During which phase(s) of cell cycle, amount of DNA in a cell remains at 4C level if the initial amount is denoted as 2C? 
G1, or first growth phase is followed by S phase or synthesis phase. DNA replication occurs in S phase and DNA amount doubles up i.e., a cell with 2C DNA in G, phase will now have 4C DNA. G2, phase is second growth phase where DNA content remains 4C.
In ‘S’ phase of the cell cycle: 
(a) During S or synthesis phase, replication or duplication of chromosomal DNA and synthesis of histone proteins takes place. During this time the amount of DNA per cell doubles.
The enzyme recombinase is required at which stage of meiosis: 
(a) The enzyme recombinase is required at Pachytene stage of meiosis. It catalyzes the exchange of short pieces of DNA between two long DNA strands, particularly the exchange of homologous regions between the paired maternal and paternal chromosomes.
A cell plate is laid down during
During cytokinesis in animal cells, a ring of actin filaments forms at the metaphase plate. The ring contracts, forming a cleavage furrow, which divides the cell in two. In plant cells, Golgi vesicles coalesce at the former metaphase plate, forming a phragmoplast.
Therefore A is the correct option.
A somatic cell that has just completed the S phase of its cell cycle, as compared to gamete of the same species, has : [2015 RS]
The correct option is Option B.
The amount of DNA and chromosome number of a somatic cell that had just completed the S-phase of its cell cycle have 4 times more DNA content and twice the number of chromosomes as compared to the gametes of the same species. In general, a gamete is haploid. A somatic cell is diploid.
So, the correct option is 'twice the number of chromosomes and four times the amount of DNA'
Choose the correct option for the following events of meiosis in correct sequence: [2015 RS]
(A) Crossing over
(C) Terminalisation of chiasmata
(D) Disappearance of nucleolus
(a) Synapsis → Crossing over → Terminalisation of chiasmata → Disappearance of nucleolus
In human females, meiosis-II is not complete until? [2015 RS]
(a) Meiosis-II does not complete untill fertilization occurs in females (in human being).
Spindle fibres attach on to 
(b) Attachment of microtubules to chromosomes is mediated by kinetochores, which actively monitor spindle formation and prevent premature anaphase onset during mitosis.
In meiosis crossing over is initiated at 
(a) Meiosis is a process (discovered by German biologist, Oscar Hertwig) where a single cell divides twice to produce four cells containing half the original amount of genetic information. These cells are our sex cells - sperm in males, eggs in females. Crossing over is the process by which two chromosomes, exchange some distal part of their DNA. This process occurs in the Pachytene stage of Prophase I of meiosis.
Which of the following statements is not true for cancer cells in relation to mutations ? 
(d) Telomerase production is increased in cancer. Telomerase has been examined in hundreds of studies as a potentially sensitive biomarker for screening, early cancer detection, prognosis or in monitoring as an indication of residual disease.
Which of the following is not a characteristic feature during mitosis in somatic cells ? 
(d) Synapsis is the pairing of two homologous chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I, Zygotene of meiosis.