Science Buddies: "Ask an Expert"

The directions say "The micropyle on each seed should point downward, in the direction of the arrow." Does this mean the micropyle is "down" as in parallel to the arrow, or literally pointing towards the arrow (so the seeds on the sides are at an angle)? Or perhaps it means "down" as pointing to the base of the petri plate when it is sitting flat on the table? Thanks for clarifying this.

Hi - your first thought is correct, the micropyle should point in the universal "down" direction, parallel to the arrow, so they are all pointing in the same direction. That way, when you stand the petri dish up vertically, for the one that doesn't rotate they will all be pointed "down" toward the ground in the direction of gravity.

bfinio wrote: ↑Thu Jan 04, 2024 6:15 am Hi - your first thought is correct, the micropyle should point in the universal "down" direction, parallel to the arrow, so they are all pointing in the same direction. That way, when you stand the petri dish up vertically, for the one that doesn't rotate they will all be pointed "down" toward the ground in the direction of gravity.

Hello friend
Indeed, placing the micropyles parallel to the arrow in the "down" direction promotes uniformity. Gravity affects all uniformly when the petri dish is upright, ensuring consistency in the experimental setup. This level of detail is required for precise and dependable findings.

We are feeling extremely frustrated with the cress seed microgravity experiment. After spending hours getting it all ready the microgravity experiment failed on several levels. The cress seeds fell down, did not stay in place in the agar in the petri dish. This is after carefully following all the instructions.
We bought the motor recommended and it kept stopping, didnot work consistently.

any suggestions?

Hello PeggyStyer,
I've merged your latest post with the thread for your original post. Keeping posts together lets the experts who have been helping you easily see that you have posted more questions on that topic.

Thanks and best of luck with your project!
Madeline
Moderator

Hi - I'm sorry you're having trouble with this experiment. I'm a mechanical engineer, not a botanist, so unfortunately I don't have a ton of experience preparing plant seeds. I didn't have trouble with the seeds falling out when I designed the experiment, but I'm not sure how much variations in the agar-making procedure can affect how well the seeds stick. Did the seeds fall out immediately when you stood the petri dish up vertically, or not until you started spinning it with the motor? Steps 15-16 in the procedure suggest first testing by putting the petri dish vertical and then re-embedding and waiting longer if any of the seeds fall out. You can also try pushing the seeds slightly deeper into the agar to begin with.

I also haven't had trouble with the motor working inconsistently.
- Can you let me know where you bought the motor, and whether you bought the Science Buddies Arduino kit or bought the parts separately?
- Can you describe in more detail what's happening? Does the motor run for a long time and only stop briefly? Is it intermittent start/stop behavior?
- How are you powering the Arduino? (Wall power, USB, battery?)

Thanks and sorry again for your frustration.

-Ben