Dec 8, 2011

A Successful Student



Introduction
The school is a friendly place; but it is also a competitive environment. The education you receive there, and the attitudes you develop, will guide you in futute. Your grades will be important. To be a successful student requires certain skills; but, these are skills that can be learned.
The Basics of Being a Good Student
- Prioritise your life: Doing well in school should be your top priority.
- Study: There is no substitute.
- Always attend class.
- Do all of the homework and assigned reading.
- Develop self-discipline.
- Manage your time.
Self-Discipline Made Easy
Human beings are creatures of habit. Therefore, form a habit of doing what you reason you should do. Is it not foolish for your behaviour to contradict your own reasoning? And what could be more harmonious than finding yourself wanting to do what you know you should?
Train yourself so there is an immediate reaction-mechanism within you:
You reason that you should do something, and thus you do it.
Other people who seem to have less difficulty with self-discipline probably have simply had more practice at it, thereby making it less difficult; because, practice is what it takes. 
Time Management
No matter how you slice it, there are only 24 hours in a day. Good time-management requires:
1. Note taking on more than you can handle.
2. Reasonably estimating the time required to perform each of the tasks at hand.
3. Actually doing what needs to be done.
Only you can do these things. A couple of thoughts, though, that may help spur you on:
- A minute now is as precious as a minute later. You can't put time back on the clock.
- If you're not ahead of schedule, then you're behind schedule. Because, if you try to remain right on  schedule, then any mishap or misjudgment will cause you to fall behind---perhaps right at the deadline, when no recovery is possible. 
Introspection
Understand, and be honest with, yourself. All else follows from this.
- Be both athlete and coach: Keep one eye on what you are doing, and one eye on yourself.
- Take command of, and responsibility for, yourself.
- Face your insecurities head-on. Some common signs of insecurity: Asking a question to which you already know the answer; being artificially social with teachers or other students, when the real reason is to temporarily kill the pain.
- Form a positive self-image: Those students who are first entering secondary school will probably have doubts about how well they will do. Try to do well immediately to instill an expectation of continuing to do well. Settle for nothing less. Nevertheless, try not be restricted by your past performance and experiences, good or bad. Learn from the past, but don't be bound by it. Seek out your weaknesses and attack them. Be realistic about your limitations; but, don't let this lead to becoming satisfied with them.
Taking a Course
Each student's attitude is some mixture of the following:
- He/She wants to learn the material.
- He/She wants to get a good grade.
- He/She doesn't care.
Each teacher's attitude is some mixture of the following:
- He/She wants students to learn the material.
- He/She wants grading to be fair and reflect students' knowledge and abilities.
- He/She doesn't care.
In order to do well, it is up to you (the student) to do two things:
- Learn the material.
- Learn the teacher.
As for the latter, pay attention in class to the teacher's patterns, to what he/she emphasises, etc. Gather information about the teacher from other students. A good teacher, however, will present their subject in such a way that it will be of little benefit for the student to try to learn him/her, thereby forcing their students to learn the material.
Homework
Keep in mind that your work is being graded by a human being. Thus:
Write legibly, orderly, and coherently.
Supply any commentary necessary to make it clear what you are attempting to do.
- Making the teacher's job easier will more likely lead to you getting the benefit of doubt when it occurs.
- Don't think that getting the right answer to a homework problem implies that you have mastered the corresponding material. All you have done is solve one particular problem; that does not mean you have necessarily learned how to solve all such problems (such as the ones to appear on your exams). It's up to you to view the homework problems from this wider perspective.
- If available, always go over the solutions provided by the teacher, even if you did well on the assignment. He/She may demonstrate methods (perhaps more efficient) or provide useful information that you hadn't thought of.
Exams
Preparation:
Roughly prioritise material as to its importance (primary, secondary, tertiary), and concentrate your studying on the most significant topics. Remember, the teacher only has a limited amount of time to test what you know and can do. Thus, keep in mind when preparing for an exam that the problems cannot be too complicated if they are to fit within the allotted time.
- Study in ways that are suited to you.
Study with a group or alone based upon which is really best for you.
Do your most strenuous and important work during those times of the day that you work best.
Summarise or outline the course or text material in your own words. Writing a summary not only forces you to examine the subject matter in detail, but provides a compendium to review just prior to the exam.
Play it safe: Memorise somewhat more than what the teacher says is required. Bring a calculator even if it's not suggested. Etc.
Study old exams if the teacher is known to give similar exams. But, don't be fooled into thinking that since you were able to work through an old exam, it means you understand all the course material in general, and can perform in a test situation.
Bring your own paper and a watch.
Fighting exam anxiety: Convince yourself that all you can do is all you can do; but, don't let that lead you to become complacent. Just be determined to be "on" for the duration of the exam. (Give yourself a pep-talk to this effect prior to each exam.)
- Starting the exam:
Read the instructions thoroughly and carefully.
Skim over the entire exam prior to beginning work.
Don't necessarily do the problems in order. Instead, get those problems out of the way you feel confident you can do quickly and well. Observe how the problems are weighted, and direct your efforts to where you believe you can pick up points most easily. This does not necessarily mean attempting the most heavily weighted problem first; rather, it means first doing the problem for which you can accumulate points at the fastest rate. Indeed, there is a good chance that this is not the most heavily weighted problem, since many instructors dislike giving any one problem significantly greater or fewer points than the average, thereby underweighting the harder problems and overweighting the easier ones.
Before writing on any given problem, think. A small investment in time at the beginning can save time overall (for you might thereby choose a more efficient method of solving the problem).
Do precisely what is requested. In particular, don't waste time doing things that will not receive credit. For example, unless explicitly required, do not rewrite the exam problems on your paper.
Pace yourself through the exam. Example: On a 50-minute exam worth a 100 points, you should be accumulating 2 points per minute; thus, a 26-point problem should be completed in 13 minutes. Do this calculation at the start of the exam if the problem weights are given.
Show your work and make clear your reasoning in order to have a chance to receive partial credit.
As with homework, and even more importantly, neatness counts.
Always check over your answers if you have time.
Further Suggestions
  • Unify and simplify your knowledge: A textbook presents the subject in a particular form, as does a teacher. By their very natures, however, textbooks and teachers tend to present subjects sequentially. Take the extra step of understanding the material in your terms, which may involve recognising relationships that could not be conveniently expressed in the order presented in the text(s) and lessons.
  • Remember, almost every logically consistent topic is simple at its foundation. Try to recognise the simple underlying relationships in the subject at hand; these are often left unstated by instructors and textbooks.
  • Try to learn general principles and methods. Learning by examples (putting the new in terms of the familiar) can only take you so far.
  • Learn as many methods of problem-solving as you can. This is especially helpful for exams, when time is of the essence.
  • Ask yourself questions. Why didn't the teacher or text(s) do this or that? Explore your own ideas. Try to understand the subject content in detail.
  • It is often said that the best way to learn something is to teach it. Do you know the subject matter well enough to explain it clearly and completely to someone else?
  • Learn by observing others. Notice what works for them and consider incorporating those methods into yourself. Ask yourself "Why didn't I think of that?", and try to develop the related ability.
  • Attempt to be methodical, neat, legible, deliberate, precise, knowledgeable, and reliable on the one hand, and creative, spontaneous, imaginative, smart, clever, articulate, and flexible on the other. The first mentality thrives on order, and inherently tries to do well what it already knows how to do; the second mentality thrives on disorder, and inherently tries to expand upon its abilities. Adopt the best of these two mentalities. Remember, every tool is a potential crutch. The first mentality may rely too heavily on already-mastered skills; but, the second mentality may fail to carefully apply those same skills.
  • Think about and question everything, even the statements appearing here (and, yourself!). But, realise that it is equally foolish to be different merely for the sake of being different, as it is to mindlessly conform to the norm.
  • For maximum efficiency, have several projects going at once. Then, if you get tired, frustrated, or bored working on one item, you can easily move onto something else, thereby staying productive as well as giving pending problems a chance to work themselves out subconsciously.
  • Anticipate. For example, you may need to ask the instructor about the present assignment, but he/she is only guaranteed to be available at certain times; therefore, you should look over the assignment early.
  • Forget pulling "all-nighters". These merely amount to borrowing from tomorrow, at which time you will find yourself considerably less functional. All-nighters are really an indication of not having properly planned your activities.
  • If possible, bring your textbook(s) to class.
  • Take your lessons notes in pencil, since any modifications can then be made quickly and neatly.
Closing
Overall, there is one basic trait that distinguishes successful students from those that are not:
Successful students force themselves to understand.
They do not merely go through the motions of attending class, reading the text(s), and doing the homework, expecting these actions to necessarily suffice. Rather, they are continually asking, "Do I really understand what's going on here?" They ask this question of themselves honestly, applying an internal barometer formed from experience to detect the slightest lack of understanding, be it ignorance or confusion. And, if the answer is "No", then the situation is viewed as unacceptable, and more effort is the response.

Nov 17, 2011

Facts about cell

Cells are the fundamental units of life. Whether they be unicellular or multicellular life forms, all living organisms are composed of and depend on cells to function normally. Scientists estimate that our bodies contain anywhere from 75 to 100 trillion cells. Cells do everything from providing structure and stability to providing energy and a means of reproduction for an organism. The following facts about cells will provide you with well known and perhaps little known tidbits of information about cells.

1. Cells are too small to be seen without magnification.
Cells range in size from 1 to 100 micrometers. The study of cells, also called cell biology would not have been possible without the invention of the microscope. With the advance microscopes of today such as the Scanning Electron Microscope and Transmission Electron Microscope, cell biologists are able to obtain detailed images of the smallest of cell structures.

2. There are two primary types of cells.
Eukaryotic and prokaryotic cells are the two main types of cells. Eukaryotic cells are called so because they have a true nucleus. Animals, plants, fungi and protists are examples of organisms that are composed of eukaryotic cells. Prokaryotes include bacteria and archaeans.

3. Prokaryotic single-celled organisms were the earliest and most primitive forms of life on earth.
Prokaryotes can live in environments that would be deadly to most other organisms. They are able to live and thrive in various extreme habitats. Archaeans for example, live in areas such as hydrothermal vents, hot springs, swamps, wetlands, and even animal intestines.

4. There are more bacterial cells in the body than human cells.
Scientists have estimated that about 95% of all the cells in the body are bacteria. The vast majority of these microbes can be found within the digetive tract.

5. Cells contain genetic material.
Cells contain DNA (deoxyribonucleic acid), the genetic information necessary for directing cellular activities. DNA is a type of molecule known as a nucleic acid. In prokaryotic cells, the single bacterial DNA molecule is not separated from the rest of the cell but coiled up in a region of the cytoplasm called the nucleoid region. In eukaryotic cells, DNA molecules are located within the cell's nucleus. DNA and proteins are the major components of chromosomes. Human cells contain 23 pairs of chromosomes (for a total of 46). There are 22 pairs of autosomes (non-sex chromosomes) and one pair of sex chromosomes. The X and Y sex chromosomes determine gender.

6. Cells contain structures called organelles which carry out specific functions.
Organelles have a wide range of responsibilities within a cell that include everything from providing energy to producing hormones and enzymes. Eukaryotic cells contain several types of organelles, while prokaryotic cells contain a few organelles (ribosomes) and none that are bound by a membrane. There are also differences between the kinds of organelles found within different eukaryotic cell types. Plant cells for example, contain structures such as a cell wall and chloroplasts that are not found in animal cells. Other examples of organelles include:
  • Nucleus
  • Mitochondria
  • Endoplasmic Reticulum
  • Golgi Complex
  • Ribosomes
7. Different types of cells reproduce through different methods.
Most prokaryotic cells reproduce by a process called binary fission. This is a type of cloning process in which two identical cells are derived from a single cell. Eukaryotic organisms have a similar type of reproductive method known as mitosis. Some eukaryotes also have the ability to reproduce sexually, which involves the fusion of sex cells or gametes. Gametes are produced by a process called meiosis.

8. Groups of similar cells form tissues.
Tissues are groups of cells with both a shared structure and function. Cells that make up animal tissues are sometimes woven together with extracellular fibers and are occasionally held together by a sticky substance that coats the cells. Different types of tissues can also be arranged together to form organs. Groups of organs can in turn form organ systems.

9. Cells have varying life spans.
Cells within the human body have different life spans based on the type and function of the cell. They can live anywhere from a few days to a year. Certain cells of the digestive tract live for only a few days, while some immune system cells can live for up to six weeks. Pancreatic cells can live for as long as a year.

10. Cells commit suicide.
When a cell becomes damaged or undergoes some type of infection, it will self destruct by a process called apoptosis. Apoptosis works to ensure proper development and to keep the body's natural process of mitosis in check. A cell's inability to undergo apoptosis can result in the development of cancer.

Nov 4, 2011

Respiration in Plants

Plants also respire aerobically to obtain energy for metabolism. They derive most energy from cellular respiration.
During cellular respiration, energy is obtained by breaking down glucose. The energy released is stored in ATP molecules.
Although plants cannot photosynthesise without sunlight, respiration continues because plants need energy constantly to sustain vital living processes.



Gaseous exchange between plant cells and the environment occurs by diffusion mainly through the stomata and lenticels. Respiratory gases enter and leave plants via stomata in the epidermis of the leaves and the stems of herbaceous plants. Lenticels are raised pores found on the stems and roots of plants.

When stomata are open, they connect the air spaces within the leaves to the atmosphere.
Oxygen from the atmosphere diffuses into the air spaces and then dissolves in the film of water around the mesophyll cells.
Oxygen is then used in aerobic respiration.
The concentration of oxygen in the cells becomes lower than the concentration of oxygen in the air spaces.
The difference in concentration gradient allows oxygen to diffuse continuously from the air spaces into the cells.
During the day, the carbon dioxide which is produced during aerobic respiration is used in photosynthesis.
The excess carbon dioxide diffuses into the air spaces and then through the stomata into the atmosphere.
Aerobic respiration is usually carried out by all plants throughout the day and night.
However, under certain conditions, plants can carry out anaerobic respiration for short periods.
For example, in flood. 
Anaerobic respiration also occurs during initial stages of seed germination.
Respiration and photosynthesis are interdependent. Photosynthesis produces the raw materials required by respiration and respiration produces the raw materials required by photosynthesis.

As light intensity increases during the day, the rate of photosynthesis also increases. Eventually a point reached at which all carbon dioxide produced during respiration is used in photosynthesis. At this point, there is no net gain or net loss in the sugar produced. The plant has reached a compensation point.
The compensation point is the light intensity at which the rate of carbon dioxide production during respiration is equal to the carbon dioxide consumption during photosynthesis.

As light intensity continues to increase during the day, the rate of photosynthesis exceeds the rate of respiration. The carbon dioxide produced during respiration is no longer sufficient fro the plants. Plants must take in carbon dioxide from the atmosphere to supplement the need for a higher concentration of carbon dioxide during photosynthesis. At the same time plants release the excess oxygen into the atmosphere.

Oct 22, 2011

Pathogen

A microorganism that affects the human host sufficiently to cause disease or death is called a "pathogen." Not all parasites, for example, are pathogens, and not all pathogens have a parasitic origin. An example of a non-parasitic pathogen is Clostridium botulinum. Some pathogens are the result of fungi, some of viruses, or protozoa, as well as bacteria.

Anthrax infection, for example, happens only by certain strains of Bacillus anthracis, which contains plasmids that encode the anthrax toxin. It is also encapsulated, protecting the pathogen. Opportunistic pathogens are those organisms that are usually a part of the body's natural flora and only become harmful after an invasion, as when surgery or accidental injury takes place.

Different pathogens act in different ways. Some produce toxins, while others invade cells or tissues and then produce toxins. Even when localized in the body, such infections can have systemic effects. Symptoms are often a result of the body over-reacting in its own defence. For instance, inflammation is an important part of the body's natural reaction to pathogens and is a response to a signal that there is a problem in a certain area. Defences are sent to increase the exposure of a pathogen to the body's own antimicrobial factors.
How does a pathogen cause disease? The following are just a few diseases to show how a pathogen works on the body.

Botulism causes muscle paralysis and death, mainly because of respiratory failure. The pathogen (strains of Clostridium botulinum) form a toxin that binds to nerve-muscle junctions, stopping the release of acetylcholine which stimulates the muscles.
>Cholera produces vomiting and profuse watery diarrhea. The pathogen causing this are strains of Vibrio cholerae, which multiply in the intestines, forming an enterotoxin which acts on the mucosal cells in the small intestine. Within the mucosal cells, the toxin stimulates an enzyme (adenylate cyclase), which causes an increase in cellular cAMP. This, in turn, leads to a massive outflow of electroytes (Na + Cl) and water into the lumen of the intestine, resulting in massive and rapid dehydration.
Cystic fibrosis is a hereditary disease characterized by severe bronchial congestion. In some cases, the respiratory tract becomes colonized by certain strains of Pseudomonas aeruginosa, which produce an abundant supply of mucusy slime that dramatically diminishes the probability of survival.
E. coli strains invade and destroy cells in the small intestine and colon, producing abdominal pain; profuse watery diarrhea; and ultimately, rapid dehydration. Some strains can even produce a toxin after adhering to the mucosal tissues of the intestine.
Oroya fever (Bartonella bacilliformis), occurring in some parts of South America, produces fever and anemia. It is transmitted through the bites of sandflies. The bacterium grows in and on erythrocytes (red blood cells) and in the endothelial cells (cells that line the cavities of the heart, blood, and lymph vessels, as well as some cavities of the body) of the host. As the bacteria invade the red blood cells, they cause the death of the cells, producing anemia.
Tetanus causes uncontrollable contractions of skeletal muscles, often leading to death from asphyxiation or exhaustion. The disease develops when wounds are contaminated with the pathogen Clostridium tetani, which produces a toxin called tetanospasmin. This toxin acts on certain cells in the CNS, preventing the release of glycine which permits muscles to move as they should.
Typhoid is caused by Salmonella typhi, which produces intestinal symptoms and septicaemia or blood poisoning. After ingestion, the pathogen invades mucosa in the small intestine. In some cases, the ileum becomes so inflamed that it causes necrosis or death of the tissue, producing hemorrhaging.

Bacterial pathogens and the diseases they cause:
Legionella pneumophila (pneumonia)
Neisseria gonorrhoeae (gonorrhea)
Mycoplasma pneumoniae (pneumonia)
Mycoplasma hominis (UTI's, PID)
Mycobacterium tuberculosis (tuberculosis)
Mycobacterium avium (tuberculosis)
Chlamydia trachomatis (venereal syndromes, trachoma)
Listeria monocytogenes (Listeriosis)
Salmonellae spp. (GI disorders)
Shigella spp. (GI disorders)
Escherichia coli (enteropathogenic strains) (GI disorders)
Yersinia enterocolitica (GI disorders)
Staphylococcus aureus (purulent discharges - boils. Blisters, pus-forming skin infections)
Staphylococcus pyogenes (Scarlet/rheumatic fever, "strep" throat).

Viral pathogens and the diseases they cause:
Hepatitis A,B,C,D (hepatitis)
Human immunodeficiency virus -- HIV (AIDS)
Cytomegalovirus (congenital viral infections, mononucleosis)
Epstein-Barr virus (Burkitts lymphoma and other lymphoproliferative diseases)
Herpes virus - types I and II (cold sores, genital herpes)
Human papilloma virus (genital warts, cervical cancer).

Protozoal pathogens and the disease they cause:
Leishmania donovanii (Leishmaniasis)
Plasmodium spp. (malaria)
Pneumocystis carinii (pneumonia)
Trypanosoma spp. (trypanosomiasis).

Infectious diseases, agents, and estimated yearly deaths:
Data, from WHO, displays the yearly worldwide deaths from each disease during the decade preceeding its publication in 1992. There are approximately fifty million deaths per year worldwide from all causes.

Acute respiratory infections (bacteria, viruses, protozoa, fungi) (6,900,000)
Diarrheal diseases (bacteria, viruses) (4,200,000)
Tuberculosis (bacteria) (3,300,000)
Malaria (protozoa) (1-2,000,000)
Hepatitis (viruses) (1-2,000,000)
Measles (virus) (220,000)
Meningitis (bacteria) (200,000)
Schistosomiasis (parasitic worm) (200,000)
Pertussis - whooping cough (bacterium) (100,000)
Amoebiasis (protozoa) (40,000-100,000)
Hookworm (parasitic worm) (50-60,000)
Rabies (virus) (35,000)
Yellow fever (virus) (30,000)
African trypanosomiasis - sleeping sickness (protozoan) (20,000+).

Oct 1, 2011

Viruses and Bacteria

video

What are viruses?

Viruses are too small to be seen by the naked eye. They can't multiply on their own, so they have to invade a 'host' cell and take over its machinery in order to be able to make more virus particles.
Viruses consist of genetic materials (DNA or RNA) surrounded by a protective coat of protein. They are capable of latching onto cells and getting inside them.
The cells of the mucous membranes, such as those lining the respiratory passages that we breathe through, are particularly open to virus attacks because they are not covered by protective skin.

What are bacteria?

Bacteria are organisms made up of just one cell. They are capable of multiplying by themselves, as they have the power to divide. Their shapes vary, and doctors use these characteristics to separate them into groups.
Bacteria exist everywhere, inside and on our bodies. Most of them are completely harmless and some of them are very useful.
But some bacteria can cause diseases, either because they end up in the wrong place in the body or simply because they are 'designed' to invade us.

How are infections with viruses and bacteria spread?

Viral and bacterial infections are both spread in basically the same ways.
  • A person with a cold can spread the infection by coughing and/or sneezing.
  • Bacteria or viruses can be passed on by touching or shaking hands with another person.
  • Touching food with dirty hands will also allow viruses or bacteria from the intestine to spread.
  • Body fluids, such as blood, saliva and semen, can contain the infecting organisms and transmission of such fluids, for example by injection or sexual contact, is important, particularly for viral infections like hepatitis or AIDS.

How to avoid infection

  • Wash your hands thoroughly (often one of the best ways to avoid catching a cold).
  • Shaking hands with someone who has a cold is risky, so avoid rubbing your eyes or nose afterwards.
  • Food should be cooked or cooled down as quickly as possible.
  • Vegetables and meat must be stored separately and prepared on separate chopping boards.
  • Meat should preferably be served well-done.
  • Remember that food with these invisible organisms does not necessarily smell bad.
  • Some organisms are killed as the food is cooked, but they can still leave toxic substances that may cause diarrhoea and vomiting.
  • The use of condoms during sexual intercourse reduces the likelihood of spreading sexually transmitted diseases.

How can the doctor treat bacterial infections?

Bacterial infections are usually treated with a special antibiotic, which only kills the bacterium that has caused the disease.
To make sure that you get the right treatment, your doctor may take a sample, for example a swab from the throat or a urine sample.

How can the doctor treat viral infections?

Viruses can't multiply until they are inside the body's cells.
This is the reason why the treatment of virus infections is usually left up to the patient's own immune system, although it may be hard to accept when the doctor says the only cure is for 'nature to take its course'.
The treatment of virus infections, such as influenza, will usually involve:
  • drinking plenty of water
  • staying at home. People who go to work or school in this condition not only risk spreading the virus to their colleagues but also run a higher risk of catching a bacterial infection
  • taking a painkiller, such as paracetamol (eg Panadol) or ibuprofen (eg Nurofen), to bring your temperature down
  • vaccines have been developed against most viral diseases. The vaccine gives the body some help in quickly and effectively fighting the virus.
An increasing number of antiviral remedies are being developed that prevent the virus multiplying and cause the illness to run its course more quickly.
Unfortunately, these remedies can still only be used on very few viruses and are of limited effectiveness.
Antibiotics have no effect upon viral infections such as colds or flu, and it's important that we limit antibiotic use only to bacterial infections that won't get better on their own.
Over-use of antibiotics reduces their effectiveness by encouraging the growth of antibiotic-resistant bacteria, which is a serious and increasing problem globally.

Sep 28, 2011

CFS



Chronic Fatigue Syndrome is a state of chronic tiredness that happens without explanation for 6 months or more. About 200 out of 100,000 adults in the U.S have this syndrome. It occurs more in middle aged adults then adolescents. It also occurs more in women then men. CFS is a very rare syndrome.

Besides fatigue, chronic fatigue syndrome has many symptoms. Including muscle pain, joint pain, sore throat, headache, fever, chills, tender lymph nodes, problems concentrating, memory loss and low blood pressure. CFS is also known as an immune disorder due to the fact people with this syndrome get sick easily and very often.

There is no cure to chronic fatigue syndrome. So there is only treatment options. Many doctors suggest rest, exercise and proper diet. Counseling and stress relieving activities may help. Many vitamins and some drugs are believed to help. Ibuprofen can help pain and fever that come along with CFS. Anxiety medications can calm the stress that comes with this syndrome. Overall, doctors agree that strict routine is needed.
CFS effects many parts of a person's life. People effected can not do as many activities as a normal person. Without doing things a person once enjoyed can create a depression situation. CFS also can create weight gain or loss. Many become more sensitive to light, sound, food and smells. Most people can not deal with a such change very well. The best way to get through CFS is a positive attitude.

Unfortunately, there is no cure or prevention for Chronic Fatigue Syndrome. This disorder alters many parts of a person's life and is a very serious syndrome. This syndrome can put a person in the hospital for many days. This syndrome should be more publicly known so people can identify the signs before it gets to the point of extreme exhaustion. Many people may not know they have this syndrome. It may be more common them doctors realise.

Sep 27, 2011

Global warming

The planet is warming, from North Pole to South Pole, and everywhere in between. Globally, the mercury is already up more than 1 degree Fahrenheit (0.8 degree Celsius), and even more in sensitive polar regions. And the effects of rising temperatures aren’t waiting for some far-flung future. They’re happening right now. Signs are appearing all over, and some of them are surprising. The heat is not only melting glaciers and sea ice, it’s also shifting precipitation patterns and setting animals on the move.

Some impacts from increasing temperatures are already happening.
Ice is melting worldwide, especially at the Earth’s poles. This includes mountain glaciers, ice sheets covering West Antarctica and Greenland, and Arctic sea ice.
Researcher Bill Fraser has tracked the decline of the Adélie penguins on Antarctica, where their numbers have fallen from 32,000 breeding pairs to 11,000 in 30 years.
Sea level rise became faster over the last century.
Some butterflies, foxes, and alpine plants have moved farther north or to higher, cooler areas.
Precipitation (rain and snowfall) has increased across the globe, on average.
Spruce bark beetles have boomed in Alaska thanks to 20 years of warm summers. The insects have chewed up 4 million acres of spruce trees.
Other effects could happen later this century, if warming continues.

Sea levels are expected to rise between 7 and 23 inches (18 and 59 centimeters) by the end of the century, and continued melting at the poles could add between 4 and 8 inches (10 to 20 centimeters).
Hurricanes and other storms are likely to become stronger.
Species that depend on one another may become out of sync. For example, plants could bloom earlier than their pollinating insects become active.
Floods and droughts will become more common. Rainfall in Ethiopia, where droughts are already common, could decline by 10 percent over the next 50 years.
Less fresh water will be available. If the Quelccaya ice cap in Peru continues to melt at its current rate, it will be gone by 2100, leaving thousands of people who rely on it for drinking water and electricity without a source of either.
Some diseases will spread, such as malaria carried by mosquitoes.
Ecosystems will change—some species will move farther north or become more successful; others won’t be able to move and could become extinct. Wildlife research scientist Martyn Obbard has found that since the mid-1980s, with less ice on which to live and fish for food, polar bears have gotten considerably skinnier. Polar bear biologist Ian Stirling has found a similar pattern in Hudson Bay. He fears that if sea ice disappears, the polar bears will as well.

Ozone layer depletion


Today, one of the most discussed and serious environmental issues is the ozone layer depletion, the layer of gas that forms a protective covering in the Earth's upper atmosphere. Ozone is formed when oxygen molecules absorb ultraviolet photons and undergo a chemical reaction known as photo dissociation or photolysis, where a single molecule of oxygen breaks down to two oxygen atoms. The free oxygen atom, then combines with an oxygen molecule and forms a molecule of ozone. The ozone molecules, in turn absorb ultraviolet rays between 310 to 200 nm wavelength and thereby prevent these harmful radiations from entering the Earth's atmosphere. In the process, ozone molecules split up into a molecule of oxygen and an oxygen atom. The oxygen atom again combines with the oxygen molecule to regenerate an ozone molecule. Thus, the total amount of ozone is maintained by this continuous process of destruction and regeneration.

Ozone layer depletion first captured the attention of the whole world in the later half of 1970 and since then, many discussions and researches have been carried out to find out the possible effects and the causes of ozone depletion. Many studies have also been directed to find out a possible solution.

Causes of Ozone Depletion
The cause of ozone depletion is the increase in the level of free radicals such as hydroxyl radicals, nitric oxide radicals and atomic chlorine and bromine. The most important compound, which accounts for almost 80% of the total depletion of ozone in the stratosphere are chlorofluorocarbons (CFC). These compounds are very stable in the lower atmosphere of the Earth, but in the stratosphere, they break down to release a free chlorine atom due to ultraviolet radiation. A free chlorine atom reacts with an ozone molecule and forms chlorine monoxide and a molecule of oxygen. Now chlorine monoxide reacts with an ozone molecule to form a chlorine atom and two molecules of oxygen. The free chlorine molecule again reacts with ozone to form chlorine monoxide. The process continues and the result is the reduction or depletion of ozone in the stratosphere.

Possible Effects of Ozone Depletion
If you are wondering why is the ozone layer important, then the answer lies in the harmful effects of ultraviolet rays. The ozone layer is responsible for absorbing the ultraviolet rays and thereby preventing them from passing through the atmosphere of Earth. Ultraviolet rays of the Sun are associated with a number of health related and environmental issues. The most important of these is the association between ultraviolet rays and an increased risk of developing several types of skin cancers including malignant melanoma, basal and squamous cell carcinoma. Even the incidents of cortical cataracts can also increase significantly with the increased exposure to ultraviolet rays.

Another observation in this regard is that a decrease in the ozone in the stratosphere can lead to an increase in the ozone present in the lower atmosphere. Ozone present in the lower atmosphere is mainly regarded as a pollutant and a green house gas that can contribute to global warming and climate change. However, researches have pointed out that the lifespan of atmospheric ozone is quiet less as compared to stratospheric ozone. At the same time, increase in the surface level of ozone can enhance the ability of sunlight to synthesize vitamin D, which can be regarded as an important beneficial effect of ozone layer depletion.

The effects of ozone depletion are not limited to humans only, as it can affect animals and plants as well. It can affect important food crops like rice by adversely affecting cyanobacteria, which helps them absorb and utilize nitrogen properly. Phytoplankton, an important component of the marine food chain, can also be affected by ozone depletion. Studies in this regard have shown that ultraviolet rays can influence the survival rates of these microscopic organisms by affecting their orientation and mobility.

The increasing concern for the causes and effects of ozone depletion led to the adoption of the Montreal Protocol, in the year 1987, in order to reduce and control the industrial emission of chlorofluorocarbons. International agreements have succeeded to a great extent in reducing the emission of these compounds, however, more cooperation and understanding among all the countries of the world is required to mitigate the problem.

Sep 24, 2011

Carbon dioxide transport

There are 3 ways in which carbon dioxide is transported in the blood:
1. Dissolved carbon dioxide
Carbon dioxide is much more soluble in blood than oxygen.
About 5 % of carbon dioxide is transported unchanged, simply dissolved in the plasma
2. Bound to haemoglobin & plasma protein
Carbon dioxide combines reversibly with haemoglobin to form carbaminohaemoglobin. Carbon dioxide does not bind to iron, as oxygen does, but to amino groups on the polypeptide chains of haemoglobin.
Carbon dioxide also binds to amino groups on the polypeptide chains of plasma proteins
About 10 % of carbon dioxide is transported bound to haemoglobin and plasma proteins
3. Bicarbonate ions
The majority of carbon dioxide is transported in this way. Carbon dioxide enters red blood cells in the tissue capillaries where it combines with water to form carbonic acid. This reaction is catalysed by the enzyme carbonic anhydrase, which is found in the red blood cells. Carbonic acid then dissociates to form bicarbonate ions (HCO3-) and hydrogen ions (H+).
The hydrogen ions, formed from the dissociated carbonic acid, combine with the haemoglobin in the red blood cell. Bicarbonate ions diffuse out of the red blood cell into the plasma whilst chloride ions (Cl-) diffuse in to take their place. This is known as the chloride shift.
The diagram above shows the reversal of the reactions which occurs at the lungs. Bicarbonate ions enter the red blood cells and combine with hydrogen ions to form carbonic acid. This is broken down into carbon dioxide and water. Carbon dioxide diffuses out of the red blood cells and into the alveoli.

Sep 15, 2011

Trial STPM Bio Kedah

Paper 1
http://www.scribd.com/doc/65081314

Paper 2
http://www.scribd.com/doc/65081515

Mark scheme
http://www.scribd.com/doc/65081697

Sep 10, 2011

Biological Terms



One of the keys to being successful in biology is being able to understand the terminology. Difficult biology words and terms can be made easy to understand by becoming familiar with common prefixes and suffixes used in biology. These affixes, derived from Latin and Greek roots, form the basis for many difficult biology words.

Below is a list of a few biology words and terms that many biology students find difficult to understand. By breaking these words down into discrete units, even the most complex terms can be understood.

1. Autotroph
This word can be separated as follows: Auto - troph.
Auto - means self, troph - means nourish. Autotrophs are organisms capable of self nourishment.

2. Cytokinesis
This word can be separated as follows: Cyto - kinesis.
Cyto - means cell, kinesis - means movement. Cytokinesis refers to the movement of the cytoplasm that produces distinct daughter cells during cell division.

3. Eukaryote
This word can be separated as follows: Eu - karyo - te.
Eu - means true, karyo - means nucleus. A eukaryote is an organism whose cells contain a "true" membrane bound nucleus.

4. Heterozygous
This word can be separated as follows: Hetero - zyg - ous.
Hetero - means different, zyg - means yolk or union, ous - means characterized by or full of. Heterozygous refers to a union characterized by the joining of two different alleles for a given trait.

5. Hydrophilic
This word can be separated as follows: Hydro - philic.
Hydro - refers to water, philic - means love. Hydrophilic means water-loving.

6. Oligosaccharide
This word can be separated as follows: Oligo - saccharide.
Oligo - means few or little, saccharide - means sugar. An oligosaccharide is a carbohydrate that contains a small number of component sugars.

7. Osteoblast
This word can be separated as follows: Osteo - blast.
Osteo - means bone, blast - means bud or germ (early form of an organism). An osteoblast is a cell from which bone is derived.

8. Tegmentum
This word can be separated as follows: Teg - ment - um.
Teg - means cover, ment - refers to mind or brain. The tegmentum is the bundle of fibers that cover the brain.

Pneumonoultramicroscopicsilicovolcanoconiosis
Yes, this is an actual word. What does it mean? Biology can be filled with words that sometimes seem incomprehensible. By "dissecting" these words into discrete units, even the most complex terms can be understood. To demonstrate this concept, let's begin by performing biology word dissections on the word above.

To perform our biology word dissection, we'll need to proceed carefully. First, we come to the prefix (pneu-), or (pneumo-) which means lung. Next, is ultra, meaning extreme, and microscopic, meaning small. Now we come to (silico-), which refers to silicon, and (volcano-) which refers to the mineral particles that make up a volcano. Then we have (coni-), a derivative of the Greek word konis meaning dust. Finally, we have the suffix (-osis) which means affected with. Now lets rebuild what we have dissected:

Considering the prefix (pneumo-) and the suffix (-osis), we can determine that the lungs are affected with something. But what? Breaking down the rest of the terms we get extremely small (ultramicroscopic) silicon (silico-) and volcanic (volcano-) dust (coni-) particles. Thus, pneumonoultramicroscopicsilicovolcanoconiosis is a disease of the lungs resulting from the inhalation of very fine silicate or quartz dust. That wasn't so difficult, now was it?

Now that we've honed our dissection skills, let's try some frequently used biology terms. For instance:

Arthritis
(Arth-) refers to joints and (-itis) means inflammation. Arthritis is the inflammation of a joint(s).

Erythrocyte
(Erythro-) means red and (-cyte) means cell. Erythrocytes are red blood cells.

Okay, let's move on to more difficult words. For instance:

Electroencephalogram
Dissecting, we have (electro-), pertaining to electricity, (encephal-) meaning brain, and (-gram) meaning record. Together we have an electric brain record or EEG. Thus, we have a record of brain wave activity using electrical contacts.

Schizophrenia
Individuals with this disorder suffer from delusions and hallucinations. (Schis-) means split and (phren-) means mind.

Thermoacidophiles
These are ancient bacteria that live in extremely hot and acidic environments. (Therm-) means heat, next you have (-acid), and finally (phil-) means love. Together we have heat and acid lovers.

Once you understand the commonly used prefixes and suffixes, obtuse words are a piece of cake! Now that you know how to apply the word dissection technique, I'm sure you'll be able to determine the meaning of the word thigmotropism (thigmo - tropism).

Sep 5, 2011

Mangrove swamps (Colonisation & Succession)

Mangrove swamps are mostly found in the tropical and subtropical region where fresh-water meets salt water.
They have muddy soft soil and are a hostile environment for normal plants. This is because the soil has very low levels of oxygen and a high concentration of salt.
In addition, mangrove swamps are exposed to high intensities of sunlight and strong winds.


The pioneer species of a mangrove swamp are the Sonneratia sp. and Avicennia sp.

Sonneratia sp.

Avicennia sp.

The presence of this species gradually changes the physical environment of the habitat.
Rhizophora sp.

The extensive root systems of these plants trap and collect sediments, including organic matter from decaying plant parts.

As time passes, the soil becomes more compact and firm. This condition favours the growth of Rhizophora sp. Gradually the Rhizophora sp. replaces the pioneer species.

The prop root system of the Rhizophora sp. traps silt and mud, creating a firmer soil structure over time.
The ground becomes higher. As a result, the soil is drier because it is less submerged by sea water.
The condition now becomes more suitable for the Bruguiera sp., which replaces the Rhizophora sp.

Bruguiera sp.

The buttress root system of the Bruguiera sp. forms loops which extend from the soil to trap more silt and mud.
As more sediments are deposited, the shore extends further to the sea. The old shore is now further away from the sea and is like terresterial ground.
Over time, terrestrial plants like nipah palm and Pandanus sp. begin to replace the Bruguiera sp.

Ecosystem

An ecosystem is a community of living organisms interacting with one another and with non-living organisms.


A habitat is the natural environment in which an organism lives.

A species consists of a group of organisms that look alike and have similar characteristics, share the same ecological niche and are capable of interbreeding.

A population consists of organisms living in the same habitat at the same time.

A community is a natural collection of plant and animal species living within a defined area or habitat in an ecosystem.

The function of an organism or the role it plays in an ecosystem is known as the ecological niche.

Aug 21, 2011

Cancer



Causes
There are about 200 different types of cancer. They can start in any type of body tissue. What affects one body tissue may not affect another. For example, tobacco smoke that you breathe in may help to cause lung cancer. Overexposing your skin to the sun could cause a melanoma on your leg. But the sun won't give you lung cancer and smoking won't give you melanoma.

Apart from infectious diseases, most illnesses are 'multifactorial'. Cancer is no exception. Multifactorial means that there are many factors involved. In other words, there is no single cause for any one type of cancer.

Carcinogens
A 'carcinogen' is something that can help to cause cancer. Tobacco smoke is a powerful carcinogen. But not everyone who smokes gets lung cancer. So there must be other factors at work as well as carcinogens.

Age
Most types of cancer become more common as we get older. This is because the changes that make a cell become cancerous in the first place take a long time to develop. There have to be a number of changes to the genes within a cell before it turns into a cancer cell. These changes can happen by accident when the cell is dividing. Or they can happen because the cell has been damaged by carcinogens and the damage is then passed on to future 'daughter' cells when that cell divides. The longer we live, the more time there is for genetic mistakes to happen in our cells.

Genetic make-up
There need to be a number of genetic mutations within a cell before it becomes cancerous. Sometimes a person is born with one of these mutations already. This doesn't mean they will definitely get cancer. But with one mutation from the start, it makes it more likely statistically that they will develop cancer during their lifetime. Doctors call this 'genetic predisposition'.

The BRCA1 and BRCA2 breast cancer genes are examples of genetic predisposition. Women who carry one of these faulty genes have a higher chance of developing breast cancer than women who do not.

The BRCA genes are good examples for another reason. Most women with breast cancer do not have a mutated BRCA1 or BRCA 2 gene. Less than 5% of all breast cancer is due to these genes. So although women with one of these genes are individually more likely to get breast cancer, most breast cancer is not caused by a high risk inherited gene fault.

This is true of other common cancers where some people have a genetic predisposition - for example, colon (large bowel) cancer.

Researchers are looking at the genes of people with cancer in a study called SEARCH. They also hope to find out more about how other factors might interact with genes to increase the risk of cancer. Information about this study is on our clinical trials database.

The Immune System
People who have problems with their immune systems are more likely to get some types of cancer. This group includes people who

* Have had organ transplants and take drugs to suppress their immune systems to stop organ rejection
* Have HIV or AIDS
* Are born with rare medical syndromes which affect their immunity

The types of cancers that affect these groups of people fall into two, overlapping groups

* Cancers that are caused by viruses, such as cervical cancer and other cancers of the genital or anal area, some lymphomas, liver cancer and stomach cancer
* Lymphomas

Chronic infections or transplanted organs can continually stimulate cells to divide. This continual cell division means that immune cells are more likely to develop genetic faults and develop into lymphomas.

Bodyweight, diet and physical activity
Cancer experts estimate that maintaining a healthy bodyweight, making changes to our diet and taking regular physical activity could prevent about one in three deaths from cancer in the UK. In the western world, many of us eat too much red and processed meat and not enough fresh fruit and vegetables. This type of diet is known to increase the risk of cancer. Drinking alcohol can also increase the risk of developing some types of cancer. There is more information about this in the page on diet causing cancer.

Sometimes foods or food additives are blamed for directly causing cancer and described as 'carcinogenic'. This is often not really true. Sometimes a food is found to contain a substance that can cause cancer but in such small amounts that we could never eat enough of it to do any harm. And some additives may actually protect us. There is more about food additives in the page on diet causing cancer.

Day to day environment
By environmental causes we mean what is around you each day that may help to cause cancer. This could include

* Tobacco smoke
* The sun
* Natural and man made radiation
* Work place hazards
* Asbestos

Some of these are avoidable and some aren't. Most are only contributing factors to causing cancers - part of the jigsaw puzzle that scientists are still trying to put together. There is more about this in the page on causes of cancer in the environment.

Viruses
Viruses can help to cause some cancers. But this does not mean that these cancers can be caught like an infection. What happens is that the virus can cause genetic changes in cells that make them more likely to become cancerous.

These cancers and viruses are linked

* Cervical cancer, and other cancers of the genital and anal area, and the human papilloma virus (HPV)
* Primary liver cancer and the Hepatitis B and C viruses
* Lymphomas and the Epstein-Barr Virus
* T cell leukaemia in adults and the Human T cell leukaemia virus
* HPV also probably leads to oropharyngeal cancer and non melanoma skin cancers in some people

There will be people with primary liver cancer and with T cell leukaemia who haven't had the related virus. But infection increases their risk of getting that particular cancer. With cervical cancer, scientists now believe that everyone with an invasive cervical cancer has had an HPV infection beforehand.

Many people can be infected with a cancer causing virus, and never get cancer. The virus only causes cancer in certain situations. Many women get a high risk HPV infection, but never develop cervical cancer. Another example is Epstein-Barr virus (EBV). These are some facts about EBV

* It is very common - most people are infected with EBV
* People who catch it late in life get glandular fever and have an increased risk of lymphoma
* In sub-Saharan Africa, EBV infection and repeated attacks of malaria together cause a cancer called Burkitt's lymphoma in children
* In China, EBV infection (together with other unknown factors) causes nasopharyngeal cancer
* In people with AIDs and transplant patients EBV can cause lymphoma
* About 4 out of 10 cases of Hodgkin's lymphoma and a quarter of cases of Burkitt's lymphoma (a rare type of non Hodgkin's lymphoma) seem to be related to EBV infection.

Bacterial infection
Bacterial infections have not been thought of as cancer causing agents in the past. But studies have shown that people who have helicobacter pylori infection of their stomach develop inflammation of the stomach lining, which increases the risk of stomach cancer. Helicobacter pylori infection can be treated with a combination of antibiotics.

Research is also looking at whether substances produced by particular types of bacteria in the digestive system can increase the risk of bowel cancer or stomach lymphomas. Some researchers think that particular bacteria may produce cancer causing substances in some people. But research into this issue is at an early stage.

If bacteria do play a part in causing cancer this could be important in cancer prevention. Bacterial infections can often be cured with antibiotics, so getting rid of the infection could be a way to reduce the risk of these types of cancer.



Aug 7, 2011

Studying skills in Biology




1. Successful biology students study a minimum of 2 to 3 hours per day, 7 days a week, throughout the term.

2. Biology is hard work, so be aggressive. Take it as a challenge and give it your time and your energy.

3. Know and understand all your terminology. This is one of the keys to success in any field. This is the basis for many seemingly difficult terms. Study these roots. Make 3" x 5" flash cards to help you memorizse them and later do the same with your terminology.

4. Pay attention.

5. Make it a practice to read over the topic or chapter before going to your biology class.

6. Attend all classes and be an active listener. It is important to be alert and concentrate on what is said in class. Successful students take full and comprehensive notes, writing down about 66% of what is said in class, while failing students write half as much. It is most important to stay current. Do not allow yourself to miss classes and fall behind or the entire course will become an effort and a struggle for you.

7. After class go over the material as soon as possible and again 8 hours later. Studies have shown that you are more likely to remember the information later. Fill in all the missing words or incomplete explanations. Recite important concepts in your own words.

8. Always remember you have the right to ask questions before, during and after class. See your teachers during their office hours for help. Notice when you are beginning to get in trouble and seek help immediately.

9. Read and study all your textbook explanations. You may wish to use at least two or more books. These books are often available in the library. Each book has a different discussion and examples on your topic, and one of these is likely to be helpful to you.

10. Whenever possible explain aloud to another person what you are learning. Work with a classmate and explain terminology and concepts to each other.

11. Describe in your own words the similarities and differences between the different concepts you are learning. Do this aloud with someone else.

12. If biology is your most difficult subject, then always study it before all other subjects. You must study biology when you are most alert and fresh. Make sure to take 5 or 10 minute breaks every 20­40 minutes in order to clear your mind.

13. Write up summary sheets of biology terminology and concepts and review often. The more you review the more you'll remember. Also visually picture the terms in your minds eye. Visualising is a powerful technique for remembering terms. Break words into small chunks and picture each chunk until you can recall it. Then put the chunks together. Remember, the knowledge of roots can be extremely helpful.

14. Making up mnemonics memory techniques may be fun as well as beneficial. For example, if you need to remember the 12 cranial nerves you can take the first letter of each nerve and make up a sentence where each word begins with the first letter of each nerves.

15. Create sample tests for yourself and test yourself often.

16. Give yourself timed tests similar to those you expect in class. Time yourself with a kitchen timer or an alarm. Practice, practice, practice.

17. Review the types of errors you make and types of questions that cause you difficulty. Give yourself more practice in these areas of difficulty.

18. If possible, have a friend or family member quiz you on your notes and text information. Done regularly this commits more information to long­term memory.

Good luck.