JUNE 2014 Flashcards
The doctors used a statistical test to compare the results for AD and LD.
They obtained a value for P of 0.047.
What does this result show about the difference between the means fro AD and LD? (2 marks)
- Probability of obtaining this difference by chance
- is less than 0.05
- Difference is significant
Mutation 1 (single base deletion on an exon) leads to the production of a non functional protein. Explain why (3 marks)
- Mutation causes a frame shift to the lefft as one base is deleted.
- Changes the Amino Acid sequence that is translated.
- Affects hydrogen/ionic/ sulfur bonds
- Changes the tertiary structure (leads to non-functional protein)
What effect might mutation 2 (single base substitution) have on the protein produced? Explain your answer (2 marks)
- Mutation present in the intron which is non coding DNA
2. Will not be translated so no effect on the protein produced
The biologist concluded that the worms’ behaviour demonstrated taxis.
How do the results support this conclusion? (2 marks)
- Taxis is a directional response towards a stimulus
2. Worms move towards the temperature they were cultured in
A myelinated axon conducts impulses faster than a non-myelinated axon.
Explain this difference. (3 marks)
- In myelinated axons, action potentials only at nodes
- Saltatory conduction occurs where action potentials jump from node to node
- Myelinated axons do not have to depolarise the entire length of the axon whereas non-myelinated axons have to depolarise the entire length
When insulin binds to receptors on liver cells, it leads to the formation of glycogen from glucose. This lowers the concentration of glucose in liver cells.
Explain how the formation of glycogen in liver cells leads to a lowering of blood glucose concentration (2 marks)
- The formation of glycogen leads to the lowering of the blood glucose levels in the liver cells
- Below the level in the blood plasma
- Glucose diffuses into the cells from the blood
- By facilitated diffusion
What is the role of phosphocreatine (PC) in providing energy during muscle contraction? (2 marks)
- Breaks down to provide phosphate
2. Used to form ATP
Use your knowledge of fast muscle fibres to explain the data in figure 5 (4 marks)
- PC takes longer to remake when people get older
- Fast muscle fibres are used for strong contractions
- PC used up rapidly during contractions
- Anaerobic respiration involved due to limited supply of oxygen
- ATP used to reform PC
- Lots of PC in fas fibres
What is a transcription factor? (2 marks)
- Binds to promoter region
2. Stimulates Transcription/ mRNA production
What measurements woul the scientist have made in order to calculate the rate of carbon dioxide production? (2 marks)
- Volume of carbon dioxide given off
- In a known area
- In a given time
The scientists calculated the mea rate of carbon dioxide production of the leaves using measurements of carbon dioxide in the dark.
Explain why they did not use the measurements taken in the light (2 marks)
- In the light photosynthesis will occur
2. In the light, carbon dioxide from respiration will be used up by photosynthesis
