- What is Reproduction? Give it types?
Ans: The process of production of offspring from parents for the survival of species. There are two types of reproduction. The first is type of reproduction is sexual reproduction and the second is asexual reproduction.
- What is mitosis? In which cells does it take place?
Ans: The type of cell division in which number of chromosomes remains constant in the daughter cells as in the parent cells is called mitosis. Mitosis can take place in haploid and in diploid cells in all parts of the body.
- What is mitotic apparatus?
Ans: The specialized microtubule structure including aster and spindle is called mitotic apparatus.
- What is Function of mitotic apparatus?
Ans: The spindles of the mitotic apparatus are larger than the nucleus. These microtubules are used to attach and capture chromosomes. So, they align the chromosome and finally separating them in such a way that equal distribution of chromosomes take place.
- What happens during metaphase of mitosis?
Ans: It is the most critical phase of the mitosis. It ensures equal distribution of chromatids in the daughter cells. The kinetochore fibers of spindle contract towards their respective poles. They exert force on the centromere and sister chromatids are separated from centromere. As a result, half of the sister chromatids travel towards each pole.
- How is Cytokinesis in plant cell take place?
Ans: Plants do not form contractile ring during Cytokinesis. Membranous vesicles are collected in the center. Membrane structure phragmoplast is formed from vesicles. These vesicles are originated from Golgi complex during metaphase. The vesicles line up in the center of the dividing cell. They finally fuse to form phragmoplast at the end of telophase.
- What does happen during Leptotene stage?
Ans: The chromosomes become shorten and thick. So, they become visible. The size of the nucleus increases and homologous chromosomes start getting closer to each other.
- What is crossing over? In which stage of meiosis does it take place?
Ans: The exchange of segment of the non-sister chromatids of homologous chromosomes is called crossing over. It takes place in Pachytene.
- What does happen in diakinesis?
Ans: Diakinesis: The condensation of chromosomes reaches to its maximum point during this phase. At the same time separation of the homologous chromosomes is completed. But still they are united at one point at ends (not by chiasmata). The nucleoli disappear.
- What is difference between anaphase of mitosis and anaphase of meiosis I?
Ans: The centromere divides and chromatids separated from each other in mitosis. But centromere does not divide and homologous separate in meiosis l.
- What is difference between metaphase of mitosis and metaphase of meiosis I?
Ans: The chromatids are arranged in homologous pairs in metaphase of meiosis I. But this pairing is not seen in metaphase of mitosis.
- What is meant by Random assortment of chromosomes?
Ans: The separation of homologous chromosomes is random during anaphase. It gives a large variety of gametes. Both these phenomena cause variations and modifications in the genome. These variations are the bases of evolution. These variations also make every individual specific, particular and unique in his characteristics.
- Define cell cycle?
Ans: The period from the time a cell is produced until it completes mitosis is called cell cycle.