The Best Biology O Level Notes compiled from all around the world at one place for your ease. MB. 24/02/ IGCSE Biology lesforgesdessalles.info MB. more examples of diffusion in biology. Diffusion: Diffusion always takes place down a concentration gradient, that means that the particles that diffuse try. Biology Notes for IGCSE · All Notes · 1. Classification · 2. Cells · 3. Enzymes · 4. Plant Nutrition · 5. Animal Nutrition · 6. Plant Transport · 7. Human.
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Prevention Eating foods rich in vitamin C every day prevents scurvy. This process of oxidation which occurs within every living cells of animals aw well as plants is called respiration. Perhaps the most common of all mineral deficiency disorders is anemia. Muhammad Motawea. All sciences Reply. Posted by Zainal Haji Ahmad at 6:
Niacin occurs naturally in foods such as liver, meat, fish, legumes, and dried yeast. Today it is added to many processed foods such as bread, flour, cornmeal, macaroni, and white rice. This practice has essentially eliminated pellagra as a medical problem in developed countries, although it remains a serious health problem in some less-developed countries of the world. Rickets is a bone disorder caused by a lack of vitamin D. Vitamin D is often called the "sunshine" vitamin because it can be produced in the human body by the effects of sunlight on the skin.
Rickets was once a common disease of infants and children. However, all milk and infant formulas now have vitamin D added to them. Thus, the disorder is rarely seen today in countries where "fortified" milk is available. Symptoms of rickets include legs that have become bowed by the weight of the body and wrists and ankles that are thickened. Teeth may be badly affected and take a longer time to mature.
Mineral deficiency diseases. About 25 mineral elements are required in the human body for the maintenance of good health.
Calcium and phosphorus, for example, are needed to produce teeth and bones. One of the exceptions is the disorder known as goiter. Goiter is a condition caused by an insufficient amount of iodine in the diet.
Iodine is used by the thyroid to produce hormones that control the body's normal functioning as well as its normal growth. If sufficient iodine is not available in a person's diet, the thyroid gland begins to enlarge its cells in an effort to produce the needed hormones. This enlargement produces the characteristic swelling in the neck characteristic of goiter.
Today, goiter has virtually disappeared from most developed nations because of the practice of adding small amounts of iodine in the form of sodium iodide to ordinary table salt. Perhaps the most common of all mineral deficiency disorders is anemia. The term anemia literally means "a lack of blood.
The human body gets the energy it needs to stay alive and function normally by oxidizing nutrients in cells. The oxygen needed for this process is carried from the lungs to cells on red blood cells.
The "working part" of a red blood cell is a complex molecule called hemoglobin. Each hemoglobin molecule contains a single atom of iron at its center. The iron atom combines with oxygen from the lungs to form a compound known as oxyhemoglobin. It is in this form that oxygen is transferred from the lungs to cells. If the body fails to receive sufficient amounts of iron, an adequate number of hemoglobin molecules will not be formed.
In that case, there are not enough functioning red blood cells to carry all the oxygen that cells need to produce energy.
A person becomes weak and listless and may suffer headaches, soreness of the mouth, drowsiness, slight fever, gastrointestinal disturbances, and other discomforts. The treatment for malnutrition and for nutrient deficiency diseases is obvious: That instruction is easy to give but in many parts of the world it is impossible to follow.
Marasmus, kwashiorkor, beriberi, scurvy, rickets, and other deficiency disorders are common in less-developed countries of the world because sufficient food is either not available or, if it is, it is not sufficiently nutritious. In more-developed countries of the world, people often have ready access to nutritious foods in sufficient quantities so that malnutrition is less of a problem than it is in less-developed countries. In addition, a very large variety of supplements are available, such as vitamin and mineral pills.
Anyone who fears that he or she may not be receiving enough of any given vitamin or mineral can easily supplement his or her diet with products available at the corner grocery store.
Scurvy is a condition caused by a lack of vitamin C ascorbic acid in the diet. Signs of scurvy include tiredness, muscle weakness, joint and muscle aches, a rash on the legs, and bleeding gums. In the past, scurvy was common among sailors and other people deprived of fresh fruits and vegetables for long periods of time. Scurvy is very rare in countries where fresh fruits and vegetables are readily available and where processed foods have vitamin C added. Vitamin C is an important antioxidant vitamin involved in the development of connective tissues, lipid and vitamin metabolism, biosynthesis of neurotransmitters, immune function, and wound healing.
It is found in fruits, especially citrus fruits like oranges, lemons, and grapefruit, and in green leafy vegetables like broccoli and spinach. In adults, it may take several months of vitamin C deficiency before symptoms of scurvy develop. The body's need for vitamin C increases when a person is under stress, smoking, or taking certain medications. Causes and symptoms. A lack of vitamin C in the diet is the primary cause of scurvy.
This can occur in people on very restricted diets, who are under extreme physiological stress for example, during an infection or after an injury , and in chronic alcoholics.
Infants can develop scurvy if they are weaned from breast milk and switched to cow's milk without an additional supplement of vitamin C.
Babies of mothers who took extremely high doses of vitamin C during pregnancy can develop infantile scurvy. In children, the deficiency can cause painful swelling of the legs along with fever, diarrhea, and vomiting. In adults, early signs of scurvy include feeling weak, tired, and achy. The appearance of tiny red blood-blisters to larger purplish blotches on the skin of the legs is a common symptom. Wound healing may be delayed and scars that had healed may start to break down.
The gums swell and bleed easily, eventually leading to loosened teeth.
Muscle and joint pain may also occur. Scurvy is often diagnosed based on the symptoms present. A dietary history showing little or no fresh fruits or vegetables are eaten may help to diagnose vitamin C deficiency. A blood test can also be used to check the level of ascorbic acid in the body. Adult treatment is usually , mg of ascorbic acid per day. Infants should be treated with 50 mg of ascorbic acid up to four times per day.
Treatment with vitamin C is usually successful, if the deficiency is recognized early enough. Left untreated, the condition can cause death. Eating foods rich in vitamin C every day prevents scurvy. A supplement containing the RDA of vitamin C will also prevent a deficiency. Infants who are being weaned from breast milk to cow's milk need a supplement containing vitamin C. Calcium and Vitamin D are nutrients that have received much attention in recent years because they work together to prevent several chronic diseases.
One of the best sources of calcium and Vitamin D is milk, but there are other sources. This post can help you understand why adequate amounts of these nutrients are needed for overall health and prevention of disease. You will also learn ways to meet the recommended intakes of each nutrient.
A major health concern is that many children and teenagers are not taking in enough calcium. One culprit may be the increased drinking of soft drinks. Health experts fear that many children will develop osteoporosis later in life, due to low calcium intakes during childhood and the teen years.
Drinking orange or grapefruit juice with added calcium is a good way to meet calcium needs. When substituting other calcium sources in place of milk, care must be taken to eat enough of these foods to equal the calcium in the milk that is replaced. The following foods provide about the same amount of calcium as 1 cup of milk mg. Contrary to previous belief, calcium from plant sources is well absorbed.
One exception is the calcium in spinach, which is not well absorbed due to compounds called oxalates. Cheese, yogurt, and buttermilk may not cause this problem since much of the "lactose" has already been broken down. Also, you may be able to drink smaller amounts of milk at one time 1 cup or less without symptoms.
Lactaid tablets from a drug store can be added to milk to reduce the lactose. Here are some things to consider, if you take a calcium supplement: Posted by Zainal Haji Ahmad at 5: Posted by Zainal Haji Ahmad at 7: FACT 1: Posted by Zainal Haji Ahmad at 6: Science Biology cell lecture.
Health Education lecture Thermodynamics. Biology notes for brunei o level Publish at Scribd or explore others: Primary and High Sch Education protocols medicinal. Aerobic respiration occurs in the presence of oxygen whereas anaerobic respiration occurs in the absence of oxygen.
Aerobic respiration releases a large amount of energy efficient in terms of energy yield whereas anaerobic respiration only releases a small amount of energy less efficient in terms of energy yield Aerobic respiration always produces carbon dioxide and water as the waste products whereas anaerobic respiration produces lactic acid as in the case of anaerobic respiration in muscle cells and ethanol and carbon dioxide as in the case of anaerobic respiration in yeast.
Respiration is necessary to supply organisms with energy which help them to maintain themselves, move, excrete, grow and reproduce. The main source of energy for organisms is the radiant energy from sunlight.
During photosynthesis, green plants transofrm this energy into chemical energy which is stored in the organic foods products of photosynthesis. This stored chemical energy is obtained by orgnisms animals by feeding on green plants or on other animals. This process of oxidation which occurs within every living cells of animals aw well as plants is called respiration.
When students were asked about their pre-conceptions about respiration, the common misconception was that respiration is thought to be a scientific name for breathing But breathing does help indirectly by bringing in oxygen into your body Respiration is the oxidation of food substances mainly glucose with the release of energy in living cells. Respiration can be of two forms: Aerobic respiration can be represented by the following equation. The process shown by the above equation involves many enzyme-catalysed reactions.
The enzymes for each of these enzyme-catalysed reactions are found in the mitochondria. Hence mitochondria are important in respiration. In fact it is the site where respiration occurs.
So does absorption of mineral salts by the root hair cells Transmission of nerve impulses Note: Yeast cells oxidise glucose during frementation. The products is ethanol which is an alcohol. For this reason, anaerobic respiration is yeast is also called alcoholic fermentation. Anaerobic respiration is yeast can be represented by the following equation: Less energy is released because the alcohol molecule is relatively large and still contains a conisderable amount of chemical energy.
The small amount of energy released is only enough for the yeast to survive. But in certain circumstances, where oxygen is not available for a very short period of time, these cells need to respire anaerobically without oxygen gas. This usually occurs during a vigorous or strenous exercise such as sprinting in a m race.
What actually happens here? Sometimes, individual experiences muscle cramp. This is due to an accumulation of lactic acid in their muslces. If the level of lactic acid exceeds the individual tolerance level depending on how fit the individual is , muslces stop contracting and cramp occurs.
Now consider the following question: What is the part of the alimentary canal that stores undigested food temporarily? For this question, no Biology students should make mistake For me one does not have to learn Biology to answer this question.
So here are some of the answers: Posted by Zainal Haji Ahmad at The question was: Movement of water molecules through semi-permeable membrane? Got it? I hope so I hope I will not encounter this misconception ever again This process is simply a process in which big fat globule is broken down into small fat droplets without changing the fat chemically So you starts with fats and ends with fats, get it?.
Its just like shaking oil in water where you would observed tiny emulsions formed. The idea here is to increase the surface area to volume ratio of the fats so that chemical digestion by LIPASE could be facilitated.
In human digestive system, during the process of digestion, this process takes place in the duodenum. Whenever chyme containing fats enters the duodenum, your gall bladder will secrete bile into the duodenum Remember: By the way after bile is secreted into the duodenum, it will emulsify the fats present in the chyme.
Unlike fats, your body simply cannot store amino acids no matter how much protein you are taking in in your diet. From the figure you can see that it consists of the amino group and the carboxylic acid group.
Otherwise, if the glycogen is not utilized within a duration of about 6 hours, it will eventually be converted into FATS and stored in the liver itself as well as in the adipose tissues under your skin.
Posted by Zainal Haji Ahmad at 1: I have an urgent need to blog about this because there were misconceptions concerning it based on some students' responses in the previous test.
Here are some of the misconceptions: It is the ALTERNATE contraction and relaxation of the circular and longitudinal muscles causing bolus to be pushed down and also at the same time to be physically digested. It is very important to do so because it shows that you understand that these muscles are actually working antagonistically that is, when one set of muscles relaxes the other set contracts - for example when the circular muscles relax, the longitudinal muscles contract.
It can be assumed that both set of muscles are actually contracting or relaxing at the same time. One is to move bolus down along the alimentary canal and the second function is to break the bolus down into smaller pieces without changing them chemically this is a kind of PHYSICAL digestion.
And lastly Not only the oesophagus but actually along the alimentary canal Causes of famine In biological terms, a population beyond its regional carrying capacity causes famine. When there is an inadequate supply of glucose, the fats are oxidized to provide energy Under normal conditions, fats are used to build protoplasm Excess fats are stored in adipose tissues Adipose tissues A layer of tissues beneath the skin, around the heart, the kidneys and in the mesenteries binding the intestines, where fats are stored.
Peristalsis o Rhythmic, wave-like contractions of the alimentary canal wall to move food along the alimentary canal o Brought about by the antagonistic actions of the circular and longitudinal muscles Dilation Circular muscles relax, longitudinal muscles contract Constriction Circular muscles contract, longitudinal muscles relax Functions of liver o Carbohydrate metabolism Glycogen is converted to glucose in the liver in the presence of glucagon from the pancreas o Fat metabolism Lipids are removed from the blood and broken down E.
Some photosynthesis occurs and this causes the cells to be turgid support Lignified xylem vessels and Xylem aids in the conduction of tracheids water and mineral salts from the Phloem tissues with sieve tubes roots to the leaves and companion cells Provides support for the leaf lamina Phloem aids in transport of products of photosynthesis from the leaves to other parts of the plant, especially to the roots, in the form of sucrose One cell thick layer Stomata allow gaseous exchange Waxy cuticle between external environment Presence of many stomata and the intercellular air spaces in the spongy mesophyll A pair of curved guard cells Gaseous exchange occurs surrounding a stomatal pore through the stomatal pore Opening or closure of guard cells regulates gaseous exchange.
Effects of carbon dioxide The normal percentage of carbon dioxide in atmospheric air is 0. Graphs show the effect of light and carbon dioxide concentration on photosynthesis rates In each case, the rates increase rapidly at first, then reach a ceiling, indicating that they are being affected by another limiting factor, for example, temperature.
For example, in the first graph, by increasing the temperature, the rate of photosynthesis showed only a small increase It is likely that temperature may not be an important limiting factor in this example In the second graph, carbon dioxide concentration is increased instead There is a significant increase in the rate of photosynthesis It is likely that carbon dioxide is an important limiting factor in this example This is true in nature as there only is 0.
In the third graph, with raised carbon dioxide concentration, temperature is increased Again, there is a significant increase in the rate of photosynthesis This shows that temperature was a limiting factor Compensation point At certain light intensity, the rate of photosynthesis and the rate of respiration is equal This means that the amount of CO2 taken in and O2 released is the same.
Transport in humans Main blood vessels o Pulmonary artery Heart to lungs o Pulmonary vein Lungs to heart o Hepatic artery Heart to liver o Hepatic vein Liver to heart o Renal artery Heart to kidneys o Renal vein Kidneys to arteries Functions of blood.
Carbon dioxide will diffuse out of the blood in the alveoli to be exhaled out to the external environment Some moisture and heat will also be exhaled out in this manner. A very fast random contraction and relaxation of muscles, which generates heat to warm the blood Blood vessels near the skin surface When one is too warm Vasodilation is brought about o More blood is brought to the surface of the skin and more heat is lost through radiation, conduction and convention Constriction of shunt vessels to allow more blood to be brought to the surface When one is too cold Vasoconstriction is brought about o This prevents blood from flowing to the surface of the skin o Instead it has to go through the capillaries which lie below the fat layer o This reduces the amount of heat lost by radiation from the blood to the air Dilation of shunt vessels to direct blood away from the surface Coordinating role of brain The hypothalamus in the brain is responsible to prevent overcompensation In other words, the brain controls when compensation is to be ceased.
Contains visual purple The pigment concerned with vision in dim light Light causes bleaching of visual purple which is involved in light detection In bright light, all the visual purple is bleached It takes a short time for visual purple to be formed again in the rods Thus, when a person enters a dark place from a bright one, he may not be able to distinguish the objects around him for some time Formation of visual purple requires Vitamin A A person with deficiency in Vitamin A may not be able to see in dim light, a condition known as night-blindness Rods are sensitive to dim light, but only let one see in black and white.
It increases the rate of conversion of glycogen to glucose in the liver, thus increasing blood sugar level so that more glucose is available for energy production Stimulus includes fear, anger, anxiety or stress. They also need to ensure that they have a ready supply of sugary food as their blood glucose concentration can drop drastically either from over-dosage of insulin, exercising too much or eating too little People with Type 2 diabetes need to control their blood glucose concentration by regulating intake of carbohydrates in their diet and by regular exercising If lifestyle changes fail, then the patients may need to take medication e.
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