QQuestion
Distinguish between Mitosis and Meiosis on the basis of the following three aspects
- Site of occurrence
- Nature of division of chromosome
- Number of cells produced
Explain the following phenomena related to meiotic cell division
- Separation of chromosome and chromatid
- Crossing over
Or
Distinguish between the cytokinesis of plant cells with the cytokinesis of animal cells on the basis of the following aspects :
- Process
- Time of initiation
- Role of Golgi bodies
Establish the interrelationships among genes, DNA and chromosome.
✓Answer
Distinguish between Mitosis and Meiosis on the following three aspects
| Aspect | Mitosis | Meiosis |
|---|---|---|
| Site of occurrence | Occurs in somatic (body) cells of plants and animals | Occurs in reproductive or germ cells (testes, ovaries, spore mother cell) |
| Nature of division of chromosome | Equational division (chromosome number remains same in daughter cells as parent) | Reductional division (chromosome number is reduced to half in daughter cells) |
| Number of cells produced | Two identical diploid daughter cells | Four non-identical haploid daughter cells |
Phenomena related to meiotic cell division
1. Separation of Chromosome and Chromatid
- In Meiosis I, homologous chromosomes are separated which reduces the chromosome number by half in the gametes/spores.
- In Meiosis II, the chromatids of each chromosome separate, similar to what happens in mitosis.
2. Crossing Over
Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes during Prophase I of meiosis. This process results in new genetic combinations and increases genetic variation among offspring.
Or
Differences between Cytokinesis of Plant Cells and Animal Cells
| Aspect | Plant Cell Cytokinesis | Animal Cell Cytokinesis |
|---|---|---|
| Process | Formation of a cell plate by fusion of vesicles at the centre, which later develops into a new cell wall (phragmoplast method) | Formation of a cleavage furrow (constriction forms at the periphery and moves inward dividing the cell) |
| Time of initiation | Begins during late telophase, generally after karyokinesis | Begins in late anaphase or early telophase, often overlaps with end of nuclear division |
| Role of Golgi bodies | Golgi vesicles collect at the equator and form the cell plate (which becomes the new cell wall) | Golgi bodies do not play a direct role in animal cell cytokinesis |
Interrelationship among Genes, DNA, and Chromosome
- Chromosomes are the gene-bearing, nucleoprotein filaments found in the nucleus of cells. They are composed mostly of chromatin and carry genes arranged linearly.
- DNA is the chemical substance that forms chromosomes and is structured as a double helix. DNA coils and folds to form chromatin reticulum, which condenses to create chromosomes.
- Genes are specific segments of DNA that carry the information necessary for the synthesis of proteins and determine hereditary traits. Each gene occupies a definite position (locus) on a chromosome.
- Thus, chromosomes are made up of DNA, and genes are functional segments of DNA located on chromosomes.
Related Questions
More WBBSE Moderate level questions
Match the words in column-A with the most appropriate words in column B and re-write the correct pair mentioning the serial no. of both columns Column-A Column-B 1. Diabetes insipidus (a) Law of Independent Assortment 2. Schwann cell (b) Brittleness of bone 3. Meiosis (c) Exists between neurolemma and myelin sheath of axon 4. Senescence phase (d) Hyposecretion of ADH 5. Genetic disease (e) Spore mother cell and germ mother cell 6. The second law of Mendel (f) Colour blindness
Compare DNA and RNA on the basis of the following features — (a) Nature of carbohydrate (b) Nature of pyrimidine base
Show the chemical constituents of chromosomes with the help of a table.
Explain the following two significances of meiotic cell division — Maintains the constant number of chromosomes in a species Origin of variation in an organism
Tabulate which changes occur in a chromosome during the Anaphase of Karyokinesis.
Distinguish between the mitosis of plant cells and the mitosis of animal cells on the basis of — Formation of spindle fibres Process of cytokinesis
The daughter cells are changed and modified in different ways during cell differentiation phase to form tissue, organ and system.
In ____ cell division spindle fibres are not formed.
Write the name of the chemical constituents of eukaryotic chromosome with the help of a table. What happens to a cell when the cell loses control at different points in cell cycle on division ? [3+2=5] OR What events occur during Anaphase stage of mitotic cell division ?Show the steps of sexual reproduction of flowering plants with the help of word diagram. [3+2=5]
Write one function each of the following five parts of a neuron: [1×5=5] (a) Dendron (b) Axon (c) Myelin Sheath (d) Schwann Cell (e) Node of Ranvier Or Write one function each of the following five parts of an eukaryotic chromosome: [1×5=5] (a) Chromatid (b) Centromere (c) Nucleolar Organizer (d) Satellite (e) Telomere
Draw a scientific diagram of neuron and label the following parts: [3+2=5] (a) Dendron (b) Myelin Sheath (c) Schwann Cell (d) Node of Ranvier OR Draw a scientific diagram of eukaryotic chromosome and label the following parts: [3+2=5] (a) Centromere (b) Satellite (c) Nucleolar Organizer (d) Telomere
Explain the following three significances of cell division- Growth Repair Reproduction Tabulate the site of occurrences of meiotic cell division in the living world. [3+2=5] OR Explain the process of micropropagation. Distinguish between asexual and sexual reproduction on the basis of the following three features - No. of Parental organisms Cell Division Origin of variation [2+3=5]