• Created by: abbie
  • Created on: 05-03-13 19:09
Development of the microscopes helped by?
Lead to discoveries about cells and microscopic life.
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What is the light microscope?
Light Microscope was invented 1600 years ago. It passes light through a material on a glass slide and uses a system of lenses to view the image.
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What is the electron microscope?
The electron microscope was invented in 1931 uses a beam on electrons instead of light (allows much greater megnifications)
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What is confocal laser scanning microscopy?
Uses lasers to build up an image via a computer by scanning an object in the microscope. Its aim is to increase magnification not to produce clearer images.
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The cell theory definition?
(theodor schwann) All living things are made from cells.
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What the cell theory now states:
1) All life is composed of cells 2)The cell is the basic unit of life 3)Cells are formed from other cells during cell division 4)Energy flow occurs within cells 5)DNA is passed on from cell to cell during cd 6)All cells have same chemical composition
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What are micro organisms?
Microscopic life forms. They include bacteria, viruses, fungi and unicellular algae.
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What is a virus?
Smallest forms of life-so simple that it is not certain they can really be called living things. Consist of DNA inside aprotein case. Can only reproduce inside another living cell- 'host' cell. They produce a new virus which destorys the host cell.
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What is yeast?
are microscopic fungi and they reproduce asexually by budding- growing a cell from an existing one after which the new cell breaks off.
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Name the function of the:NUCLEUS and also weither it is an animal or plant cell
Both: Controls the activities of the cells vua DNA
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Name the function of the:CELL MEMBRANE and also weither it is an animal or plant cell
Both: Controls which substances enter and leave the cell
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Name the function of the:CYTOPLASM and also weither it is an animal or plant cell
Both: Where most of the chemical reacrions in the cell take place
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Name the function of the:CELLULOSE CELL WALL and also weither it is an animal or plant cell
Plamt Cells: Supports the cell
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Name the function of the:CHLOROPLAST and also weither it is an animal or plant cell
Some plant cells: Absorbs light for photosynthesis
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Name the function of the:LARGE CENTRAL VACUOLE and also weither it is an animal or plant cell
Plant cells: Space filled with liquid sap which stores nutrients
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Describe the bacterial cell
DNA is not contained in a nucleus. Capsule flagella and pilus (not present in bacteria). Cell wall is not made of cellulose.
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Describe a Yeast cell
Cell wall is not made of cellulose. Vacuole is smaller than the large centeral vacuole of a plant cell, and there may be more than one.
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Describe an algal cell
Algal cells vary in basic structure. Most but not all have a flagellum. Some have a cellulose cell wall. The eyespot and vacuole are often absent.
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What is protein?
Important chemicals which are found in many forms in living things. One of the most important groups of proteins is enzymes. Enzymes control all the chemical reactions which occurs in a cell. Other important poteins are hormones and muscle tissue.
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Structure of Proteins
Chain of molecules called amino acids.
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How do enzymes work?
The substance that an enzme works on is called its substrate. The enzyme must make contact with its substrate and therefore the substrate has match to enzyme so they can lock together ENZYME-SUBSTRATE COMPLEX. Place of attachment is the ACTIVE SITE.
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Properties of enzymes?
1) Enzymes are biological catalysts-speed up chemicalreactions without taking part in them 2)Each ensyme has an OPTIMUM pH and temp 3)Enzymes are DENATURED by high temps as heat breaks bonds that hold enzymes in shape4)Denatured if pH is far from opt
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Enzymes and temp?
The increase in activity with temp is becuase the hat is making the enzyme and substrate molecules move faster and therefore collide more often allowing them to lock together. The enzyme DENATURES when heat causes the bonds in the active site to blow
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Uses of enzymes (2)
Washing detergents- Digestive enzymes (lipasesm porteases and carbs) are put into the detergent to catalyse the breakdown of stains such as Greases (broken down by lipases) and grass stains (by proteases). Without emzymes they'd be washed at high tem
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Who made the discovery of DNA? What did they discover?
DNA had been discovered in mid-19 century. The link was first discovered between DNA and Genes by Oswald Avery in 1944. Francis Crick & James Watson used the chmical theory and ball and stick atomic models to work out the structure.
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What is the structure of DNA?
It has 2 long chains of sugar & phosphate molecules: 2 chains twist into a DOUBLE HELIX which are joined by BASES, There are 4 bases ACGT that form a code which determines the link between different amino acids and protiens, A joins with T & C with G
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What is a Triplet code?
The squence of 3 bases along the DNA chain make codes (triplet codes) for each amino acids.
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Why is DNA important?
It is a chemical that provides instructions for every cell to work. It does this by determining which amino acids are linked together to form the different proteins that the cell needs in order to work.
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What is cell division?
New cells are constantly being formed from old cells by cell division. These new cells may be needed for growth, repair,replacement or sex cells. In cell division the original cell is called the mother cell and the new cells formed are daugher cells.
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What is Mitosis? (Imagine you are wearing a mitton and you cut yourself..)
Takes place all tissues bar gametes. Produces new cells for growth, repair, and replace. The mother cell duplicates so each new cell is provided with a full set of chromosomes.Two new daughter cells are produced each genetically identical to mother.
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What is Meiosis? (Only takes place in..) (Imagine Tegans cats breeding..)
(less common) When gametes (sperm,egg,pollen) form they need half the amount of chromosomes as when fertilisation occurs the number of chromosomes are doubled. 4 cells formed as it is double division. Each daughter cell has 1/2 chromosomes. DIFFERENT
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3 ways animals grow
All regions of their body grow. Tend to grow to a certain size then stop grwoing. Usually have a compact growth (no branching)
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3 ways plants grow
Restricted to special growing points (meristems) The main ones are at the trips of the roots and shoots. Usually grwo throught their life. Usually have a spreading, branched growth form.
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How is animal growth good for their life style?
Animals have a variety of organs/tissues so growing all over ensures that all these organs grow in constrction with eachother. Growig for a time and then stopping allows animals to use energy for other purposes (movement).
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How is Plants growth good for their life style?
The main requirements for plants are light and water. The growing points allow them to grow up towards light and down towards the soil. The spreading body forms a greater surface area for absorbing light. Parts are eaten so eternal growth replaces it
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Where are stem cells?
Found in both animals and plants in embroys, in certain adult tissues (bone marrow) in the growing points of plants.
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How to humans use Stem cells?
Cure many human conditions as they can replace damaged cells of many different types. EMBRYONIC stem cells are slightly more useful than adult stem cells becuase they have greater powers of differentiation.
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Many chemical travel into/out of cells through the cell membrane. They move by one of three processes. Name/Define them?
DIFFUSION: Substances move from high conc to lower conc. OSMOSIS: diffusion of water molecules though the cell membrane. ACTIVE TRANSPORT: This is the pumping of substances from low conc to higher conc using enegy from the cell
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Molecules dont know where they are going and as there is more room to move into areas of lower conc their instinct is to spread from higher conc to lower. Membrane is SELECTIVELY PERMABLE-lets certain things in but not others. H20 02 C02 can diffuse.
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Explain Active Transport?
When a cell needs to increase its concentration (go to an area of low to high) diffusion makes this unnatural (as it is opposite) so in order to move chemicals the cell has to use energy to PUMP the subs up the gradient. Usually moves subs into cell.
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Explain the Concentration Gratients (CG)
Movement into and out of cells is often described in terms of this. It occurs where subtances are present in varing concentrations. A gradient is a slope between a high/low value. MOVEMENT CAN OCCUR DOWN A CG BY DIFFUS/OSMOSIS OR UP BY ACTIVE TRANSPO
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What is the definition of Osmosis?
Diffusion of water through a selectively permeable membrane. The movement is from a MORE DILUTE solution (more water) to a MORE CONCENTRATED solution (less water). The subst must be H20 and it must move through a membrane for it to be called osmosis
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How does Osmosis work?
When moving molecules come into contact with the memb if it hits a PORE then it will go through if it is a water molecule(small enough to fit-solute molecules are too big) There is more H20 molecules in the dilute solution so more will go to op side
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Describe osmosis in plant and animal cell when placed in water?
No matter how much water moves in the solution inside the cell will always be more concentrated than the water. So as the water moves in eventually the ANIMAL cell will burst. PLANT cells do not as thier cell wall is strong enough to prevent it.
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Describe osmosis in plant and animal cell when placed in concentrated solution?
The cytoplasm of both animal and plant cells will shrivel up due to loss of water and the cell may die. In plant cells the cytoplasm may pull away from the cell wall a condition kown as plasmoltsis.
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What is photosynthesis?
The process by which green plants make food using raw materials from the atmosphere and energy from sunlight. Without it no life could exist on the planet.
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What can photosynthesis and why?
All life needs energy and the only supply of usable energy that the planet gets is sunlight-Green plants are the only organisms that can use this energy directly as they have chlorophyll which absorbs light.
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Where does photosynthesis take place?
Green parts of the plant (mostly leaves) as they contain cells with chlorophyll in their chloroplasts.
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What does photosynthesis create/dispose?
Plants make food (glucose) by photosynthesis for their own use but animals depend on the plants for food. A waste product of photosynthesis is OXYGEN which living organisms need for respiration.
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What is the word equation for photosynthesis?
carbon dioxide + water --(sunlight/chlorophyll)---> glucose + oxygen
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When can photosynthesis not occur? (enzymes)
Photosynthesis ic controlled by many chemical reactions to do with enzymes. As enzymes are denatured when the temperature gets too high if the temp is above 50 degrees photosynthesis cannot occur.
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What does the plant do to the glucose made from photosynthesis?
It can be used directly to provide energy by respiration. It can be used to make other substances-proteins (for new cells) or cellulose (cell walls)-Proteins also require nigtrogen which comes from the soil.
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What does the plant do to the glucose made from photosynthesis? (continued)
It may be transported from leaves to other parts of the plant (to growing parts). Any excess glucose is stored in the leaf as STARCH. (the fate of glucose is made in photosynthesis:used,transported or tansformed)
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Test for photosynthesis?
TEST FOR STARCH NOT GLUCOSE! Because glucose is rapidly used,changed into starch or transported. Its easier to test for starch stored but the starch has 2 b used up by keeping the plant in the dark overaday (destarching) 2 b sure its new starch found
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Name 5 factors that are needed for photosynthesis?
Light (provides energy to make carbs) Carbon Dioxide (from air as its a raw material for the manufacture of carbs) Water (from soil, other raw mat) Chlorophyll (in chloroplasts of the leaf-absorbs light energy) Temperature (so enzymes can work well)
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Describe how temperate affects the rate of photosynthesis?
This effects the enzymes that control photosynthesis. Low temps photosynthesis wont happen/slow. As temp increases so will the rate of photosynthesis, up to a point when the temp gets so high it denatures the enzymes, stopping photosynthesis.
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Describe how light intensity affects the rate of photosynthesis?
This providesthe energy for photosynthesis-more light, more photosynthesis, more energy.. up to a point where there is as much light as can be absorbed and the RATE LEVELS OFF.
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Describe how level of carbon dioxide affects the rate of photosynthesis?
The atmosphere contains a low amount of C02 (0.04%) so increasing the level will allow a higher rate of photosynthesis. Eventually the rate will level off when there is enough C02 for the plants needs.
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Why does water and chlorophyll not affect the rate of photosynthesis?
Water: if there is enpugh water for a plant to survive there is plenty for photosynthesis. Chlorophyll: because the amount in a plant at any one time cannot be changed.
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What is a Limiting Factor? Examples?
The factor that is controlling the rate of photosynthesis at a given time, and the one that will if increased, boost the rate. At night, light will be a limiting factor. During the day its usually C02 or temp during the winter.
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Photosynthesis Experiments: Testing leaves for starch... see if it has occured. It involves boiling the leaf in alcohol to remove the colour then staining with iodine: blue-black indicates starch (which is how glucose is stored)
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Photosynthesis Experiments: Removing Carbon Dioxide...
..with sodium hydroxide solution, to test the need for carbon dioxide in photosynthesis.
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Photosynthesis Experiments: Using oxygen and carbon dioxide sensors.. monitor the rate of photosynthesis.
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What is respiration?
A feature of ALL living things. It is the PROCESS that occurs INSIDE cells to RELEASE ENERGY from FOOD substances. This energy is needed for all life processes.
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What is breathing?
NOT RESPIRATION! Breathing is simply the process that gets oxygen into the body FOR respiration. It only occurs in SOME animals.
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What is the difference between Aerobic respiration and Anaerobic respiration?
Aerobic USES OXYGEN in a series of chemical reactions that make up respiration. When there is NOT enough oxygen cells switch to ANAEROBIC respiration which DOESNT require oxygen but releases LESS energy. All reactions in respiration are by enzymes.
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What is the word equation for AEROBIC RESPIRATION?
Glucose + Oxygen ----> Carbon Dioxide + water + ENERGY
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How many reactions take place in respiration?
It is a complex series of reactions. The equation summarises the process.
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Is all the ENERGY produced used?
No, some is always lost has HEAT to the surroundings.
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How can we measure the RATE of respiration? (3)
By measuring the amount of CARBON DIOXIDE or HEAT given off in a certain time. Or by measuring the OXYGEN used in a given time.
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What is AEROBIC respiration?
When OXYGEN is used during respiration.
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What is ANAEROBIC respiration?
It is the type of respiration that occurs when NO OXYGEN is present.
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Which type of respiration is less efficient?
ANAEROBIC because less energy is released per molecule of glucose.
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ANAEROBIC is different in which two places?
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Word equation for respiration in animals?
Glucose ---> Lactic acid + ENERGY
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When does ANAEROBIC respiration occur?
It occurs in human muscle cells during vigorous exercise and the demand for oxygen is GREATER than the supply.
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What is oxygen debt? And how does the body react to it?
It is the shortage of oxygen. The body 'pays back' the oxygen debt by breathing faster and deeper after the exercise has finished.
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How does breathing deeply help get rid of oxygen debt?
The extra oxygen taken in this way breaks down the lactic acid into carbon dioxide and water.
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What is the word equation for ANAEROBIC respiration in YEAST?
Glucose -----> ethanol + carbon dioxide + ENERGY (C02 is produced in yeast not animals)
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What can this process be used for?
As ethanol is alcohol it can be used to brew drinks.
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What is fermentation?
Anaerobic respiration in yeast.
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What is the job of the respiratory system?
To get OXYGEN into the BLOOD to be carried around the body for RESPIRATION, and the REMOVE waste CARBON DIOXIDE from the blood.
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What is the NEED for the respiratory system?
Large animals (humans) need it because DIFFUSION of oxygen through the body surface would be too slow to supply the innermost tissues.
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What happens in the lungs?
They are organs of gas exchange
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What are alveoli/what happens there?
Are air sacs at the end of bronchioles (in lungs) where gas exchange takes place.
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How are the alveoli adapted for gas exchange? (4)
Large number of them provide a large surface area. The thin walls of the alveoli mean that gases can easily pass through them. The moist linings allow oxygen to dissolve (necessary before it can diffuse through wall) Good blood supply
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What is inspired and expired air?
Inspired is breathed in, expireed is breathed out. The body absorbs oxygen from INSPIRED air, and adds cardbon dioxide and water vapour to EXPIRED.
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How does expired air differ to inspired?(4)
Has less oxygen. Has more carbon. Has more water vapour. Is breathed out.
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Breathing is caused by movements of the rib cage and the diaphragm. Describe the sequence?
1 The DIAPHRAGM moves down and the RIB CAGE moves up and out (causes volume increase/pressure decrease in thorax)2 Lower pressure allows lungs to EXPAND Air is drawn in 3 The D moves upwards & RC in/down (decre volume/incre pressure in thorax=air out
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What are enzymes role in the DEGESTIVE SYSTEM?
They are important as different enzymes break down the different food groups.
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What enzymes can be found in the gut? And what do they break down?
Carbohydrases: break down carbohydrates. Proteases: break down proteins. Lipases: break down fats.
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What is bile? Where is it produced/stored?
A liquid that is produced in the liver and stored in the gall bladder.
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Where does bile go?
Down the bile duct into the small intestine.
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Explain what bile has to do with enzymes?
Contains NO enzymes but helps in th edigestion of fats- breaks them down into small droplets, giving a bigger surface area for lipase enzymes to act on.
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Functions of the digestive organs: MOUTH
Breaks up food by chewing. Carbohydrase in saliva break down starch.
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Functions of the digestive organs: STOMACH
Acid in the stomach kills bacteria. Stomach produces protease and lipase enzymes.
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Functions of the digestive organs: PANCREAS
Produces protease, lipase and carbohydraseenzymes. These enzymes act in the small intestine.
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Functions of the digestive organs: SMALL INTESTINE
Digestion is completed by carbohydrase enzymes in the small intestine. The food is absorbed in the second half of the small intestine.
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Functions of the digestive organs: LARGE INTESTINE
Water from the degestive juices is re-absorbed into the blood.
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Explain the movement of food?
It is moved alongt he small intestine by a process called peristalsis. This involves the contraction of circular gut muscles behind the ball of food to push the food down the gut. A wave of contraction continues to push the food further down the ds
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What is Biodiversity?
Means the variety or number of DIFFERENT species in a given area.
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Why is Biodiversity important?
The more SPECIES there are in an area, the more stable the ECOSYSTEM is. (The habitat plus all its living things)
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Give an example of why Biodiversity is important? (Why does having a large supply of species in an area help predators?)
If a species (fox) only has one prey (rabbit) it can survive provided the number of prey are high. However if a disease strikes which decreases the amount of prey the predator will have no alternative food and may not be able to survive there.
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What are the other benefits of Biodiversity? (2)
It provides potential food supply, raw materials and new medicies for human well-being. 2)Stable ecosystems help regulate the atmosphere, water supply and nutrient cycles and provide fertile soil.
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How do we maintain Biodiversity?
Try to stop species becoming EXTINCT. An ENDANGERED species is one whose population is so low they might become extinct. Example: Red squirrel in the UK.
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Name four reasons for a reduction in species numbers?
1)Changes in land:Cutting forests for land/crops.2)Climate change:Certain species can no longer survive in given areas. 3)Over-exploitation:Over-fishing and activities threaten populations.4)Introduction of alien species:Grey squirrels replacing red.
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Name 3 ways in which endangered species and Biodiversity can be conserved?
1) The Convection on International Trade in Endangered Species 2)Sites of Special Scientific Interest-designated areas with protected status. 3)Legally enforcing fishing quatations.
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How can Zoos help Biodiversity?
Set up breeding programmes to re-introduce species. National Parks help too. Set up seed banks. Join local action plans.
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How can computers help Biodiversity?
Can predict possible climate changes or environmental procedures so that the future problems may be averted.
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Card 2


What is the light microscope?


Light Microscope was invented 1600 years ago. It passes light through a material on a glass slide and uses a system of lenses to view the image.

Card 3


What is the electron microscope?


Preview of the front of card 3

Card 4


What is confocal laser scanning microscopy?


Preview of the front of card 4

Card 5


The cell theory definition?


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