In S–phase, DNA is replicated in a medium containing radioactive thymidine. Radioactivity will be observed in:
1.  Euchromatin
2.  Heterochromatin
3.  Both
4.  Nucleolus

At which stage of the cell cycle does DNA replication occur:
1. G₁ - phase
2. S - phase
3. G₂ - phase
4. M - phase

The best material for the study of mitosis in the laboratory:

1. Anther

2. Root tip

3. Leaf tip

4. Ovary

The cells of the quiescent centre are characterised by: 

1. Having dense cytoplasm and prominent nuclei

2. Having light cytoplasm and small nuclei

3. Dividing regularly to add to the corpus

4. Dividing regularly to add to tunica

In the somatic cell cycle:
 

At what stage of the cell cycle are histone proteins synthesized in a eukaryotic cell:

1. During telophase
2. During S-phase
3. During the G-2 stage of prophase
4. During the entire prophase