A technician counts 200 sperms in a sample of semen…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A technician counts sperms in a sample of semen. Of these, have normal shape and size, and show vigorous motility. The sample has a volume of mL, with million sperms in each mL.
- What per cent have normal shape and size?
- What per cent show vigorous motility?
- How many sperms does the whole sample hold, in millions?
- Does the sample meet both textbook tests?
Need a reminder? The key ideaShow
A sperm has a head with the acrosome, a neck, a middle piece with mitochondria and a tail. An ovum has a nucleus, cytoplasm with food, a plasma membrane, the zona pellucida and the corona radiata. Textbook tests for fertile semen: at least normal shape and size, and at least vigorous motility. A sperm and an ovum are haploid, with chromosomes.
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. Counted: . Normal: . Motile: . Sample: mL at million per mL.
Plan. Find the two shares. Multiply for the total. Compare with the two tests.
Step 1. Normal. .
Step 2. Motile. .
Step 3. Total. million sperms.
Step 4. The tests. is at least , so the first test is met. is less than , so the second test is not met.
Answer: ; ; million; no, only one test is met.
Check. million is inside the usual to million of a sample, so the count is fine. The sample fails on motility.
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