mock feedback flashacards

Question 1

if an investigation was carried out into allopatric speciation, and the same species of fruit flies were left to breed in different mediums, one containing starch and one containing maltose, then were mixed and their breeding was monitored

Explain why the results showed that more fruit flied bred with those in their original solution

Answer 1

• most fruit flied bred with those that were grown in the same medium as them
• this is due to reproductive isolation
• and physical separation separates the exchanging of genes

Question 2

the molecular formula for stearic acid is C16H36O2
explain why it is an ideal energy storage molecule for birds

Answer 2

• it contains a lot of hydrogens so it releases a lot of energy relative to its mass
• therefore the bird can carry more lipids relative to its body mass

Question 3

• Fatty acids can be used in respiration, they enter the mitochondria and are converted into molecules of acetyl coA in the link reaction
• explain why stearic acid and linoleic acid release different amounts of energy during respiration
  stearic acid: C18H36O2
  linoleic acid: C18H32O2

Answer 3

• because they have a different amount of hydrogens
• so more hydrogens are passed through the intermembrane space
• Then hydrogen diffuses through hydrogen channels to produce ATP

Question 4

Describe the fate of acetyl coA in the Kreb cycle

Answer 4

• combines with a 2 carbon sugar to make a 6 carbon molecule
• Then decarboxylation occurs
• Then oxidation occurs and ATP is produced directly

Question 5

what are the stages of respiration that occur in the matrix

Answer 5

• the link reaction
• the Kreb cycle

Question 6

An investigation was carried out into the effect of sodium azide on aerobic respiration, sodium azide prevents oxidation of the final electron transport protein
- why was pyruvate used in this investigation

Answer 6

• because it is the substrate needed for the link reaction

Question 7

describe how glucose in converted into pyruvate in glycolysis

Answer 7

• Two ATP molecules are hydrolysed to ADP
• 2 phosphate groups attach to glucose to form glycerate-3-phosphate
• NAD is the reduced to NADH and pyruvate is formed with 4 ATP molecules

Question 8

• Patients with leukaemia were given injections of radioactive thymidine so that the growth rate of leukaemia cells could be measured
• Thymide is a molecule containing thymine and deoxyribose
• how does radioactive thymidine give indication of the growth rate of leukaemia cells

Answer 8

• radioactive thymidine would be used in DNA synthesis
• therefore daughter cells having radioactive DNA gives an indication of the growth rate

Question 9

• Leukaemia cells have a rapid growth rate and they tend to be small
• explain which of the three stages would be shorter in a leukaemia cell
• between interphase, mitosis and cytokinesis

Answer 9

• Interphase, this is because since the leukaemia cell is so small so not much growth needs to take place
• cytokinesis and mitosis are not likely to occur any faster

Question 10

Explain how the influenza virus has a pathogenic effect

Answer 10

• The virus can infect cells of the throat or lungs
• The virus has receptors on it surface
• This leads to damage of the tissues
• and an immune response is triggered which is what causes symptoms