Capt Review

Review of Some Important Topics

1 Energy Uses in CT

• Energy is used everyday to heat and light our homes, schools and business

• Where does this energy come from?

Energy Sources

• Nuclear• Hydroelectric• Coal• Natural gas• Biomass

– Wood/waste/plant material

Nuclear power How does it work?

The reactor uses Uranium rods as fuel, and the heat is generated by nuclear fission

Nuclear powerAdvantages• Does not pollute the air -• Small solid waste generation (during normal operation) • Low fuel costs - because so little fuel is needed • Large fuel reserves - again, because so little fuel is needed • No green house gas emissions

Disadvantages :• Risk of major accidents • Nuclear waste - high level radioactive waste produced can remain dangerous for

thousands of years. • Plutonium produced from nuclear reactions can be used to make nuclear

bombs,) • High initial costs • High energy inputs during construction (equivalent to ~7 years power output) • High maintenance costs • Security concerns • High cost of decommissioning plants • Thermal pollution

Hydroelectric PowerHow it works

• A dam is built to trap water, usually in a valley where there is an existing lake.

• Water is allowed to flow through tunnels in the dam, to turn turbines and thus drive generators.

Advantages and Disadvantages

• Advantages – Once the dam is built, the energy is virtually free. – No waste or pollution produced.– Much more reliable than wind, solar or wave power. – Water can be stored above the dam ready to cope with peaks in demand.– Hydro-electric power stations can increase to full power very quickly, unlike other

power stations. – Electricity can be generated constantly

• Disadvantages– The dams are very expensive to build.– However, many dams are also used for flood control or irrigation, so building costs

can be shared. – Building a large dam will flood a very large area upstream, causing problems for

animals that used to live there. – Finding a suitable site can be difficult - the impact on residents and the environment

may be unacceptable. – Water quality and quantity downstream can be affected, which can have an impact on

plant life.

Coal PowerHow it works

• Coal is mined out of the ground • Used for heating when burned

– Homes and industries• Used in power plants

– Coal burned to produce heat– Heat turns water into steam– Steam powers generators– Produces electricity

• Or turned into gas

Advantages and Disadvantages of Coal

• Advantages – Large resource base– Relatively cheap to mine – Inexpensive to transport by rail

• Disadvantages– When burned more CO2 emissions than other fuel– Mining above ground ruins the environment– Mining underground is dangerous

Energy from Waste

High energy crops grown to be used as fuelAdvantages• Every gallon of biofuels used reduces the hazard of

toxic petroleum product spills from oil tankers and pipeline leaks (average of 12 million

• Decreases contamination by storage tanks• Substantially reduced net greenhouse gas emission• Decrease dependency on fossil fuelsDisadvantages• Large amounts of plant material needs to be grown• Waste fuel more expensive to produce

Solar Energy Energy Captured from the Sun

• Solar energy can be used to heat water• Convert to electricity • Even cook for with a solar cooker

Solar Cooker

• Most people in the United States use an electric stove or a natural gas stove to cook their food. This is not the case in much of the world. Approximately 50% of the people on Earth cook using fire from burning wood. However, due to overuse, wood is becoming a scarce commodity in many countries. In addition, burning wood is a major source of air pollution.

• One alternative to cooking with wood is using solar cookers. These devices use energy from the sun to cook food without producing any pollution. While there are many designs for solar cookers, a simple solar cooker can be made from everyday materials. There are many factors that can influence the effectiveness of a solar cooker including the size of the collector, the orientation of the panel and the color of the container.

http://solarcooking.orgGo to the site listed and be able to design your own solar cooker

2 Polymers

• Substance composed of large numbers of repeating covalently bonded molecules

• Monomer- covalently bonded repeating unit in a polymer

• Examples-– Polyethylene- repeating units of Ethylene

• (H2-C=C-H2)

• Used in trash & shopping bags

– Polypropylene- repeating propylene units• Used in auto trim & interiors

• Containers

2 General Types of Polymers

• Linear– Long chains of repeating monomers– No links between polymer chains– Like cooked spaghetti– Lower melting– High elongation

2 General Types of Polymers

• Branched or Cross-linked– Long chains that are linked– Bonds between polymer chains– Lower elongation– Higher melting– Can be more abrasion resistant

3 Acid Rain

• Occurs when Sulfur dioxide, Nitrogen dioxide, and Carbon dioxide are emitted into the atmosphere

• These chemicals undergo chemical transformations to form acids

• They then get absorbed by water droplets in clouds.

• The droplets then fall to earth as rain, snow, hail or sleet.

Acid Rain Sources

• Carbonic Acid – H2CO3

– From CO2

– Naturally occurring– Natural rain has pH of about 5.6

• Sulfuric Acid – H2SO4

– From Sulfur in Coal & Oil– Major source of acid rain in CT

• Midwest power plants

Acid Rain Sources

• Nitric Acid – HNO3

– Primary source is from combustion of Coal & Oil

– Autos are a major source

• Rain in CT can have a pH as low as 4.5

• Coal power plants in the Midwest produce large quantities of sulfur which can react and fall as acid rain in CT

Major effects of acid rain

• Increases the acidity of the soil

• Acidification of rivers, streams, lakes and some forests

• Both of these effects will kill plants and animals

More effects of acid rain

• Weathering in carbonate rocks

• Acceleration in building erosion

4 Enzymes

• Proteins that help speed up a reaction – Catalyst

• Enzymes control many important functions– Enzymes help break down nutrients into their

smaller molecules– Energy is released during the breakdown of

nutrients

Some Examples of Enzymes

• Proteinases- help break down proteins• Cellulase and pectinase- both enzymes helps

break down plant material • Peroxidase- decomposes peroxide into

hydrogen and oxygen

Bioengineered Foods

• Food sources that have altered DNA– Scientists insert genes into the DNA of plants– The altered DNA produces new proteins– New proteins lead to new characteristics in

plants

Advantages of Bioengineered Foods

• Most bioengineered food technologies have been developed for farm-level characteristics of agricultural crops– Soybeans– Corn– Cotton– Canola

• These traits include fungal resistance, herbicide tolerance, and insect resistance, this leads to larger agriculture production

Disadvantage of Bioengineered Foods

• DNA does not always fully break down in the digestive tract– Gut bacteria can take up genes and this

opens up the possibility of the spread of antibiotic resistance.

• Decrease in natural selection decrease in biological diversity

• Some insertions of genes are unpredictable – – may lead to allergic reactions

5 Populations

• Population dynamics is the study of marginal and long-term changes in the numbers, individual weights and age composition of individuals in one or several populations

• Biological and environmental processes influencing those changes.

Human Populations

• The human population has existed for a little more than 500,000 years. About 10,000 years ago, the total human population was about 3 million people, most of them hunters and gatherers. The development of early agriculture provided a stable supply of food and as a result the human population increased rapidly and reached one billion (1,000,000,000) in 1840. The development of technology and medicine in the 20th century reduced the death rate and increased the growth rate even further. Despite these advances, human population growth differs dramatically country by country

Population growth

• Birth rate (or crude birth rate): The number of live births per 1,000 population in a given year. Not to be confused with the growth rate.

• Growth rate: The number of persons added to (or subtracted from) a population in a year– Growth rate affected by

• Births• Deaths• Net migration

Underdeveloped vs developed countries population growth

Less developed countries: Less developed countries include all countries in Africa, Asia (excluding Japan), and Latin America and the Caribbean, and the regions of Melanesia, Micronesia, and Polynesia. More developed countries: More developed countries include all countries in Europe, North America, Australia, New Zealand, and Japan

Population Growth

• The growth of populations and the maximum population size of a habitat are affected by: – Availability of nutrients– Physical parameters of the environment– Biotic interactions.

• All of these factors interact to set a limit on the population size in a habitat at a level called the CARRYING CAPACITY

Yeast PopulationsThe small organism continually reproduce and the population grows until the population, runs out of food, and space in the petri dish

At that point they reach their carrying capacity, which is limiting value of the population that can be supported in a particular environment

Reading the graph

The (population) grows exponentially until the population reaches its carrying capacity then the curve levels off.