<span>Anton van Leeuwenhoek learned to grind lenses ( 1668) and develop simple microscopes.
</span>
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.
Answer:
D. Transport of oxygen through a placenta to a fetus.
Explanation:
Zygotes are fertilized egg cell, zygotes aren't produced in the ovaries but ovums or egg cells are produced in the ovaries. So option A is false.
Fertilization is internal not external in human. Option B is wrong.
Production of milk happens in the mammary gland (the breast) not in the reproductive system. Option C is false.
Transport of oxygen through a placenta to a fetus. The placenta is a vascular organ which is implanted in the wall of the uterus (a part of the female reproductive system) and links to the foetus through the umbilical cord.
Answer:
rr
Explanation:
Alleles that are recessive will be lower case. Alleles that are dominant are upper case. Since we have two recessive alleles represented by 'R', the alleles would be written as 'rr'.
Answer:
main difference between freshwater and marine life is the habitat they come from in the wild. Freshwater fish live in streams, rivers and lakes that have salinity of less than 0.05 percent. Depending on the species, fish can survive in temperatures ranging from 5 and 24 degrees Celsius
Explanation:
