Question

(a) State the difference between meiocyte and gamete with respect to chromosome number.
(b) Why is a whiptail lizard referred to as partheno-genetic?

Answer 1

In a process called fertilisation two haploid gametes unite to create a diploid cell known as a zygote. Zygote contains all gametes of genetic material. Multiple cell divisions form a multicellular diploid process or generation without altering the chromosomes number.

Complete Answer:
- Sexual reproduction is a form of reproduction involving a complicated life cycle in which a single chromosome (haploid) gamete interacts with a separate organism to create an organism made up of cells with two chromosome sets (diploid).
- In many cellular eukaryotes such as mammals, fungi and plants, sexual reproduction is the most common life cycle. Sexual reproduction does not take place in prokaryotes but has related consequences, like bacterial conjugation, transformation and transductions that may have preceded early eukaryotic sexual reproduction.
- Diploid mother cells differentiate in order to create Haploid cells or Gametes in a process called meiosis involving genetically engineered cells in the development of sex cells in eukaryotic cells. Homologous chromosomes match to suit their DNA sequences, and the genetic material is then shared among them.
- Two rounds of the cell division then create four haploid gametes, with one-half of each cell parent chromosome, but with recombined genetic data in the parental chromosomes. In a process termed fertilization two haploid gametes unite to create a diploid cell named as a zygote. Zygote contains all gametes of genetic material.
- Multiple cell divisions form a multicellular diploid process or generation without altering the number of chromosomes.

(a) Meiocyte is a type of cell that is meiotically separated to develop a gamete. The gamete comprises a haploid set of (n) chromosomes, and meiocyte comprises a diploid set of (2n) chromosomes.

(b) Parthenogenesis is a normal type of asexual breeding in which embryos are developed and produced without sperm fertilisation. The formation of an embryo from an unfertilized egg indicates parthenogenesis. Whiptail lizard is parthenogenetic because an unfertilized egg in this species transforms into a new developing animal.

Note: Most squamata reptiles reproduce sexually, although it has been noted that parthenogenesis happens spontaneously in some whiptails, geckos or rock lizards, dragons of Komodo and snakes. Some are unisexual and necessarily Parthenogenetic.