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A Chapter Made of Numbers and Pairs
The circulatory system is the most reliably scoring topic in general science, because examiners barely ever ask you to explain it. They ask you to recall a number or complete a pair: how long a red cell lives, which valve sits on which side, which group can donate to anyone.
That is good news, because numbers and pairs can be locked in a single sitting. It is also the risk. Every number in this chapter has a neighbour that looks like it — 120 days against 12 to 20 days, 120/80 against 140/90, five million against five thousand. Every pair has a mirror image that is equally memorable and completely wrong.
So do not read this chapter for understanding alone. Read it the way you would read a price list: fix the value to the item, fix the valve to the side, and give each of them a hook you can pull under pressure. The mnemonics on the next cards exist for exactly that.
1. Which blood group is known as the universal donor?
2. The valve located between the left atrium and the left ventricle of the human heart is the:
3. Which structure is called the pacemaker of the human heart?
4. Which blood vessel carries oxygenated blood despite being a vein?
5. What is the average lifespan of a human red blood cell?
6. Which is the largest type of white blood cell in human blood?
7. Which organ is known as the 'graveyard of red blood cells'?
8. The normal blood pressure of a healthy adult human is approximately: