Answer is: Petrochemical production
Much like a thermostat regulates the temperature inside your home the hypothalamus regulates your body temperature. (hopefully that'll help a little. all i could find)
SOS:
The answers is:
In a dihybrid cross, the F2 will have nine genotypes, but only four phenotypes because the <u><em>Heterozygous</em></u> genes cause the <u><em>Dominant</em></u> traits to mask the <u><em>Recessive</em></u> traits.
<em>Hope this helps!</em>
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Your question is rather unclear but from what I can tell either there were not an even amount of Petri dishes or some of them were left open while others were not.