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प्रश्न
With the help of suitable diagrams, explain the five stages of prophase-I of meiosis.
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उत्तर
Prophase I is the longest phase of meiosis and is further sub divided into 5 phases:
- Leptotene
Condensation makes chromosomes become distinct and compact. - Zygotene
Homologous chromosomes start pairing together by a process called synapsis to form a complex structure called synaptonemal complex. Two synapsed homologous chromosomes form a complex called bivalent or tetrad. - Pachytene
Longest phase of prophase I
Recombination nodules appear in this stage at the sites where crossing over has to take place between non-sister chromatids of homologous chromosomes. - Diplotene
Synaptonemal complex dissolves and recombinants separate from each other except at crossover sites to form X-shaped structure called chiasmata. - Diakinesis
Chiasmata terminalises and chromosomes condense. Meiotic spindle assembles and nucleolus and nuclear envelope disappear.
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संबंधित प्रश्न
Describe anaphase in mitosis.
Differentiate between Centrosome and centromere.
Draw a well-labelled diagram to show the anaphase stage of mitosis in plant cells having four chromosomes.
Name the following:
Replacement of dead cells is accomplished by which process.
Name the following:
The kind of division normally seen at the tip of the root and shoot system.
Name the Following
Name the stage during which nuclear membrane and nucleoli reappear.
Give Technical Terms
The stage in mitosis when the nucleolus starts disappearing.
Give Technical Terms
The stage at which spindle fibres begin to be formed.
Give Technical Terms
Division of nucleus.
Complete the following sentence with appropriate word :
______means the splitting of the nucleus.
Complete the following sentence with appropriate word :
Colchicine arrests cell division at __________.
Mention, if the following statement is True or False. If false rewrite the wrong statement in its correct form:
The alkaloid colchicine inhibits the formation of the mitotic spindle.
Multiple Choice Question:
The nuclear membrane disappears in
Multiple Choice Question:
The nuclear membrane and nucleolus become indistinguishable during
Write the functional activity of the following structure:
Colchicine
The diagram given below represents a stage in mitosis.
- Identify the stage given above.
- Give one reason to support your answer in (a).
- Mention the number of chromosomes given in the diagram.
The phase of karyokinesis which is almost the reverse of prophase is ______.
