Question

1. At least 200 different types of cancer can affect different organs –or the same organ in different ways. Despite these differences, all cancers

A. derive from cells with cell-cycle checkpoint failures

B. require growth factors from other cells

C. remain in the same tissue from which they derive

D. result from UV-type radiation

2. For biology, energy is readily available from electron bonds between atoms of equal:

		electronegativity
		magnetism
		atomic weight
		charge

Answer 1

1. A. Derive from cells with cell-cycle checkpoint failures.

If the checkpoints detect some problems, normally the cell cycle is halted. So, cell cycle check point failures will result in continuous proliferation of cells. Normal cells show an absolute requirement for growth factors for proliferation and the decreased requirement for specific growth factors is a cardinal feature of cancer cells. Malignant tumor is a group of cells that divide excessively and can invade other tissues. Most of the skin cancers result from UV type radiations.

2. A. Electronegativity

Electron sharing between atoms of equal electronegativity is important in living systems. They are important in energy storage.