3.19 Biological Molecules

Question 1

What are biological molecules produced by?

Answer 1

Cells

Question 2

What are nutrients?

Answer 2

Substances that are needed for growth, repair and metabolism.

Question 3

What are carbohydrates?

Answer 3

Molecules made from atoms of carbon, hydrogen, and oxygen.

Question 4

Describe how carbohydrates can come in different sizes

Answer 4

Carbohydrates come in different sizes. with the smallest carbohydrates being simple sugars, such as glucose and fructose. We call these simple sugars “monomers”. Carbohydrate monomers can join together to form carbohydrate polymers, such as glycogen and starch.

Question 5

Chemical bonds in a complex carbohydrate

Answer 5

In a complex carbohydrate, there are chemical bonds between the monomers. If these chemical bonds are broke, the complex carbohydrate can be broken down into simple carbohydrates (e.g. starch can be broken down into glucose molecules).

Question 6

What are long-chain carbohydrates made from?

Answer 6

Glucose and other sugars.

Question 7

What breaks down complex carbohydrates in the human body?

Answer 7

Enzymes in the mouth and small intestine

Question 8

Which three elements are found in carbohydrates?

Answer 8

• Hydrogen
• Oxygen
• Carbon

Question 9

Is glucose a monomer or a polymer?

Answer 9

Monomer

Question 10

What are proteins made from?

Answer 10

Amino acids

Question 11

Is glycogen a monomer or a polymer?

Answer 11

Polymer

Question 12

Proteins

Answer 12

Proteins are made up of long chains of amino acids bonded together. A protein is a polymer, whilst the amino acids it is made from are the monomers.

Question 13

What are amino acids made from?

Answer 13

Mainly from carbon, hydrogen, oxygen and nitrogen atoms.

Question 14

What breaks down proteins in the human body?

Answer 14

Enzymes in the stomach and small intestine.

Question 15

Lipids

Answer 15

The term “lipids” refers to both fats and oils. A fat is a lipid that’s solid at room temperature, whilst an oil is a lipid that’s liquid at room temperature. Lipids contain a single glycerol molecule attached to three fatty acid molecules.

Question 16

What determines whether a lipid is a fat or an oil?

Answer 16

The length and structure of the fatty acid molecules.

Question 17

What three elements are lipids made from?

Answer 17

• Carbon
• Hydrogen
• Oxygen

Question 18

Are lipids monomers or polymers?

Answer 18

Monomers

Question 19

What breaks down lipids in the body?

Answer 19

Small intestine

Question 20

How do plants build up organic molecules in their biomass? (7)

Answer 20

• Producers take in the elements they need to survive from their environment e.g. plants take in carbon from the air and nitrogen compounds from the soil.
• Producers use carbon (along with oxygen and hydrogen) to make glucose during photosynthesis.
• Glucose is then used to make other small organic molecules, e.g. other sugars, fatty acids and glycerol.
• Glucose and nitrate ions are combined to make amino acids.
• These small molecules are then used by the producer to create long-chain carbohydrates, lipids and proteins.
• These larger molecules are used to build structures like cell membranes and organelles.
• All these synthesis reactions are catalysed by enzymes.

Question 21

How do consumers get organic molecules?

Answer 21

Unlike plants, consumers can only get carbon and nitrogen compounds by eating and digesting the large organic molecules in producers or other consumers in the food chain.

Question 22

How do consumers digest organic molecules?

Answer 22

Digestion breaks large molecules down into smaller ones, which can be more easily absorbed by the consumer. Proteins are broken down into amino acids, starch is broken down into simple sugars, and lipids are broken down into fatty acids and glycerol. Digestion reactions are also catalysed by enzymes. The small molecules are then transported to the consumers’ cells (usually in the blood supply) to be built up into larger molecules (proteins, etc.) again. These form the biomass of the consumer.