During cell growth, DNA synthesis takes place in

(1) S-phase                       

(2) ${\mathrm{G}}_1$-phase

(3) ${\mathrm{G}}_2$-phase                     

(4) M-phase 

When cell has stalled DNA replication fork, which checkpoint should be predominantly activated?

(1) G₁/s

(2) G₂/M

(3) M

(4) Both G₂/M and M

A cell at telophase stage is observed by a student in a plant brought from the field. He tells his teacher that his cell is not like other cells at telophase stage. There is no formation of cell plate and thus the cell is containing more number of chromosomes as compared to other dividing cells. This would result in

(1) polyploidy

(2) somaclonal variation

(3) polyteny

(4) aneuploidy

Which of the following is not a characteristic feature during mitosis in somatic cells
1. Disappearance of nucleolus

2. Chromosome movement

3. Synapsis

4. Spindle fibres

Spindle fibres attach on to 

1. Kinetochore of the chromosome

2. centromere of the chromosome

3. Kinetosome of the chromosome

4. telomere of the chormosome 

In meiosis crossing over is initiated at 

1. leptotene

2. Zygotene

3. diplotene

4. pachytene

Arrange the following events of meiosis in correct sequences

I. Crossing Over

II. Synapsis

III. terminalisation of chaismata

IV. Disapperance of nucleolus

(1) II, I, IV, III

(2) II, I, III, IV

(3) I, II, III, IV

(4) II, III, IV, I

A somatic cell that has just completed the S-phase of its cell cycle, as compared to gamete of the same species has

1. twice the number of chromosomes and twice the amount of DNA

2. same number of chromosomes but twice the amount of DNA

3. twice the number of chromosomes and four times the amount of DNA

4. four times the number of chromosomes and twice the amount of DNA

During which phase(s) of cell cycle, the amount of DNA in a cell remain at 4C level if the

initial amount is denoted as 2C?

1. G₀ and G₁

2. G₁ and S

3. Only G₂

4. G₂ and M

In S-phase of the cell cycle 

1. amount of DNA doubles in each cell

2. amount of DNA remains same in each cell

3. chromosome number is increased

4. amount of DNA is reduced to half in each cell