This is the most difficult a level bio question I’ve seen Watch
Upon looking at the MS
All I could comprehend were marking points 1,2,4 and 5.
The pictures might not be clear so here are links:
3. If you look at the intervals (on x axis = horizontally) between the beats , this interval is steady on the ECG on left [normal], but is shorter between the 1st normal beat and the ectopic beat on ECG on right [abnormal], yeah? So the ectopic beat is premature i.e. it has come too early.
6. ECG on right [abnormal]: For the interval between the 2nd [= ectopic] beat and the 3rd beat [normal one] the gap is much longer, so this tells you that "a beat has been missed" [to put it simply], with me?
7. (v unfair Q for A level): the pulmonary artery pressure trace on right (abnormal) shows no peak at the time of the ectopic beat [looking directly vertically below the abnormal ECG above it], so this tells you that there was effectively no blood pumped out by the heart in timing with the ectopic beat [however, it is actually not ideal to measure pulmonary artery pressure here but aortic pressure, but I suppose at A level, these items cannot be fully correct [the examiners are extremely unlikely to be doctors]].
8. (look up refractory period in your books).
9. (difficult to predict this wording i.e. difficult to read examiner's mind here)
10. (as in 8).
EXTRA INFO: Yes, this is a very difficult Q for A level.
1. An ectopic beat has a different waveform from normal beats (you can see that the shape of "E" is very different from that of the other QRS complexes.
2. "E" has no P wave before it, yeah? Do you remember what generates the P wave? …………………………
© Copyright The Student Room 2017 all rights reserved
The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.
Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE