Brown eye-color is dominant while the blue-eye color is recessive. Therefore, the homozygous for brown color is BB and the homozygous for brown color is bb. Thus, the heterozygous will be Bb (brown color). Since James has blue colored eyes a child of Jenna (brown color) and bill (blue color) then it means Jenna is heterozygous (Bb). Jenna is described as being a carrier of the allele for blue eyes.
<span>Anton van Leeuwenhoek learned to grind lenses ( 1668) and develop simple microscopes.
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Leeuwenhoek heated the middle of a small soda glass rod , over a flame. On pulling apart the two ends, the glass rod elongated into thin whiskers .
Heating the end of this whisker resulted in a tiny high quality glass sphere. These glass spheres then became the lens of his microscope, with the smallest sphere providing the greatest magnification.
Leeuwenhoek's designs were very basic. The body of the microscope was a single lens mounted in a tiny hole on a brass plate. The specimen was then mounted on a sharp point that sticks up in front of the lens. It's position and focus could be adjusted by turning the two screws.
The entire instrument was about 3 to 4 inches long and had to be held up close to the eye, requiring good lighting and great patience to use.
When it gets cold, the accumulated water inside the pipes freezes, expands and creates extreme pressure.
