Dec 31, 2010

What is Biology?

video

Happy New Year 2011


Bygones are bygones! New Year has finally arrived. Time to express gratitude, clear off all the blemishes and complains, motivate the week, congratulate the winners and play pranks on friends. A new start ought to be marked with love and care.
I wish you Health...
So you may enjoy each day in comfort.
I wish you the Love of friends and family...
And Peace within your heart.
I wish you the Beauty of nature...
That you may enjoy the work of God.
I wish you Wisdom to choose priorities...
For those things that really matter in life.
I wish you Generosity so you may share...
All good things that come to you.
I wish you Happiness and Joy...
And Blessings for the New Year.
I wish you the best of everything...
That you so well deserve.
HAPPY NEW YEAR!

Dec 28, 2010

New Year's Resolution Tips


Chances are, at some time in your life, you've made a New Year's Resolution -- and then broken it. This year, stop the cycle of resolving to make change, but then not following through. If your resolution is to take better care of yourself and get your inflammatory bowel disease (IBD) under control, you'll have a much better year if your resolution sticks. Here are some tips to help get you started.

Be realistic
The surest way to fall short of your goal is to make your goal unattainable. For instance, resolving to never eat your favourite food again because it bothers your IBD could be a bad choice. Strive for a goal that is attainable, such as avoiding it more often than you do now.
 
Plan ahead
Don't make your resolution on New Year's Eve. If you wait until the last minute, it will be based on your mindset that particular day. Instead, it should be planned well before December 31 arrives.

Outline your plan
Decide how you will deal with the temptation to skip that exercise class or have one more cigarette. This could include calling on a friend for help, practicing positive thinking and self-talk, or reminding yourself how your bad habit affects your IBD.

Make a "pro" and "con" list
It may help to see a list of items on paper to keep your motivation strong. Develop this list over time, and ask others to contribute to it. Keep your list with you and refer to it when you need help keeping your resolve.

Talk about it
Don't keep your resolution a secret. Tell friends and family members who will be there to support your resolve to change yourself for the better or improve your health. The best case scenario is to find yourself a buddy who shares your New Year's resolution and motivate each other.

Reward yourself
This doesn't mean that you can eat an entire box of chocolates if your resolution is to diet. Instead, celebrate your success by treating yourself to something that you enjoy that does not contradict your resolution. If you've been sticking to your promise to eat better, for example, perhaps your reward could be going to a movie with a friend.

Track your progress
Keep track of each small success you make toward reaching your larger goal. Short-term goals are easier to keep, and small accomplishments will help keep you motivated. Instead of focusing on losing 30 pounds, say, focus on losing that first 5. Keeping a food diary or a symptom journal may help you stay on track.

Don't beat yourself up
Obsessing over the occasional slip won't help you achieve your goal. Do the best you can each day, and take each day one at a time.

Stick to it
Experts say it takes about 21 days for a new activity, such as exercising, to become a habit, and 6 months for it to become part of your personality. Your new healthful habits will become second-nature in no time.

Keep trying
If your resolution has totally run out of steam by mid-February, don't despair. Start over again! There's no reason you can't make a "New Year's resolution" any time of year.

Fast Facts About New Year's Resolutions
63% of people say they are keeping their resolutions after two months
67% of people make three or more resolutions

Top four resolutions:
Increase exercise
Be more conscientious about work or school
Develop better eating habits
Stop smoking, drinking, or using drugs (including caffeine)

People make more resolutions to start a new habit than to break an old one.
 
Adios.....

Dec 26, 2010

Tips for Time Management



Perhaps you have a heavy workload and want to find ways to become more effective so you can get more done in less time.

Maybe you feel overwhelmed or “stressed out” and want to find ways to do less and enjoy more. Or maybe you simply want to feel more focused and in control of your time, instead of feeling like you rush madly from one activity to the next until you fall into bed exhausted every night.

Benjamin Franklin said, “Do you love life? Then do not squander time, for that's the stuff that life is made of.”

Time management is a set of principles, practices, skills, tools, and systems working together to help you get more value out of your time with the aim of improving the quality of your life.

The important point is that time management is not necessarily about getting lots of stuff done, because much more important than that is making sure that you are working on the right things, the things that truly need to be done.

Smart time managers know that there is much more to do than anyone could possibly accomplish. So instead of trying to do it all, smart time managers are very picky about how they spend their time.

They choose to focus and spend their time doing a few vital projects that will really make a difference, rather than spending all their time doing many trivial things that don't really matter all that much.

If you become a good time manager, you’ll not only get a lot more done in less time, but you’ll feel more relaxed, focused and in control of your life.

You’ll be able to use your time in a much more balanced and effective way, and you’ll be able to make time for the people and activities that you love. When you get to the end of a busy day, you’ll feel a strong sense of accomplishment from everything that you actually got done.

Improving your time management skills can even help you get better results by doing less work, because you're focusing on the things that really matter rather than all the low-priority busywork that just keeps you busy.

If you don’t learn how to manage your time well, you’ll be far less productive than you could be and you’ll get a lot less done. You’ll also feel much more stressed and overwhelmed, and you’ll struggle to find time to spend with the people you care about and to do the things you enjoy.

In the end, time management comes down to choices. Good choices lead to better results, while poor choices lead to wasted time and energy.

The good news is that time management skills can be learned and mastered by anyone. All it takes is practice and dedication.

Like any other skill, you can learn time management the easy way or you can learn it the hard way.

The hard way usually involves years of trial and error and lots of false starts trying to figure out what works and what doesn't.

If you'd like to save yourself some time, money and effort, I recommend you try the easy way: learn from someone who has already done it.

Makes sense, right?

15 Time Management Tips
In the meantime, here are 15 practical time management tips to help you get started...

1. Write things down
A common time management mistake is to try to use your memory to keep track of too many details leading to information overload. Using a to-do list to write things down is a great way to take control of your projects and tasks and keep yourself organised.

2. Prioritise your list
Prioritising your to-do list helps you focus and spend more of your time on the things that really matter to you. Rate your tasks into categories using the ABCD prioritisation system described in the time management course.

3. Plan your week
Spend some time at the beginning of each week to plan your schedule. Taking the extra time to do this will help increase your productivity and balance your important long-term projects with your more urgent tasks. All you need is fifteen to thirty minutes each week for your planning session.

4. Carry a notebook
You never know when you are going to have a great idea or brilliant insight. Carry a small notebook with you wherever you go so you can capture your thoughts. If you wait too long to write them down you could forget. Another option is to use a digital recorder.

5. Learn to say no
Many people become overloaded with too much work because they overcommit; they say yes when they really should be saying no. Learn to say no to low priority requests and you will free up time to spend on things that are more important.

6. Think before acting
How many times have you said yes to something you later regretted? Before committing to a new task, stop to think about it before you give your answer. This will prevent you from taking on too much work.

7. Continuously improve yourself
Make time in your schedule to learn new things and develop your natural talents and abilities. For example, you could take a class, attend a training program, or read a book. Continuously improving your knowledge and skills increases your marketability, can help boost your career, and is the most reliable path to financial independence.

8. Think about what you are giving up to do your regular activities
It is a good idea to evaluate regularly how you are spending your time. In some cases, the best thing you can do is to stop doing an activity that is no longer serving you so you can spend the time doing something more valuable. Consider what you are giving up in order to maintain your current activities.

9. Use a time management system
Using a time management system can help you keep track of everything that you need to do, organize and prioritise your work, and develop sound plans to complete it. An integrated system is like glue that holds all the best time management practices together.

10. Identify bad habits
Make a list of bad habits that are stealing your time, sabotaging your goals, and blocking your success. After you do, work on them one at a time and systematically eliminate them from your life. Remember that the easiest way to eliminate a bad habit, it to replace it with a better habit.

11. Don’t do other people’s work
Are you in the habit of doing other people’s work because or a ‘hero’ mentality? Doing this takes up time that you may not have. Instead, focus on your own projects and goals, learn to delegate effectively, and teach others how to do their own work.

12. Keep a goal journal
Schedule time to set and evaluate your goals. Start a journal and write down your progress for each goal. Go through your goal journal each week to make sure you are on the right track.

Keeping a journal on your computer has never been easier!

13. Don’t be a perfectionist
Some tasks don’t require your best effort. Sending a short email to a colleague, for example, shouldn’t take any more than a few minutes. Learn to distinguish between tasks that deserve to be done excellently and tasks that just need to be done.

14. Beware of “filler” tasks
When you have a to-do list filled with important tasks, be careful not to get distracted by “filler” tasks. Things such as organising your bookcase or filing papers can wait until you tackle the items that have the highest priority.

15. Avoid “efficiency traps”
Being efficient doesn’t necessarily mean that you are being productive. Avoid taking on tasks that you can do with efficiency that don’t need to be done at all. Just because you are busy and getting things done doesn’t mean you are actually accomplishing anything significant.

Dec 25, 2010

Memorising facts in Biology


  • Mnemonics can be used wherever possible. don't give it up totally.
  • Sometimes writing the first letters of names & amp; reading them in a nonsensical & amp; funny way can help.
  • Write down the points, after reading the answers; draw pictures like parts of the plant, body parts, nerves etc. to connect to the point.,
  • Write the number of points you have to learn for an answer & amp; arrange them in a sequence easy for you to remember.
  • When learning objective type answers you can request a family member to ask the qns. This may look funny but mothers are a wonderful support in this.
  • Divide your portions & amp; learn thoroughly before going to the next one
  • Don't accumulate too much of study material.
  • Prepare a time table & amp; follow it sincerely.
  • Keep your goal in mind & amp; work towards it.
Nothing is impossible when you work hard.
Like what you are doing at present.
Best of luck.

Understand what you are learning and have confidence.

Dec 23, 2010

Good relationship with your teachers


A good relationship between students and teachers makes the classroom a more inviting place. When you like your teacher, it's easier to pay attention to his explanations and improve your grades. When you consider your teacher a friend, you'll certainly have more respect for him. When your teachers consider you to be a friend and not only a student, they'll feel freer in class and that will probably affect the classroom in a very positive way. Now here are some tips to develop a friendly relationship with your teachers:

Ask questions. If you have any questions about that subject, ask them. Teachers like to teach and asking questions is the first way of interacting with them. Show them that you're interested in their subject. That will make them notice you. But never ask questions that you already know the answer to. If your teachers realise that you are not asking real questions, they might think that you're not actually trying to learn, but only trying to make an impression.

No need for compliments. Don't say things like "You look lovely today, Mrs. Lim" or "Did you lose weight, Mr. Smith?" Your teacher will probably think you're being false and only trying to get some advantage, and that's not what you want. Instead, you could do some innocent jokes (jokes that won't offend your teacher). The moment they start doing some of the same jokes (but towards you), then you'll know that your relationship is becoming friendly.
 
When you see one of your teachers in the hall, greet him and ask if he's going to that concert or if he's seen that movie. That way you'll show that you consider him a friend, and that's why you talk about common subjects. Some teachers don't like to have a friendly relationship with a student, but most of them want to have those simple talks with their students. And after a while, they will start to talk with you about non-school subjects in the class. That will make more students in your class get involved in those talks, and everyone will start to consider that teacher to be a friend.

The rest is totally up to you; it is very easy to develop a friendly relationship with any of your teachers. If you want to be friends with your teachers, just treat them as friends, but don't forget that no matter how good of friends you are, they will still be your teachers and deserve your respect.

Tata.....

Dec 22, 2010

Don't give up

video

Dec 18, 2010

Careers in Bio



Pursuing a career in biology can be immensely rewarding and exciting. Studying biology teaches us to ask questions, make observations, evaluate evidence, and solve problems. Biologists learn how living things work, how they interact with one another, and how they evolve. They may study cells under a microscope, insects in a rainforest, viruses that affect human beings, plants in a greenhouse, or lions in the African grasslands. Their work increases our understanding about the natural world in which we live and helps us address issues of personal well being and worldwide concern, such as environmental depletion, threats to human health, and maintaining viable and abundant food supplies.

What do biologists do?
There are several career paths you can follow as a biologist, including these:

Research: Research biologists study the natural world, using the latest scientific tools and techniques in both laboratory settings and the outdoors, to understand how living systems work. Many work in exotic locations around the world, and what they discover increases our understanding of biology and may be put to practical use to find solutions to specific problems.

Health care: Biologists may develop public health campaigns to defeat illnesses such as tuberculosis, AIDS, cancer, and heart disease. Others work to prevent the spread of rare, deadly diseases, such as the now infamous Ebola virus. Veterinarians tend to sick and injured animals, and doctors, dentists, nurses, and other health care professionals maintain the general health and well being of their patients.

Environmental management and conservation: Biologists in management and conservation careers are interested in solving environmental problems and preserving the natural world for future generations. Park rangers protect state and national parks, help preserve their natural resources, and educate the general public. Zoo biologists carry out endangered species recovery programs. In addition, management and conservation biologists often work with members of a community such as landowners and special interest groups to develop and implement management plans.

Education: Life science educators enjoy working with people and encouraging them to learn new things, whether in a classroom, a research lab, the field, or a museum.

Colleges and universities: Professors and lecturers teach introductory and advanced biology courses. They may also mentor students with projects and direct research programs.

Secondary school: Teaching younger students requires a general knowledge of science and skill at working with different kinds of learners. Secondary school teachers often specialise in biology and teach other courses of personal interest.

Science museums, zoos, aquariums, parks, and nature centres: Educators in these settings may design exhibits and educational programs, in addition to teaching special classes or leading tours and nature hikes.

New directions in biological careers: There are many careers for biologists who want to combine their scientific training with interests in other fields. Here are some examples:

Biotechnology: Biologists apply scientific principles to develop and enhance products, tools, and technological advances in fields such as agriculture, food science, and medicine.

Forensic science: Forensic biologists work with police departments and other law enforcement agencies using scientific methods to discover and process evidence that can be used to solve crimes.

Business and industry: Biologists work with drug companies and providers of scientific products and services to research and test new products. They also work in sales, marketing, and public relations positions.

Mathematics: Biologists in fields such as bioinformatics and computational biology apply mathematical techniques to solve biological problems, such as modeling ecosystem processes and gene sequencing.

Science writing and communication: Journalists and writers with a science background inform the general public about relevant and emerging biological issues.

Art: All the illustrations in your biology textbook, as well as in newspaper and magazine science articles, were created by talented artists with a thorough understanding of biology.

Dec 17, 2010

Human papillomavirus

Vaccinating 13 year old girls with human papillomavirus vaccine (HPV) can help reduce cases of cervical cancer and genital warts. Studies had shown that teenage girls aged less than 15 have a better immunity response compared with older girls or women.

Immunity among teenagers (15 years and below) vaccinated with HPV is very high even after five and a half years. Free HPV vaccination programme carried out by the government for teenage students was an initiative to prevent cervical cancer. HPV is a common virus that is passed on through genital contact, most often during sex and most sexually active people will get HPV at some time in their lives, though most will never even know it and is most common among people in their late teens and early 20s.  Malaysian women were at a high risk of HPV which can led to cervical cancer due to their smoking habits, diet and family history.

According to the World Health Organisation (WHO) 80 percent of women who have reached 50 years would have been affected by HPV and almost 20 percent of them would have reached a chronic stage, resulting in cervical cancer. The government would be spending RM150 million to vaccinate about 300,000 teenagers throughout the country.

A human papillomavirus (HPV) is a member of the papillomavirus family of viruses that is capable of infecting humans. Like all papillomaviruses, HPVs establish productive infections only in the stratified epithelium of the skin or mucous membranes. While the majority of the nearly 200 known types of HPV cause no symptoms in most people, some types can cause warts (verrucae), while others can – in a minority of cases – lead to cancers of the cervix, vulva, vagina, and anus in women or cancers of the anus and penis in men.

More than 30 to 40 types of HPV are typically transmitted through sexual contact and infect the anogenital region. Some sexually transmitted HPV types may cause genital warts. Persistent infection with "high-risk" HPV types—different from the ones that cause skin warts—may progress to precancerous lesions and invasive cancer. HPV infection is a cause of nearly all cases of cervical cancer; however, most infections with these types do not cause disease.

Most HPV infections in young females are temporary and have little long-term significance. 70% of infections are gone in 1 year and 90% in 2 years. However, when the infection persists—in 5% to 10% of infected women—there is high risk of developing precancerous lesions of the cervix, which can progress to invasive cervical cancer. This process usually takes 15–20 years, providing many opportunities for detection and treatment of the pre-cancerous lesion. Progression to invasive cancer can be almost always prevented when standard prevention strategies are applied - however the lesions still cause considerable burden necessitating preventive surgeries which do in many cases involve loss of fertility.

In more developed countries, a cervical Papanicolaou (Pap) test is used to detect abnormal cells which may develop into cancer. During a colposcopic inspection biopsies can be taken and abnormal areas can be removed with a simple procedure, typically with a cauterizing loop or—more common in the developing world—by freezing (cryotherapy).

Pap smears have reduced the incidence and fatalities of cervical cancer in the developed world, but even so there were 11,000 cases and 3,900 deaths in the U.S. in 2008. Cervical cancer has substantial mortality in resource-poor areas; worldwide, there are 490,000 cases and 270,000 deaths.

HPV vaccines (Cervarix and Gardasil), which prevent infection with the HPV types (16 and 18) that cause 70% of cervical cancer, may lead to further decreases.



Dec 12, 2010

Highly sensitive person?

Are you?

Now, as an introduction to the trait of high sensitivity, see if some of these statements resonate with you, or relate to someone important in your life...

  • You, your partner, or someone important to you have a heightened awareness of subtleties in your environment, whether it's sight, sound, touch, taste, or smell.
  • You can become stressed out and upset when overwhelmed and may find it necessary to get away, maybe into a darkened room, to seek solitude, relief and comfort.
  • You are very creative.
  • You are very conscientious, hard working, and meticulous, but may become uncomfortable and less efficient or productive when being watched or scrutinised.
  • You feel compelled to file and organise things and thoughts, also enjoy simplicity and may become overwhelmed or even immobilised by chaos, clutter, or stress.
  • You are very uncomfortable when feeling things are getting out of your control.
  • You get a sense of comfort and well being when around a lake, river, stream, the ocean, or even a fountain.
  • You may experience mood swings, sometimes occurring almost instantly and can also be affected by other people's moods, emotions and problems.
  • You have a deep, rich, inner life, are very spiritual, and may also have vivid dreams.
  • You are very intuitive and you feel that you can usually sense if someone isn't telling the truth or if something else is wrong.
  • You get concerned and think or worry about many things, and have also been told "you take things too personally."
  • You have had the experience of "cutting people out" of your life.
  • You were considered quiet, introverted, timid, or shy as a child.
Here are a few more to consider... Can be startled easily. Cautious in new situations. May have trouble sleeping. Extra sensitive to pain. Don't like crowds (unless they are kindred spirits). Avoids violent movies and TV shows. Has a deep respect and appreciation of nature, music and art.

Do some, or many, of these statements ring true for you, your partner, or someone important in your life? If so, you or they may be a highly sensitive person.

Tata....

Dec 11, 2010

Scientific Names

There are many times where you might need to know or write down the scientific name of a plant or an animal. Scientific names allow us to talk about species with a greater degree of accuracy than if we were to just use the common name. Many plants and animals have a more than one common name and so using the correct scientific terms makes talking about plant and animal species less ambiguous.


The scientific name of a species is made up of a combination of two special terms The first name is the genus of the organism and is capitalised, while the second is the species which is not capitalised. Below I will show you the conventions used when writing down a scientific name correctly.

Genus name
The genus name of a species is always written first and it is also underlined (in written) or italicised (only when using computers). Another point to note is that the first letter of the genus name is always capitalised.

  • in the STPM if students write in italic the scientific names, you'll get 0 mark
  • students must underline separately; don't underline the whole thing
Species name
The species name of an organism is written second and the specific epithet is always underlined (in written) or italicised (using computers).

Example of a correct scientific names :

Homo sapiens for human

Oryza sativa for paddy

Nephelium lappaceum for rambutan

Once you get to understand the convention then you will find that learning the correct scientific name for a plant or animal is not that hard. By learning the correct scientific names for a plant or animal you will be able to communicate with other scientists around the world unambiguously.

Kingdom     : Animalia
Phylum        : Chordata
Class           : Mammalia
Order          : Primates
Family         : Hominidae
Genus         : Homo
Species       : sapiens

Dec 6, 2010

Facts about your body

The length from your wrist to your elbow is the same as the length of your foot.

Your heart beats 101,000 times a day. During your lifetime it will beat about 3 billion times and pump about 400 million litres (800 million pints) of blood.

It is impossible to lick your elbow. Well, for almost everyone… but a few can.

Your mouth produces 1 litre (1.8 pints) of saliva a day.

The human head contains 22 bones. More on the head and brains

On average, you breathe 23,000 times a day.

Breathing generates about 0.6g of CO2 every minute.

On average, people can hold their breath for about one minute. The world record is 21 minutes 29 seconds, by David Merlini.

On average, you speak almost 5,000 words a day – although almost 80% of speaking is self-talk (talking to yourself).

Over the last 150 years the average height of people in industrialised nations increased by 10 cm (4 in).

In the 19th century, American men were the tallest in the world, averaging 1,71 metres (5’6″). Today, the average height for American men is 1,763 m (5 feet 9-and-half inches), compared to 1,815 m (5’10″) for Swedes, and 1,843 m (5’11″) for the Dutch, the tallest Caucasians.

The tallest nation in the world is the Watusis of Burundi: 1.98 m (6 feet 6 inches) tall.

If the amount of water in your body is reduced by just 1%, you’ll feel thirsty.

It is impossible to sneeze and keep one’s eyes open at the same time.

55% of people yawn within 5 minutes of seeing someone else yawn.

A person can live without food for about a month, but only about a week without water.

You’ll drink about 75,000 litres (20,000 gallons) of water in your lifetime.

After a certain period of growth, hair becomes dormant. That means that it is attached to the hair follicle until replaced by new hair.

Hair on the head grows for between two and six years before being replaced. In the case of baldness, the dormant hair was not replaced with new hair.

Men loose about 40 hairs a day. Women loose about 70 hairs a day.

In the Middle Ages the length from the tip of the middle finger to the elbow was called an ell.

A person remains conscious for eight seconds after being decapitated.

The first successful human sex change took place in 1950 when Danish doctor Christian Hamburger operated on New Yorker George Jorgensen, who became Christine Jorgensen.

The muscle that lets your eye blink is the fastest muscle in your body. It allows you to blink 5 times a second.

On average, you blink 15 000 times a day. Women blink twice as much as men.

A typical athlete’s heart churns out 25 to 30 litres (up to 8 gallons) of blood per minute.

Unless food is mixed with saliva you cannot taste it.

The liver is the largest of the body’s internal organs. The skin is the body’s largest organ.

On average a hiccup lasts 5 minutes.

Fingernails grow nearly 4 times faster than toenails.

Your middle fingernail grows the fastest.

Your finger nails grow at 1 nanometre per second (0.000 000 001 m/s). Your hair grows at 4 nanometres per second (0.000 000 004 m/s).

It takes about 3 months for the transplanted hair to start growing again.

About 13% of people are left-handed. Up from 11% in the past.

In 1900, a person could expect to live to be 47. Today, the average life expectancy for men and women in developed countries is longer than 70 years.

A newborn baby’s head accounts for one-quarter of its weight.

King Henry I, who ruled in the England in the 12th century, standardised the yard as the distance from the thumb of his outstretched arm to his nose.

The bones in your body are not white – they range in colour from beige to light brown. The bones you see in museums are white because they have been boiled and cleaned.

Our eyes are always the same size from birth.

Every person has a unique tongue print.

If all your DNA is stretched out, it would reach to the moon 6,000 times.

Approximately two-thirds of a person’s body weight is water. Blood is 92% water. The brain is 75% water and muscles are 75% water.

The coloured part of the eye is called the iris. Behind the iris is the soft, rubbery lens which focuses the light on to a layer, called the retina, in the back of the eye. The retina contains about 125 million rods and 7 million cones. The rods pick up shades of grey and help us see in dim light. The cones work best in bright light to pick up colors.

We actually do not see with our eyes – we see with our brains. The eyes basically are the cameras of the brain.

Hormones involved in Menstrual Cycle

Can be divided into 2 groups :
 i) hormones that control the changes in the ovaries - FSH and LH
 ii) hormones that control the changes in the uterus - oestrogen and progesterone

FSH
secreted by - anterior pituitary gland
stimulates the development in the ovary

LH
secreted by - anterior pituitary gland
stimulates ovulation, the development of corpus luteum
promotes the secretion of progesterone

Oestrogen
secreted by - follicle cells of the ovary
stimulates further growth of the follicles
promotes the repair of endometrium from 12th day of the menstrual cycle, it has positive feedback action on the secretion of FSH and LH

Progesterone
secreted by - corpus luteum
stimulates the endometrium to become thick, folded & highly vascular (enriched with blood vessels) for the implantation of an embryo
inhibits the secretion of FSH & LH to prevent the development of Graafian follicles &  ovulation