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Unit 2.2

The Biosphere

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Biosphere

• Outer layer of the earth

• Capable of supporting life

• Includes the physical environment in which all life lives

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Why Life on Earth?

• Water – essential in chemical reactions• Steady supply of energy from the sun• Suitable temperature range (distance from the

sun)• Stabilizing moon with a high mass relative to the

mother planet (unique in our solar system)• Organic & inorganic elements available• Gaseous atmosphere• Gravity strong enough to hold atmosphere

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Biosphere

• Atmosphere– Gaseous component

• Lithosphere– Rocky component

• Hydrosphere– Water component

• Magnetosphere– Magnetic field

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Atmosphere

• Nitrogen 78%• Oxygen 21%• Carbon Dioxide .03%• Water vapor• Ozone layer

– Reflects harmful ultraviolet light

Atmosphere• N2 is inert and non-

reactive • It is the byproduct of the

photolysis of ammonia from volcanoes over the eons

• Thus, it has accumulated over time

• Other gas components are the result of biochemical processes or have been here since the creation of the earth

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Plants and Algae Produce Oxygen & Sequester CO2

• Photosynthesis traps carbon by converting it into biomass and releases oxygen for respiration

• 6CO2 + 6H20 = C6H12O6 + 6O2

• Some sugars are utilized during respiration and that CO2 is released back into the atmosphere

• Other sugars are converted into biomass that is buried underground or falls to the bottom of the ocean

Global Warming

Magnetosphere• Magnetic field provides protection from the

radiation and plasma that comprises solar wind.• Without the magnetic field, DNA would be

severely damaged and life may cease to exist

Polar Magnetic Shift• The earth’s magnetic field has shifted ~180’ an average

of 4 times every 1,000,000 years for the last 15 million years

• Each shift may last from 1,000 to 28,000 years and the time between shifts may vary greatly

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Polar Magnetic Shift• This was discovered in

the 1950’s while studying the Mid-Atlantic Ridge

• Iron oxides in lava align themselves with the earth’s magnetic field before hardening and locking into place

• Able to measure orientation and distance from ridge to determine shift history

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Lithosphere• Source of minerals for

living organisms• Lighter continental plates

“float” over the denser oceanic plates

• Subduction zones occur in areas where oceanic & continental plates meet

• Mountains arise from areas where two continental plates have collided

Subduction

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Hydrosphere

• Water is essential for life– Solvent to dissolve

chemicals– Needed for chemical

reactions– Resists temp changes– Low viscosity

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Ice Floats• Allows life to exist in water

under the ice during the winter

• During its liquid phase, water molecules will pull closely to each other due to hydrogen bonds

• During its solid phase, the water molecules will arrange in a less dense crystal lattice framework and float on top of the liquid water

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Biome

• Major biotic area with certain defining characteristics and plant & animal life uniquely adapted to that type of area– Climate– Plant life– Animal life

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Savanna

Rainforest

AlpineDesert

Chaparral

GrasslandsTundra

Taiga

Deciduous Forest

Tundra• Average annual temp is -

18° F (-28° C) but may range from -94° F (-70° C) in the winter to 54° F (12° C) in the summer

• Very windy year round• Carbon sink – it takes in

more carbon than is released due to permafrost trapping dead material instead of allowing it to decompose

Tundra• Vegetation consists of

grasses, shrubs, mosses, & lichens

• Animals include shrews, hares, rodents, wolves, foxes, bears, & deer

• Very fragile environment that takes a long time to repair – footprints may be visible for years

Taiga• Boreal (needleleaf)

evergreen forests of Canada and Siberia

• Cold, snowy winters with warm, humid, & rainy summers

• The winter temperature range is -54 to -1° C (-65 to 30° F)

• The summer temperature range is -7° C (20° F) to 21° C (70° F)

Taiga• Plants include some

lichens & mosses, but are primarily carboniferous trees such as pine, spruce, hemlock, & fir trees

• Animals include lynx, bobcats, weasels, wolverines, deer, elk, & moose

• Many birds migrate to taigas to feed & breed in the summertime, but fly south again for the winter

Grasslands• Found in the middle

latitudes in the interiors of continents

• Consist of large rolling terrains of grasses, herbs, and flowers

• Erratic precipitation creates conditions where drought & fires keep larger trees from growing

Steppe Grasslands

• Very low humidity due to distance from oceans and close proximity to mountains

• Usually found between deserts and mountains

• Steppes have warm summers and very cold winters

Prairie Grasslands

• Decreasing rainfall as you move from east to west

• Hot summers and cold winters

• Prone to fires due to periodic drought and seemingly constant high winds

Pampas Grasslands• More humid and warmer

year round than other types of grasslands

• Dry season in the summer and a wet season during the relatively mild winters

• Deep soil and more friendly climate create one of the richest grazing areas in the world

Deciduous Forest• The average annual

temperature in a deciduous forest is 50° F

• The average rainfall is 30 to 60 inches a year.

• The deciduous forest has four distinct seasons

• The animals adapt to the climate by hibernating in the winter and living off the land in the other three seasons.

Deciduous Forest• Plant life includes broad,

leafy trees like oak, beech, maple, walnut, etc., as well as smaller leafy plants like mountain laurel and azaleas under the main canopy

• Animals include white-tail deer, black bears, pandas, weasels, squirrels, etc…things with which we are familiar

Chaparral• Chaparral is

characterized as being very hot and dry.

• Winter is very mild and is usually about 10 °C.

• Summer is so hot and dry at 40 °C that fires and droughts are very common.

• Most of the plants have small, hard leaves which hold moisture

Chaparral• Plants include poison

oak, scrub oak, Yucca Wiple and other shrubs, trees, and cacti.

• The animals are all mainly grassland and desert types adapted to hot, dry weather

• These animals include coyotes, jack rabbits, mule deer, alligator lizards, horned toads, praying mantis, honey bee and ladybugs.

Deserts• Deserts cover about

one fifth of the Earth's land surface. Most deserts are near the Tropic of Cancer or the Tropic of Capricorn.

• Desert temperatures may range from 5 to 50° C in a single day

• Rainfall usually averages out to under 15 cm a year

Deserts

• Desert plants include Turpentine Bush, Prickly Pears, Cacti, and Brittle Bush

• Animals include armadillo lizards, Gila monsters, coyotes, desert kangaroo rats, and horned vipers

Savanna• Savannas are rolling

grasslands, with scattered trees & scrubs, that are located between tropical rainforest and desert biomes.

• Savannas are hot year round with a long, dry season in the winter and a shorter, wet season in the summer

• Savannas in Australia are wetter and are considered to be tropical savannas

Savanna

• The best known plants in savannas other than grasses are acacia trees. These are replaced by eucalyptus trees in the Australian tropical savannas

• Primary animals include large ungulates like wildebeest, rhinos, & antelope and large carnivores like lions, cheetahs, and hyenas

Tropical Rainforest• The temp in a rain forest

rarely gets > than 93 °F (34 °C) or < 68 °F (20 °C)

• An average of 50 - 260 inches (125 - 660 cm) of rain falls yearly.

• Though rainforests now cover < 6% of Earth's land surface, scientists estimate that more >1/2 of all the world's plant and animal species live there

Tropical Rainforest• Many of the trees have

straight trunks that don't branch out for 100 feet or more

• The majority of the trees have smooth, thin bark because there is no need to protect the them from water loss and freezing temperatures

• Different areas of the same rain forest may have completely different species of plant life

Tropical Rainforest• About 1/4 of all the medicines we

use come from rainforest plants. • Curare comes from a tropical

vine, and is used as an anesthetic and to relax muscles during surgery.

• Quinine, from the cinchona tree, is used to treat malaria.

• A person with lymphocytic leukemia has a 99% chance that the disease will go into remission because of the rosy periwinkle.

• More than 1,400 varieties of tropical plants are thought to be potential cures for cancer.

Tropical Rainforest

• Common characteristics found among many animals include adaptations to life in the trees

• Other characteristics are bright colors and sharp patterns, loud vocalizations, and diets heavy on fruits.

• Insects make up the largest single group of animals that live in tropical forests. They include brightly colored butterflies, mosquitoes, camouflaged stick insects, and huge colonies of ants.

Alpine

• Alpine biomes are found in the mountain regions all around the world.

• They are usually at an altitude of about 10,000 feet or more

• In the summer average temperatures range from 10 to 15° C . In the winter the temperatures are below freezing

• Rainfall may be as low as is seen in desert biomes

Alpine• Because of the cold and wind,

most plants are small perennial groundcover plants which grow and reproduce slowly

• Alpine animals have to deal with 3 types of problems: the cold temperatures, low oxygen, & too much UV radiation

• Animals will tend to have shorter legs, tails, and ears to reduce heat loss. Alpine animals also have larger lungs, more blood cells, and higher hemoglobin levels because of the decrease of pressure and lack of oxygen at higher altitudes.

Alpine• Allen’s Rule:

Endotherms from colder climates usually have shorter limbs than equivalent animals in warmer climates

• Bergmann’s Rule: Within a species, body mass increases with latitude and elevation

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Allen’s Rule

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Ocean Biome• Salt water covers ~70% of

the earth’s surface making it the largest biome on the planet

• Life originated in the oceans ~3 bya

• Presently home to more diverse & abundant life forms than any other biome

• Divided into 2 major zones

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Ocean Biome• Photic zone – depth in

which there is still enough light penetration to carry out photosynthesis

• Light penetration must be >1% of surface intensity

• Varies depending on turbidity of the water

• ~90% of all marine life is found in the photic zone

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Ocean Biome• Aphotic zone – area below

the point at which <1% of light penetrates the water

• All food that aphotic creatures consume ultimately comes from shallower waters – hydrothermal vents are an exception

• Bioluminescence is the only light found in this biome

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Freshwater Biome

• Defined as an aquatic biome in which the salinity is <1%

• Extremely important to terrestrial life in all other biomes as most land animals must ingest a certain amount of freshwater to survive

• Divided into 3 major categories

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Freshwater Biome

• Streams & Rivers• Flow in a single

direction from headwaters to mouth

• As waters head towards the mouth of the river, flow rate, dissolved oxygen, & species diversity decrease while turbidity, width, & temperature increase

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Freshwater Biome

• Wetlands• Areas of standing

water that support aquatic plants; marshes, swamps, bogs, & mangroves

• Most productive ecosystems on the planet

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Freshwater Biome• Ponds & Lakes• Very greatly in size,

etymology, and geographical distribution

• Divided into 3 regions: littoral, limnetic, & profundal zones

• Water usually becomes stratified in the summer & winter and mixes in the spring & fall

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Lake Turnover

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Eutrophication• Process by which the

nutrient content of a lake is increased

• Causes an increase in primary productivity resulting in algal blooms

• May be harmful to many organisms due to anoxia and toxic byproducts

• Increases rate of lake aging

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