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Ks3 science

QuestionAnswer
Three things that plants need for photosynthesis are: carbon dioxide, water and light.
Two things that plants make by photosynthesis are: glucose and oxygen.
What is photosynthesis in a word equation? carbon dioxide + water (+ light energy) → glucose +oxygen. Light energy is shown in brackets because it is not matter.
Plants get carbon dioxide from the air through the pores in their leaves and water from the ground through their roots.
Light energy comes from the sun.
The oxygen produced in photosynthesis is released into the air from the pores in the leaves.
The glucose produced in photosynthesis can be turned into other substances, such as starch, which releases energy gradually. This can be released through cellular respiration.
Cell membrane control what substances can get into and out of the cell. (In both plant and animal cells).
Cytoplasm are jelly-like substances, where [] reactions happen chemical reactions happen. In plant cells there's a thin lining, whereas in animal cells, most of the cell is cytoplasm. (In both plant and animal cells).
Nucleus controls what happens inside the cell and carries g[] information genetic information. (Don't call it the 'brain'). (In both animal and plant cells).
Vacuoles contain a liquid called cell sap, which keeps the cell firm. (Vacuoles are found in plant cells only).
Cell walls are made of a tough substance called cellulose, which supports the cell. (Cell walls are in plant cells only).
Three parts of a cell that are found in plant cells only are the Chloroplast, Cell wall and Vacuole.
oxygen plus nitrogen= Nitrogen oxide
Photosynthesis takes place inside plant cells in the Chloroplast. It contains a green substance which absorbs light energy called chlorophyll. (Chloroplast are in plant cells only).
Aerobic Respiration is a form of cellular respiration in which glucose or another organic substrates release energy by reacting with oxygen.
Cellular respiration; A series of metabolic processes that take place within a cell.
Mrs Gren Movement, reproduction, sensitivity, Growth, respiration, excretion, nutrition.
5 specialised cells are the Sperm cell- designed to fertilise eggs, the ovum(egg)- cell designed to be fertilised, the palisade cell- designed for photosynthesis, the ciliated cell- designed to stop lung damage and the root hair cell- designed for absorbing.
A group of similar cells come together to make a tissue
A group of different tissues work together to make an organ.
A group of organs work together to make an organ system or organism.
A sperm cell digests through an egg membrane using enzymes.
A sperm can carry genetic information from a father to a child because its nucleus contains chromosomes
A ovum can carry genetic information from a mother to a child because its nucleus contains chromosomes
The formula for converting Fahrenheit to Celcius is 5/9(Fahrenheit-32)
Three main types of micro-organisms are fungi, bacteria and viruses.
Usually the size of order from biggest to smallest for the three main types of microbes are fungi, bacteria, viruses.
A tail-like organelle on a bacterium is possibly a flagellum which helps it to swim.
Five parts of a fungus cell are [] [] [], [], [] [], [] and [] food storage granules, nucleus, cell membrane, vacuole, cytoplasm.
Mushrooms and toadstools are fungi, but they are not microbes because they are made of lots of cells.
Yeasts are single-celled fungi, so they are microbes.
Some viruses contain DNA or RNA in a protein capsid.
Instead of a nucleus a virus contains a strand of genes.
Instead of a cell walls viruses have protein coats.
A flagellum is an organelle of locomotion and an organelle is a specialised part of a cell.
A virus is composed of a protein coat and a strand of genes instead of a nucleus.
When reproducing a virus might reprogram a cell's DNA and force it to make more viruses. That is a process called a lytic infection.
When reproducing a virus might combine with the invaded cell's DNA so that every time the cell reproduces it also makes more viruses. That is called a lytic infection.
As viruses reproduce inside cells some people might not be convinced that viruses are living things.
The cell wall of fungi is hard and the cell wall of bacteria is soft.
Anaerobic respiration is a form of cellular respiration that occurs when oxygen is absent or scarce.
In cellular respiration biochemical energy is harvested from an organic substance like glucose.
In cellular respiration harvested biochemical energy might be stored as energy carriers (ATP) for use in energy-requiring activities of the cell.
Two things that Yeast cells can change sugar into are carbon dioxide gas and alcohol. This makes Yeast useful to bakers and brewers.
Yeast cells change sugar into carbon dioxide gas and alcohol through fermentation.
Yeast is useful to bakers because the released carbon dioxide helps bread rise and it might be considered useful to brewers because it can add alcohol used for their drinks.
Milk might be changed to make yogurt and cheese using bacteria.
When a starter culture of bacteria is used in the changing of milk to yogurt; bacteria ferments lactose to lactic acid with the use of anaerobic respiration. The acid produced causes the milk to clot and solidify into yogurt.
When a starter culture of bacteria is used in the changing of milk to yogurt; in the milk bacteria produces solid curds which got seperated from the liquid whey. More bacteria is then added to the curd which is left to ripen before moulds are added.
Athlete's foot and Thrush might be caused by Fungi.
Tuberculosis and Salmonella can both affect the lungs while salmonella can cause food poisoning. Tuberculosis, Salmonella and whooping cough are all caused by bacteria.
Chicken pox (affects skin and nerves), influenza(flu) and a common cold can all be caused by Viruses.
measles (affects skin and lungs), mumps (affects salivary glands) and rubella(German measles) can all be caused by Viruses.
When Bacteria are able to reproduce in the body they can cause diseases.
Bacteria might release harmful substances called toxins which can damage tissues and organs.
Five ways that microbes might be spread are through air,animal contact, food,touch and drinks(like water).
If people sneeze or cough in the air they might send out droplets. Droplets contain microbes and might get inside people if they breath in.
Two ways animals can send microbes into people are by scratching and biting.
Antiseptics destroy micro-organisms on living tissue.
Disinfectants are substances that are applied to non-living objects to destroy micro-Organisms. It doesn't necessarily kill all micro-organisms and is resisted by bacterial spores plus some other micro-organisms; it is considered less effective than sterilisation.
Micro-Organisms can enter can enter a person's body if they touch something previous in contact with or has been handled by an infected person. Athlete's foot spreads like this.
Thorough boiling or adding chemicals like chlorine to water can reduce the chance of Microbes spreading.
If in the Stomach, Microbes can be killed by [] [] and [] hydroclauric acid and enzymes.
If in the Lungs Microbes can be trapped by Mucus and swept by Cilia.
Microbes might be stopped from getting into the body by the skin.
To stop microbes getting into the body, cuts can be covered by scabs.
Tears contain substances that kill microorganism.
Microbes are killed and 'swallowed' by White-blood-cells. Some white blood cells then die but some stay alive as memory cells.
Microbes and their poisons or toxins may be neutralised by Antibodies. Antibodies may also make it easier for Microbes to get swallowed by White-blood-cells by causing them to clump together.
Microbes have chemicals called antigens. Different microbes have different antigens.
White blood cells may release cells/chemicals called Antibodies.
White blood cells can stick to microbes if the white blood cell has the right antibody to match the antigen on the microbe. When this happens the microbes can be killed, or clumped together to make it easier for other white blood cells to swallow them.
Some Antibiotics kill Bacteria while others stop the Bacteria r[] reproducing.
Antibiotics might be used to treat diseases related to Bacteria but not diseases related to v[] viruses.
After the microbes have been killed, the amount of antibodies goes down.
After a second infection by the same microbe, your body is quicker at releasing the correct antibodies.The microbe doesn't get a chance to make you ill this time, and people might say that you are immune.
Vaccine might contain copies of the disease causing microbes that are dead or weak. Instead it might contain some of its Antigens.
In response to the vaccine your immune system may produce White-blood-cells with the correct Antibodies.
Carbohydrase or amylase enzymes break down starch into Sugar. The saliva in your mouth contains a[] amylase, which is a another [] digesting enzyme. starch digesting enzyme. If you chew a piece of bread for long enough, the starch it contains is digested to sugar, and it begins to taste sweet.
Protease enzymes break down proteins into molecules of Amino acids .
Lipase enzymes break down fats into [] [] and [] fatty acids and glycerol.
The 3 places that Carbohydrates are digested are in the mouth, stomach and small intestine.
Three types of Carbohydrates are Starches(also known as complex carbohydrates), Sugars and Fiber.
The saliva in your mouth contains some protein called Amylase, which is a Starch digesting Enzyme.
Proteins are digested in both the small Intestine and stomach where the digestion of proteins can be aided by [] a[] Hydroclauric acid in the Stomach which can kill []-[] that may be in the food. micro-organisms
Digestion of fat can take place in the Small Intestine and might be helped by Bile.
Bile breaks the globules of fat into small droplets that are easier for the Lipase enzymes to work on.
Maybe in the digestion of Fats the main emulsifier is Bile.
Bile is excreted by the liver and stored in the Gall bladder.
Three things that aren't digested as they were already small enough are Minerals, Vitamins and Water.
Digestive enzymes don't break down Fibre, which is why it isn't absorbed by the body.
Digested food molecules that are able to be dissolved are absorbed in the Small Intestine. They pass through the wall of the small intestine and into the bloodstream where they are carried off to where they're 'needed'. For substances to pass across the wall of the small intestine, they have to be s[] and s[] small and soluble, large and insoluble objects 'cannot' pass through.
Allowing absorption to happen quickly and efficiently, the inside wall of the small intestine is [] and has a large [] [] thin and has a large surface area (so the digested food doesn't pass out of the body before it's had a chance to be absorbed. To get a big surface area, the inside wall of the small intestine is lined with Villi (one of them is called a villus). These stick out and give a big surface area. They also contain blood capillaries to carry away the [] [] [] absorbed food molecules.Villi have blood v[] vessels and walls with thickness of a single cell.
Excess water is absorbed back into the body in the large intestine. What is left then is undigested food.
Undigested food is stored in the rectum (the lower part of the large intestine) until it comes out through the Anus as faeces. This process is called egestion.
After we swallow, our food passes through these organs in turn: Oesophagus, stomach, small intestine and large intestine.
The pancreas produces chemicals called digestive enzymes.
Mineral are used in small amounts to maintain health.
Vitamins are used in small amounts to maintain health.
Fibres are used to provide roughage to help to keep the food moving through the gut.
Iron can help to make Red-Blood-Cells.
Sounds can be seen as waves on an Oscilloscope.
Amplitude is the loudness of sound.
If a wave on an Oscilloscope is louder it has a larger amplitude.
Amplitude shows how much energy there is in a sound.
On an Oscilloscope the higher the wave goes the higher the amplitude.
On an Oscilloscope the more frequent the waves are, the higher pitched it is and the higher the pitch, the higher the frequency.
The more vibration there are, the higher the frequency.
Sound waves vibrate the air, which eventually vibrates the ear drum, which vibrates the Ossicles, which leads to the vibration of hairs in the Cochlea sending a message to the Auditory nerve.
Humans hear up to around 20,000 hertz whereas some animals can hear sounds of up to and over 120,000 hertz.
The vibrations are passed on through air when sound waves are travelling from air particle to air particle.
Often to move, sound travels through a medium because usually when sound travels, something vibrates.
Sound carries energy.
Poor hearing can be caused by both wax.. blocking ears and the auditory nerve becoming damaged.
Apart from illnesses poor hearing can be caused by micro-organisms creating infections as well as old age and general deterioration.
When there was an object in the way of 'rays' you might have seen a shadow.Assuming there was a 'torch' shining on n when both get closer; n's 'shadow' gets smaller, but if both move further away; n's 'shadow' gets bigger.
Between Light and sound, the faster is considered to be light.
Objects that give out light are known as Luminous objects.
Non- luminous objects reflect light which then reaches our eyes.
With mirror the angle of incidence is equal to the angle of reflection.
Rough surfaces may look dull as the light is reflected in lots of different directions. This is called a diffuse reflection.
Between younger and older humans; higher and softer noises tend to be more audible to younger people.
Dispersion of white light may occur when white light hits a [] or [] [] white light hits a prism or rain drop.
Red, orange, yellow, green, blue, indigo and violet are are known as the colours in a rainbow or sometimes; 'spectrum'.
The breakdown of rocks into smaller fragments is called weathering.
In alphabetical order, the 3 types of weathering are: biological weathering, chemical weathering and physical weathering.
Freeze-thaw weathering is the repeating of both freezing and thawing. This is done to both water and ice in the gaps inside rocks. When the water freezes, turns to ice and expands, it makes the gaps larger and eventually causes pieces of rocks to break away.
Often with freeze-thaw weathering, the water in the rock freezes during day, while it thaws during night. This process is repeated until the fragment of rock breaks off.
Freeze-thaw weathering is a type of physical weathering.
Exfoliation weathering or onion skin weathering is the repeating of both heating and cooling of rocks, which causes the surface layer to flake off, possibly leading to that rock splitting.
With exfoliation weathering, often the heating is done during the day, while the cooling is done during the night.
Exfoliation weathering is a type of physical weathering as that rock keeps [] and [] expanding and contracting, pieces of that rock's surface begin to flake and eventually fall off.
With exfoliation weathering, during the day, the surface of that rock is heated by the sun, causing that rock to expand. During the night, instead of being heated, that rock cools and then contracts.
With biological weathering, plant roots and shoots can get into minute cracks in rocks. As the plant grows, roots and shoots can push their way through the rock, which (in those rocks) forces cracks. The growth of cracks in this way causes small pieces of rock to break off.
Rainwater is naturally acidic because rainwater reacts with carbon dioxide in the air to form carbonic acid. This type of acid rain is weakly acidic and reacts slowly with some or all substances.
With biological weathering, plant roots and shoots can get into minute cracks in rocks. As the plant grows, roots and shoots can push their way through the rock, which (in those rocks) forces cracks. The growth of cracks in this way causing small pieces of rock to break off.
Chemical weathering is the break-down of rocks when there are chemical reactions between acid rain and certain minerals in rocks.
The word equation for aerobic respiration is glucose + oxygen → carbon dioxide + water (+ energy). Energy is shown in brackets because it's not a substance. The chemical equation for aerobic respiration is (numbers ss) C6H12O6 + 6O2 → 6CO2 + 6H2O (+ energy).
|Glucose from food to cells| Glucose is a type of c[] carbohydrate, obtained through [] of the [] we []. digestion of the food we eat. Digestion breaks food down into small molecules. These can be absorbed across the wall of the small intestine into the bloodstream.
Glucose is carried round the body dissolved in blood plasma, the pale yellow liquid part of our blood. The dissolved glucose can diffuse into the [] of the body cells of the body from the c[] capillaries. Once in the cell glucose can be used in respiration.|
|Oxygen from the air to cells| When we breathe in oxygen enters the small air sacs, called alveoli, in the lungs. Oxygen diffuses from there into the bloodstream.
Oxygen is carried by the [] [] cells red blood cells. These contain a red substance called haemoglobin, which joins onto oxygen and carries it around the body in the blood, then lets it go when necessary. Like glucose, oxygen can diffuse into cells from the capillaries.| Red blood cells carry oxygen around the body.
|Carbon dioxide from cells to the air| The carbon dioxide produced during respiration diffuses out of the cells and into the blood plasma. It is then carried by the blood to the lungs. It then diffuses across the walls of the alveoli and into the air, ready to be exhaled.
The human respiratory system contains the organs that allow us to get oxygen and to remove the waste carbon dioxide we don't need. It contains these parts: l[] lungs, [] leading from the [] to the [] and [] tubes leading from the lungs to the mouth and nose, various structures in the [] that allow air to move in and out of the [] various structures in the lungs that allow air to move in and out of the lungs.
When you inhale: there is a [] in pressure and [] is drawn into lungs there is a decrease in pressure and air is drawn into the lungs; the intercostal muscles [], expanding the [] the intercostal muscles contract, expanding the ribcage; the diaghpragm [], pulling []; the diaphragm contracts, pulling downwards.
|Ventilation/Breathing:| movements of the ribs, rib muscles and diaphragm allow air into and out of the lungs. Air passes between the [] and the outside of the [] between the lungs and the outside of the body, through the windpipe, called the trachea. The trachea divides into two bronchi, with one bronchus for each lung.
{Each bronchus divides further in the lungs into smaller tubes called bronchioles. At the end of each bronchiole, there is a group of tiny [][] air sacs. These air sacs have bulges called alveoli to increase their surface area.}
We get oxygen into the blood, and we remove waste carbon dioxide from the blood. Moving gases like this is called gas exchange.
The alveoli make gas exchange in lungs happen easily and efficiently. Here are some features of the alveoli that allow this: they give the lungs a big [] a[...] surface area, they have moist, thin walls (just one cell thick), they have a lot of tiny blood vessels called capillaries.
During gas exchange, the gases move by diffusion from where they have a high concentration to where they have a low concentration: Oxygen diffuses from the air in the alveoli into the blood, Carbon dioxide diffuses from the blood into the [] in the [] air in the alveoli.
{Some water vapour is lost from the [] of the alveoli into the [] some water vapour is lost from the surface of the alveoli into the lungs} - we can see this condensing when we breathe out on cold days
Our skeleton is made of more than 200 bones. Calcium and other minerals make the bone s[] strong but slightly flexible. Bone is a living t[] tissue with a [] supply blood supply. (Exercise and a balanced diet are important for a healthy skeleton.){It is constantly being di[] and l[] down dissolved and laid down, and it can repair itself if a bone is broken.}
The skeleton has three main functions: to support the b[] body, to protect some of the vital [] of the body vital organs of the body, to help the body m[] move.
The backbone protects the spinal cord.
Some bones in the skeleton are joined rigidly together and cannot [] against each other move against each other. Bones in the skull are joined like this. Other bones are joined to each other by f[] j[] flexible joints. To move bones attached by joints, [] are used muscles are used.
If two bones just moved against each other, they would eventually wear away. This can happen in people who have a disease called arthritis. To stop this happening, the ends of the bones in a joint are covered with a tough, smooth substance called cartilage. This is kept slippery by s[] f[] synovial fluid. Tough [] join the two bones in the joint and stop it falling apart ligaments (join the two bones).
Different types of joint allow different types of movement. [] joints allow simple movement, the same as a door opening and closing. Knee and elbow joints are this type hinge joints. [] and [] joints allow movement in more directions. Hip and shoulder joints are like that Ball and socket (joints). The bones cannot move on their own - they need muscles for this to happen.
Muscles work by c[] contraction. Muscles are attached to bones by strong tendons. When a muscle contracts, it [] on the bone, pulls on the bone and the bone can move if it is part of a joint.
As muscles pull (and don't push), they work in pairs called antagonistic muscles. The biceps and triceps are antagonist muscles: to lift the forearm, the biceps contracts and the triceps relaxes; to lower the forearm again, the triceps contracts and the biceps relax.
Animal cells usually have an irregular shape, while the shape of plants is usually regular.
Animal cells and plant cells both contain cell membrane, cytoplasm, nucleus. Three parts that are found in plant cells, but not in animal cells are the chloroplasts, vacuole and cell wall.
|Specialised cells| The function of red blood cells is to carry oxygen; special features: the cells have a large s[] a[] surface area for [] to pass through oxygen--; it also contains [], which joins to the oxygen haemoglobin.
The function of nerve cells is to carry n[] im[] nerve impulses to different parts of the body. Special features: in terms of size, the cells are long; at each end of the cells, there are c[] connections; the cells can carry e[] signals electrical signals.
The function of the female reproduction cell (egg cell) is to join with the male cell, and then to provide food for the new [] that's been formed cell. Special features: in terms of size, the egg is large (relatively), it contains lots of cytoplasm.
The function of the male reproductive cell (sperm cell) is to reach the female cell, and to [] with it join. Special features: long tail for swimming, head for getting into the female cell.
The function of a root hair cell (a plant cell) is to absorb both water and minerals. Special features: large surface area, cell membrane with thin cell wall, which makes it easier for [] to pass across into the root itself minerals. (A root hair cell also has a vacuole.)|
Animal cells and plant cells can form t[] tissues, like muscle tissues. A living tissue is made from a group of cells with a similar s[] and f[] structure and function, which all work together to do a particular j[] job. Examples: muscle, the lining of the intestine, the lining of the lungs, phloem (tubes that carry dissolved sugar around a plant), root hair tissue (for plants to take up water and minerals from the soil).
An organ system is made from a group of different organs, which all work together to do a particular job. Examples: circulatory system, respiratory system, digestive system, nervous system, reproductive system, leaf canopy.
The two testes (one of them is called a testis) are contained in a bag of skin called the scrotum. They have two functions: to produce millions of male [] cells sex cells called sperm and to make male sex hormones, which affect the way a man's body d[] develops.
The sperm pass through the [] [] sperm ducts, and mix with fluids produced by the glands. The fluids provide the sperm cells with nutrients. The mixture of sperm and fluids is called semen.
The penis has two functions: to pass [] out of the man's body urine out of a man's body and to pass s[] semen into the vagina of a woman during sexual intercoruse.
The urethra is the tube inside the penis that can carry either urine or semen. A ring of [] makes sure that there is no chance of urine and semen getting mixed up muscle.
The two ovaries contain hundreds of undeveloped female [] cells sex cells called [] cells or o[] egg cells or ova. Women have a finite amount of these cells in their bodies from birth - whereas men produce new sperm continually.
Each ovary is connected to the uterus by an [] [] egg tube. This is sometimes called an o[] or F[] tube oviduct or Fallopian. The egg tube is lined with c[] cilia, which are tiny [] on cells hairs on cells.
Every month, an egg d[] develops and becomes m[] mature, and is released from an ovary. The [] waft the egg along The cilia waft the egg along inside the egg tube and into the uterus.
The uterus is also called the womb. It is a muscular bag with a soft lining. The uterus is where a baby d[] until its birth. develops. The cervix is a ring of muscle at the lower end of the uterus. It keeps the baby in place while the woman is pregnant.
The vagina is a muscular tube that leads from the cervix to the outside of the woman's body. The opening to the vagina has [] of skin folds of skin called labia that meet to form a vulva. The urethra also opens into the vulva, but it is separate from the vagina, and is used for passing urine from the body.
|The female reproductive system includes a cycle of events called the menstrual cycle. It lasts about 28 days, but it can be slightly less or more than this. The cycle stops while a woman is pregnant. At the start of the cycle, there is some bleeding. This is called m[] menstruation. By the end of day 5, the loss of blood stops. The lining of the uterus begins to regrow.
On day five of the menstrual cycle, egg cells start to mature in one of the ovaries. At about day 14, the mature egg cell is released from the ovary. This is called ovulation. The egg travels through the egg tube towards the uterus.
If the egg does not meet with a sperm cell, the lining of uterus begins to [ ][] break down and the cycle repeats. If the egg cell meets and joins with a sperm cell, it is f[] fertilised. It attaches to the lining of the uterus and the woman becomes pregnant.|
During sexual intercourse, sperm cells travel in semen from the penis and into the top of the vagina. They enter the u[] uterus through the cervix and travel to the egg tubes. If a sperm cell meets with an egg cell there, [] can happen. Fertilisation can happen. Fertilisation happens when an egg cell meets with a sperm cell and joins with it.
The reproductive system of a child is not mature and needs to change as a boy or girl develops into an adult, so that the system is fully working. These changes begin between the ages of ten and fifteen. The time when the changes happen is called puberty. The changes happen because of sex hormones produced in boys - by the testes and in girls - by the ovaries.
Changes that happen to both boys and girls during puberty: underarm hair grows, pubic hair grows, body smell gets stronger, emotional changes, growth rate increases. The time when the physical changes and emotional changes happen is called puberty.
Changes that happen to boys only: voice becomes deeper ("breaks"), testes and penis get bigger, testes start to produce sperm cells, shoulders get wider, hair grows on both the face and the chest.
Changes that happen to girls only: breasts develop, ovaries start to release egg cells (menstruation starts), hips get wider.
Minerals are used in the body in [] amounts small amounts to maintain health (good sources: salt, milk (for calcium) and liver (for iron)). Vitamins are used in the body in [] amounts small amounts to maintain health (good sources: dairy foods, fruit, vegetables). Fibre is used in the body to provide roughage to help to keep the food moving through the gut (good sources: vegetables, bran). Water is 'needed' in the body for c[] and b[] [] cell and body fluids (good sources: fruit juice, milk, water).
If you have too little of a particular nutrient, we say that, in that nutrient, you have a deficiency. For example, fibre is needed to keep food easily moving through the intestines, and people who have a fibre deficiency in their diet may get constipation. People with iron deficiency may have too few [] [] cells red blood cells (and have anaemia). People with iodine deficiency may get a swelling in the neck called a goitre.
Although we only need small amounts of the different vitamins in our diet, we become ill if we don't get enough. For example, vitamin A deficiency can cause blindness. Vitamin C deficiency causes scurvy, which makes the gums bleed, and vitamin D deficiency causes rickets, which makes the legs bow outwards in children.
Food is a store of chemical energy. It is usually measured in kilojoules, kJ. If we eat too little food, we will use up our store of fat and become too thin. If we eat too much food, especially foods rich in sugar and fat, we will increase our store of fat and become too fat. It is important to balance the amount of food we eat with who we are and what we do. The amount of energy we need from our food depends on our a[], our h[] and how much e[] we get our age, our height and how much exercise we get.
The food we eat has to be broken down into other s[] that our bodies can use substances that our bodies can use. This is called d[] digestion. Without digestion, we could not absorb food into our bodies and use it. Digestion happens in the [] system digestive system, which begins at the mouth and ends at the anus. After we swallow, our food passes through these organs in turn: oesophagus or gullet, stomach, small intestine, large intestine.
Stages of digestion: food is digested in the m[], s[] and [] [] mouth, stomach and small intestine; digested food is a[] absorbed into the bloodstream in the small intestine; excess water is a[] back absorbed back into the body in the large intestine; any undigested food passes out of the [] as [] anus as faeces.
The liver and the pancreas play important part in digestion. The liver produces bile, which helps the digestion of fat. The pancreas produces chemicals called [] [] digestive enzymes.
Food has to be broken down c[] chemically into really small p[] particles before it can be absorbed. [] are needed so that this break-down happens quickly enough to be useful. enzymes
Tar in cigarettes causes c[] cancer of the [], [] and [] lungs, mouth and throat. It coats the surface of the [] tubes and the [] the breathing tubes and the alveoli. This causes co[] coughing and damages the alveoli, increasing the difficulty of gas exchange.
Cells in the lining of the breathing tubes produce sticky mucus to trap d[] and m[] dirt and microbes. Mucus is usually moved out of the lungs by cells with tiny hair-like parts called cilia. Hot smoke and tar from smoking damages the cilia. So smokers cough to move the mucus and are more likely to get bronchitis.
Nicotine is a[] addictive. Nicotine also increases the heart rate and blood pressure, and makes blood vessels [] than normal narrower than normal. This can lead to heart disease.
Carbon monoxide is a gas that takes the place of oxygen in red blood cells. This reduces the amount of oxygen that the blood can carry. This means that the circulatory system has to work harder, causing heart disease.
Medicines are drugs that help people suffering from p[] or d[] pain or disease. Recreational drugs are taken for pleasure. Some recreational drugs are legal, such as tobacco, alcohol and caffeine. Most other recreational drugs are illegal, such as cannabis, ecstasy and heroin.
Recreational drugs can be classified as either stimulalnts or depressants. Most recreational drugs can be addictive. All drugs can damage the l[] liver, because it is the liver that breaks down drugs in the body. Any drug that is misused can cause damage to the b[] body, as well as p[] and s[] problems Personal and social problems. Injecting any drug with a needle and syringe that someone else has used may lead to a number of d[] diseases from [] blood infected blood, including H[] and h[] HIV and hepatitis.
Depressants slow down m[] messages in the b[] and along the [] in the brain and along the nerves. Alcohol is a d[] depressant. It is found in beer, wines and spirits such as vodka.
Here are some of the typical effects depressants have on the body: feelings of []-[] well-being, [] inhibition lowered inhibition (the ability to tune out irrelevant stimuli), [] thinking slowed thinking, [] muscular activity slowed muscular activity and a distorted view of the world or hallucinations.
Some of the long-term effects of depressants on the body include damage to the liver, brain and heart. They can also have the following effects: alcohol can cause weight gain, solvent abuse causes a [] around the nose and mouth a rash around the nose and mouth, cannabis causes loss of m[] and c[] memory and concentration (as well as an increased risk of mental I[] illness.
Stimulants speed up messages in the [] and along the [] brain and along the nerves. This makes you feel more a[] alert. Caffeine is a simulant found in cola drinks, coffee and tea, but it can cause difficulty in s[] sleeping (insomnia), head.. aches and n[] nervousness. Cocaine, ecstasy and amphetamines are all illegal stimulants. They make you feel more energetic and confident, but they can damage the l[] and h[] liver and heart. They can also cause loss of m[] and c[] memory and concentration, and bring an increased risk of mental illness.
Bacteria have many different s[] shapes.
Out of the three main types of microbes, the ones that have a cell membrane are fungi and bacteria.
Instead of a cell nucleus, bacteria have chromosomes.
Microbes cause disease when they are able to reproduce in the body. They produce harmful substances called toxins, and damage t[] and o[] tissues and organs. WE say that someone who has harmful disease-causing microbes in them is infected.
Many harmful microbes can pass from one person to a[] another. Diseases caused by such microbes are said to be diseases that are infections. Here are some ways that harmful microbes can be spread: in a[] air, through contact with a[] animals, through contaminated food, through t[] touch, in w[] water.
Droplets containing microbes fly into the air when people s[] or c[] sneeze or cough. The microbes they contain get into other people if [] in breathed in. Chicken pox, colds, flu, measles and tuberculosis are spread like this.
In and on food, there can be harmful microbes. Food can have harmful microbes in and on it. The microbes get into the body when the food is eaten, causing food poisoning. Thorough cooking kills most microbes, but they can survive under-cooking. Careless handling of food increases the risk from harmful microbes.
Washing your hands decreases the chances of spreading microbes.
In water, there can be harmful microbes. The microbes get into the body when the water is swallowed. Cholera is a disease caused by a bacterium that spreads like this. Thorough boiling or adding chlorine to the water can reduce the chance of spreading microbes in this way.
The skin stops m[] from getting into the body microbes.
When you are infected by a microbe, it takes [] for your body to start fighting the infection time for your body to start fighting the infection. It does this by making enough [] [] [] white blood cells with the correct antibody. During the time, you continue to feel unwell. You begin to recover when enough [] have been produced antibodies. After the microbes have been killed, the amount of antibodies goes down. But some of the white blood cells that produce the correct antibody remain in your blood.
After a second infection by the same microbe, your body makes the correct antibodies much faster, because of the [] [] [] that remain the white blood cells that remain from when you had your first infection. The microbe doesn't get a chance to make you ill this time: we say that, to the microbe and the disease it causes - you are immune.
Immunisation is a process that doctors use to make people immune from certain illnesses, even before they have been infected. It involves you receiving an injection containing a v[] vaccine. Vaccines containing a d[] or w[] form of the disease causing microbe dead or weak form of the disease causing microbe, or some of its antigens. In response to the vaccine your immune system produces white blood cells with the correct antibody to kill the microbe, so, without falling ill, you become immune.
Vaccines work on both b[] and v[] bacteria and viruses.
Plants get carbon dioxide from the air through their leaves. The carbon dioxide d[] diffuses through small holes in the underside of the leaf called stomata. (One of these holes is called a stoma. The plural is stomata.) The lower part of the leaf has loose-fitting cells, to allow carbon dioxide to reach the other cells in the leaf. This also allow the oxygen produced in photosynthesis to leave the leaf easily. -|- [http://www.bbc.co.uk/bitesize/ks3/science/images/leaf_diagram.gif]
So that it can absorb a lot of light, a leaf usually has a large surface area. Its top surface is protected from water loss, disease and weather damage by a waxy layer. The leaf's upper part is where falls the light, and it contains a type of cell called a palisade cell. This is adapted to absorb a lot of light. It has lots of chloroplasts and is shaped like a tall box.
Plants get the water they need for photosynthesis through their roots. The roots have a type of cell called a root hair cell - these project out from the root into the soil. Roots have a big surface area and thin walls, which allow [] to pass into them easily water. The water absorbed by the root hair cells passes through the plant in [] tubes xylem tubes, and eventually reaches the leaves. If a plant does not absorb enough water, it will wilt or go floppy. Without water it may also not photosynthesise quickly enough, and it may die. -|-
Photosynthesis v respiration. When it's dark, there is [], but no [] there is respiration, but no photosynthesis; overall result: oxygen is taken in and carbon dioxide is given out. When light is dim, the photosynthesis rate and the respiration rate are equal; overall result: neither gas is [] [] or [] [] taken in or given out, as each [] the other out. cancels. In bright light, the photosynthesis rate is (compared to the respiration rate) larger; overall result: carbon dioxide [] [] and oxygen [] [] Carbon dioxide taken in and Oxygen given out.
Once respiration has been accounted for, photosynthesis usually results in a [] [] gain net food gain. This means that there is an increase in the plant's biomass (it grew).
{Plants that lose their leaves in winter store food (produced during the summer by photosynthesis). They store enough food to last them over winter, and to provide energy reserves for new growth in the spring.}
A food chain shows the different organisms that live in a habitat, and what eats what. A food chain always starts with a producer, which is an organism that makes food. (It is usually a green plant, because plants can make their own food by photosynthesis.) A food chain ends with a consumer.
The first consumer in the chain is also called the primary consumer, the next one is the secondary consumer and the one after that is the tertiary consumer.
The population of each organism in a food chain can be shown in a sort of bar chart called a pyramid of numbers. The more there are, the wider the bar. For example: a lot of clover is needed to support the snail population, so the bar for clover would be big. -|-
In a food chain, often, as we go from one level to the next, energy is lost to the surroundings.
When all the food chains in a habitat are joined up together they form a food web. Some animals have one predator, while others have more than one. This leads to some interesting effects if the population of a particular organism in the food web decreases. Some animals can just eat more of another organism if food is in short supply, while others may starve and die. This in turn can affect the populations of other organisms in the food web.
If toxic material is taken up somewhere in a foodweb, it can pass along.
I[] let animals form groups for protection, choose mates, fight to be in charge, and show many other behaviours instincts. Instincts are useful, because they don't have to be learned.
Reflexes are a type of instinct. They happen automatically because of a particular stimulus.
An example of a reflex occurs when your hand touches something hot: there is a stimulus (heat), thus stimulating the pain receptor. After a signal is sent along the sensory neuron and passed along the relay neuron (message sent to the brain). In response, a message is sent along the motor neuron. Finally, the effector muscle contracts (response).
Conditioning is a type of behaviour involving a response to a s[] stimulus that is different from the [] one natural one. It's a type of l[] behaviour learned behaviour. (For example: electric fences can be used to stop grazing animals) [Pavlov's dogs].
Animals may use imitation to learn s[] skills.
When you exhale, the pressure is increased and air is forced out of the lungs, the [] relaxes and moves up diaphragm--, the intercostal muscles relax, allowing the ribcage to [] []wards and [] to drop inwards and downwards.
Objects that reflect light well often have smooth, shiny surfaces.
Glucose (and other simple sugars, e.g. maltose), Amino acids, Glycerol and Fatty acids are able to pass through the wall of the a[] c[] Alimentary Canal into the blood, then again somewhere else into the body [] cells and are used.
The penis becomes erect as blood rushes into the erectile tissue.
The lungs are big air sacs. They are good for absorbing gases as they have a big [] [] surface area, they're m[] moist and they have a good [] supply blood supply.
In exhaled air, there's less oxygen and more carbon dioxide, because oxygen is [] up used up and carbon dioxide is [] in the body produced.
Tar contains [] which causes cancer carcinogens.
Alcohol can impair j[] judgement (which can lead to accidents) and can also be addictive.
Photosynthesis is a chemical process that happens in every [] plant green plant.
Four factors affect photosynthesis: [], [], [] and [] levels light, water, temperature and CO2 levels.
When light goes from a less dense medium to a denser medium; light bends towards the normal, but when light goes from a denser medium to a less dense medium; light bends away from the normal. The 'normal' is the 'line' perpendicular to the interface.
Some rocks may be different shapes and sizes as they be changed by the conditions in their environment.
The seven different nutrients are carbohydrates, proteins, fats, minerals, vitamins, fibre and water. The use of Carbohydrates in the body is to provide energy (good sources: cereals, bread, pasta, rice and potatoes. Protein is used in the body for [] and [] growth and repair (good sources: Fish, meat, eggs, beans, pulses and dairy products). Fat is used in the body to provide energy. Also to store, in the body, energy and i[] it insulate it against the cold (good sources: butter, oil and nuts).
Created by: Toluo