How does a new hypothesis replace an older explanation of something in the natural world? To understand this let us look at one of the classical example of geocentric theory and heliocentric theory. The geocentric theory states the Earth is at the centre of the solar system and the Sun, Moon, and all the other planets revolve around it. This ancient theory failed to explain the phenomenon like the phases of Moon, solar eclipse and lunar eclipse. The modern heliocentric theory which states that the Sun is at the centre of solar system, and all the planets including the Earth revolve around it. This theory was able to explain all the phenomenons unlike the geocentric theory. Hence the heliocentric theory replaced the geocentric theory.
The right option is; B) the total variety of organisms on Earth
The total variety of organisms on Earth explains biodiversity
Biodiversity is the variety and variability of all species (different plants, animals and microorganisms) from all sources (marine, terrestrial and other aquatic ecosystem) on earth or within a particular region. Biodiversity involves genetic diversity, species diversity and ecosystem diversity which all functions together to form the complexity of life on earth.
The each chromosome makes the copy of itself before the M Phase in mitosis because the resultant daughter cell the chromosomes is genetically identical.
<u>Explanation:</u>
The parent cell in the chromosomes make the copy before mitosis. The copy is occurred during the S phase of inter phase. During the mitotic M phase, the cell divides the copied DNA and cytoplasm to make two new cells.
M phase involves two distinct related processes which is mitosis and cytokineses ;the cell growth steps into the new stage and cellular energy is developed on the division in the phase
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Layers of cross-bedded sand can be indicative of a DESERT environment wind is responsible for the formation of these sedimentary structures. Sand dunes preserved in rocks can be quite large. These structures form as a result of the migration of dunes due to the action of the wind. Dunes are not often preserved but a few can be observed in thick sandstone units.
