Help plz: 6. Describe the range of variation in the nervous systems of invertebrates.

7. Distinguish among asymmetry, radial symmetry, and bilateral symmetry.

1. Although most invertebrates have a nervous system, the complexity of the system varies from one organism to another.

Some invertebrates such as the hydra and starfish have a simplified system of nerves, which is called a nerve net. It consists of just nerves, capable of sense and touch only. Meanwhile, other invertebrates such as the planarian have a more developed nervous system, complete with a brain and nerve cord.

2. The key difference between radial and bilateral symmetry is that radial symmetry generates identical body halves around the central axis whereas bilateral symmetry generates only two sides as left and right.

Explanation:

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.