Genetics, Biodiversity and Classification Progress Check

Question 1

State two differences between prokaryotic and eukaryotic DNA

Answer 1

Prokaryotic DNA is free floating and not associated with histone proteins whereas eukaryotic DNA is contained within the nucleus and is associated with histone proteins

Question 2

Sketch a graph to show the result of stabilising selection on the normal distribution curve

Answer 2

Graph drawn with a narrower and taller peak than the normal distribution curve

Question 3

State the difference between pre-mRNA and mRNA

Answer 3

Pre-mRNA contains introns and exons whereas mRNA only contains exons

Question 4

State the process by which pre-mRNA is synthesised

Answer 4

Transcription

Question 5

Define the term ‘triplet code’

Answer 5

Three bases code for one amino acid

Question 6

Define the term ‘Universal’

Answer 6

The same triplet codes for the same amino acid

Question 7

Define the term ‘Non-overlapping’

Answer 7

Each triplet code is distinct from one another with no cross-over

Question 8

Birth weight is an example of what form of selection. Explain your choice.

Answer 8

Stabilising
If the baby is too small it will not develop/ survive
If the baby is too large it may cause harm to mother during pregnancy or birth

Question 9

What is splicing?

Answer 9

The removal of introns from the pre-mRNA sequence

Question 10

Why is splicing required?

Answer 10

Pre-mRNA is too large to leave the nucleus through the nuclear pores so without splicing the amino acid chain couldn’t be formed

Question 11

What is the enzyme required to break apart the double helix?

Answer 11

DNA helicase

Question 12

What bond is broken when the double helix is broken?

Answer 12

Hydrogen bonds

Question 13

What is the role of the Golgi apparatus?

Answer 13

Stores, modifies and packages proteins and lipids

Question 14

What is meant by the term ‘degenerate’?

Answer 14

Multiple triplet codes can code for the same amino acid

Question 15

What is a mutation?

Answer 15

A random change in the genetic sequence

Question 16

Where does translation occur?

Answer 16

Ribosome

Question 17

What enzyme is requires to re-synthesise the backbone in mRNA?

Answer 17

RNA polymerase

Question 18

Why does crossing over result in genetic variation?

Answer 18

Exchange of sections of the chromatid resulting in new combinations of alleles

Question 19

What is the loci?

Answer 19

The position of a gene on a chromosome

Question 20

What term is used to describe the structure of a protein made of two or more polypeptides?

Answer 20

Quaternary

Question 21

Identify one event that occurs during division 2 of meiosis but not during division 1

Answer 21

Separation of sister chromatids

Question 22

Not all mutations result in a change to the amino acid sequence of the encoded polypeptide. Explain why.

Answer 22

The code may be degenerate

Question 23

The genetic code uses four different DNA bases. What is the maximum number of different DNA triplets that can be made using these four bases?

Answer 23

64

Question 24

Name two substances that make up the backbone of a pre-mRNA molecule

Answer 24

-Phosphate
-Ribose

Question 25

The sequence of bases on a pre-mRNA molecule are as follows: A U C C G U
Give the sequence of bases on the DNA strand from which this pre-mRNA has been transcribed

Answer 25

T A G G C A

Question 26

Give one way in which the structure of an mRNA molecule is different from the structure of a tRNA molecule

Answer 26

A tRNA molecule has an amino acid attachment site whereas mRNA does not