Answer:
Chromosomes were first named by cytologists viewing dividing cells through a microscope. The modern definition of a chromosome now includes the function of heredity and the chemical composition. A chromosome is a DNA molecule that carries all or part of the hereditary information of an organism. In eukaryotic cells, the DNA is packaged with proteins in the nucleus, and varies in structure and appearance at different parts of the cell cycle.
Explanation:
Cells reproduce genetically identical copies of themselves by cycles of cell growth and division. The cell cycle diagram on the left shows that a cell division cycle consists of 4 stages:
G1 is the period after cell division, and before the start of DNA replication. Cells grow and monitor their environment to determine whether they should initiate another round of cell division.
S is the period of DNA synthesis, where cells replicate their chromosomes.
G2 is the period between the end of DNA replication and the start of cell division. Cells check to make sure DNA replication has successfully completed, and make any necessary repairs.
M is the actual period of cell division, consisting of prophase, metaphase, anaphase, telophase, and cytokinesis.
Evolution is the gradual process resulting in the changes in the genetic material of a population over generations. The mechanism that Darwin proposed for evolution is the process of natural selection. Natural selection is the key mechanism of evolution which increases the frequency of advantageous alleles in a population. Due to the limited resources in nature, organism with heritable traits favoring their survival and reproduction produce more offspring. It causes the population to become adapted to their environment and results in organisms with better survival ability and reproduction. These traits become heritable due to the reproductive advantage and are passed from the parents to the offspring. Over generations, the advantageous heritable trait becomes dominant in the population. It is responsible for the variation in the gene pool of the population which increases their fitness.
<span>Identical twins are the result of an egg being fertilized by one sperm and then splitting, creating two eggs with identical genetic information. Non-identical twins are formed when two eggs are fertilized by two separate sperm and develop together in the uterus with unique genetic information.</span>
Answer: B. Blood dripping from the murder weapon.
Explanation: In bloodstain pattern analysis, blood spatters behave in accordance with some scientific laws in relation to what caused the bloodshed, the position of the victim and the perpetrators, and the velocity at which the blood is spattered. Since the blood trail is leading away from the stabbed victim, the blood trail is most likely created by the dripping of blood from the murder weapon
