Biology {Biomolecules, Balanced Diet and Digestive System Summer} 🏖

Biomolecules

Balanced Diet

Digestive System
{Alimentary Canal}

Ingestion- Mouth: teeth breakdown food (larger surface area) for mechanical digestion tongue lubricates bolus with saliva containing amylase enzyme for chemical digestion.

Peristalsis- Oesophagus: circular and longitudinal muscle relax and contract like a wave to push down bolus.

Digestion- Stomach: hydrochloric acid provides optimum pH for proteases like the pepsin enzyme for chemical digestion and churning for mechanical digestion. Mucus lining protects stomach from acid. Food stays there for three hours before the sphincter muscle pushes it into the small intestine

Assimilation/synthesis- Liver: gall bladder stores bile (green liquid) which is alkaline and put into the small intestine to neutralise the stomach acid. It also emulsifies lipid droplets to increase the surface area for lipases.

Digestion- Small Intestine: Duodenum where most chemical digestion happens Absorption- Ileum- large surface area- highly folded, villi, microvilli -short diffusion distance- walls of villus one cell thick steep -steep concentration gradient- network of blood capillaries taking glucose and amino acids, lacteals take glycerol and fatty acids= hepatic portal vein transports this from small intestine to liver

Large Intestine: Absorption Colon- water reabsorbed into blood stream Rectum- stores faeces

Egestion -Anus removal of undigested waste(never been part of cells)

Pancreas carbohydrase, protease and lipase. These enzymes are secreted from here into the small intestine.

Proteins- Carbon, Hydrogen Oxygen, Nitrogen. Larger Insoluble Molecules: protein Smaller Soluble Molecules: amino acids

Lipids (fats and oils)- Carbon, Hydrogen, Oxygen. Larger Insoluble Molecules: lipids Smaller Soluble Molecules: 1 glycerol and 3 fatty acids

Carbohydrates- Carbon, Hydrogen, Oxygen. Larger Insoluble Molecules: starch, glycogen Smaller Soluble Molecules: glucose

Tests for Biomolecules

Test for Glucose Benedict's Test Pale Blue->Brick Red Heat(using a water bath~ boil)

Test for Starch Iodine Test Yellow/Brown->Dark Blue/Black

Test for Protein Biuret's Test Pale Blue-> Violet

Test for Lipids Emulsification Test (ethanol) Colourless-> Cloudy

Investigate the Energy Content in a Food Sample {Calorimetry}

Water - chemical reactions, prevent dehydration (chapped lips, lethargy, hallucinations, urine weakness)

Dietary Fibre gives gut muscle something to push against (prevents constipation)

Lipids insulation, protection of organs, energy store

Vitamins- Vitamin A, C, & D VA- night vision (carrots, green veg) VC- prevents scurvy (citrus fruits, green veg) VD- prevents rickets (sunlight, oily fish)

Proteins growth and repair of tissues

Carbohydrates main energy source

Minerals- Iron, and Calcium Iron- needed to make haemoglobin to transport oxygen (red meat, spinach) Calcium- strong bones (milk, cheese, eggs)

Safety Wear safety glasses/gloves, tie hair, lab coat, (tongs glucose), ethanol is flammable

Large Molecule->
Enzyme->
Small Molecule

protein-> protease-> amino acids

lipid-> lipase->glycerol, fatty acids

starch->amylase->maltose->maltase->glucose

Factors Affecting Energy Needed

Age

Sex

Height & Weight

Physical Activity Levels

Pregnancy

Safety Wear safety glasses, gloves, needle, hot water.

Method
1) Measure a set volume of cold water and pour it into a boiling tube using a measuring cylinder.
2) Record the starting temperature of the water using a thermometer.
3) Record the mass of the food sample using an electronic balance.
4) Set food sample alight on a needle and put it underneath the boiling tube to heat the water until it burns out.
5) Record the final temperature of the water.
6) energy(J) = mass of water(g) x4.2 x temperature increase/mass of food

Sources of Error heat lost to surroundings, incomplete combustion, mistakes in measuring water volume, angle of tilted boiling tube inconsistent.

Equipment bunsen burner, pipette, test tubes

Sources of Error Colour change of Benedict’s test and Biuret test may be subtle and difficult to judge if the
concentration of the tested molecule is low.

Assimilation is the movement of digested food molecules into the cells of the body where they are used. For example: glucose is used in respiration to provide energy. amino acids are used to build new proteins.