<u>Answer:</u>
In ecology, catastrophes permanently alter the physical structure of the existing environment.
<u>Explanation:</u>
- The ecological disturbances include flood, strom, plague, fires, earthquakes, tsunami, volcanic eruptions, climatic change and impact of humans on the environment like deforestation ,nuclear testing etc.
- These factors can have a visible impact on the structure of the earth and permanently alter the environment.
- The visible effects of these disturbances are global warming, extinction of selective species, change in the course of rivers, submergence of coastal areas, sudden movement of the tectonic plates and formation of sudden cracks on the earth's crust.
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Answer:
it has dna that is not contained within a nucleus
Explanation:
The word prokaryote is of Greek origin and means “anterior nucleus” or “before having nucleus”. This meaning gives the impression that it is a primitive structure, and that is exactly what these organisms are about. When compared to eukaryotes, prokaryotic cells are simpler, which leads to the belief that they are more primitive elements in evolutionary history. Thus, it is believed that the first cell was that of a prokaryote being.
The composition of this cell group has few membranes, in general, the only one present is the one that delimits the cell. The prokaryotic cell is characterized by the absence of very well-known and common membranous organelles, such as mitochondria, chloroplast, Golgi complex and nucleus. Regarding the absence of a nucleus, the DNA of this cell is not separated from the cytoplasm by a nucleus.
The prokaryotic cell has a plasma membrane, cytoplasm, free and non-compartmented genetic material (DNA) and ribosomes.
Weathering erosion deposition compaction cementation
Most flatworms take in food via their mouth, then move it into a digestive gut that attaches to the digestive structures. The food then breaks down and is absorbed out into the rest of the organism. Some have an anus to remove wastes, but most don't and will simply excrete unused food through the mouth.
