How does meiosis ensure that the chromosome number in each cell remains constant in each generation?

The first thing to know is the difference between a chromatid and a chromosome.

Next, let's look at the basics of chromosome numbers in mitosis.

So it's more or less straightforward in mitosis:

The chromosome number remains constant (46 total chromosomes or 23 pairs of chromosomes).The chromatids replicate during interphase to produce a total of 92 chromatids, but they're only found in pairs and remain connected at the center by the centromere. After mitosis, the chromatid pairs separate, so each daughter cell gets 46 chromatids.
Now meiosis is tricky. Meiotic cells undergo a more complicated process to ensure the correct number of chromosomes.

Here's what happens:

At  first the cells have the same number of chromosomes as mitosis. DNA  replication occurs, giving a total of 46 chromosomes (or 23 chromosome  pairs) and 92 chromatids (or 46 chromatid pairs).Meiosis I: In meiosis I, the homologous chromosomes separate.  In this case, the pairs of sister chromatids are still attached to each  other. So at this stage, the daughter cells get 23 chromosomes each (of  the pair of homologous chromosomes) and 46 chromatids in total (which  are actually 23 pairs of sister chromatids attached at the centromere).  This is known as reductional division, as the total number of chromosomes is halved at this stage. Meiosis II: Meiosis  II follows the same division as mitosis, except that there are only  half as many chromosomes. So the 23 chromatid pairs from the previous  cells (or 46 chromatids in total) split equally, so each daughter gets  23 chromatids exactly, which correspond to 23 chromosomes. Meiosis II is  known as equational division.
So to summarize, in mitosis, the total number of chromosomes is unchanged in the daughter cells; whereas in meiosis, the total number of chromosomes is halved in the daughter cells.

The answer is 0.01 meter

Environmental science studies the interactions between the physical, chemical, and biological components of the environment, including their effects on all types of organisms. earth science (also known as geoscience), is an inclusive term for all sciences related to earth (geology, meteorology, oceanogr maphy, etc).  although environmental and earth science cover essentially the same material, environmental science places greater emphasis on the biological realm, while earth science places greater emphasis on the physical realm.    environmental and earth science study the interactions of four major systems or “spheres” (figure 8.6).  the  geosphere  consists of the core, mantle and crust of the earth.the  atmosphere  contains all of the earth’s air and is divided into troposphere, stratosphere, mesosphere, thermosphere and ionosphere.the  hydrosphere  contains all of the solid, liquid and gaseous water on earth, extending from the depths of the sea to the upper reaches of the troposphere where water is found.  ninety-seven percent of the hydrosphere is found in salty oceans, and the remainder is found as vapor or droplets in the atmosphere and as liquid in ground water, lakes, rivers, glaciers and snowfields.  the  biosphere  is the collection of all earth’s life forms, distributed in major life zones known as biomes:   tundra, boreal forest, temperate deciduous forest, temperate grassland, desert, savannah, tropical rainforest, chaparral, freshwater, and marine.although the four systems have their unique identities, there is substantial interaction between them.  environmental scientists study the effects of events in one sphere on the other spheres. for example, a volcanic eruption in the geosphere may cause profound direct and indirect effects on the hydrosphere, atmosphere and biosphere as follows: example 1 (volcano)    on may 18, 1980, mount saint helens, in the state of washington, erupted.  this event altered the surrounding environment, and provided scientists with an opportunity to study the effects of volcanic eruptions on the geosphere, hydrosphere, atmosphere and biosphere.  such studies are vital because volcanic eruptions will continue to occur, and will have increasing impact on humans as people continue to settle lands closer to dormant volcanoes. the following are but a few of the myriad of interactions resulting from a volcanic