Biological molecules

Question 1

What chemical elements is a glucose molecule made from?

Answer 1

Carbon, hydrogen and oxygen

Question 2

What large molecules are made from glucose?

Answer 2

Cellulose- plants use to make cell wall
Starch- plants use to store energy
Glycogen- animals use to store energy in the liver

Question 3

What is the function of glucose?

Answer 3

To produce energy from respiration. Plants transport sucrose which is then converted into glucose and used for respiration

Question 4

How can we test for reducing sugars?

Answer 4

Benedict’s solution

Question 5

What is the range of colours reducing sugar turns when heated over time?

Answer 5

Blue(none)-> green(low)-> yellow(medium)-> orange(medium-high)-> red(lots of reducing sugar)

Question 6

What chemical elements is a carbohydrate made up of?

Answer 6

carbon, oxygen and hydrogen

Question 7

What chemical elements is a lipid made up of?

Answer 7

carbon, oxygen and hydrogen

Question 8

What chemical elements is a protein molecule made up of?

Answer 8

carbon, oxygen, hydrogen, nitrogen and sometimes sulfur

Question 9

What is the basic unit of fats?

Answer 9

1 glycerol molecule chemically bonded to 3 fatty acid chains

Question 10

What two parts are lipids divided into?

Answer 10

Fats (solids at room temperature contains saturated fats) and oils (liquids at room temperature contains unsaturated fats)

Question 11

What is protein made up of?

Answer 11

Long chains of amino acids

Question 12

What is the function of fats?

Answer 12

Fats are an energy dense molecule. The fat stored under the skin is called adipose tissue and it insulates the body. Fat is also used to produce cell membranes and some hormones. Additionally, plants store oils in their seeds

Question 13

How to test for fats?

Answer 13

• The ethanol emulsion test
  1. Mix food with ethanol
  2. Pour ethanol into water
  3. If fat is present, the solution will turn cloudy

Question 14

What is the function of protein?

Answer 14

It’s used to make new proteins and enzymes, used for growth and repair of cells and used to make antibodies which are used to kill bacteria and viruses

Question 15

How to test for glucose?

Answer 15

1. Add Benedict’s solution into the sample
2. Heat in a water bath
3. Observe colour change from blue to red

Question 16

How to test for starch?

Answer 16

1. Add drops of iodine onto the food sample
2. Watch the colour change if it is blue/black there’s starch in it. If it stays yellow/brown there’s no starch in it

Question 17

How to test for proteins?

Answer 17

The biuret test
1. Mix the food with water
2. Add Biuret A and B solutions
3. If protein is present it turns from blue to purple

Question 18

How to test for vitamin C?

Answer 18

1. Add 1cm^3 of DCPIP solution to a test tube
2. Add a small amount of food sample
3. If there is vitamin C the blue colour of the dye will disappear, if there isn’t the solution will stay blue

Question 19

What is the structure of DNA?

Answer 19

Two strands coiled together to form a double helix. The backbone is made of sugar and phosphate while on the inside the double helix contains chemicals called bases which determine the code of the DNA. The bonds between pairs of bases hold the
strands together

Question 20

Which bases bind together in DNA?

Answer 20

A with T and G with C