In a diploid organism, where did the two different sets of chromosomes originall
ID: 161506 • Letter: I
Question
In a diploid organism, where did the two different sets of chromosomes originally come from? If a diploid cell containing 40 chromosomes undergoes a meiotic cell division, how many chromosomes will be in each of the four cells that result? The genetic variability of gametes is increased by two processes which occur during a meiotic cell division. Give the name for each of these processes and tell at which meiotic stage each occurs. What distinguishes sexual reproduction from asexual reproduction? Why is meiosis so important to sexual reproduction?Explanation / Answer
3. A diploid organism, such as humans, animals, and plants, possess two sets of chromosomes in the nucleus of their cells. These are the somatic or body cells and the full set of chromosomes possessed by them are referred as the diploid number of chromosomes. Half of these chromosomes are received from each parent, maternal and paternal.
The germ cells or sex cells of the parents are haploid, i.e. these contain the half set of chromosomes (n). During fertilization, the gametes fuse and give rise to a diploid (2n) zygote, leading to the formation of a new individual.
4. When a diploid cell containing 40 chromosomes undergoes meiotic division, each of the four cell contains 20 chromosomes.
Diploid number: 2n =40
Meiosis is a process of reductional division, and produce gametes having 'n' number of chromosomes.
therefore n = 2n/2 = 40/2 = 20 chromosomes.
5.The genetic variability during Meiosis or meiotic division occurs at certain stages of the division process. These are known as:
name: Crossing over occurs at: Prophase I
name: Arrangement of chromosomes occurs at: Metaphase
6. Following are the points of difference between sexual and asexual reproduction:
7. Meiosis is the type of cell division which produces daughter cells having half the number of chromosomes. This is important since gametes are haploid and can only be produced by the process of meiosis. The gametes are essential for sexual reproduction.
Sexual reproduction Asexual reproduction Occurs in multicellular organisms and leads to gamete formation Occurs in single-celled organisms and in lower eukaryotes Requires participation of both parents Only one parent is involved