DNA and RNA Past Mock Questions

Question 1

Distinguish between DNA profiling and genetic screening

DNA profile

Answer 1

DNA profiling is a method of making a unique pattern of bands from the DNA of a person, which can then be used to compare with the DNA profile of another person

Question 2

Distinguish between DNA profiling and genetic screening

Genetic screening

Answer 2

Genetic screening means testing DNA for the presence of absence of a particular gene or an altered gene

Question 3

During your investigation to isolate DNA from a plant cell, describe how you broke down the cell wall

Answer 3

The union was also chopped into small cubes and blended for three seconds to break down the cell walls and release DNA

Question 4

During your investigation to isolate DNA from a plant cell, describe how you broke down the cell membrane

Answer 4

Washing up liquid was used as it dissolved the cell and nuclear membranes to release the DNA

Question 5

During your investigation to isolate DNA from a plant cell, describe how you precipitate the DNA

Answer 5

Freezer-cold/ice cold ethanol was added

Question 6

What does need to be done to a plant cell but not a blood cell when trying to extract DNA?

Answer 6

The sample doesn’t need to be blended as there is no cell wall

Question 7

On what basis are DNA fragments separated by during gel electrophoresis

Answer 7

They are separated based on size

Question 8

Why are DNA fragments stained after electrophoresis?

Answer 8

To make them more visible and easier to see

Question 9

To which group of bases does Guanine belong to?

Answer 9

Purines

Question 10

Name the type of bonding that exists between strands of the DNA double helix

Answer 10

Hydrogen bonds

Question 11

What causes the double helix of DNA to unwind?

Answer 11

Enzymes

Question 12

Explain the function of the enzyme RNA polymerase

Answer 12

Causes a sequence of RNA bases to join together to form messenger RNA i.e. it joins nucleotides together to form mRNA

Question 13

In which part of the cell does transcription occur?

Answer 13

Nucleus

Question 14

In which part of the cell does translation occur?

Answer 14

Cytoplasm

Question 15

Why is it necessary for a protein to fold?

Answer 15

A protein only becomes functional once its folded into its correct shape

Question 16

What group of biomolecules provide the nitrogen needed to make the nitrogenous bases contained in DNA?

Answer 16

Protein

Question 17

Name one of the purine bases found in DNA

Answer 17

Adenine or guanine

Question 18

In the DNA molecule what base does adenine bond to?

Answer 18

Thymine

Question 19

In the DNA molecule what base does guanine bond to?

Answer 19

Cytosine

Question 20

Explain the importance of complementary base bonding in DNA

Answer 20

The bonding between complementary base pairs hold two strands of DNA in a double helix shape

Question 21

In RNA what does R stand for?

Answer 21

Ribose

Question 22

Name the type of RNA molecule made during the process of transcription?

Answer 22

Messenger RNA (mRNA)

Question 23

In which structure of the cell does transcription occur?

Answer 23

Nucleus

Question 24

Describe the relationship between messenger RNA (mRNA) and the DNA molecule
(2)

Answer 24

The mRNA molecule has complementary bases to those on the DNA strand from which it was transcribed

Thymine is replaced with uracil on the mRNA molecule

Question 25

What is the final step in protein formation which gives it it's function?

Answer 25

The protein must be folded into it's correct shape

Question 26

Explain the importance of heredity to living organisms

Answer 26

Heredity is the passing on of features from parents to offspring by means of genes Heredity is also called genetic inheritance

Question 27

Explain the phrase gene expression

Answer 27

Gene expression is the way in which the genetic information in a gene is decoded in the cell and used to make a protein

Question 28

Explain why it is important that the correct sequence of bases is maintained during DNA replication

Answer 28

If the correct sequence of bases is not maintained then the production of an incorrect amino acid will result

Question 29

Apart from the nucleus, name one other organelle where DNA may be found

Answer 29

Chloroplast | Mitochondrion

Question 30

Explain what is meant by junk DNA

Answer 30

Junk DNA or non-coding DNA is DNA that does not cause the production of a protein

Question 31

To which base does uracil bond?

Answer 31

Adenine

Question 32

Explain the difference between the terms genetic screening and genetic engineering (Genetic screening)

Answer 32

This means testing DNA for the presence or absence of a particular gene or an altered gene

Question 33

Explain the difference between the terms genetic screening and genetic engineering (genetic engineering)

Answer 33

Genetic engineering is the artificial manipulation or alteration of genes

Question 34

Explain why it is necessary to break down the cell walls during DNA profiling

Answer 34

The cells are broken down to release their DNA

Question 35

During DNA profiling, how is the DNA cut into sections?

Answer 35

Using restriction enzymes

Question 36

Give an example of heredity

Answer 36

Humans inherit features such as number of fingers, the production of nails and the ability to form tears Plants inherit features such as the number of petals, the colour of petals and the shape of leaves

Question 37

Name the five carbon sugar found in DNA

Answer 37

Deoxyribose

Question 38

Indicate any one way that RNA and DNA differ | 1/3 differences

Answer 38

DNA - contains the sugar deoxyribose - bases are AT GC (thymine) - double stranded (double helix) RNA - contains ribose - bases are AU GC (Uracil) - single-stranded

Question 39

Give one reason why a genetic screening may be carried out

Answer 39

To test for the present or absence of a specific gene i.e. the gene for albinism or cystic fibrosis To test for the presence of abnormal or altered genes

Question 40

What does the m stand for in mRNA?

Answer 40

Messenger

Question 41

During protein synthesis, transcription occurs. What organelle does the mRNA travel to when it leaves the nucleus?

Answer 41

Ribosome

Question 42

How many bases code for an amino acid?

Answer 42

3

Question 43

Name one other type of RNA other than mRNA that is involved in protein synthesis

Answer 43

tRNA - transfer RNA

Question 44

Where in the cell is tRNA located

Answer 44

Cytoplasm

Question 45

Name one other type of RNA other than mRNA or tRNA

Answer 45

rRNA - ribosomal RNA

Question 46

Where in the cell is rRNA located?

Answer 46

Ribosome

Question 47

Name the everyday substance which is used in the isolation of DNA to break down cell membranes

Answer 47

Washing-up liquid

Question 48

How does mRNA pass out of the nucleus?

Answer 48

Through nuclear pores

Question 49

How does mRNA attach itself to a ribosome?

Answer 49

The mRNA strand forms weak bonds with rRNA

Question 50

What does the letter t stand for in tRNA?

Answer 50

Transfer

Question 51

How does the tRNA know at exactly what position on the mRNA to deposit the amino acid it is carrying?

Answer 51

It binds with the complementary bases on mRNA

Question 52

Name the organelle where protein synthesis takes place

Answer 52

Ribosomes

Question 53

Explain the term triplet

Answer 53

Also called a codon A sequence of three bases in DNA or RNA that act as a code for an amino acid

Question 54

State the role of triplets in protein synthesis

Answer 54

Each codon/triplet codes for an amino acid

Question 55

Describe the role played by mRNA in protein synthesis | 6

Answer 55

mRNA is a complementary strand to the DNA mRNA contains a start codon and a stop codon as well as many other codons specifying amino acids The mRNA moves from the nucleus to the cytoplasm The mRNA strand carries instructions for the production of a protein from DNA The mRNA bond forms a weak bond with rRNA tRNA will then bind with mRNA until the stop codon is reached

Question 56

Describe the role played by tRNA in protein synthesis | 2

Answer 56

tRNA has a complementary anticodon to mRNA codon tRNA carries an amino acid to the ribosome

Question 57

Name one component of a nucleotide other than a base pair

Answer 57

Sugar - deoxyribose | Phosphate

Question 58

Give a brief account of the stages involved in DNA profiling

Answer 58

DNA is released from cells DNA is cut into fragments of different lengths using restriction enzymes DNA fragments are separated according to size by electrophoresis The patterns produced by the fragments are compared or analysed

Question 59

What is a gene?

Answer 59

A section of DNA that causes the production of a protein

Question 60

Name the two purine bases

Answer 60

Guanine | Adenine

Question 61

Give an application of DNA profiling

Answer 61

Forensic science - identifying a suspect Medicine- identifying the paternity or maternity of a person