

surface of the ocean.

Levels of Organizations

• Species

– Group of organisms so

similar to one another that

they can breed and

produce fertile offspring

• Population

– A group of individuals that

belong to the same species

and live in the same area

• Community

– All the different populations

that live together in a defined

area

• Ecosystem

– Collection of all the organisms

that live in a particular place,

together with their nonliving

environment

• Biome

– A group of ecosystems that

have the same climate and

dominant communities

Ecosystems

• Influenced by a

combination of

Biological and

Physical Factors

• Depend on biotic

factors and abiotic

factors

Biotic vs. Abiotic

• Biotic Factors

– The biological influences

on organisms within an

ecosystem

– Ex: birds, trees,

mushrooms, and bacteria

• Abiotic Factors

– Physical or nonliving

factors that shape

ecosystems

– Ex: temperature,

precipitation, humidity,

wind, nutrient

availability, soil type,

and sun light

What is a Biome?

• Areas that have

distinctive

climates and

organisms

What are the Major Land Biomes?

• Tropical Rain Forest

• Temperate Forest

• Taiga

• Savanna

• Temperate Grassland

• Chaparral

• Desert

• Tundra

• Mountain

How are Biomes Named?

• According to their

plant life

• Plant life

determine which

organisms live

there

Organisms in Biomes

• Plants & animals

have adapted to

specific

environments

• Threatened by

human activities

Water Ecosystems

• Either Freshwater or

Marine

– Freshwater = no salt

– Marine = salt water

Freshwater Ecosystems

• Includes lakes, ponds,

rivers, streams and

wetlands

• Distinguished by:

– Depth of the water

– How fast the water

moves

– Availability of mineral

nutrients, sunlight, and

oxygen

Marine Ecosystem

• Identified by the

presence of salt

water

• Includes estuaries,

coral reefs, oceans

and ice caps

What is Biodiversity?

• Term used to

indicate the number

and diversity of

species on Earth

• There are now an

estimated 13 million

species of living

organisms

Why is Biodiversity important? • Earth’s greatest natural

resource

• Species of many kinds

have provided us with:

– Food: beef, chicken,

salad

– Industrial Products:

paper, rubber

– Medicines: painkillers,

antibiotics, anticancer

drugs

What effects Population?

•Limiting factors are

resources or other factors

in the environment that

can lower the population

growth rate.

•The carrying capacity (K) is

the maximum population

size that can be supported

in a particular area without

destroying the habitat.

Limiting Factors •Limiting factors include a low food supply and a lack of

space.

•Limiting factors can lower birth rates, increase death

rates, or lead to emigration.

Carrying Capacity

•Limiting factors determine the carrying capacity of a

population.

•When organisms face limiting factors, they show logistic

growth.

•When there are no limiting factors, the population grows

exponentially.

Genetic Diversity •The total number of genetic characteristics in a

given population

•These variations serve as a way for a population

to adapt to changing environment.

•Greater variation increases the chance that

some individuals of that population will possess

variations that are suited to the new

environment.

–They’ll live and pass on those traits to the

next generation, preventing extinction of their

species!

Imagine:

•One individual has a mutation that makes it darker color

than the rest of the population.

•After a volcanic eruption, so the cover is no longer pale

yellow, but a dark.

•The darker individual will then survive in the new

environment and reproduce more than the other

individuals, passing on “dark color” genes to the next

generation.

Variation in an Ecosystem

•Every organism has a role

to play in its environment.

•This role, which includes

where it lives in the

environment, what it uses,

what it eats, and who eats

it, is called its niche.

•No two species can ever

share the SAME niche.

Variation in an Ecosystem

•When a species is lost in a

diverse ecosystem, then

another species may take

over its role…

•Or all the organisms that

depend on it may die if

there is not a diversity of

organisms already in that

ecosystem.

•But it takes a LONG time.

How can humans reduce biodiversity?

• Altering habitats

• Hunting species to

extinction

• Introducing toxic

compounds into food

webs

• Introducing foreign

species to new

environment

Loss of Biodiversity

•The greatest threat to biodiversity is habitat loss.

•Habitats (places where organisms live) are “lost” due to

land use changes

–Agriculture

–Urbanization

Habitat Alteration

• When land is developed,

natural habitat may be

destroyed

• Habitats supply

organisms what they

need

• Habitat destroyed means

that organisms will die

• Ex: Florida Panther

Introduced Species

• Invasive Species

– Non-native animals that

thrive in new territory

where they are free of

predators, diseases, or

resources limitations that

may have controlled

their population in their

native habitat

• Can cause the extinction

of native species

• Ex: Pythons in Florida

Extinction

• Occurs when a species

disappears from all or part

of its range

• Caused by habitat

destruction, introduced

species, and hunting

• Endangered Species

– If a species numbers have

fallen so low that it is likely

to become extinct

Endangered Species Act

• Began in 1973

• Protect plants and

animals near extinction

• Protect the land where

the organism lives

• Helps to increase

populations that are in

danger of extinction

Nutrient Cycles

• https://www.youtube.com/watch?v=A98S-BqP4Po

•A biogeochemical cycle is a pathway by which a

chemical substances moves through both biotic

(biosphere) and abiotic (lithosphere, atmosphere, and

hydrosphere) compartments of Earth.

•Water, for example is recycled through the water cycle

The Carbon Cycle

•Carbon is one of the most common elements found in

living organisms. Carbon is constantly cycling between

living organisms and the atmosphere through:

–photosynthesis

–cellular respiration

–burning of fossil fuels.

•Global Climate Change

occurs when more carbon

dioxide, a greenhouse

gas, is released into the

atmosphere than can be

used for photosynthesis.

The Nitrogen Cycle •Nitrogen is one of the most common elements in living

organisms. It is important for creating proteins and

nucleic acids, like DNA.

•The air that we breathe is mostly nitrogen gas, but

unfortunately animals and plants cannot use the

nitrogen when it is a gas.

–In order for plants to make use of nitrogen, it must

be transformed into molecules they can use by:

lightning, nitrogen fixation by bacteria, or

decomposition.

–Nitrogen can be turned back into a gas by bacteria

through denitrification.

The Nitrogen Cycle •Humans cause acid rain by burning fossil fuels

releasing nitrogen gasses into the atmosphere.

Energy Flow

•Ecosystems maintain themselves by cycling nutrients and

transferring energy.

•Most ecosystems depend on sunlight as the main energy

source. The first step trophic level uses solar energy to

produce chemical energy through photosynthesis. On

average, only about 10 percent of net energy produced at

one trophic level is passed on to the next.

What Eats What in an Ecosystem

• Producers

– Makes its own food

– Plants, trees, algae

• Consumers

– Gets energy by eating

other organisms

– Animals

• Herbivore

– Eats only producers

– Cows, sheep, deer,

grasshoppers

• Carnivores

– Eats only other

consumers

– Lions, hawks, spiders

• Omnivore

– Eats both producers and

consumers

– Bears, pigs, humans

What is a Food Chain

• A sequence in which

energy is transferred

from one organism to

the next as each

organism eats

another

What is a Food Web?

• A group of

interrelated food

chains

• No one path

• Shows feeding

relationships in an

ecosystem

What is a Trophic Level?

• Each step in the transfer

of energy through an

ecosystem

• Each time energy is

transferred, less of it is

available to organisms

at the next trophic level

• Producer→ Primary Consumers→ Secondary Consumers→ Tertiary Consumers