Cell Cycle and Cell Division quiz

DNA replication takes place in the:

Chromosomes align at the equatorial plate during:

Crossing over occurs during:

Synapsis occurs during:

The enzyme involved in crossing over is:

Cell plate formation is seen in cytokinesis of:

The chromosome number is halved during:

In which stage do chiasmata first become visible?

In which stage does the centromere split and sister chromatids separate in mitosis?

Interkinesis is the stage between:

Why is interphase called the resting phase, and why is this term misleading? (2 marks)

What happens in the G2 phase? (2 marks)

What is the significance of mitosis? (2 marks)

Why is mitosis called an equational division? (2 marks)

What is the synaptonemal complex? (2 marks)

What is terminalisation of chiasmata? (2 marks)

What happens during anaphase I of meiosis? (2 marks)

What is the significance of the diplotene stage in oocytes? (2 marks)

Distinguish between karyokinesis and cytokinesis. (2 marks)

What is the role of the spindle fibres? (2 marks)

A cell with 24 chromosomes undergoes mitosis. How many chromosomes and chromatids are present at metaphase and in each daughter cell? (3 marks)

How many meiotic divisions are required to produce 400 seeds in a plant, considering both the male and female gametes? (3 marks)

A yeast cell divides every 90 minutes. How many cells are formed from one cell in 9 hours? (3 marks)

If the DNA content of a gamete is 10 pg, calculate the DNA content of a cell in G1, after S phase, and after meiosis I. (3 marks)

In an onion root tip, 50 out of 1,000 cells are in mitosis. If the cell cycle is 24 hours, estimate the duration of M phase in minutes. (3 marks)

Read the passage and answer the questions. A student prepared a slide of an onion root tip and observed the following: some cells had condensed chromosomes with the nuclear envelope breaking down; some showed chromosomes arranged at the centre; some had sister chromatids moving to opposite poles; and some had two nuclei with a forming cell plate. (i) Name the stages observed. (ii) Why are root tips used for this study? (iii) What would be the chromosome number in each daughter cell if onion has 16 chromosomes? (5 marks)

Read the passage and answer the questions. Meiosis is the mechanism by which conservation of a specific chromosome number of each species is achieved across generations in sexually reproducing organisms. It also increases the genetic variability in the population of organisms from one generation to the next. (i) Why is meiosis called reductional division? (ii) How does it increase variation? (iii) In which cells does meiosis occur? (5 marks)

Read the passage and answer the questions. Pachytene is characterised by the appearance of recombination nodules, the sites at which crossing over occurs between non-sister chromatids of the homologous chromosomes. Crossing over is the exchange of genetic material between two homologous chromosomes. It is an enzyme-mediated process. (i) Which enzyme is involved? (ii) Between which chromatids does it occur? (iii) What is the result of crossing over? (5 marks)

Read the passage and answer the questions. In animals, mitotic cell division is seen only in diploid somatic cells. Against this, plants can show mitotic divisions in both haploid and diploid cells. Some cells in the adult animals do not appear to exhibit division and many other cells divide only occasionally, as needed to replace cells that have been lost. (i) Name a type of animal cell that does not divide. (ii) What phase are such cells in? (iii) Give two uses of mitosis in plants. (5 marks)

Read the passage and answer the questions. A cell in the S phase replicates its DNA. If the initial amount of DNA is 2C, it increases to 4C. However, there is no increase in the chromosome number. If the cell had diploid or 2n number of chromosomes at G1, even after S phase the number of chromosomes remains the same. (i) Why does the chromosome number not increase? (ii) What happens to the centriole in animal cells during S phase? (iii) State the DNA content at the end of mitosis in each daughter cell. (5 marks)

Describe the phases of the cell cycle with a labelled diagram. What is the significance of each phase? (6 marks)

Describe the stages of mitosis with labelled diagrams. What is the significance of mitosis? (6 marks)

Describe the stages of meiosis I with labelled diagrams, with emphasis on prophase I. (6 marks)

Describe meiosis II. Compare it with mitosis and explain the significance of meiosis. (6 marks)

Compare mitosis and meiosis with a chart. Explain the changes in DNA content and chromosome number during both. (6 marks)