Biology Questions

In a nucleosome, the DNA is wrapped around histone octamer.

Trypanasoma is a protozoan animal. It lives as a parasite in the blood and later invades the cerebrospinal fluid to cause the sleeping sickness. This parasite is transmitted by the Tsetse fly.

The blood of some invertebrate animals like the earthworm is red due to haemoglobin pigment, but the pigment is dissolved in the plasma. In vertebrates the same pigment is found in the red corpuscles and not in the plasma.

All living cells arise from pre-existing cells is one component of the cell theory.

The Cell Theory is one of the basic principles of biology.

The Cell Theory states:

1. All living organisms are composed of cells. They may be unicellular or multicellular.

2. The cell is the basic unit of life.

3. Cells arise from pre-existing cells.

The prostate gland is a walnut-sized structure that is located below the urinary bladder in front of the rectum. The prostate gland contributes additional fluid to the ejaculate. Prostate fluids also help to nourish the sperm. The urethra, which carries the ejaculate to be expelled during orgasm, runs through the center of the prostate gland.

During most of the cell cycle, interphase, the chromosomes are somewhat less condensed and are not visible as individual objects under the light microscope. However during cell division, mitosis, the chromosomes become highly condensed and are then visible as dark distinct bodies within the nuclei of cells. The chromosomes are most easily seen and identified at the metaphase stage of cell division and most of the chromosome images in this gallery are pictures of metaphase chromomosomes.

The cell division takes place in mitosis stage.