Frank Brothers Solutions for ICSE Class 10 Biology Chapter 1 Cell Division for Class 10

Cell division is important for a variety of reasons. One reason is that cell division is important for the growth of an organism. It is also important for cells to divide so that they can remain efficient. Think about how a small baby grows into a tall adult - this happens because cells keep dividing to make new cells. As all the cells are produced by the division of pre-existing cells, so each organism needs new cells for growth, replacement, repair and reproduction.

The cell cycle is a series of events that take place in a cell leading to its division and duplication. Just like how you follow a daily routine of waking up, eating, studying and sleeping, cells also follow steps in order. This process helps living things grow bigger and repair damaged parts.

Interphase is a long resting phase in the cell cycle during which the cell grows, multiplication of DNA, synthesis of RNA and proteins takes place. Think of it like a student preparing for exams by studying and gathering all materials needed. During this time, the cell doubles its size and makes copies of all important parts. Thus interphase is important in the cell cycle as it allows the cell to grow and develop into a mature cell before it is able to reproduce.

Meiosis results in the formation of ova. This special type of cell division reduces the number of chromosomes by half. Meiosis results in the formation of ova.

Mitosis is the process of cell division where one parent cell divides to form two identical daughter cells. The main steps are: Prophase - chromosomes become visible and nuclear membrane disappears. Think of it like packing your school bag before leaving home - everything gets organized and ready. Metaphase - chromosomes line up at the center of the cell. Anaphase - chromosomes separate and move to opposite ends. Telophase - nuclear membranes reform around each set of chromosomes. Finally, cytokinesis occurs where the cytoplasm divides completely forming two separate cells.

In anaphase, the two chromatids separate at the centromere and begin to move in opposite direction towards either end of the spindle network called the poles. This happens because the spindle fibers pull them apart like invisible ropes. The chromosomes bend around the centromere showing a 'V' or 'J' or 'L' shaped structure based on the length of its arms.

The different phases of mitosis are Prophase, Metaphase, Anaphase and Telophase. Think of it like a school assembly where students first gather, then line up in the middle, then split into two groups, and finally form two separate classes.

Mitosis takes place in the body cells or somatic cells of the organisms. This includes cells in your skin, muscles, and organs. These are different from the special cells that make babies.

Mitosis is important because: It helps in the growth of tissues, organs and thus the entire organism. It helps in the repair of damaged tissues and organs. For example, when you get a cut on your skin, new cells are made through mitosis to heal the wound. It is the method by which lower organisms reproduce. It helps in the maintenance of the hereditary characters by the replication of chromosomes

Some characteristic features of mitosis are: It takes place in somatic cells. Chromosome number is preserved. This is why you have the same number of chromosomes in every cell of your body. Daughter cells produced are identical to the parent cell. It results in increase in the number of cells.

Few important characteristics of Meiosis are: Meiosis occurs in germ cells only. It results in the formation of gametes. This is why you get features from both your mother and father. Chromosome number of the parent cell is halved. Daughter cells differ from the parent cell.

Different stages involved in meiosis: This process happens inside the reproductive organs of your body to make special cells. Think of it like dividing your favorite chocolates equally between friends - one cell becomes four smaller cells with half the genetic material each.

In humans, meiosis occurs in testes producing sperms and in the ovaries resulting in ova. This is why boys and girls can have babies when they grow up. Meiosis makes special cells with half the normal number of chromosomes.

Due to meiosis, chromosome number is reduced to half in gametes and chromosome number of species is maintained. This is why humans always have 46 chromosomes even though sperm and egg cells have only 23 each. Genetic variations occur due to meiosis. The zygote on fertilization gets one maternal and one paternal chromosome in each homologous pair.

As a result of crossing over, the paternal and maternal homologous chromosomes of an organism pair up and exchange certain portions of their chromatids which lead to genetic variations. Think of it like mixing cards from two different decks to create new combinations. It makes the genetic information in each haploid cell unique

In mitotic telophase, one nuclear membrane forms around each set of chromosomes at opposite poles of the cell, and the chromosomes begin to uncoil. Think of it like unwrapping gifts after a birthday party. In meiotic telophase I, nuclear membranes may or may not form around the chromosome sets, and in telophase II, nuclear membranes form around each of the four sets of chromosomes, resulting in four nuclei instead of two.

No, cytokinesis is not necessary after karyokinesis in meiosis I. Think of it like dividing the nucleus first, then waiting to split the whole cell later. It generally takes place at the end of meiosis II when the four daughter cells are formed.

(i) Karyokinesis – It is the nuclear division where nucleus divides into two. Think of it like splitting a ball into two equal halves. (ii) Cytokinesis – It is the division of cytoplasm in which the entire cell splits separating each nuclei. This happens right after the nucleus has divided. (iii) Chiasmata – is the point where two homologous non-sister chromatids exchange genetic material in chromosomal crossover during meiosis.

In an animal cell, the cytoplasm between the two daughter nuclei constricts i.e. a furrow starts forming in the plasma membrane at the middle. This deepens towards the interior of the cell and the cytoplasm splits into two similar daughter cells. Think of it like pinching a balloon in the middle until it splits into two parts. In plant cells on the other hand, the constriction is not observed during cytokinesis. Instead a new cell wall is laid down along the equatorial region of the spindle network beginning at the Centre. Thus, two distinct, daughter cells are cut off.

Difference between mitosis and meiosis: 1) Mitosis produces two identical diploid cells, while meiosis produces four genetically different haploid cells. 2) Mitosis involves one division, while meiosis involves two divisions. Think of it like photocopying - mitosis makes exact copies while meiosis mixes things up like shuffling cards. 3) Mitosis maintains the same chromosome number, while meiosis reduces it by half. 4) Mitosis occurs in somatic cells for growth and repair, while meiosis occurs in reproductive cells. 5) Crossing over rarely happens in mitosis, but it is common in meiosis.

Meiosis is a reductional division as in meiosis the number of chromosomes of parent cell is reduced to half in the daughter cells. For example, if a parent cell has 46 chromosomes, each daughter cell will have only 23 chromosomes. Now, this reductional division is significant because it restores the number of chromosomes in a species.

Yes, meiosis is responsible for maintaining the chromosome number of a species as meiosis being a reductional division involves formation of daughter cells with half the number of chromosomes. For example, humans have 46 chromosomes but their egg and sperm cells have only 23 chromosomes each. When fertilization happens, the full 46 chromosomes are restored in the baby.

(i) If four cells undergo mitosis, eight daughter cells will be produced. This is like how your skin cells divide to heal a cut. (ii) Sixteen daughter cells will be produced.(iii) Eight daughter cells will be produced if four cells undergo amitosis.

(i) Mitosis(ii) ATP(iii) Homotypic(iv) Reduction(v) Mitosis. Think of mitosis like making copies of your school notebook - each new cell gets exactly the same information as the original cell. ATP works like a battery that gives power to the cell during division.

(i) Anaphase in a plant cell(ii) A – Spindle fiberB – Cell wall(iii) The homologous daughter chromatids or chromosomes begin to move towards opposite poles. Think of it like two groups of people walking to opposite ends of a room. (iv) This type of cell division occurs usually in the somatic cells.(v) Two daughter cells are formed from this type of cell division.(vi) The dividing cell shown is a plant cell because of the presence of cell wall and the absence of centriole.

(i) A – Duplicated chromosomesB – Centromere(ii) The structure C is Spindle fiber. Its function is to help in the movement of chromosomes. Think of spindle fibers like invisible ropes that pull chromosomes to their right places. (iii) The type of cell division is mitosis because all chromosomes appear to be same as there is no crossing over.(iv) Metaphase.(v) Prophase occurs before metaphase and after metaphase anaphase takes place