B) attraction to itself. adhesion is attraction to other surfaces.
With a light microscope one can view the nucleus and endoplasmic reticulum, large vacuoles etc
The resolution of a light microscope is dependent on the wavelength of light that is the main beam of illumination. Light has approximately 0.4 um (UV)- 0.7um (Infrared) wavelength. Organelles smaller than about 0.5 um will be difficult to discern with a light microscope.
With an electron microscope one can view, in addition, even the ribosomes and mitochondria, chromosomes, tubules etc.
An electron microscope can discern very minute details of a cell. This is because its resolution is dependent on the very small wavelength of a beam of electrons which is approximately 0.002 um (about 10,000 times powerful than a light microscope)
Using the concept that :
<span>The skin cell has twice the number of chromosomes as the sperm cell has.
</span>Hence,
<span>The sperm cell has 39 chromosomes.
The skin Cell will have = 39 x 2
= 78 </span><span>chromosomes.</span>
Allopatric speciation, also referred to as geographic speciation, is a method of the formation of new species due to isolation of the species from one another through geographic means.
The first step in this process is geographic isolation, which means that the original population is divided into two groups due to geographical reasons such as movement of continents or formation of water bodies.
Next, the species are subjected to different selection pressures due to their different environments. Eventually, the gene pool becomes very different for the two species due to the different selection pressures and because they are not allowed to mix.
Finally, after enough time passes, speciation occurs, which means that the two populations cannot breed to form fertile offspring.
