Pp Questions

Question 1

Describe the primary structure of all proteins.

Answer 1

A sequence of amino acids joined by peptide Bonds

Question 2

This question is about genetic code.

Define universal, non-overlapping, degenerative

Answer 2

Universal= The same codon always codes for the same amino acid.
Non-overlapping= Each base is only part of one codon
Degenerate= Morethan one codon for each amino acid

Question 3

Describe one difference between the structure of DNA in a prokaryotic cell and in a eukaryotic cell.

Answer 3

In prokaryotes…
DNA is circular NOT linear
Has no introns

Question 4

Describe 2 differences between the structure of triglycerides and phospholipids.

Answer 4

Triglycerides….
3 Easter bonds rather than 2
No phosphate group
3 fatty acids rather than 2

Question 5

Explain why phospholipids can form a bilayors but triglycerides cannot. (3 marks)

Answer 5

Phospholipids are polar
OR
Have a hydrophilic and hydrophobic end,
Phosphate group is charged,
So attracts water.
Triglycerides are hydrophobic.

Question 6

Describe the role of tRNA in translation. (2 marks)

Answer 6

Anticodon binds to codon,
Brings specific amino acids

Question 7

Describe how gas exchange occurs in single-celled organisms and explain why this method cannot be used by large, multicellular organisms.

Answer 7

Diffusion across cell surface membrane.
Large organisms have a smaller SA:V ratio
So diffusion pathway would be too long.

Question 8

Name two enzymes that are involved in replicating the DNA of a virus and describe their roles in the replication process.

Answer 8

DNA helicase breaks hydrogen bonds
DNA polymerase joins adjacent nucleotides via condensation reaction

Question 9

A student prepared a plant route to observe cells undergoing mitosis
He put the root into a small bottle of hydrochloric acid in a 40 degrees water bath.
Why did he put the plant root in acid?

Answer 9

Breakdown the cell wall