True or False?
Carbohydrates, proteins, and lipids contain carbon.
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True or False?
Carbohydrates, proteins, and lipids contain carbon.
True.
Carbohydrates, proteins, and lipids contain carbon.
What are the chemical elements present in carbohydrates?
Carbohydrates are made of carbon, oxygen and hydrogen.
True or False?
Starch, glycogen, and cellulose are all made of glucose.
True.
Starch, glycogen, and cellulose are all carbohydrates built from many molecules of glucose joined together.
What are the chemical elements present in proteins?
Proteins contain carbon, oxygen, hydrogen and nitrogen.
Some contain small amounts of other elements such as sulfur.
What is the product when proteins are broken down into smaller molecules?
When proteins are broken down into smaller molecules amino acids are produced.
What are the chemical elements present in lipids?
Lipids are made of carbon, oxygen and hydrogen.
True or False?
Fats and oils are built from many glycerol molecules.
False.
Each molecule within fats and oils contain a single glycerol molecules joined to three fatty acids.
What is the test for starch?
The test for starch involves adding iodine solution to a food sample. A positive result is a colour change from orange-brown to blue-black.
True or False?
A positive iodine test will turn the solution from red to blue-black.
False.
A positive test for starch using iodine will turn the solution from brown/orange to blue-black.
What is the test for glucose (a reducing sugar)?
The test for glucose involves adding Benedict's solution to a sample and heating it in a boiling water bath. A positive result is a colour change from blue to brick red.
What is the starting colour of Benedict's solution?
The starting colour of Benedict's solution is blue.
What is the test for the presence of protein?
The protein test involves adding Biuret solution to a food sample. A positive result is a colour change from blue to violet/purple.
What is the starting colour of Biuret solution?
The starting colour of Biuret solution is blue.
What is the test for lipids?
The test for lipids involves mixing a sample with ethanol and then adding the ethanol solution to cold water. A positive result is a cloudy white emulsion forming.
Note that a sample containing solid pieces of food may need to be strained before a positive result can be clearly seen.
What does the DCPIP test for vitamin C involve?
The DCPIP test for vitamin C involves the addition of a food sample to blue DCPIP solution. If vitamin C is present then the DCPIP will become colourless.
Which of the food tests must be heated to observe the results?
The Benedict's test for glucose (a reducing sugar) must be heated to observe the results.
Describe the structure of DNA. (Extended Tier Only)
DNA consists of two strands coiled around each other to form a double helix. The strands are held together by a series of paired bases with bonds in between.
Identify the four nucleotide bases found in DNA. (Extended Tier Only)
The four nucleotide bases in DNA are:
A
T
C
G
True or False?
Nucleotide base A pairs with G in DNA. (Extended Tier Only)
False.
A pairs with T in DNA base pairing.
Describe how bases pair together in DNA. (Extended Tier Only)
Bases in DNA pair together via complementary base pairing:
A pairs with T
C pairs with G
What sequence of bases would pair with the DNA base sequence below (Extended Tier Only):
ACCGTTTGCAA
The base sequence would be paired as follows:
Original sequence: ACCGTTGCA
Paired sequence: TGGCAACGT