Answer:
Most cells within planarians tend to be very close to their gastrovascular cavity, in addition to their external environments. Also, planarians have the ability for oxygen and carbon dioxide to diffuse through the cells on their body walls: this makes it unnecessary for these varieties of flatworms to need a dedicated bodily system.
I think the deficiency of dedicated respiratory and circulatory systems in Planarians does not cause a problem because none of their cells are far removed from the gastrovascular cavity or from the external environment. Planarians are free-living flatworms and form the class Turbellarians in the Phylum Platyhelminthes. Flatworms have three tissue layers, that is the ectoderm, mesoderm, and endoderm.
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Explanation:
The fossil record shows a sequence from simple bacteria to more complicated organisms through time, it is very reliable because it is physical evidence and by studying fossils, scientists can learn how much (or how little) organisms have changed as life developed on Earth.
Smith is pursuing an ekg technician certification program. He will be one of the healthcare professionals referred to as cardiovascular technologists and technicians. They help monitor heart health on a broader level.
Answer:
Most damage to DNA is repaired by removal of the damaged bases followed by resynthesis of the excised region. Some lesions in DNA, however, can be repaired by direct reversal of the damage, which may be a more efficient way of dealing with specific types of DNA damage that occur frequently.
Answer: to study genetics
