Biology Chapter 3 biological molecules

Question 1

What are the top 10 genetically modified foods

Answer 1

Corn, soy, cotton, papaya, rice, canola, potatoes, tomatoes, dairy products and peas

Question 2

Why do we need food?*

Answer 2

The nutrients in food are needed to:
- release energy
- supply raw materials to make new protoplasm
- help us stay healthy

Question 3

What are nutrients?*

Answer 3

Nutrients are chemical substances in food that release energy and materials needed by the body

Question 4

What are carbohydrates

Answer 4

(Major categories of carbo can be like starch, glucose)
Carbohydrates are organic molecules made up of carbon, hydrogen and oxygen
- The general formula for carbohydrates is CnH2mOm
The ratio of hydrogen atoms to the oxygen atoms in carbo is 2:1

Question 5

What are the monosaccharides(single sugars) of carbs

Answer 5

• Glucose
• Fructose
• Galactose

Question 6

Disaccharides (double sugars)

Answer 6

• Maltose
• Sucrose
• Lactose

Question 7

Polysaccharides (complex carbs) just means a lot of sugars together

Answer 7

Starch- plant store
Glycogen- animal store
Cellulose

Question 8

How many carbons are present glucose, galactose and fructose?

Answer 8

Glucose has 6 carbons, in the shape of a hexagon, same as galactose
Fructose(present in fruits) only has 5 carbons

Question 9

How is maltose formed

Answer 9

glucose + glucose = maltose- two unit sugar

Question 10

How is lactose formed

Answer 10

glucose + galactose = lactose (present in milk)*, it’s a milk sugar

Question 11

how is sucrose formed and consequences of too much of it

Answer 11

glucose + fructose = sucrose (found in fruits) too much can lead to fatty liver, more health risks, not really a good sugar

Question 12

How starch is formed, also an example of it breaking down

Answer 12

4 glucose are stringed up together to form starch
Example: If we bite bread for long enough, it will taste sweet as starch breaks it down into glucose

Question 13

How cellulose (cell wall) if glucose

Answer 13

4 glucose again like starch but stringed up in another way

Question 14

How glycogen is formed

Answer 14

6 glucose, highly branched glycogen

Question 15

Which ones are reducing sugars

Answer 15

All monosaccharides which are glucose, galactose and fructose, and all disaccharides which are lactose and maltose, they do not include sucrose

Question 16

How are disaccharides formed

Answer 16

• A condensation reaction is a chemical reaction in which two smaller, simple molecules are joined together to form a larger, complex molecule with the removal of one molecule of water
  For example, when two glucose molecules join together via the condensation reaction, maltose is formed

Question 17

Hydrolysis of disaccharides

Answer 17

• A chemical reaction in which a water molecule is needed to break down one larger, complex molecule into two smaller, simple molecules
• A double sugar can be split into two single sugar molecules by hydrolysis in teh presence of an enzyme
  For example, maltose + water and maltase —> glucose + glucose

Question 18

Starch description

Answer 18

• A storage form of carbohydrates in plants
• Found in storage organs in plants

Question 19

Cellulose description

Answer 19

• Cellulose cell wall protects plant cells
• Serves as dietary fibres to prevent constipation
  ( the kind of bond cellulose has makes it indestructible, cannot be broken down)

Question 20

Glycogen description

Answer 20

• A storage form of carbs in mammals in liver and muscles ( as the liver and muscles contain a lot of mitochondria to release energy for cellular functions, a lot of glucose is needed too)
• digested to form glucose when needed

Question 21

Hydrolysis of starch example

Answer 21

Starch is digested into maltose molecules by amylase (enzyme)
Maltose molecules are digested into glucose by maltase (enzyme)

Question 22

How carbohydrates can be bad if too much

Answer 22

Can cause diabetes, can be turned into too much fats, leading to obesity, and fats are much harder to lose than carbs

Question 23

How we can test for starch

Answer 23

Iodine test- add 2cm^3 of food sample to a clean test tube. Add a 2-3 drops of iodine solution to the test tube
Positive: blue-black
negative: solution remains brown

Question 24

How can we test for reducing sugar’s and how to see the results

Answer 24

Benedict’s test-
1. add 2cm^3 of Benedict’s solution to 2cm^3 of food sample in a test tube
2. Shake the mixture
3. Heat the contents in a boiling water bath for 2-3 minutes
Positive: Green precipitate- trace amount
- yellow/orange precipitate- moderate amount
orange red precipitate- large amount
negative: solution remains blue

Question 25

What are fats? and what are their proportions when it comes to oxygen and hydrogen, as well as their elements?

Answer 25

Fats are organic compounds mad up of carbon, hydrogen and oxygen (the elementals of fats are C, H and O, which is why carbs can turn into fats)
- Fats contain much less oxygen in proportion to hydrogen
- The proportions of the elements in fats are not fixed

Question 26

What is a fat molecule made up of?

Answer 26

A fat molecule is made up of:
1 glycerol molecule
3 fatty acid chains

Question 27

Hydrolysis of fats, the process and what it is broken down into

Answer 27

Fats can be broken down into simpler compounds by hydrolysis
Hydrolysis of fats produces fatty acids and glycerol

Fat molecule + 3 of H2O —>lipase (enzyme) for glycerol + 3 fatty acid

Question 28

About saturated fats’ molecule’s shape and what state of matter they are in at room temp

Answer 28

Mostly found in animal sources
Fatty acid chains are straight in saturated fats
- A saturated fat molecule tends to be a semi-solid at room temp
Most are solid at room temp (e.g. butter, cheese, biscuits )

Question 29

About Unsaturated fats and what state of matter they are in at room temp as well as the shape of their molecule

Answer 29

Fatty acid chain has kinks
Liquid at room temperature (e.g. sunflower seed oil, peanut oil, olive oil)
- comes from plant sources

Question 30

Consequences of eating too much saturated fats and how unsaturated fats are better for us

Answer 30

Since saturated fats tend to be solid or semi-solid at room temp, there would be a risk of the saturated fats depositing on the walls of the blood vessels and clogging the blood vessels, resulting in cardiovascular disease. Therefore, unsaturated fats are better for us as they are liquid at room temp, so unsaturated fats are healthier

Question 31

Functions of fats

Answer 31

• A source and store if energy
• act as an insulating material to prevent excessive heat loss
• are a solvent for fat soluble vitamins and some hormones
• form the main part of cell ,membrane
• help reduce water loss from skin surface
• essential for growth, repair and synthesis of cells

Question 32

What fats is an alternative source of

Answer 32

Fats is an alternative source of energy for carbohydrates when burning energy

Question 33

Example of carbs

Answer 33

Banana, bread- both rich in sugars and starch, offers immediate source of energy

Question 34

How can we test for fats?*

Answer 34

Ethanol emulsion test-
1.Add 2cm^3 of ethanol to 2cm^3 of food sample in a test tube
2. Shake the contents of the tube vigorously
3. Decant the ethanol into another test tube with 2cm^3 of water and shake the mixture
Positive: cloudy white emulsion is formed if fats are present
Negative: Solution remains clear and colourless if fats are absent

Question 35

What are proteins and what they consist of, also what are they are made of

Answer 35

Proteins are organic compounds made up of carbon, hydrogen, oxygen, nitrogen and sulfur
- Each protein molecule is made up of smaller basic units, which are amino acids

Question 36

The building blocks of proteins

Answer 36

Amino acids, the building blocks of proteins, are made up of:
- an amino group
- an acid group
- a side chain

Question 37

Amino acids —> peptide bonds —> protein process

Answer 37

(There are 20 different types of amino acids)
Amino acids are the building block of proteins
Peptide bonds link up amino acids to form a polypeptide chain(a chain of amino acids)
Two or more polypeptide chains fold to form a three-dimensional molecule, that is protein ( only when in 3-D then it is considered a protein)

Question 38

A break hehe, look at your notability notes for how the picture is like on how peptide bonds link up to form a polypeptide

Question 39

Functions of proteins

Answer 39

Proteins are needed for:
- the synthesis of new protoplasm for growth and repair of worn-out cells
- the synthesis of enzymes and some hormones
- the synthesis of antibodies

Question 40

How can we test for proteins

Answer 40

Biuret test-
1. Add 2cm^3 of sodium hydroxide solution to 2cm^3 of food sample into a test tube
2. Shake the mixture thoroughly
3. Add 1% copper (II) sulfate solution drop by drop, shaking mixture after each drop
OR
1. add 2cm^3 of Biuret solution to 2cm^3 of the food sample and shake the mixture thoroughly
Positive: A violet solution is formed if proteins are present
Negative: Solution remains blue if absent

Question 41

How do protein molecules maintain their 3-D structure

Answer 41

Through hydrogen bonds