Year 9 KS3 Biology

3 topics KS3 biology

  • Created by: caitlin
  • Created on: 18-04-11 11:17


Equation: Word= Carbon dioxide+water=(through sunlight & Chlorophyll)=glucose+oxygen  Symbol= 6CO2+6H2O= C6H12O6+ 6O2

4 things needed... 1)Sunlight 2) Chlorophyll 3)Water 4)CO2

4 Factors affect... 1) Light- the more light, the faster the rate of Photosynthesis

 2) Water- too little water makes photosynthesis slow down

3) Temperature- The ideal temp for photosyntheis to take place is around 30oC, it will continue to work up until around 40oC, But once above 40oC it slows down bigstyle,

4) CO2 levels- if a parrafin (heated oil) is burned in a greenhouse the Co2 levels rise and so does the rate of photosynthesis- which increases growth...

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-Is a chemical reaction which happens in every cell of every plant or animal.           -is when glucose(or other sugars) react with oxygen to release energy.               - the reaction produces carbon dioxide and water as by products.                       -bloodstream transports glucose + oxygen to the cells and takes the by products away.

 - RESPIRATION is NOT BREATHING- breathing is simply taking air into the lungs.

 EQUATION: Word=Glucose+Oxygen=Carbondioxide+water, Symbol= C6H12O6+ 6O2 = 6CO2+6H2O

Products: H2O (water), CO2 (carbondioxide) and ENERGY!  ENERGY IS USED FOR- Work, rest, play, Cell division, uptake of minerals,gwoth and repair.        

Respiration is truning glucose into energy, its what all cells do, all the time!   

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Is about making large insoluable molecules of food into smaller soluable molecules of food, which the body can then use and absorb.

DIGESTION IS BREAKING DOWN FOOD! Two steps... 1)MECHANICALLY, e.g chewing with teeth. 2) CHEMICALLY, using biological agents called enzymes.

8 Steps to the Alimentary Canal...

1) MOUTH- digestion starts here, teeth chew food and mix with saliva (amylase is the specific name for carbohydrase enzyme in saliva)                                            2) GULLET- Links the mouth to stomach.                                                                   3) STOMACH- 1) Here the food mixes with proteases enzymes which digest the proteins. 2) Hydrochloric Acid is present to kill bacteria and give a low PH for the enzymes to work.                                                                                                     4) LIVER- makes bile, which emulsifies (breaks up) fats. It's also alkaline to give the right PH for the enzymes in the small instestine.                                               5) PANCREAS- makes 3 enzymes, 1)Protease digests protein,  2)Carbohydrase digests carbohydrates.           

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Digestion Continued....

6) SMALL INTESTINE- 1) produces more enzymes, to digest further protein, carbohydrates and fats. 2) Food is also absorbed through the gut wall, into the blood. Which then takes it around the body to where it is needed.                                                                                                              7) LARGE INTESTINE- Water is absorbed so we don't shrivel up.                                                                                                                      8) RECTUM-Food often contains cellulose (plant material which can't be digested). so it's stored as faeces. Here the digestion ends, when it plops out the anus-egestion.

Big Food Molecules...

1) Enzymes are used to break up big molecules into small ones.                            2) These molecules can pass through the gut wall into the blood., they then pass into cells and are cells.

STARCH (with carbohydrase enzymes) = Glucose (and other simple sugars)  PROTEIN (with protease enzymes) = Amino acids                                         FATS(with lipase enzymes) Glycerol and Fatty Acids

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Digestion Continued (2)....

The small intestine is covered with millions of Villi...

Villi are tiny finger-like projections which line the small intestine, villi are perfect for absorbing food because...                                                                                       1) They have a thin outer layer of cells                                                                     2) They have a good blood supply                                                                            3) They provide a large surface area for absorbtion.

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