T2 - Cell organisation, enzymes, digestion, food tests

Question 1

What are the levels of organisation in organisms, from least complex to most complex?

Answer 1

Organelles ➔ cells ➔ tissues ➔ organs ➔ organ systems

Question 2

What is a tissue?

Answer 2

A group of similar cells that work together to carry out a particular function.

Question 3

What is an organ?

Answer 3

An organ is a group of different tissues that work together to perform a certain function.

Question 4

What is an organ system?

Answer 4

An organ system is a group of organs working together to perform a particular function.

Question 5

Give two reasons why we can’t just make our cells even warmer to increase the rate of reactions

Answer 5

1) Higher temperatures could damage our cells

2) Higher temperatures would also speed up non-useful reactions

Question 6

What is a catalyst?

Answer 6

A catalyst is a substance which increases the speed of a reaction, without being changed or used up in the reaction.

Question 7

What is an enzyme?

Answer 7

Enzymes act as biological catalysts. They are large proteins made up of long chains of amino acids. These chains are then folded into unique shapes.

Question 8

What is the name of special region of an enzyme that binds to the substrate?

Answer 8

Active site

Question 9

In order for an enzyme to catalyse a reaction, the active site of the enzyme must be _____________ to the substrate.

Answer 9

Complementary

Question 10

What is the name of the model of enzyme action where the substrate fits perfectly into the active site?

Answer 10

Lock and key model

Question 11

What is the name of the model of enzyme action where the enzymes active site changes shape slightly as it binds to the substrate?

Answer 11

Induced fit model

Question 12

Explain how increasing the temperature can cause an enzyme to denature.

Answer 12

High temperatures start to break the bonds holding the enzyme together.
This causes the enzyme and it’s active site to change shape.
This means the enzymes active site will no longer be complementary to the substrate.

Question 13

What affect does extremely high pH have on enzymes?

Answer 13

It denatures them.

Question 14

What is pH?

Answer 14

A measure of acidity

Question 15

What does the term ‘optimum’ mean for enzyme temperature?

Answer 15

The temperature at which the enzyme activity is the highest.

Question 16

How does bile help with the digestion of lipids?

Answer 16

It emulsifies the lipids which increases the surface area for lipase enzymes to break them down.

Question 17

How are carbohydrates broken down?

Answer 17

Carbohydrases convert carbohydrates into simple sugars.
Starch ➔ amylase enzyme ➔ maltose

Question 18

Where is amylase made?

Answer 18

1) The salivary grands
2) The pancreas
3) The small intestines

Question 19

How are proteins broken down?

Answer 19

Proteins ➔ Protease enzymes ➔ Amino acids

Question 20

Where is protease made?

Answer 20

1) The stomach (pepsin)
2) The pancreas
3) The small intestines

Question 21

How are lipids broken down?

Answer 21

Lipid ➔ Lipase enzymes ➔ Glycerol and fatty acids

Question 22

Where is lipase made?

Answer 22

1) The pancreas
2) The small intestine

Question 23

What are the 2 main roles of the digestive system?

Answer 23

Digestion - Process of breaking down large molecules into smaller molecules.
Absorption - Process of of absorbing these small food molecules into the body

Question 24

What are the 3 roles of the stomach?

Answer 24

The stomach contracts its muscular walls to churn and mix the food.
It produces pepsin, which is a type of protease enzyme, and breaks proteins down into amino acids.
It produces hydrochloric acid, which provides the right
pH for pepsin to function, and kills microorganisms.

Question 25

What are the 2 roles of bile?

Answer 25

Bile is made by the liver, but it is stored in the gallbladder,
After we have meal, it is released into the small intestine where it helps in two ways: One is to emulsify lipids, which means separate large droplets of lipid into smaller droplets.
The other is to neutralise the acid from the stomach, which bile can do because it is alkaline.

Question 26

What are the functions of the pancreas?

Answer 26

Produces amylase, protease and lipase enzymes. It releases these into the small intestine.

Question 27

What is the function of the salivary gland?

Answer 27

Produce amylase enzyme in the saliva.

Question 28

What is the function of the liver?

Answer 28

Where bile is produced.

Question 29

What is the function of the gall bladder?

Answer 29

Where bile is stored before it’s released into the small intestine.

Question 30

What is the function of the large intestine?

Answer 30

Where excess water is absorbed from the food.

Question 31

What is the function of the small intestine?

Answer 31

Produces protease, amylase and lipase enzymes to complete digestion.
This is also where the digested food is absorbed out of the digestive system into the blood.

Question 32

How do you prepare a food sample?

Answer 32

1) Get a piece of food and break it up using a pestle and mortar.
2) Transfer the ground up food to a beaker and add some distilled mortar.
3) Stir the mixture with a glass rod to dissolve some of the food.
4) Filter the solution using a funnel lined with filter paper to get rid of the solid bits of food.

Question 33

What is the test for reducing sugars?

What colour will the solution change to if reducing sugar is present?

Answer 33

Benedict’s test

Blue ➔
green (low concentration of reducing sugar)
yellow (medium concentration of reducing sugar)
brick red (high concentration for reducing sugar)

Question 34

What is the test for starch?

What colour will the solution change to if starch is present?

Answer 34

Iodine

Browny-orange ➔ Black or blue-black

Question 35

What is the test for protein?

What colour will the solution change to if protein is present?

Answer 35

Biuret test

Blue ➔ Purple

Question 36

What is the test for lipids?

What colour will the solution change to if lipids are present?

Answer 36

Sudan III test

The mixture will separate into 2 layers. The top layer will be bright red.

Question 37

How do you do the Benedicts test?

Answer 37

Prepare a food sample and add 5cm³ to a test tube.
Prepare a water bath so that it’s set to 75°C.
Add some benedicts solution to the test tube (about 10 drops) using a pipette.
Place the test tube in the water bath using a test tube holder and leave it in there for 5 minutes. Make sure that the tube is pointing away from you.

Question 38

How do you do the Iodine test?

Answer 38

Make a food sample and transfer 5cm³ of your sample to a test tube.
Then add a few drops of iodine solution and gently shake the tube to mix the contents.

Question 39

How do you do the Biuret test?

Answer 39

Prepare a sample of your food and transfer 2cm³ of your sample to a test tube. Add 2cm³ of biuret solution to the sample and mix the contents of the tube by gently shaking it.

Question 40

How do you do the Sudan III test?

Answer 40

Prepare a sample of the food you’re testing (don’t need to filter it). Transfer 5cm³ into a test tube.
Use a pipette and add 3 drops of Sudan III stain solution to the test tube and gently shake the tube.