i highly think that the answer is A
In a hydra, digestion is completed intracellularly.
Hence option (a) is correct.
Small, freshwater organisms of the phylum Cnidaria and class Hydrozoa are grouped under the genus Hydra. They are indigenous to temperate and tropical climates.
The digestion takes place intracellularly in Hydra.
Because of their ability to regenerate and the fact that they don't appear to age or experience old age, hydra have drawn the attention of biologists.
Like most other cnidarians, hydras have a pretty straightforward digestive system.
They have a two-way digestive system, which differs from mammals in that food and waste enter and exit through the same aperture. A "blind gut" is the name for this configuration.
The center of the hydra's body is occupied by its digestive tract.
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A control group of the experiment is the one in which no treatment or intervention is given. So, in your case, the pea plants in which was not subjected any of the fertilizers, will serve as a control group. This is a negative control. A positive control group is the one in which an established treatment is given, which definitely leads to the production of the desired character. So, in your case, a very good well-known fertilizer which has a positive control on the growth of the pea plant, would serve as a positive control.
<span>Ecosystems are named according to the vegetative inhabitants of the ecosystem which means that the answer is B. by the plants that inhabit the ecosystem. The plants themselves however depend on the climate that is found in the place where they are found, which means that they wouldn't be able to thrive and spread in any other ecosystems.</span>