Topic 1.3.1 - Biology

Question 1

What is a nucleotide

Answer 1

molecules with 3 parts - a pentose sugar, a nitrogenous base and a phosphate group - joined by condensation reactions

Question 2

what are the functions of nucleotides

Answer 2

• provide an energy currency in the form of ATP
• provide the building blocks for the mechanisms of inheritance in the form of RNA and DNA

Question 3

state the difference between RNA and DNA

Answer 3

the pentose sugar in RNA is ribose, and in DNA is deoxyribose, which has 1 less oxygen atom than ribose

Question 4

what do the most common nucleotides have

Answer 4

purine base or a pyrimidine base

Question 5

compare the purine base with the pyrimidine base

Answer 5

the purine base has 2 nitrogen-containing rings, and the pyrimidine base has 1 nitrogen-containing base. They are both weak bases

Question 6

Give 2 examples of purines

Answer 6

• Adenine (A)
• Guanine (G)

Question 7

give 3 examples of pyrimidines

Answer 7

• Cytosine (C)
• Thymine (T)
• Uracil (U)

Question 8

what is the result of having a phosphate group in a nucleotide

Answer 8

nucleotide is an acidic molecule and carry a negative charge

Question 9

how is a nucleotide formed

Answer 9

the sugar, base and phosphate group are joined together by condensation reaction, with the elimination of 2 water molecules

Question 10

what is ATP

Answer 10

a nucleotide that acts as the universal energy supply molecule in cells. It is made up of the base adenine, the pentose sugar ribose and 3 phosphate groups

Question 11

what is Adenine

Answer 11

a purine base found in RNA and DNA

Question 12

what is Guanine

Answer 12

a purine base found in RNA and DNA

Question 13

what is Cytosine

Answer 13

a pyrimidine base found in DNA and RNA

Question 14

what is Thymine

Answer 14

a pyrimidine base found in DNA

Question 15

what is Uracil

Answer 15

a pyrimidine base found in RNA

Question 16

what is ATPase

Answer 16

an enzyme that catalyses the formation and the breakdown of ATP, depending on conditions

Question 17

what is ADP

Answer 17

a nucleotide formed when ATP loses a phosphate group and provides energy to drive reactions in the cell

Question 18

what is a redox reaction

Answer 18

reactions in which one reactant loses electrons (is oxidised) and another gains electrons (is reduced)

Question 19

when energy is needed in a cell, what happens?

Answer 19

the 3rd phosphate bond in ATP is broken in a hydrolysis reaction, catalysed by ATPase. The products are ADP, another nucleotide, and a free inorganic phosphate group, this releases energy

Question 20

how is energy lost when ATP is split

Answer 20

by heat

Question 21

how is the energy produced used

Answer 21

for energy-requiring biological activity e.g. active transport, nerve impulses & muscle contraction

Question 22

what type of reaction is the breakdown of ATP into ADP

Answer 22

reversible reaction