B3 organisation and the digestive system

Question 1

What is a tissue?

Answer 1

a group of cells that have similar structure and function working together

Question 2

What is a organ?

Answer 2

A collection of tissues that all working together to perform a specific function

Question 3

3 types of tissues in the stomach and their function

Answer 3

Muscular tissue churn the food and digestive systems together
Glandular tissue produces the digestive juice
Epithelial tissue-Covers the inside and outside of the organ

Question 4

What is an organ system

Answer 4

a collection of organ with adaptations to perform their task for the human body

Question 5

What is the digestive system for?

Answer 5

To absorb nutrients from food and transfer to the bloodstream as they would be too big to fit in.

Question 6

What do enzymes do?

Answer 6

Break up food in to smaller soluble particles

Question 7

How is the small intestine adapted to perform digestion?

Answer 7

Lots of microvilli which have a large surface area and blood supply to have more space for diffusion to take in nutrients.

Question 8

What do the different organs so in the digestive system.

Answer 8

Salivary glands have amylase to digest carbs
the stomach have acids and churns the food and is where protein is digested
the pancreas produces enzymes like protease and lipase and amylase
the small intestine is where the nutrients is extracted and where the enzymes meet the food
the liver makes bile that digests fat and vitamins
large intestine has bacteria to digest some carbs and extracts the water from the stool

Question 9

What is carbohydrates for?

Answer 9

energy for metabolic reaction

Question 10

What is lipids for?

Answer 10

the most efficient store of energy, hormones and cell structure and the brain

Question 11

What are proteins used for

Answer 11

Are made of amino acids
for tissues and cells and growth and body repair and enzymes

Question 12

What are enzymes?

Answer 12

Biological catalysts and they have a active site that is complementary to the substrate that fits in the active site and gets broken down

Question 13

Why are enzymes important in metabolism?

Answer 13

They speed the amount of reactions making it more efficient

Question 14

How does temperature affect enzymes?

Answer 14

Enzymes get more active when the temperature rises as they kinetic energy increases so the amount of collisions occur
At 37 degrees which is the optimum close to the body temperature where they work best
After 40 degrees the amino acid bonds break and the active site is no longer complementary to the substrate so the enzyme is denatured.

Question 15

How does a change in pH affect enzymes

Answer 15

The pH affects the bonds of the active site denaturing it

Question 16

What does the liver do?

Answer 16

Make bile which helps with the digestion of fat and is stored in the gall bladder

Question 17

What are the different enzymes for the macronutrients

Answer 17

Protease or pepsin for protein
Amylase for carbohydrates
Lipase for fats

Question 18

What are the different reagents for food testing

Answer 18

Glucose-Benedicts reagent and the solution turns red
Starch-Iodine turns blue black
Fat-Ethanol solution turns cloudy
Protein-Biurets reagent and solution turns lilac

Question 19

What does the stomach produce?

Answer 19

Pepsin and hydrochloric acid in equal proportions to break down protein and hcl also kills any bacteria.

Question 20

Why does the stomach produce mucus?

Answer 20

To protect the stomach lining from getting attacked by protease and hcl.

Question 21

What are some functions of bile

Answer 21

Neutralises acid so enzymes in the small intestine wont get damaged and emulsifies fat so it gets into smaller globules so lipase can digest it easier.

Question 22

Required practical:enzymes

Answer 22

You will investigate the breakdown of
starch by amylase at different pHs.

The different pHs under investigation will be produced using
buffer solutions
. Buffer solutions produce a particular pH, and will maintain it if other substances are added.

The amylase will break down the starch.

A series of test tubes containing a mixture of starch and amylase is set up at different pHs.

A sample is removed from the test tubes every 10 seconds to test for the presence of starch.
Iodine solution
will turn a blue/black colour when starch is present, so when all the starch is broken down, a blue-black colour is no longer produced. The iodine solution will remain orange-brown.
A control experiment must be set up – without the amylase – to make sure that the starch would not break down anyway. The result of the control experiment must be negative – the colour must remain blue-black – for results with the enzyme to be valid.

When the starch solution is added:

start timing immediately
remove a sample immediately, and test it with iodine solution
sample the starch-amylase mixture continuously, for example every 10 seconds.

The time taken for the disappearance of starch is not the rate of reaction.

It will give us an indication of the rate, but is the
inverse
of the rate – the shorter the time taken, the greater the rate of the reaction.

We can calculate the rate of the reaction by calculating 1/t, obtaining a measure of the rate of reaction by dividing one by the time taken for the reaction to occur.

Question 23

Required Practical: Food Tests

Answer 23

Test for sugar: Sugars classed as reducing sugars
will react with Benedict’s solution on heating for a few minutes. Glucose is an example of a reducing sugar. Reducing sugars give a red-brown precipitate with Benedict’s solution. The precipitate takes a while to settle in the tube – you’re more likely to see simply a red or brown colour. If there’s not much glucose present, the final colour may be green or yellow, or orange if there’s a little more.

Test for Starch:
Foods containing starch will turn a blue-black colour with iodine.

Test for Protein:
The biuret test is used to detect proteins. If protein is present it turns purple or pink

Test for Lipids:
Ethanol when added to a food with lipids turn the solution cloudy.