Q1.
Assertion (A): Growth and reproduction are characteristics of cells, indeed of all living organism.
Reason (R): Cycle of growth and division allow a single cell to form a structure consisting of millions of cells.
Q2.
Assertion (A): Distribution of replicated chromosomes (DNA) to daughter nuclei by a complex series of events is almost accurate phenomenon.
Reason (R): Such distribution of replicated chromosomes to daughter nuclei by a complex series of events is under genetic control.
Q3.
Assertion (A): Cells in quiescent stage (G₀) are metabolically inactive, so don't show cell division.
Reason (R): Quiescent stage appears on exit of cell from G₂ phase of cell cycle.
Q4.
Assertion (A): In plant cells cell plate method is found for cytokinesis instead of cell furrow method.
Reason (R): Plant cell are enclosed by a relatively inextensible cell wall.
Q5.
Assertion (A): Meiosis involves two sequential cycles of nuclear and cell division called meiosis-I & meiosis-II, but only a single cycle of DNA replication.
Reason (R): Meiosis is aimed to produce reduced cells having half number of chromosome that mother cell.
Q6.
Assertion (A): Meiosis-I is most significant phenomenon from evolution point of view.
Reason (R): Meiosis-I leads to reduction in chromosome so that consistency of chromosome can be maintained.
Q7.
Assertion (A): Zygotene is characterized by formation of synaptonemal complex.
Reason (R): Synaptonemal complex helps in synapsis of non homologous chromosomes.
Q8.
Assertion (A): During pachytene crossing over takes place which is dependent on recombinase.
Reason (R): Recombinase is the group of enzymes involved in crossing over and crossing over in an enzyme dependent process.
Q9.
Assertion (A): Telophase-I leads to formation of diad of cells.
Reason (R): Telophase-I is marked by completion of karyokinesis and cytokinesis as well.
Q10.
Assertion (A): During meiosis-I there is no division of chromosome.
Reason (R): During meiosis-I there is separation and movement of homologous, in order to reduce the number of chromosome half in daughter cells.
Q11.
Assertion (A): In meiosis, each bivalent is composed of four chromatids.
Reason (R): Pairing of homologous chromosomes take place in meiosis.
Q12.
Assertion (A): Replication of DNA not occurs during interkinesis.
Reason (R): Division of chromosomes takes place during meiosis-II.
Q13.
Assertion (A): Meiosis is also known as reduction division.
Reason (R): Meiosis reduces the number of chromosomes in daughter cells.
Q14.
Assertion (A): Meiosis is necessary for sexual reproduction.
Reason (R): Meiosis produces genetical identical cells.
Q15.
Assertion (A): Crossing over take place during pachytene stage.
Reason (R): It is a process of interchange of chromatid material between non sister chromatid of homologous chromosomes.
Q16.
Assertion (A): M-phase represents the phase when the actual cell division occurs.
Reason (R): Interphase represents the phase between two successive M-phase.
Q17.
Assertion (A): During S-phase, amount of DNA per cell doubles.
Reason (R): During S-phase, there is no increase in chromosome number.
Q18.
Assertion (A): G₀ (quiescent) stage is an inactive stage.
Reason (R): In G₀ stage, cells remain metabolically active.
Q19.
Assertion (A): M-phase is the most dramatic period of the cell cycle.
Reason (R): It involves a major reorganization of virtually all components of the cell.
Q20.
Assertion (A): Small cells are metabolically less active.
Reason (R): K.I. of small cells is less.
Q21.
Assertion (A): Crossing over is the only difference between mitosis & meiosis cell divisions.
Reason (R): Mitosis and Meiosis both are important to bring genetic variations.
Q22.
Assertion (A): Crossing over take place during pachytene sub stage.
Reason (R): It is a process of interchange of chromatid material between chromatid of nonhomologous chromosomes
Q23.
Assertion (A): In meiosis II division is equational.
Reason (R): Homologous chromosomes are separated in anaphase II.
Q24.
Assertion (A): Cell division is a very important process in all living organisms.
Reason (R): During the division of a cell, DNA replication and cell growth also take place.
Q25.
Assertion (A): The interphase of the cell cycle is also called the resting phase.
Reason (R): No metabolic activity takes place inside the cell during the interphase.
Q26.
Assertion (A): Meiosis ensures the production of haploid phase in the life cycle of sexually reproducing organisms.
Reason (R): Syngamy restores the diploid condition in sexually reproducing organisms.
Q27.
Assertion (A): Metaphase is the stage at which morphology of chromosomes is most easily studied.
Reason (R): At this stage, metaphase chromosome is made up of two sister chromatids, which are held together by the centromere.
Q28.
Assertion (A): The cells that do not divide further exit G1 phase to enter an inactive stage called quiescent stage (G₀) of the cell cycle.
Reason (R): Cells in G₀ stage no longer remain metabolically active and no longer proliferate unless called on to do so depending on the requirement of the organism.
Q29.
Assertion (A): Meiosis conserves specific chromosome number of each species across generations in sexually reproducing organisms.
Reason (R): Meiosis, per se, results in reduction of chromosome number by half.