Cell and Cell Division Test - 1

The plasma membrane is selectively permeable; hydrophobic molecules and small polar molecules can diffuse through the lipid layer, but ions and large polar molecules cannot. Integral membrane proteins enable ions and large polar molecules to pass through the membrane by passive or active transport.

Bilirubin and biliverdin are found in bile. Bilirubin is created by the activity of biliverdin reductase on biliverdin, a green tetrapyrrolic bile pigment that is also a product of heme catabolism. Bilirubin, when oxidized, reverts to become biliverdin once again.

The size of a cell depends upon its oxygen requirement, minerals and materials requirements and regulating ability of the nucleus.

Nucleus, nuclear sap and cell membrane are present in both animal and plant cells. Centrosome is exclusive to only animal cell. Cellulose and plastids are exclusive to plant cells.

Energy producing substances are glucose, proteins and fats. Vitamins do not produce energy.

Nucleus was discovered by Robert Brown.

Glycogen is the stored form of glucose in human body. In humans, glycogen is made and stored primarily in the cells of the liver and the muscles hydrated with three or four parts of water.

In anaphase stage, chromatids start moving towards the opposite poles, while the chromosomes are drawn to each side of the cell. The non-kinetochore spindle fibres push against each other, in a ratcheting action, that stretches the cell into an oval.

The smallest size of a cell, which can be seen unaided with naked eye, is 100 μ.

The longest cell in the human body is nerve cell. Neuron is an electrically excitable cell that processes and transmits information through electrical and chemical signals.