The Block X in the figure shows that the producers utilized the carbon dioxide present in the environment and produced food by the process of photosynthesis.
Then the consumers feed on the producers and used the food prepared by the producers.
The Block Y in the figure shows that when the consumers died, the decomposers came into action and decomposed the body of the consumers and returned the carbon back into the atmosphere.
A primary producer corresponds, in an ecosystem, to an autotrophic living being, that is to say capable of producing organic matter from mineral matter. It is the first element of the food chain. This organism is totally or partially ingested by a primary consumer, itself being the potential target of secondary consumers.
Decomposers are living creatures that contribute to the degradation of dead organic matter or feces by returning them in mineral form. They play a crucial role in an ecosystem because they participate in the recycling of the elements.
They can use a technique called Polymerase Chain Reaction. This can be done in a test tube or even in a organism. It usually relies on something called Thermostable DNA Polymerase and Taq polymerase. It requires DNA primers that is designed specifically for that DNA region (interest).
They can't tranfuse because they will have an ABO incompatibility reaction. In an ABO incompatibility reaction, your immune system attacks the new blood cells and destroys them
If you have type AB you have both A and B antigens. Therefore you have B too that's why you can't only tranfuse with A after all you have to have to have both types.
