Topic 1 - B : More biological molecules

Question 1

Structure of nucleotide

Answer 1

Phosphate group————-pentose sugar (deoxyribose sugar in DNA or ribose sugar in RNA)——–nitrogen containing organic base

Question 2

What bonds bases

Answer 2

hydrogen bonds

Question 3

What bonds nucleotides together to make polynucleotides

Answer 3

ester bonds

Question 4

DNA structure

Answer 4

double helix
long
coiled up tight

Question 5

DNA nucleotide structure

Answer 5

Phosphate group
deoxyribose sugar
nitrogen containing organic base
A,C,T,G

Question 6

Antiparellel

Answer 6

two polynucleotide strands run in opposite directions and twist to form a DNA double helix

Question 7

RNA structure

Answer 7

Single polynucleotide structure
Phosphate group
ribose sugar
nitrogen containing organic base
A,C,U,G
Shorter than DNA

Question 8

DNA replication process

Answer 8

1) DNA helicase breaks hydrogen bonds between bases on the two polynucleotide DNA strands unwinding the helix
2) Each original single strand acts as a template for new strand, complementary DNA bases are attracted to exposed complementary bases
3) DNA polymerase joins nucleotides of the new strand together via condensation reaction forming hydrogen bonds

Question 9

ATP structure

Answer 9

Nucleotide base Adenine
Ribose sugar
Three phosphate groups

Question 10

How is water a important metabolite

Answer 10

hydrolysis reaction require a water molecule to break the bond
condensation reaction releases a molecule of water as a new
bond is formed

Question 11

How is water a good solvent

Answer 11

as water is polar, the slightly positive charged end of a water molecule is attracted to negative end of an ion, and the opposite
this means ions get completely surrounded by water. This means organisms can take up useful substances dissolved in water and these dissolved substances can be transported around body.

Question 12

How is water cohesive

Answer 12

as water is polar the molecules are very cohesive
the strong cohesion means it is good to transport substances
strong cohesion also means water has high surface tension when in contact with air

Question 13

How does water have high latent heat of vaporisation

Answer 13

water evaporates when hydrogen bonds are broken
it takes a lot of energy to break hydrogen bonds between water molecule meaning it has a high latent heat of vaporisation
this is useful as animals can use water loss through evaporation without losing too much water

Question 14

how is water a buffer

Answer 14

as a lot of energy is needed to break the hydrogen bonds, this means water doesn’t experience rapid temperature changes