UNIT 1 past papers

Question 1

Explain how differentiation of tissue stem cells leads to the production of
specialised cells such as red blood cells.

Answer 1

they produce the proteins characteristic for that type of cell

Question 2

Research has developed a type of stem cell that can be cultured in a laboratory
directly from a patient’s own somatic cells.
Suggest a benefit to the patient of using these stem cells in therapeutic
treatments.

Answer 2

patient does not need a donor

Question 3

Suggest an advantage of using a heat tolerant form of DNA polymerase during
PCR.

Answer 3

it will not be denatured when heated

Question 4

Describe how alternative RNA splicing leads to the formation of different proteins.

Answer 4

different exons are retained

Question 5

suggests how introns being retained in the mature mRNA transcript may affect the structure of the protein formed

Answer 5

the sequence of amino acids will have changed

Question 6

Explain why some individuals with mitochondrial disease are unable to
carry out endurance activities such as long distance running.

Answer 6

Their mitochondria does not produce enough ATP

Question 7

Describe the role of oxygen after ATP has been synthesised

Answer 7

final electron acceptor which combines with hydrogen ions and electrons to form water

Question 8

which type of mutation results from a mutation in which a nucleotide is inserted into a gene

Answer 8

frame shift

Question 9

Explain why DNA replication must take place before a cell divides

Answer 9

ensures new cells have the same chromosomes

Question 10

Describe what happens to the genes of a cell as differentiation occurs

Answer 10

genes are expressed

Question 11

Describe a therapeutic use of stem cells

Answer 11

bone marrow transplants

Question 12

Explain why the 10 000 metre runner requires a high percentage of slow
twitch muscle fibres.

Answer 12

they sustain contractions for longer

Question 13

The condition is caused by a mutation in which an extra nucleotide is inserted into the gene that codes for an enzyme.
Explain the likely effect of this mutation on the structure of the enzyme

Answer 13

the sequence of amino acids is changed which will change the shape of the enzyme

Question 14

What processes involve specific base pairing

Answer 14

DNA replication
mRNA synthesis

Question 15

What gene mutations are the result of single nucleotide substitutions

Answer 15

missense
nonsense

Question 16

what term describes the breakdown of carbohydrate into pyruvate during respiration

Answer 16

glycolysis

Question 17

Explain the role NADH when cells do not get sufficient oxygen for aerobic respiration

Answer 17

hydrogen is transferred to pyruvate to produce lactate
this generates the NAD needed to maintain ATP production through glycolysis

Question 18

It has been proposed that tissue cells could be used to repair
severely damaged muscle tissue.
Suggest how this might be done.

Answer 18

the stem cells are cultured

Question 19

identify what confirms that the step is the energy investment phase of glycolysis

Answer 19

ATP is broken down

Question 20

explain how a feedback mechanism conserves the cells resources

Answer 20

ensures the cell only produces ATP when required

Question 21

explain why embryonic stem cells can differentiate into all cell types

Answer 21

all genes can be expressed

Question 22

Why does each type of human cell have a different structure and function

Answer 22

different genes are expressed in each

Question 23

describe what happens to chromosomes during the first and second division during meiosis

Answer 23

homologous chromosomes are separated
chromatids are separated

Question 24

Explain why the primary mRNA transcript is so much shorter than chromosomal DNA

Answer 24

only one gene is transcribed

Question 25

suggest why the temperature is increased during the final stage of PCR

Answer 25

to provide a better temperature for DNA polymerase

Question 26

sickle cell disease is caused by a substitution mutation in the gene that codes for haemoglobin. Describe how this form of mutation affects the structure of the gene. and explain how this might change the structure of a protein such as haemoglobin

Answer 26

it alters the DNA nucleotide sequence one amino acid is replaces with another in the protein

Question 27

explain why the lagging strand is replicated in fragments

Answer 27

DNA polymerase can only add DNA nucleotides to the 3' end

Question 28

Describe how a substitution mutation would alter the gene coding for an enzyme

Answer 28

one nucleotide is replaced with another

Question 29

when oxygen debt is repaid what is lactate in the liver converted to

Answer 29

pyruvate and glucose

Question 30

state the role of primers in PCR

Answer 30

allows nucleotides to be added

Question 31

state the term for the process of deciding which drug to use to treat a disease

Answer 31

pharmacogenetics

Question 32

Explain how gene activity leads to specialised function

Answer 32

certain genes are expressed produce the proteins characteristic to that type of cell with a specialised function

Question 33

explain why red blood cells contain haemoglobin after differentiation but white blood cells dont

Answer 33

the genes coding for haemoglobin are expressed in red blood cells but is not expressed in white blood cells

Question 34

explain why lactate concentration increases as intensity of exercise increases

Answer 34

muscle cells do not get enough oxygen so pyruvate is converted to lactate

Question 35

What happens during the energy pay off phase of glycolysis

Answer 35

ATP is produced