Bio C4

Question 1

1. What chemical elements are present in carbohydrates, lipids, and proteins?

Answer 1

Carbohydrates: carbon(C), hydrogen(H), oxygen(O)
Lipids: carbon(C), hydrogen(H), oxygen(O)
Proteins: carbon(C), hydrogen(H), oxygen(O), nitrogen(N) (and sulfur(S) in small amount)

Question 2

2. What smaller molecules are starch, cellulose, and glycogen made from?

Answer 2

glucose

Question 3

3. What smaller molecules are proteins, DNA, fats and oils made of?

Answer 3

Protein: amino acid
DNA: nucleotide
Fat and oil : glycerol and fatty acid

Question 4

4. How do you test for starch, reducing sugars, proteins, and fat? What will you observe in
   a positive test for them?

Answer 4

Starch: Add iodine to the sample;
- Positive: The yellow/brown solution turns blue/black
Reducing sugar: - Add a few drops of Benedict’s solution. Warm in a water bath for 3 minutes at about 80 degrees
- Positive: from blue to green, yellow, orange and red, The more reducing sugar present, the closer to red the colour is
Protein: Biuret test;
- Positive: The solution turns from blue to purple
Fat: Emulsion test;
- Positive: cloudy white

Question 5

5. How do you test for Vitamin C? What will you observe in a positive test for Vitamin C?

Answer 5

Vitamin C: add into DCPIP; Positive: The solution will turn the DCPIP from dark blue to colourless permanently

Question 6

6. Give 2 functions of proteins?

Answer 6

Antibodies, enzyme, transport, form the structure of cell and body (any 2 of them)

Question 7

7. Describe the structure of DNA

Answer 7

It is made of many nucleotide
- It is made of 2 strands in the shape of a double helix
- Each strand contains bases (A, T, C, G)
- The 2 strands are linked between the bases

Question 8

8. How do the bases in DNA pair up?

Answer 8

A always pairs with T
C always pairs with G