Biology Revision for "O" level examinations

In the video below, the process of Mitosis is explained. 

Skin lightening, or skin bleaching, is a cosmetic procedure that aims to lighten dark areas of skin or achieve a generally paler skin tone. Side effects of skin-lightening creams can include: skin irritation and inflammation (redness and swelling) a burning or stinging sensation itchy and flaky skin uneven colour loss increased risk of cancer Skin whitening creams contain ingredients that act to slow the production of melanin in the skin’s outer layer.

-It is  a medical process for ending pregnancy -Persons choice to undergo abortion is largely influenced by their religious beliefs and cultural beliefs as well as legality of the process in their country Reasons for Abortion -pregnancy may be at a greater risk to the woman’s life than ending the pregnancy -pregancy may cause a greater risk of injury to the woman’s mental or physical health When it should be done -It should occur as early as possible during pregnancy (ideally before 12 th week), when it is easier and safer. If a woman’s life is in danger, then there is no legal time limit for it to occur. -up to 9 weeks in pregnancy (9 weeks since last period) an abortion pill may be used -from 14 weeks onwards, a surgical method is usually required. -Abortion should always be carried out under medical supervision

-Smoking (first or second hand) may result in miscarriage, stillbirth, or premature birth: chemicals in the smoke affect the placenta ( placental abruption: a condition when the placenta separates from the uterus before childbirth ), and causes slow foetal development. -Alcohol affects development of baby's nervous system. -Illicit drugs such as marijuana and cocaine  can cause mental retardation, miscarriage, or physical defects of child - Only drugs prescribed by doctors should be used. Aspirin, Advil, and Motrin can cause fetal heart defects -X-ray: during pregnancy, this can cause genetic mutations in foetus, causing abnormal development. Ultra sound is a safer method, to do internal examination of the body

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Hello everyone. I know that there are thousands of you out there who are anxiously waiting your cxc grades. I really hope that your Grades are as you expect. However, it is not the end of the world if you did not achieve what you expected. There is always going to be another opportunity for you to excel. Never give up. Below is the link that you can use to log in to check your CSEC Grades. According to CXC the grades should be available from tonight at 22:00 hours (Today is 16th August). However, it is possible that students in Guyana might have some issue because the government may block it from students who did not submit their text book. We have to wait and see. Click on the link below to access the student portal CXC Student Portal: Student Results Best wishes everyone!

Red Blood cells/erythrocytes -they are formed in red bone marrows of the ribs, skull and vertebrae -survive for approximately 120 days and are then destroyed in the liver and spleen Structure and Function -contains no nucleus: this allows more room for haemoglobin (also: cells cannot divide/reproduce ) -they have biconcave disc shape to increase surface area -contains hemoglobin that allows the transport of oxygen White Blood cells/Leucocytes a. Phagocytes Function: They engulf and digest invading bacteria and viruses.   Structure:             -their shape may vary             -they move using pseudopodia             -its nucleus is lobed shape             -they are formed in red bone marrows             b. Lymphocytes Structure:          -round, large cells                         -large, round nucleus                         -they are made in lymph glands and spleen

Hypertension •          B lood flows through the blood vessels with a force greater than normal i.e. with a blood pressure reading of 140/90 •          When the blood pushes harder against the walls of your arteries, your blood pressure goes up Prevention •          Quit smoking •          Exercise regularly •          Reduce amount of sodium •          Eating a healthy diet Coronary Heart Disease/ Heart  attack •          A heart attack happens when the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked and the heart can’t get oxygen. •          If blood flow isn’t restored quickly, the section of heart muscle begins to die. •          Coronary Heart disease •          CHD is a condition in which plaque builds up inside the coronary arteries. •          When plaque builds up in the arteries, the condition is called  atherosclerosis •          The buildup of plaque occurs over many years. •          Coronary thrombosis-

Hello everyone. Most of the contents be be posted on my new website. I will also be placing past examinations papers on my new website. Link : http://www.biologynotes101.com/index.html

Types of joints 1.       Movable joints      The bones of these joints are separated by a pad of flexible cartilage. There are two type of movable joints: a.        Slightly movable joints: -are found adjacent between adjacent vertebrae. The cartilage between the joints (called intervertebral disc) absorbs shock. They can be displaced due to injury. Other e.g. Pivot joints: between neck and cranium. b.       Synovial joints: the bones are held together by ligaments and are separated by synovial fluid. The fluid lubricates the joints, preventing the joints and cartilage caps of the bone from rubbing against each other. e.g. hinge joints: elbow, and knee         ball and socket: at shoulder and hips 2.       Immovable joints       These joints are held firmly in position by fibers. They exist between bones of the skull and of the pelvic girdle.  They are referred to as sutures. Types of Joints NB:      Tendons: connect muscles to bones          

How the xylem vessel carries water ROOT PRESSURE Water that is present in the soil, is absorbed by osmosis into the root hairs of plants. The water then travels through the cortex of the root, from cell to cell. A root pressure is therefore created, and this forces water from the cortex into the xylem vessel CAPILLARITY Through capillarity, water moves up the xylem in a continuous stream. The water molecules are attracted to the walls of the vessels (adhesion) and they are also attracted to each other (cohesion). This cause an upward movement of water in the xylem, against gravity TRANSPIRATION PULL Transpiration occurs in leaves of plants. This loss of water causes a vacuum to be created in the xylem. There is therefore a high water pressure at the bottom, and a lower water pressure at the top of the xylem. Therefore, there is an upward pull of water.

From my previous posts, it was mentioned that Zika rarely causes death, and hospitalization is also uncommon. So what is the most devastating effect of the Zika virus? It can cause  microcephaly in infants. When the virus first began to spread like wildfire in Brazil, Doctors were not very certain of the implications. However, what was observed, was that there was a raising number of microcephaly in infants. Based on further investigation, a link was established between the virus and microcephaly.  What is Microcephaly Microcephaly (my-kroh-SEF-uh-lee) is a rare neurological condition in which an infant's head is significantly smaller than the heads of other children of the same age and sex. Sometimes detected at birth, microcephaly usually is the result of the brain developing abnormally in the womb or not growing as it should after birth. Microcephaly can be caused by a variety of genetic and environmental factors. Children with microcephaly often have developmental

Zika virus is affecting hundreds of thousands of people across South America but what is this devastating virus? Unfortunately,there is no treatment, vaccine or cure for this disease as yet. This outbreak will certainly brings more focus of researchers towards a treatment or vaccine.  However, as a  Forbes post  mentioned, it seem as if the world waited a bit too long to develop a suitable vaccine. Only after the outbreak has been so devastating, that funds are being made available for research. "A new epidemic hits the news, leaving everyone scurrying to develop a vaccine. Previously, there was SARS. In 2009, it was H1N1 influenza, two years ago it was Ebola. Now it is Zika. Each time a vaccine was not available in time to substantially impact the course of the epidemic" (Bruce Y Lee,  Forbes ) The  Following is a  DNews  video, explaining about the devastating Zika virus 

What is Zika? Zika virus is a member of the Flaviviridae virus family and the Flavivirus genus, transmitted by daytime-active Aedes mosquitoes, such as  A. aegypti. How does the virus spread? Aedes aegipti Mosquito Zika virus is transmitted to people primarily through the bite of an infected Aedes species mosquito. These are the same mosquitoes that spread dengue and chikungunya viruses. These mosquitoes typically lay eggs in and near standing water in things like buckets, bowls, animal dishes, flower pots and vases.  They are aggressive daytime biters, prefer to bite people, and live indoors and outdoors near people. Mosquitoes become infected when they feed on a person already infected with the virus. Infected mosquitoes can then spread the virus to other people through bites. What are some of the Symptoms of Zika? -About 1 in 5 people infected with Zika virus become ill (i.e., develop Zika). Symptoms of Zika infection -The most common symptoms of Z

What is H1N1 flu? H1N1 is a flu virus. When it was first detected in 2009, it was called “swine flu” because the virus was similar to those found in pigs. The H1N1 or swine  flu  is a respiratory disease caused by  influenza   viruses  that infect the respiratory tract of pigs and result in a barking  cough ,  decreased appetite , nasal secretions, and listless behavior; the virus can be transmitted to humans. The H1N1 virus is currently a seasonal flu virus found in humans. Although it also circulates in pigs,  you cannot get it by eating properly handled and cooked pork or pork products Transmission Swine flu is transmitted from person to person by  inhalation  or ingestion of droplets containing virus from people  sneezing  or  coughing . Symptoms Symptoms of H1N1 Symptoms of swine flu are similar to most influenza infections. Some symptoms are listed below:    Fever (100 0 F /37 0 C or greater), Cough. Nasal secretion,fatigue   and headache.