Chapter 2 – (a) Cell Division And Cell Cycle | Life Science Solution Class 10

1. Mitochondria
2. Chlorophyll 
3. Nucleus
4. Centrosome

Question

1. The cell division of body cell is called ____.
2. The hereditary unit is the ____.
3. The cell division of reproductive cell is _____.
4. Cytokinesis is the division of ______.
5. Cell wall of prokaryote is made up of ________.
6. Centromere is located in the ____.
7. In human ____ pairs of autosomes are present.

Answer

1. Mitosis.
2. Gene.
3. Meiosis.
4. Cytoplasm.
5. Peptidoglycan.
6. Middle of the two sister chromatids.
7. 22 pairs of autosomes.

Very Short Answer (VSA) type questions

Question 1

What is cell? Mention the main types of cell found in nature.

Answer

A cell is the fundamental unit of life, which is capable of carrying out all the processes of life.

The main types of cells found in nature are prokaryotic cells, which are simple and lack a nucleus, and eukaryotic cells, which are more complex and contain a nucleus and other membrane-bound organelles.

Question 2

Answer

The cell cycle is a series of events that take place in a eukaryotic cell leading to its division and duplication of its DNA to produce two daughter cells.

Question 3

What is the full form of DNA? Where it is present?

Answer

The full form of DNA is deoxyribonucleic acid. It is a molecule that contains genetic instructions used in the development and function of all living organisms.

Question 4

What is the full form of RNA? Where is it present?

Answer

The full form of RNA is ribonucleic acid. RNA is present in both the nucleus of the cells.

Question 5

What is the role of centrosome in cell division?

Answer

Question 6

What is mitosis cell division?

Answer

Mitosis cell division is a type of cell division that occurs in eukaryotic cells to produce two identical daughter cells.

Question 7

Why mitosis is called equatorial division?

Answer

Mitosis is sometimes referred to as equatorial division because during the metaphase stage of mitosis, the chromosomes align themselves along the equator, or equatorial plane, of the cell.

Question 8

What are the different phases of mitosis?

Answer

The different phases of mitosis are:

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Question 9

What is cytokinesis?

Answer

Cytokinesis is the final stage of cell division that follows the division of the nucleus (mitosis or meiosis). It involves the division of the cytoplasm and the organelles between the two newly formed daughter cells.

Question 10

Write two distinguishing features of mitosis and amitosis.

Answer

Here are two distinguishing features of mitosis and amitosis:

1. Mitosis involves a complex series of stages, including prophase, metaphase, anaphase, telophase, and cytokinesis, while amitosis is a simpler form of cell division that does not involve the same distinct stages.
2. Mitosis typically results in the formation of two genetically identical daughter cells, while amitosis can result in the formation of multiple daughter cells with varying genetic material, which may lead to genetic diversity within a population.

Question 11

Write three differences between Prokaryotic and Eukaryotic cells.

Answer

Here are three differences between prokaryotic and eukaryotic cells in a table:

Short Answer (SA) type questions

Question 1

Where is meiosis cell division seen? Why is it called reduction division?

Answer

Meiosis cell division is seen in sexually reproducing organisms, such as plants, animals, and fungi.

Meiosis is called a “reduction division” because it reduces the number of chromosomes in each cell by half.

Question 2

Distinguish between the prophase stage and the telophase stage of mitosis.

Answer

Question 3

Write notes on the composition of chromosomes in a eukaryotic cell.

Answer

Chromosomes in a eukaryotic cell are composed of DNA, protein, and small amounts of RNA. The DNA is tightly coiled around histone proteins to form a structure called chromatin, which can further condense into visible chromosomes during cell division. The precise composition and organization of chromatin can vary between different cell types and can play a role in gene expression and regulation.

Question 4

How many types of cell division are there and what are these?

Answer

There are two main types of cell division:

1. Mitosis: A process of cell division that results in two daughter cells that are genetically identical to the parent cell.
2. Meiosis: A type of cell division that produces four daughter cells, each with half the number of chromosomes as the parent cell.

Question 5

Give one example of each type of cell division.

Answer

Here is one example of each type of cell division:

1. Mitosis: Mitosis occurs in the skin cells of animals during wound healing or tissue repair. For example, when you get a cut, the skin cells undergo mitosis to replace the damaged tissue and heal the wound.
2. Meiosis: Meiosis occurs in the ovaries and testes of animals during the formation of gametes (eggs and sperm). For example, during human reproduction, meiosis occurs in the ovaries of females to produce mature eggs, and in the testes of males to produce mature sperm.

Question 6

In what types of cells do mitosis and meiosis occur?

Answer

Mitosis and meiosis occur in eukaryotic cells. Mitosis occurs in somatic cells, which are all the cells in the body that are not involved in sexual reproduction and is responsible for the growth, development, and maintenance of the body. Meiosis, on the other hand, occurs in the germ cells, which are the cells that give rise to the gametes (sperm and eggs) involved in sexual reproduction.

Question 7

Give in brief the cytokinesis process in plant cells.

Answer

In plant cells, cytokinesis is the process of dividing the cytoplasm and organelles between the two daughter cells following mitosis. Plant cells have a cell wall that must be divided during cytokinesis, so they use a specialized process known as cell plate formation. During cell plate formation, vesicles containing cell wall materials and other components fuse together to form a disc-like structure called the cell plate, which grows outward and eventually fuses with the cell wall at the periphery of the cell to form two new cell walls.

Question 8

Describe in brief the morphological structure of an eukaryotic chromosome.

Answer

The morphological structure of a eukaryotic chromosome consists of a linear DNA molecule wrapped around a protein complex known as histones to form nucleosomes. These nucleosomes are then further coiled and packaged into a condensed structure that can be seen as distinct structures under the microscope during cell division.

Long Answer (LA) type questions

Question 1

Describe the different parts (components) of nucleus.

Answer

The nucleus is a membrane-bound organelle found in eukaryotic cells that contains genetic material in the form of DNA. Here are the different parts or components of the nucleus:

1. Nuclear envelope: The nuclear envelope is a double membrane that surrounds the nucleus and separates its contents from the cytoplasm. It has pores that allow molecules to move between the nucleus and the cytoplasm.
2. Nucleoplasm: The nucleoplasm is the fluid-like substance that fills the space inside the nuclear envelope. It contains various proteins and enzymes that are involved in DNA replication, transcription, and other nuclear processes.
3. Chromosomes: Chromosomes are structures made up of DNA and protein that carry genetic information. They condense and become visible as distinct structures during cell division.
4. Nucleolus: The nucleolus is a structure found within the nucleus that is involved in the synthesis of ribosomes. It contains DNA, RNA, and proteins.
5. Nuclear lamina: The nuclear lamina is a network of protein filaments that supports the shape of the nucleus and helps to organize the DNA within it.
6. Nuclear pores: Nuclear pores are channels that allow molecules to move between the nucleus and the cytoplasm. They are composed of proteins and are found in the nuclear envelope.

Question 2

Write short notes on nucleus.

Answer

The nucleus is a membrane-bound organelle found in eukaryotic cells that contains genetic material in the form of DNA. It is considered the “control center” of the cell because it regulates gene expression and controls cell growth and division. The nucleus is surrounded by a double membrane called the nuclear envelope, which has pores that allow molecules to move between the nucleus and the cytoplasm. Within the nucleus, the DNA is organized into chromosomes, and various proteins and enzymes are involved in DNA replication, transcription, and other nuclear processes. The nucleolus, a structure found within the nucleus, is involved in the synthesis of ribosomes.

Question 3

State the differences between Nucleus and Nucleolus.

Answer

Question 4

What are the differences between prokaryotic and eukaryotic cells?

Answer

Question 5

Name the stages of mitosis and state the function of each stage.

Answer

The stages of mitosis are:

1. Prophase: The function of prophase is to prepare the chromosomes for separation and organize the spindle fibres.
2. Metaphase: The function of metaphase is to ensure that each chromosome is properly aligned and attached to the spindle fibres before they are separated.
3. Anaphase: The function of anaphase is to ensure that each daughter cell receives a complete set of chromosomes.
4. Telophase: The function of telophase is to complete the separation of the chromosomes and prepare for the division of the cytoplasm.
5. Cytokinesis: The function of cytokinesis is to divide the cytoplasm and other cell components between the two daughter cells, completing the process of cell division.

Question 6

What is the prophase stage of mitosis? State its characteristics.

Answer

The prophase stage is the first stage of mitosis, during which the chromatin condenses into visible chromosomes and the nuclear envelope breaks down. Here are some characteristics of prophase:

1. Chromosome condensation: The chromatin fibers condense into visible chromosomes, each consisting of two identical sister chromatids joined at the centromere.
2. Nuclear envelope breakdown: The nuclear envelope, which encloses the genetic material in the nucleus, disintegrates, allowing the spindle fibers to access the chromosomes.
3. Spindle formation: The spindle fibers, which are composed of microtubules and proteins, begin to form and extend from opposite poles of the cell towards the equator.
4. Centrosome movement: The centrosomes, which are microtubule-organizing centers, move towards opposite poles of the cell, and the spindle fibers emanate from them.
5. Mitotic apparatus organization: The spindle fibers attach to the kinetochores, which are protein structures on the centromeres of the chromosomes, and begin to organize the mitotic apparatus.

Question 7

What is the metaphase (second phase) of mitosis? State its some important characteristics.

Answer

Metaphase is the second stage of mitosis, during which the chromosomes line up along the equator of the cell and the spindle fibers attach to the centromeres. Here are some important characteristics of metaphase:

1. Chromosome alignment: The spindle fibers pull the chromosomes towards the center of the cell, where they line up along the equator in a single plane, called the metaphase plate.
2. Chromosome attachment: The spindle fibers attach to the kinetochores, protein structures located on the centromeres of each chromosome, ensuring that each chromosome is properly aligned and attached to the spindle fibers.
3. Chromosome inspection: The cell inspects the alignment of the chromosomes and ensures that each chromosome is attached to the spindle fibers before proceeding to the next stage of mitosis.
4. Checkpoint activation: The metaphase checkpoint is activated, which monitors chromosome alignment and ensures that each daughter cell will receive the correct number and type of chromosomes.

Drawing based questions (DBQ)

Question 1

Draw a neat sketch of the second and third stages of mitosis cell division in the animal body and label any two parts of each of the stages.

Answer

The second and third stages of Mitosis are Metaphase and anaphase respectively

Question 2

Draw a diagram of the first and second stages of mitotic division of an animal cell and name each of the two stages with labelling of any two parts of each.

Answer

The first and second stages of Mitosis are prophase and metaphase respectively

Question 3

Draw a neat diagram of prophase and metaphase of mitosis in animal cells and label the following parts: centriole, centromere, chromatid and spindle fibre.

Answer