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Respiration and Photosynthesis

February 20, 2009 Leave a comment

Summary:

If it is dark, respiration takes place but no photosynthesis.
Overall result: oxygen taken in, carbon dioxide given out.

If dim light, photosynthesis rate is equal to the respiration rate.
Overall result:neither gas is taken in or given out.

If bright light, photosynthesis rate is greater than respiration rate.
Overall result: Carbon dioxide taken in, oxygen given out.

USES OF CARBON DIOXIDE

February 17, 2009 Leave a comment

Carbon dioxide is a colorless gas with a weak odor. It is about 1.5 times as dense as air. The carbon dioxide molecule
O=C=O
contains two double bonds and has a linear shape. It has no electrical dipole. As it is fully oxidized, it is not very reactive and in particular not flammable.
Carbon dioxide can be reduced to a liquid and solid form by intense pressure. At standard pressure, it is never liquid: it directly passes between the gaseous and solid phase at -78°C in a process called sublimation.
Water will absorb its own volume of carbon dioxide, and more than this under pressure. About 1% of the dissolved carbon dioxide turns into carbonic acid, resulting in a slightly acidic taste. The carbonic acid in turn dissociates partly to form bicarbonate and carbonate ions.

Uses

Carbon dioxide in its solid frozen form it is also known as dry ice. It is used
for cooling
to produce ‘dry ice fog’ for special effects: when dry ice is put into contact with water, the resulting mixture of CO2 and cold humid air causes condensation and a fog
for cleaning: shooting tiny dry ice pellets at a surface cools the dirt and causes it to pop off
Dry ice is produced by compressing CO2 to a liquid form, removing excess heat, and then letting the liquid carbon dioxide expand quickly. This expansion causes a drop in temperature so that some of the CO2 freezes to “snow” which is then compressed.
Carbon dioxide extinguishes flames, and some fire extinguishers[?] contain pressured liquid carbon dioxide. Life jackets[?] often contain capsules of pressured liquid carbon dioxide used for quick inflation.
Water containing dissolved carbon dioxide is also known as carbonated water or soda water. Carbonated water is contained in many soft drinks and some natural springs. Some beverages, such as beer and sparkling wine contain carbon dioxide as a result of fermentation.
Many leavening agents used for baking produce carbon dioxide to cause the dough to rise. Examples are baker’s yeast and baking powder.

Biology

Carbon dioxide is a waste product in organisms that obtain energy from breaking down sugars or fats with oxygen as part of their metabolism, in a process known as cellular respiration. This includes all animals, many fungi and some bacteria. In higher animals, the carbon dioxide travels in the blood (where most of it is held in solution) from the body’s tissues to the lungs where it is exhaled.
Carbon dioxide, when breathed in high concentrations (about 5% by volume), is toxic to humans and other animals. Hemoglobin, the main molecule in red blood cells, can bind both to oxygen and to carbon dioxide. If the CO2 concentration is too high, then all hemoglobin is saturated with carbon dioxide and no oxygen transport takes place (even if plenty of oxygen is in the air). Carbon dioxide and dry ice should therefore only be handled in well ventilated areas.
Plants remove carbon dioxide from the atmosphere by photosynthesis, which uses light energy to produce organic plant materials by combining carbon dioxide and water. This releases free oxygen gas. Sometimes carbon dioxide gas is pumped into greenhouses to promote plant growth.

Atmosphere

Despite its low concentration of about 0.037% or 370 ppm by volume, CO2 is a very important component of Earth’s atmosphere, because it traps infrared radiation and thus participates in the greenhouse effect. Atmospheric CO2 has increased about 30 percent since the early 1800s, with an estimated increase of 17 percent since 1958 (burning fossil fuels such as coal and petroleum is the leading cause of increased CO2, deforestation the second major cause).
The increased amounts of CO2 in the atmosphere are widely believed to enhance the greenhouse effect and thus contribute to global warming; this has led to international agreements such as the Kyoto Protocol which aim to limit the release of CO2 into the atmosphere. Some have proposed carbon sequestration as a method to reduce the concentration (or at least slow the rate of increase) of human-made CO2 from entering the atmosphere.
Carbon dioxide is the main component of the atmospheres of Mars and Venus.

Oceans

The Earth’s oceans dissolve a major amount of carbon dioxide. The resulting carbonate anions bind to cations present in sea water such as Ca2+ and Mg2+ to form deposits of limestone and dolomite.

History

Carbon dioxide was first described in the 17th century by the Belgian chemist Jan Baptist van Helmont.

All about stomata

February 16, 2009 Leave a comment

What are stomata?

Figure 1: Stomata of Tall fescue grasses.
Stomata are tiny plant structures found on the outer skin layer, also known as the epidermis, of plants (Figure 1). They consist of two specialized cells, called guard cells that surround a tiny pore called a stoma. The word stomata means “mouth” in Greek because they allow communication between the internal and external environments of the plant. Their main function is to allow gases such as carbon dioxide, water vapor and oxygen to move rapidly into and out of the leaf. Stomata are found on all above-ground parts of plants including the petals of flowers, petioles, soft herbaceous stems and leaves. They are formed during the initial stages of the development of these various plant organs and therefore reflect the environmental conditions under which they grew.
Stomatal density, size and shape
Stomatal density refers to the number of stomata per squared millimeter. Typical densities can vary from 100 to 1000 depending on the plant species and the environmental conditions during development. More stomata are made on plant surfaces under higher light, lower atmospheric carbon dioxide concentrations and moist environments. Grasses typically have lower stomatal densities than deciduous trees. The size and shape of stomata also vary with different plant species and environmental conditions. For example, grasses have guard cells that resemble slender dumbbells whereas trees and shrubs have guard cells that resemble kidney beans.
Physiological function of stomata
Leaves are the main “food manufacturing” organs of plants. They make food from carbon dioxide and water in the presence of light during a process called photosynthesis. As stomata open in the presence of light, carbon dioxide will diffuse into the leaf as it is converted to sugars through photosynthesis inside the leaf. At the same time, water vapor will exit the leaf along a diffusive gradient through the stomata to the surrounding atmosphere through the process of transpiration. Consequently, plants face the dilemma of taking up carbon dioxide while losing water vapor through their stomata. If this water loss remains unchecked, they can deplete their water reserve. This depletion can become catastrophic to the physiological functioning of the plant given that is the most essential solvent in which biochemical and growth processes occur. Based on Darwinian principles, it is presumed that selective adaptation has driven plants to acquire characteristics which enable them to grow more quickly without diminishing the probability of survival. If plants have not acquired the characteristics to withstand changes in water availability in their growth environment, plants may exacerbate their water shortage by not regulating the size of their stomatal apertures in an optimal manner and may fail to survive when water availability declines.
Optimal size of stomatal apertures
The Optimisation Theory, first proposed by Ian Cowan and Graham Farquhar (1977) suggests that the gas exchange of a plant is optimal if the plant is maximizing photosynthesis at a given average rate of transpiration. This ratio of photosynthesis to transpiration defines the instantaneous water-use efficiency (WUE) of the plant. The WUE of the leaf, when compared to economic principles, can be considered to be analogous to the interest rate on an invested resource. The invested resource in this case is water transpired, while the interest is the carbon gained through photosynthesis. The optimal stomatal aperture size is one in which the interest rate, WUE, is maximized as the environmental conditions change.
Stomatal apertures will typically vary in response to changes in light intensity, saturation deficit of ambient water vapor and soil moisture availability. As stomatal aperture size changes, rates of photosynthesis and transpiration will vary because the pore size will provide a corresponding resistance to the diffusion of CO2 into and H2O out of the leaf. The inverse of this resistance can be calculated as the conductance to these two gases across a leaf surface.
Stomatal conductance
Plant biologists typically measure stomatal conductance using a specialized instrument called an IRGA (Infra Red Gas Analyzer).

Figure2: Leaf chamber attached to Infra red gas analyzer connected to computer console
This instrument allows one to clamp a leaf into a chamber and the relative mole fractions of CO2 and water vapor entering and leaving the chamber are monitored over time. The leaf touches a temperature thermocouple inside the chamber so that leaf temparature can be monitored in conjunction with air temperature that exits the chamber. The leaf temperature is used to determine the saturated molar concentration of water vapor inside the leaf intercellular air spaces. The resistance to the diffusion of water vapor from inside the leaf to the air stream passing over the leaf is calculated from the difference between the molar concentrations of saturated water vapor inside the leaf air spaces in the air stream passing over the leaf. The resistance will increase as the stomatal aperture size decreases. The stomatal conductance to water vapor decreases as the resistance increases. Because H2O has a lighter molecular mass than CO2, water typically diffuses 1.6 times faster than CO2. The conductance to CO2 into a leaf is going to be 0.625 times the conductance to H2O out of the leaf.
As stomatal conductance declines, WUE will increase if the reduction in photosynthesis is lower than the reduction in transpiration. Plant species typically show this physiological response under mild drought stress. Under severe drought stress, the photosynthetic biochemical machinery can become damaged. As a result, WUE will decrease as stomatal conductance declines if the reduction in photosynthesis becomes larger than the reduction in transpiration.

Virus Or Bacterium?

November 11, 2008 Leave a comment

Our Challenge: Determine the ways that viruses and bacteria are different.

Because bacteria and viruses cause many of the diseases we’re familiar with, people often confuse these two microbes. But viruses are as different from bacteria as goldfish are from giraffes.

For one thing, they differ greatly in size. The biggest viruses are only as large as the tiniest bacteria.

Another difference is their structure. Bacteria are complex compared to viruses.
cross section of a bacterium

© Eric MacDicken

A typical bacterium has a rigid cell wall and a thin, rubbery cell membrane surrounding the fluid, or cytoplasm (sigh-toe-plasm), inside the cell. A bacterium contains all of the genetic information needed to make copies of itself—its DNA—in a structure called a chromosome (crow-moe-soam). In addition, it may have extra loose bits of DNA called plasmids floating in the cytoplasm. Bacteria also have ribosomes (rye-bo-soams), tools necessary for copying DNA so bacteria can reproduce. Some have threadlike structures called flagella that they use to move.
cross section of a virus

© Eric MacDicken

A virus may or may not have an outermost spiky layer called the envelope. All viruses have a protein coat and a core of genetic material, either DNA or RNA. And that’s it. Period.

Which brings us to the main difference between viruses and bacteria—the way they reproduce.

Viral vs. Bacterial Reproduction

Bacteria contain the genetic blueprint (DNA) and all the tools (ribosomes, proteins, etc.) they need to reproduce themselves.

Viruses are moochers. They contain only a limited genetic blueprint and they don’t have the necessary building tools. They have to invade other cells and hijack their cellular machinery to reproduce. Viruses invade by attaching to a cell and injecting their genes or by being swallowed up by the cell.

Here’s an example of viral infection. This is virus version of the horror movie Alien.
bacteriophage landing on bacterium

James A. Sullivan

These are T4 bacteriophages (back-tear-e-oh-faj-es). They are a kind of virus that infects bacteria. Here they are landing on the surface of an E. coli bacterium.
bacteriophage injects its genes

© James A. Sullivan

The bacteriophage cuts a hole in the E. coli’s cell wall. It then injects its genetic material into the bacterium. By taking over the E. coli’s genetic machinery, the viral genes tell the bacterium to begin making new virus parts. These parts come together to make whole new viruses inside the bacterium.

Eventually so many new viruses are made that the E. coli bursts open and dies, releasing all those new viruses to infect more cells!
Bacterium bursts open

Plants: their uses for human life

October 21, 2008 Leave a comment

Humans have always used plant in one capacity or another. Plants are becoming known more and more for their vital usage in many arenas, including medicinal purposes.

Plants are thought of mostly as growing and thriving in pleasant, sunny atmospheres; but many plants also can be found in areas that do not seen likely in promoting growth. All that is required for growth of plant life is air, sunlight, and soil.

In Greenland, the Arctic poppy can be found, rising up out of massive layers of ice. Mountainsides are filled with large, colorful blooms, even when packed in heavy snow. On the other end of the temperate zone, many types of cacti are found in barren deserts that may go for many years with rainfall.

Humans are very dependent upon plant life; without it, all would perish. Plants provide fuel, food, clothing, and even shelter, either directly or indirectly. The dependence upon corn and wheat, major parts of life-giving nutrients, is not in doubt; but without grasses and grains that sustain livestock, which feed and clothe humans, they, too, would perish.

USES FOR PLANTS:

FOOD

The chief food plants in North America are cereal grains. The major types of grain crops include wheat, corn, rice, oats, barley, and rye. Next are legumes, such as peas, beans, soybeans, and peanuts.

For centuries, people have used the herbs and spices derived from plants as seasonings for their food. Pepper and nutmeg are two examples of seasonings derived from dried fruit, while others such as sage and rosemary come from leaves. A common baking spice, cinnamon, is found in the stem of the plant.

Even beverages come from plant life. By steeping plants in hot water, coffee, tea, and cocoa are produced. Nature makes many other beverages naturally, such as fruit juices, cider, and milk.

CLOTHING

Much of our clothing comes from the plants found in nature, such as cotton, the foremost fiber used to manufacture clothing. Synthetic fibers, too, such as rayon, are produced from plants; the cellulose required to manufacture the rayon is found in the cell walls of plants.

PAPER

Papyrus, a grasslike plant, was used more than four thousand years ago in the first endeavor, by Egyptians, to make paper. It is from this plant that paper has derived its name.

The Chinese, around 100AD, invented a method of manufacturing paper that is still in use today. The fibers from the plant are placed in water, reduced to but a pulp. After the water has been sieved off, the remaining pulp is pressed, then allowed to dry to yield a very thin sheet of paper.

Almost any plant that is found to be high in cellulose is considered excellent for making the pulp which produces paper, the most common today being trees such as aspen and pine varieties.

SHELTER

In many parts of the world wood is used for creating proper shelter against the elements. Items found in the wooded structures we call home are also made with wood, a plant product. Furniture, for example, is made up mainly of wood and cloth, from the fibers of plants. Walls in homes may be decorated with wallpaper, and many paints are derived from plant extracts.

FUEL

Green plants, which lived on the Earth very long ago, are the origin for the coal, oil, and gas that humans use for heating and cooking purposes. Compression and heat have converted these plants into fossil fuels. In Ireland, a common fuel is peat, which is formed by the same process as coal. The oldest form of fuel is wood, burned to create heat for warmth and for cooking.

MEDICINES

In ancient cultures, medicine men used the extracts from plant life to soothe and relieve aches and pains. In the very beginnings of Botany, doctors in both Europe and America researched herbs in their quest to cure disease.

Many of the plants that were discovered by ancient civilizations are still in use today. The leaves of willows, which contain a compound very similar to aspirin, were chewed by Native Americans to relieve aches and pains. A major treatment in heart disease is digitalis, which is found in foxglove. The cinchona tree, found in South America, yields from its bark quinine, used to fight malaria.

Even today plants are being discovered that yield important and much needed medicines. The periwinkle plant was discovered to have vincristine, a medicine that is effectively used to fight leukemia in children. Many other plants have proven invaluable as sources of vitamins, an important part of growth and proper development.

As detailed above, plant life is a very vital part of human life; without plants, both land and sea dwelling, human life could not be sustained.

Hong Kong world’s best airport for 7th time

July 17, 2008 Leave a comment


CANBERRA (Reuters Life!) – Hong Kong International Airport was voted the world’s best for the seventh year in a annual survey of passengers, with Asian airports dominating the top positions in the list.

The annual survey conducted by Skytrax, a UK-based consultancy, judges airports on more than 40 categories, ranking them after collecting 8.2 million questionnaires completed by passengers over a 10-month time period from 2007 to 2008.

The passengers judged 190 airports on factors like shopping, dining, staff courtesy, baggage delivery and wait-times at security.

Overall, airports in Asia did well. Hong Kong, with its reputation for efficiency and comfort, beat Singapore’s Changi Airport and Seoul’s Incheon Airport in South Korea, which were ranked second and third respectively.

Hong Kong has held the title of best airport seven times. Only once, in 2006, it was knocked from the No. 1 slot by Singapore’s Changi Airport.

“In recent years, the whole air travel experience has become much more focused on the time customers spend in the airport environment, and Hong Kong has established itself as a clear passenger favorite in this respect,” said Skytrax CEO Edward Plaisted in a statement.

Also in the top 10 were airports in Kuala Lumpur, Malaysia, and Kansai in Japan.

Munich in Germany was voted the top European airport, ranked fifth in the world, while Copenhagen in Denmark, Zurich, Switzerland, and Helsinki, Finland also made the top 10. Cape Town, South Africa rounded out the list at No. 10.

There were no North American airports in the top 10 list. San Francisco did best, ranked 11th, followed by Vancouver in Canada and Dallas/Forth Worth.

In the Middle East, passengers ranked the best airport for the region as Tel Aviv, followed by Bahrain.

Plaisted said waiting times at security checkpoints was a major cause of passenger discontent.

“Easy transportation, quick check-in, good shopping and dining facilities, clean terminal areas – all the positives can easily be undone when confronted by a 20 minutes security queue, especially if one also finds that only half the security facilities are operational,” he said.

Plaisted said total customer satisfaction for many airports had improved in the past year but the financial crisis ahead would impact the airline industry and bring on a rash of operational difficulties, cancelled and consolidated flights and more airlines going under.

“In turn, this will put pressure on airports being able to react to and cope with the pressure points as they arise,” he said.

FIRST COUNTRIES TO SEND A PERSON TO SPACE

June 30, 2008 Leave a comment
Rank Country Date
1 USSR April 12, 1961
2 United States February 20, 1962
3 Czechoslovakia March 2, 1978
4 Poland June 27, 1978
5 East Germany August 26, 1978
6 Bulgaria April 10, 1979
7 Hungary May 26, 1980
8 Vietnam July 23, 1980
9 Cuba September 18, 1980
10 Mongolia March 22, 1981

Countries with the Highest Electrical Consumption in the World

June 30, 2008 Leave a comment
Countries with the Highest Electrical Consumption in the World
Rank Country Electricity – consumption(kWh)
1 United States 3,602,000,000,000
2 China 1,312,000,000,000
3 Japan 964,200,000,000
4 Russia 773,000,000,000
5 Germany 506,800,000,000
6 Canada 504,400,000,000
7 India 497,200,000,000
8 France 415,300,000,000
9 United Kingdom 346,100,000,000
10 Brazil 335,900,000,000
11 Italy 289,100,000,000
12 Korea, South 270,300,000,000
13 Spain 210,400,000,000
14 Mexico 186,700,000,000
15 Australia 184,400,000,000
16 South Africa 181,200,000,000
17 Ukraine 152,400,000,000
18 Sweden 134,900,000,000
19 Poland 118,800,000,000
20 Iran 115,900,000,000
Source: CIA World Factbook

INTERNET DOMAINS OF EACH COUNTRY IN THE WORLD

June 30, 2008 Leave a comment
Country Internet Domain
Afghanistan .af
Albania .al
Algeria .dz
Andorra .ad
Angola .ao
Antigua and Barbuda .ag
Argentina .ar
Armenia .am
Australia .au
Austria .at
Azerbaijan .az
Bahamas, The .bs
Bahrain .bh
Bangladesh .bd
Barbados .bb
Belarus .by
Belgium .be
Belize .bz
Benin .bj
Bhutan .bt
Bolivia .bo
Bosnia and Herzegovina .ba
Botswana .bw
Brazil .br
Brunei .bn
Bulgaria .bg
Burkina Faso .bf
Burma .mm
Burundi .bi
Cambodia .kh
Cameroon .cm
Canada .ca
Cape Verde .cv
Central African Republic .cf
Chad .td
Chile .cl
China .cn
Colombia .co
Comoros .km
Congo, Democratic Republic of the .cd
Congo, Republic of the .cg
Costa Rica .cr
Cote d’Ivoire .ci
Croatia .hr
Cuba .cu
Cyprus .cy
Czech Republic .cz
Denmark .dk
Djibouti .dj
Dominica .dm
Dominican Republic .do
East Timor .tp
Ecuador .ec
Egypt .eg
El Salvador .sv
Equatorial Guinea .gq
Eritrea .er
Estonia .ee
Ethiopia .et
Fiji .fj
Finland .fi
France .fr
Gabon .ga
Gambia, The .gm
Georgia .ge
Germany .de
Ghana .gh
Greece .gr
Grenada .gd
Guatemala .gt
Guinea .gn
Guinea-Bissau .gw
Guyana .gy
Haiti .ht
Holy See (Vatican City) .va
Honduras .hn
Hungary .hu
Iceland .is
India .in
Indonesia .id
Iran .ir
Iraq .iq
Ireland .ie
Israel .il
Italy .it
Jamaica .jm
Japan .jp
Jordan .jo
Kazakhstan .kz
Kenya .ke
Kiribati .ki
Korea, North .kp
Korea, South .kr
Kuwait .kw
Kyrgyzstan .kg
Laos .la
Latvia .lv
Lebanon .lb
Lesotho .ls
Liberia .lr
Libya .ly
Liechtenstein .li
Lithuania .lt
Luxembourg .lu
Macedonia, The Former Yugoslav Republic of .mk
Madagascar .mg
Malawi .mw
Malaysia .my
Maldives .mv
Mali .ml
Malta .mt
Marshall Islands .mh
Mauritania .mr
Mauritius .mu
Mexico .mx
Micronesia, Federated States of .fm
Moldova .md
Monaco .mc
Mongolia .mn
Morocco .ma
Mozambique .mz
Namibia .na
Nauru .nr
Nepal .np
Netherlands .nl
New Zealand .nz
Nicaragua .ni
Niger .ne
Nigeria .ng
Norway .no
Oman .om
Pakistan .pk
Palau .pw
Panama .pa
Papua New Guinea .pg
Paraguay .py
Peru .pe
Philippines .ph
Poland .pl
Portugal .pt
Qatar .qa
Romania .ro
Russia .ru
Rwanda .rw
Saint Kitts and Nevis .kn
Saint Lucia .lc
Saint Vincent and the Grenadines .vc
Samoa .ws
San Marino .sm
Sao Tome and Principe .st
Saudi Arabia .sa
Senegal .sn
Seychelles .sc
Sierra Leone .sl
Singapore .sg
Slovakia .sk
Slovenia .si
Solomon Islands .sb
Somalia .so
South Africa .za
Spain .es
Sri Lanka .lk
Sudan .sd
Suriname .sr
Swaziland .sz
Sweden .se
Switzerland .ch
Syria .sy
Tajikistan .tj
Tanzania .tz
Thailand .th
Togo .tg
Tonga .to
Trinidad and Tobago .tt
Tunisia .tn
Turkey .tr
Turkmenistan .tm
Tuvalu .tv
Uganda .ug
Ukraine .ua
United Arab Emirates .ae
United Kingdom .uk
United States .us
Uruguay .uy
Uzbekistan .uz
Vanuatu .vu
Venezuela .ve
Vietnam .vn
Yemen .ye
Zambia .zm
Zimbabwe .zw

Countries with the Most Telephones in the World

June 30, 2008 Leave a comment
Countries with the Most Telephones in the World
Rank Country Telephones – main lines in use
1 China 263,000,000
2 United States 181,599,900
3 Japan 71,149,000
4 Germany 54,350,000
5 India 48,917,000
6 Brazil 38,810,000
7 Russia 35,500,000
8 United Kingdom 34,898,000
9 France 33,905,400
10 Italy 26,596,000
11 Korea, South 22,877,000
12 Canada 19,950,900
13 Turkey 18,916,700
14 Spain 17,567,500
15 Mexico 15,958,700
16 Iran 14,571,100
17 Poland 12,300,000
18 Ukraine 10,833,300
19 Australia 10,815,000
20 Netherlands 10,004,000
Source: CIA World Factbook

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