Biology, Nutrition

Biology, Nutrition

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  • Created by: jesper
  • Created on: 18-03-12 04:12


Photosynthesis is the convertion of light energy into chemical energy. This takes mostly place in the palisade layer of the plant. 

Plants take in carbon through the leaves. 
HYdrogen are taken in through water

Equations:                    Light
Carbon dioxide + Water -------> Glucose + Oxygen

Symbol equations:

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Factors affecting the rate of photosynthesis

The temperature must be optimum to increases the rate of reaction 

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Leave Adaptations to photosynthesis

  • Large surface area, to collect light
  • Thin, allows fast diffusion of gases 
  • Palisade cells contain chloroplast
  • Chloroplast contain chlorophyll (Light collecting)
  • Carbon dioxide - Pores. Stomata formed by gaurd cells.
  • Mesophyll layer/ sponge space allows diffusion of Carbon dioxide
  • Presence of vascoule bundle
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Balanced diet

On one side:
Diet which consits of:

  • Fibre
  • Water 
  • Proteins 
  • Carbohydrate 
  • Lipids
  • Vitamins
  • Minerals 

On the other side:
Lifestyle which consits of:

  • Age 
  • Gender
  • Preganancy
  • Activity 
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The human alimentary canal

Ingestion= Bringing food into the digestive system.
Chewing and lubrication helps it into the digestive system

No digestion in the oesophagus/ by the process of peristalsis.

the food is stored in the stomach where acid will be added to kill the bacteria. Presence of proteases begin digestion of proteins.

Bile= neutralise the stomach acid/ Break the fat in the diet into small parts.

Food going to the small intestine pass the pancreas which will completly break down the food.  

Small intestine= is the absorbtion of digested food to the blood. then the food passed into the large intestine where we absorb water into the blood stream.

Undigestive components are stored in the rectum and finally excreted through the anus.

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The stages of the digestion of food

Ingestion Mouth Mastication (Chewing)/ which creat a Bolus.Mucus for lubrication and also add amylase (Digest the strarch into maltose) Digestion Small Intestine, Stomach Insoluble food particles are digested to become soluble with the ue of enzymes. Absorption Small Intestine Villi/ micro villi these wil absorb food from the gut into blood vessels Assimilation Tissues/ Organs Blood diffuses in to the cells for use. Egestion Rectum/ Anus of the large intestine Removal of undigested materails

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Digestive Enzymes

Insoluble food into soluble molecules which can then be absorbed into the blood stream which occurs in the small intestine.

Using Amylase
Starch---------> Maltose

Maltose--------> Glucose

Using Proteases
Proteins --------> Amino acid

Using lipase
Lipid-----------> Glycerol 

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Liver is responsible for the production of bile which is stored in the gall blader. Bile is released by the bile duct. the bile mixes with the digestive enzymes.

Effects of bile

to neutralise the stomach acid, turn the Ph to 7.
Fat molecules are brocken down into smaller droplets. Known as emulsification.

Bile is not an enzyme reaction.

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Villi structure and function

Villi increases surface are for absorbtion.
Small diffusion distance.
Concentrated gradient which is retained blood flow.
Lacteal collects the lipid. 

This provides a massive area in contact with the digested food. As well as this, each of the villus has even more projections known as microvilli. 

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