Component one past papers

Question 1

What are the two major biochemical components present in all viruses (1)

Answer 1

*Proteins
* nucleic acid / RNA / DNA

Question 2

Describe the biochemical structure of a glycoprotein (2)

Answer 2

• (globular) protein
• with a carbohydrate attached to it

Question 3

Describe how the ebola virus enters the host cell via cell membrane (3)

Answer 3

• binds to receptor / protein
  *phagocytosis / endocytosis / pinocytosis
• Cell membrane engulfs the virus in a vesicle

Question 4

Why is it not possible to use a standard curve determined by colourimeter for glucose determination in whole blood sample (1)

Answer 4

• blood is coloured so it could not get a colorimeter reading / light cannot pas through

Question 5

Give two advantages of using immobilized enzymes for blood glucose monitoring in biosensors (2)

Answer 5

• only glucose will give a result / enzyme specific to glucose
• detects very low concentration
• reading is more accurate enzyme is more stable
• works at different temperatures

Question 6

What would be the products of a condensation reaction between glucose and galactose (1)

Answer 6

• lactose and water

Question 7

Explain why there is no decrease in mass at any sucrose concentrations when sweet potato is used instead of potato (1)

Answer 7

• sucrose has a very high sugar concentration

Question 8

Describe how you could modify the method to determine the water potential of sweet potato (2)

Answer 8

• increase the sucrose concentration
• a wider range of sucrose concentrations
• where water will flow out of the potato

Question 9

Explain why the indicator turns pink to colourless when lipase is added to milk in an experiment (3)

Answer 9

• hydrolysis of lipids
  *causing production of fatty acids
• fatty acids cause the milk to become more acidic changing it to colourless

Question 10

Why would the milk and lipase experiment not be suitable for assessing the effect of different pH values on lipase (1)

Answer 10

results depend on pH change in test tube so cannot change pH of experiment

Question 11

Explain why it is important that the RNA which is finally translated consists only of exons (2)

Answer 11

• introns do not code for the primary structure of a protein
• if introns are included there would be a different protein structure produced

Question 12

Explain how a change in sequence of base in DNA of the gene (a mutation) would effect the protein produced if it was in an intron and an exon (2)

Answer 12

• intron - no effect
  may change amino acid sequence in polypeptide chain

Question 13

Describe the significance of meiosis and mitosis and explain the cells produced by the process and how mitosis can form a tumour (9)

Answer 13

mitosis
* daughter cells are genetically identical
* growth
repair from damage and disease
* repeated cell renewal
* maintains chromosome number
Meiosis
*produces non identical daughter cells
* gamete production
* raw material for survival of the fittest
*sexual reproduction for environmental changes / disease
*crossing over in prophase 1 and random assortment - genetic variation
haploid cells produced so at fertilisation diploid cell is regained
tumour formation
* genetic change allow mitosis change in unrestricted ways
*solid mass of cell prevent normal cells from functioning
* benign malignant
* cell division stops after meiosis