In an experiment the antibody level after a first exposure to an antigen peaked at 25 units after 7…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
In an experiment the antibody level after a first exposure to an antigen peaked at units after days. After a second exposure to the same antigen, it peaked times as high, and the rise began after only days.
- What was the peak after the second exposure?
- How many days sooner did the second response start?
- By what per cent was the second peak higher than the first?
Need a reminder? The key ideaShow
After a second meeting with an antigen, the response is quicker and stronger because of memory cells. An antibody has two heavy and two light chains, HL, and two antigen-binding sites. In active immunity the body makes its own antibodies. In passive immunity the antibodies are given ready made. Herd immunity needs a share of at least of the population to be immune.
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. First peak: units after days. Second peak: times as high, starting after days.
Plan. Multiply for the peak, subtract for the days, and use the increase for the per cent.
Step 1. The peak. units.
Step 2. The start. days sooner.
Step 3. The rise. The increase is units. .
Answer: units; days; .
Check. A peak times as high is times higher, which is .
Watch out. Do not mix up " times as high" with " per cent higher".
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