What selection(s) from this text about marine microbes supports the argument that microorganisms are critical to survival of other organisms? i. "these organisms are capable of existing in practically any environment". ii. "they play many different roles in the marine environment". iii. that they are "the base of the food chain". iv. they control "much of the flow of marine energy and nutrients".

The answer is I, II and III. These microbes can be funds even in hydrothermal vents at the bottom of ocean trenches where they convert chemicals to organic matter. Most are critical in the many nutrient cycles such as the nitrogen and carbon cycles. These microbes form the base of the food chain since they support higher organisms such as paramecium which are in turn eaten by higher organism such as amoeba. The amoebas are then fed by tadpoles, for example, and the tadpoles are eaten by fish…and etcetera.

prophase: we can observe the chromosomes to coil up and condense. they become visible. nuclear membrane and envelope disintigrate.s

metaphase: chromosomes align at the center, the metaphase plate. spindle fibers attach to centromeres of the sister chromatids. they meet at kinetochores.

anaphase: sister chromatids are pulled towards each opposing centromere, set on different poles.

telophase: chromosomes are now clustered up only on either sides of the cell. nuclear membranes reform, and a new cell wall forms along the cell plate. this will lead to cytokinesis, the process that divides the cell membrane and forms the cell wall.