Quiz Time

I have a question you can ponder over the holiday weekend. Below is a picture of Tetrahymena, a single-celled eukaryotic organism that is related to the paramecium you might have seen in a high school biology class.

And here’s what the critter looks like with an electron microscope:

Time for your quiz.

You are given two flasks, A and B, each filled with a 10 mls of a solution that contains all the nutrients needed for Tetrahymena to survive and grow.

On Friday, you are given a tube that is filled with thriving Tetrahymena and transfer 10,000 of these cells to flask A. Drawing from the same tube, you then add 1,000 cells to flask B.  You go home and celebrate Easter, returning to the lab on Monday.  You find the cells in flask A to be thriving, having spawned millions of new cells.  But when you look at flask B,  the cells have not grown and divided.  On the contrary, they all died!

Why did the cells in flask B all die in a sea of food?

[Note: I gave this quiz on my previous blog that was hacked, so if you saw that and know the answer, don’t tell.]

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17 responses to “Quiz Time

  1. Yeah, I remember this quiz. I just don’t remember the answer. Was it because the food in flask B wasn’t Kosher?

  2. The lesser amount of cells transferred to flask B might be a clue, but not really sure.

  3. Probably something to do with them being highly communal

  4. Maybe they all over-ate.

    IOW flask B organisms had more food available, they ate it all and exploded.

    And that is why we can throw-up. We evolved to avoid that fate…

  5. I don’t think so, according to the description, the same amount of nutrients was in Flask B as was in Flask A.

  6. Right- same amount of nutrients with fewer organisms.

    And that means more to eat per individual.

    Also just to be clear I am not being serious…

  7. Okay, so in flask A, the cells can live at a concentration of 1000 cells/ml. But when the density drops to 100 cells/ml, they all die. Front-loading logic may help here. 😉

  8. Umm flask A 10,000 not 1000

    flask B 1000 not 100

    That is according to your OP…

    On Friday, you are given a tube that is filled with thriving Tetrahymena and transfer 10,000 of these cells to flask A. Drawing from the same tube, you then add 1,000 cells to flask B.

  9. 10 mls of a solution

    1000 x 10 = 10000 cells

    100 x 10 = 1000 cells

  10. The 10 mls solution was the nutrients:

    You are given two flasks, A and B, each filled with a 10 mls of a solution that contains all the nutrients needed for Tetrahymena to survive and grow.

  11. Nice find Guts-

    So if they cannot sense enough of their “kind” they commit suicide?

  12. I think it has more to do with some kind of secretory factor, it’s getting diluted in flask B

  13. Ding, ding, ding. Very good.

  14. I’m right? Where’s my prize money

  15. I showed this quiz to a friend of mine she said she saw the same thing from human culture cells.

  16. Hey, that’s kind of like using the present to explain the past.

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