A red blood cell goes 6 times round the whole body…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A red blood cell goes times round the whole body.
- How many times does it pass through the heart if it is in a fish?
- How many times if it is in a mammal?
- How many more passes does the mammal cell make?
Need a reminder? The key ideaShow
Arthropods and molluscs have an open circulatory system, with sinuses. Annelids and chordates have a closed one. A fish heart has chambers and a single circulation. Amphibians and reptiles, except crocodiles, have chambers and mixed blood. Crocodiles, birds and mammals have chambers and a double circulation, so the blood passes the heart twice in each round.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Rounds: .
Plan. Find the passes for one round in each animal, then multiply.
Step 1. Fish. One pass for each round. .
Step 2. Mammal. Two passes for each round. .
Step 3. The difference. .
Answer: ; ; .
Check. The mammal always has twice as many passes as the fish.
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