CELL CYCLE AND CELL DIVISION
i. Centromeres split and chromosomes separate. (½)
ii. Chromosomal material condenses to form compact mitotic chromosomes. (½)
2. What is quiescent stage? (1)
3. Mention the importance of crossing over. (1)
1. A diagram of Prophase I stage of meiosis is given below. Draw similar diagrams to illustrate the following stages: (3)
a. Metaphase I
b. Telophase I
c. Anaphase II
1. Mitosis is divided into four stages: Prophase is the first stage of mitosis and ……. Is the second stage. (1)
2. A cell with a chromosome number 42 undergoes mitosis and another cell with 42 chromosomes undergoes meiosis. Give the chromosome number of daughter cells after mitosis and meiosis. Give reasons for your answer. (2)
1. Prophase I of meiosis I is subdivided into five phases. The sub phases and the chromosome behavior of the prophase I are listed below. Arrange them in proper order. (2½)
Chromosome starts pairing
Bivalents become tetravalents and cross over between non-sister chromatids
Terminalization of chiasmata
Chromosomes become gradually visible under light microscope
Recombined homologous chromosome separate from each other except chiasmata
2. Pairing of homologous chromosomes is called ----------- (½)
a. Identify the stage (½)
b. Label the parts A and B (1)
c. Mention any one peculiarity of the pachytene stage of meiosis. (1)
1. Observe the diagram given below representing a stage of mitosis. (3)
b. Distinguish it from corresponding stage of meiosis I
c. Mention the role of spindle fibres in mitosis.
1. A diagrammatic view of a cell cycle is given below.
i. DNA synthesis takes place.ii. Chromosomes are arranged at the equator of the spindle. (1)
b. Mention two significant points of mitosis in the life of an organism. (2)
1. Observe the following phases of nuclear division during mitosis and answer the following questions: (3)
a. Name the two phases of A & B
b. What are the main events occurring in these two stages?
1. Prophase of the first meiotic division is typically longer and complex. It has been further subdivided into five phases. The major events of these sub-stages are given below.
a. Pairing of homologous chromosomes.
b. Terminalization of chiasmata.
c. Occurs crossing over.
d. Chromosomes are visible under a light microscope.
e. Formation of chiasmata.
i. Identify the stages a, b, c, d and e. (2½)ii. Arrange these stages in correct order of occurrence. (½)
1. The diagram shows below represents a stage in mitosis.
a. Label the parts (A) and (B).b. Identify the stage.c. Mention any two events occurring in this stage. (3)
1. Observe the diagrammatic view of a cell cycle and answer the questions:
a) Identify the phase in which DNA synthesis takes place. (1)
b) Mention any one event that takes place in the stages marked as 'x' and 'y'. (2)
Write five sub-stages in prophase-I of meiosis. Point out in which sub-stage crossing over occurs.
1. a) identify the substages of meiosis in which crossing over is occurring.
i) Leptotene ii) Zygotene
iii) Pachytene iv) Diplotene
b) Summarize the significance of meiosis in sexually reproducing organisms. (3)
1. Given below is the metaphase of mitosis. Analyze the diagram and draw a sketch of anaphase. Write any two events of anaphase. (3)
1. "Meiosis is highly significant in sexually reproducing organisms". Justify. (2)
1. First phase of meiosis I is typically longer and complex one. Name it. Mention the five subdivisions of this Phase.
2. Certain stages in cell cycle are given below.
Choose the statements (from those given below) that match with these stages and prepare a table.
- Centromere split and chromosomes move to opposite poles.
- Chromosomes cluster at opposite poles and nuclear envelope assembles around.
- Chromosomes seems to be with two chromatids attached at centromere.
- Chromosomes arranged at spindle equator.
- Separation of daughter chromosomes.
- Division of cytoplasm.