Digestion - bio

Tissue definition with examples

A group of similar cells performing a specific function e.g. smooth, epithelial, muscle

Organ definition with examples

A group of different tissues performing a shared function e.g. liver, leaf, pancreas, stomach, root

Organism definition

A group of organ systems working together e.g. human, plant

3 tissues in the stomach and their function

Glandular - secretes protease

Muscular- churn the food

Epithelial- protects the stomach from acid

2 functions of the digestive system

Breaks down large molecules in food into smaller molecules

Digested small food molecules absorbed into the blood for use in the body

Adaptations of small intestine

• Have villi which increase SA so diffusion of products can take place quicker

• Walls are only one cell thick meaning a shorter diffusion distance

• Rich blood supply which maintains the concentration gradient

(all the same for alveoli)

what are fats broken down into

fatty acids and glycerol

Test for fats (RQP)

Use ethanol and distilled water

Positive- Milky white

Negative- No milky layer

Which test do you heat to above 65 degrees (RQP)

Benedicts (sugar and carbohydrate)

Which test do you shake vigorously (RQP)

Fats/ emulsion test

amylase protease and lipase

AMYLASE

• Produced in salivary glands, small intestine and pancreas

• Takes place in the mouth and small intestine

PROTEASE

• Produced in stomach, pancreas and small intestine

• Takes place in stomach and small intestine

LIPASE

• Produced in small intestine and pancreas

• Small intestine

enzyme practical

1. put a drop of iodine in each well of a spotting tile

2. put amylase, pH buffer and starch solution in a water bath and leave for 5 mins to reach the same temperature.

3. add 2 cm³ amylase and 1cm³ pH buffer to a test tube ,mix, then add starch solution and start a stopwatch

4. after 10 seconds add a drop of solution to iodine in spotting tile

5. repeat every 10 seconds until iodine stops turning blue-black

6. repeat these steps using buffer solutions of a different pH.

enzyme test IV CV and DV (RQP)

IV- pH

DV- time taken for starch to stop being broken down

CV- temperature of water bath, interval times, volume of amylase, volume of pH buffer, volume starch

How to prepare a food sample (RQP)

• Break up the food using a pestle and mortar

• Transfer to a test tube and add distilled water

• Mix the food with the water by stirring with a glass rod

• Filter the mixture using a funnel and filter paper, collecting the solution

• Proceed with the food tests

Emulsion test

Emulsion test - fats/lipids

• add food sample to test tube

• Add a few drops of distilled water and ethanol

• Shake solution gently and note changes

• colourless to cloudy

Benedicts test

sugars

• Set up a water bath using bunsen burner and beaker

• add food sample to test tube and add a few drops of benedicts solution

• put the test tube in the water bath at 80 degrees for 5 minutes

• blue - green (less sugar present) to brick red (more sugar present)

Biuret test

protein

• add food sample to test tube

• add 2cm³ biuret solution

• blue - purple

Iodine test

starch

• add food sample to test tube

• few drops of iodine

• orange/brown - blue/black