Four jars hold the same kind of seeds on cotton wool…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Four jars hold the same kind of seeds on cotton wool.
Jar 1 is dry and kept warm. Jar 2 is kept moist and warm in the open air. Jar 3 is filled to the top with water and sealed, so that there is no air. Jar 4 is kept moist but is placed in a freezer.
- In which jar will the seeds grow?
- For each of the other jars, name the condition for growth that is missing.
Need a reminder? The key ideaShow
Arithmetic growth: , a straight line. Geometric growth: , a sigmoid curve with a lag, a log and a stationary phase. Absolute growth rate is the total gain in a unit of time. Relative growth rate is the gain per unit of the starting size. A part that doubles in a time has . Growth needs water, oxygen, nutrients and a suitable temperature.
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.
Step 1. (a) Jar 2 has water, air and a suitable temperature, so the seeds grow in Jar 2.
Step 2. (b) Jar 1. It is dry, so water is missing. Cells cannot take in water and enlarge, and the enzymes cannot work.
Step 3. Jar 3. It is sealed with no air, so oxygen is missing. There is no respiration to release the energy for growth.
Step 4. Jar 4. It is far too cold. The temperature is not in the right range, so the enzymes work badly.
Answer: Jar 2; Jar 1 lacks water, Jar 3 lacks oxygen, Jar 4 has the wrong temperature.
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