Advertisements
Advertisements
प्रश्न
With the help of suitable diagrams, explain the five stages of prophase-I of meiosis.
Advertisements
उत्तर
Prophase-I is the first stage of meiosis-I and is the longest and most important stage. It is divided into five sub-stages:
1. Leptotene
- Chromosomes begin to condense.
- They become long, thin, and distinct.
2. Zygotene
- Homologous chromosomes pair together by a process called synapsis.
- A synaptonemal complex is formed.
- Paired chromosomes form bivalents or tetrads.
3. Pachytene
- It is the longest stage of Prophase-I.
- Chromosomes become shorter and thicker.
- Crossing over occurs between non-sister chromatids of homologous chromosomes.
- Recombination nodules appear at crossing-over sites
4. Diplotene
- Synaptonemal complex dissolves.
- Homologous chromosomes begin to separate.
- Chiasmata appear at crossover points.
5. Diakinesis
- Chiasmata terminalise.
- Chromosomes condense further.
- The nuclear membrane and nucleolus disappear.
- Meiotic spindle fibres begin to form.
APPEARS IN
संबंधित प्रश्न
The diagram given below represents a certain stage of mitosis:
- Identify the stage of cell division.
- Name the parts labelled A and B.
- What is the unique feature observed in this stage?
- How many daughter cells are formed from this type of cell division?
Genetic recombination occurs in ______ phase of prophase of meiosis-I.
All chromosomes are arranged parallel to equatorial plane of cell in ______ phase of mitosis.
Define the following:
Karyokinesis
The diagram given alongside represents a stage in cell division.
Study the same and answer the questions that follow:
(i) Identify the stage of cell division.
(ii) Name the parts labeled A,B,C and D.
(iii) What is the unique feature observed in this stage?
(iv) Where does this type of cell division usually occur?
(v) How many daughter cells are formed from this type of cell division?
(vi) Is the dividing cell shown a plant or an animal cell?
Give a reason to support your answer.
The fig given alongside shows a certain stage in a cell division in a cell with four chromosomes.
(i) Name the parts of the chromosome labeled A and B.
(ii) Name the structure C. what is its function?
(iii) Name the type of division . Give a reason.
(iv) Name the stage of division.
(v) Name the stages before and after the stage shown in diagram.
Choose the correct answer:
Which division takes most time?
Choose the correct answer:
Nuclear membrane reappears in ____________
Differentiate between Centrosome and centromere.
Identify the stages of mitosis given below and label the figures.
Draw a labeled schematic representation of mitosis cell division.
Explain the Term Pachytene
Name the Following
Nuclear envelope and nucleoli reappear in which stage.
Give Technical Terms
The stage in mitosis when the nucleolus starts disappearing.
Complete the following sentence with appropriate word :
Colchicine arrests cell division at __________.
The karyotype (set of chromosomes) shown below is taken from a dividing cell in a certain individual.
(i) Is the individual male or female? Explain your answer.
(ii) How would you expect
(a) a female cell and
(b) sperm cell to differ in chromosome composition?
The phase of karyokinesis which is almost the reverse of prophase is ______.
Name these:
Two steps of the process Mitosis
Match List - I with List - II.
| List - I | List - II |
| A. Centromere | I. Mitochondrion |
| B. Cilium | II. Cell division |
| C. Cristae | III. Сell movement |
| D. Cell membrane | IV. Phospholipid Bilayer |
Choose the correct answer from the options given below:
