Explanation:
- Catastrophism is a theory developed by Georges Cuvier that states that natural history has been punctuated by catastrophic events that altered the way live developed. Gradualism is a theory that stipulates that changes of organic life and earth itself occur through gradual increments with transitions that are slow rather than periodic and rapid. Uniformitarianism suggests that the Earth's geological processes acted in the same manner in the same intensity in the past as they do in the present and that such uniformity is accountable for all the geologic change.
- Jean-Baptiste de Lamarck's theory proposes a change through use and disuse when environments changed, organisms had to change their behavior to survive, if they began to use an organ more often it would increase their lifetime and their offspring will inherit this modified organ. As these organisms adapted, nature also drove them from simple forms to increasingly complex ones.
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Answer:
1. They must be removed before sister chromatids or homologous chromosomes can separate
Explanation:
During the S-phase of the cell cycle, not only does DNA have to be replicated, but also newly synthesized DNA molecules have to be connected with each other. This replicated DNA (sister chromatids) remain physically connected with each other from S phase until metaphase. This physical connection is called Sister chromatids cohesion.
Sister chromatid cohesion depends on COHESIN, a tripartite protein complex that forms a ring structure to hold sister chromatids together during mitosis and meiosis. Cohesin regulates the separation of sister chromatids during cell division, either mitosis or meiosis. This sister chromatid cohesion is essential for the biorientation of chromosomes on the mitotic or meiotic metaphase spindle, and is thus an essential prerequisite for chromosome segregation. Without the cohesion, sister chromatids would not be segregated symmetrically between the forming daughter cells, resulting in aneuploidy.
Cohesion is established during S-phase of DNA replication, and the cohesins hold the sister chromatid together after DNA replication until anaphase when the removal of cohesin leads to separation of sister chromatids (meiosis II and mitosis) and homologous chromosomes (meiosis I).
You can also find photosynthesis, the carbon cycle, the water cycle and others
option B:is correct answer
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