<h3><u>The Food webs are preferred over food chains for representing the flow of energy in an ecosystem for the following reasons:
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- The food webs are higher in complexity when compared to food chains and also, in food web, more than one primary producers is present which increases the 'flow of energy' in the ecosystem.
- Food web represents the real life better than the food chains do.
- Food web shows many different paths through which the organisms can be connected.
I believe the correct answer is mRNA. Dicer is a part of RNase III which leaves double stranded RNA and pre-microRNA into short double stranded RNA fragments called small interfering RNA and microRNA respectively. The Dicer facilitates the activation of RNA induced silencing complex (RISC), which are essential for RNA interference. The RISC has a catalytic component argonate, which is an endonuclease capable of degrading mRNA. siRNAs are specfic to the mRNA sequence unlike miRNAs which are not completely complementary to the mRNA sequence.
Approximately 1,000 to 30,000 years old
The substance must be able to alter its physical characteristic (for example, its color) in accordance to a change in pH. One example of this is litmus paper, which becomes red under acidic conditions and blue under basic conditions.
