Question:

Distinguish cytokinesis from karyokinesis.

Answer:

1. Understand the meaning of cytokinesis and karyokinesis. Cytokinesis is the process of cell division in which the cytoplasm of a single cell divides into two new cells. Karyokinesis is the process of nuclear division in which the nucleus of a single cell divides into two new nuclei.

2. Compare and contrast cytokinesis and karyokinesis. Cytokinesis involves the division of the cytoplasm of a single cell, while karyokinesis involves the division of the nucleus of a single cell. Cytokinesis occurs after karyokinesis and is necessary for the formation of two new cells.

Question:

Why is mitosis called as equational division?

Answer:

Answer:

1. Mitosis is a type of cell division which results in two daughter cells, each with the same number and kind of chromosomes as the parent cell.
2. During mitosis, the chromosomes in the nucleus of the parent cell are duplicated and then separated into two identical sets, which are then distributed into two daughter cells.
3. This type of division is called equational division because both daughter cells receive an equal number of chromosomes, or an “equation” of chromosomes.

Question:

Find examples where the four daughter cells from meiosis are equal in size and where they are found unequal in size.

Answer:

1. Examples of four daughter cells from meiosis being equal in size: a. The four daughter cells produced during the meiosis of a pollen grain in plants. b. The four daughter cells produced during the meiosis of a spermatocyte in animals.

2. Examples of four daughter cells from meiosis being unequal in size: a. The four daughter cells produced during the meiosis of an oocyte in animals. b. The four daughter cells produced during the meiosis of an egg in plants.

Question:

Can there be DNA replication without cell division?

Answer:

Step 1: Understand the meaning of the question.

The question is asking whether DNA replication can occur without the process of cell division.

Step 2: Research the answer.

DNA replication can occur without cell division, as it is a process that occurs in both prokaryotic and eukaryotic cells. In prokaryotes, DNA replication can occur without cell division through a process called binary fission, while in eukaryotes, DNA replication can occur without cell division through a process called endomitosis.

Question:

Name the stage of cell cycle at which one of the following events occur. (i) Chromosomes are moved to spindle equator. (ii) Centromere splits and chromatids separate. (iii) Pairing between homologous chromosomes takes place. (iv) Crossing over between homologous chromosomes takes place.

Answer:

(i) Anaphase (ii) Anaphase (iii) Prophase (iv) Prophase

Question:

Distinguish anaphase of mitosis from anaphase I of meiosis.

Answer:

Step 1: Understand the difference between mitosis and meiosis. Mitosis is a process of cell division that produces two identical daughter cells from a single parent cell, while meiosis is a type of cell division that produces four daughter cells, each with half the number of chromosomes of the parent cell.

Step 2: Learn the stages of mitosis and meiosis. Mitosis consists of four stages: prophase, metaphase, anaphase, and telophase. Meiosis consists of two stages: meiosis I and meiosis II.

Step 3: Understand the differences between anaphase of mitosis and anaphase I of meiosis. Anaphase of mitosis is the third stage of mitosis, in which the sister chromatids are separated and pulled to opposite poles of the cell. Anaphase I of meiosis is the first stage of meiosis, in which homologous chromosomes separate and move to opposite poles of the cell.

Question:

Discuss with your teacher about (i) Haploid insects and lower plants where cell division occurs. (ii) Some haploid cells in higher plants where cell division does not occur?

Answer:

1. Greet your teacher and explain why you want to discuss haploid insects and lower plants where cell division occurs and some haploid cells in higher plants where cell division does not occur.

2. Ask your teacher to explain the process of cell division in haploid insects and lower plants.

3. Ask your teacher to explain why some haploid cells in higher plants do not undergo cell division.

4. Ask your teacher to provide examples of haploid cells in higher plants that do not undergo cell division.

5. Ask your teacher for any other insights or information they may have about haploid insects and lower plants where cell division occurs and some haploid cells in higher plants where cell division does not occur.

6. Thank your teacher for their time and assistance.

Question:

What is the average cell cycle span for a mammalian cell?

Answer:

Step 1: Understand what a mammalian cell is.

Step 2: Research the average cell cycle span for a mammalian cell.

Step 3: Calculate the average cell cycle span for a mammalian cell.

Question:

What is G0​ (quiescent phase) of cell cycle?

Answer:

Answer: G0 (quiescent phase) is a phase of the cell cycle where the cell is not actively dividing. It is a period of dormancy where the cell is in a resting state, and cell division is suspended. During G0, the cell can remain in this state for a long period of time, or it can enter a new phase of the cell cycle. G0 is an important part of the cell cycle, as it allows cells to adapt to environmental changes and conserve energy.

Question:

Describe the following : (a) Synapsis (b) Bivalent (c) Chiasmata Draw a diagram to illustrate your answer.

Answer:

(a) Synapsis: Synapsis is a process during prophase I of meiosis in which homologous chromosomes pair up and exchange genetic material. This process is also known as “crossing over” because it involves the exchange of genetic material between the chromosomes.

(b) Bivalent: A bivalent is a pair of homologous chromosomes that have paired up during synapsis. This pairing is necessary for genetic recombination to occur.

(c) Chiasmata: Chiasmata are the visible points of contact between homologous chromosomes that form during synapsis. They are visible under a microscope and are the result of genetic recombination.

Diagram:

[Diagram of two homologous chromosomes with chiasmata points of contact]

Question:

How does cytokinesis in plant cells differ from that in animal cells?

Answer:

Step 1: Understand the terms. Cytokinesis is the division of the cytoplasm during cell division. In plant cells, it is the division of the cell wall, while in animal cells it is the division of the cell membrane.

Step 2: Research the differences between cytokinesis in plant cells and animal cells. Plant cells form a cell plate between the two daughter cells during cytokinesis, which forms the cell wall of the daughter cells. Animal cells use a contractile ring of proteins to pinch the cell membrane and divide the cytoplasm into two daughter cells.

Step 3: Summarize the differences. Plant cells divide by forming a cell plate between the two daughter cells, which forms the cell wall of the daughter cells. Animal cells divide by using a contractile ring of proteins to pinch the cell membrane and divide the cytoplasm into two daughter cells.

Question:

What is the significance of meiosis?

Answer:

Step 1: Meiosis is a type of cell division that produces gametes, which are reproductive cells.

Step 2: During meiosis, the number of chromosomes in the parent cell is reduced by half, resulting in four daughter cells with half the number of chromosomes as the parent cell.

Step 3: This process is important in sexual reproduction as it allows for genetic diversity by creating new combinations of genetic material in the gametes. It also ensures that the offspring will have the correct number of chromosomes.

Question:

Can there be mitosis without DNA replication in S phase?

Answer:

1. Mitosis is a process of cell division in which a single cell divides into two identical daughter cells.

2. DNA replication occurs during S phase of the cell cycle, which is the period of the cycle when the cell is synthesizing DNA in preparation for cell division.

3. Therefore, mitosis cannot occur without DNA replication in S phase.

Question:

Analyse the events during every stage of the cell cycle and notice how the following two parameters change: (i) Number of chromosomes (N) per cell (ii) Amount of DNA content (C) per cell

Answer:

Step 1: During the Interphase stage of the cell cycle, the number of chromosomes (N) per cell remains the same, while the amount of DNA content (C) per cell increases.

Step 2: During the Prophase stage of the cell cycle, the number of chromosomes (N) per cell doubles, while the amount of DNA content (C) per cell remains the same.

Step 3: During the Metaphase stage of the cell cycle, the number of chromosomes (N) per cell remains the same, while the amount of DNA content (C) per cell remains the same.

Step 4: During the Anaphase stage of the cell cycle, the number of chromosomes (N) per cell doubles, while the amount of DNA content (C) per cell remains the same.

Step 5: During the Telophase stage of the cell cycle, the number of chromosomes (N) per cell returns to its original number, while the amount of DNA content (C) per cell remains the same.

Question:

Describe the events taking place during interphase. What is the G0​ (quiescent phase) cell cycle?

Answer:

Interphase is the first stage of the cell cycle and is composed of three distinct phases: G1, S, and G2. During this period, the cell grows and prepares for cell division.

G1 phase: During G1, the cell synthesizes proteins and other components necessary for DNA replication. It also prepares for mitosis by organizing its chromosomes.

S phase: During S phase, DNA replication occurs. The cell’s chromosomes are duplicated, and the cell’s DNA content doubles.

G2 phase: During G2, the cell synthesizes proteins and other components necessary for cell division. The cell also checks for any errors in its DNA.

G0 phase (quiescent phase): G0 is an optional phase of the cell cycle. Cells in G0 are not actively dividing, but are still alive and functioning. Cells may enter G0 due to environmental conditions or in response to certain signals from other cells.

Question:

List the main differences between mitosis and meiosis?

Answer:

1. Mitosis is a type of cell division that produces two identical daughter cells, while meiosis is a type of cell division that produces four haploid daughter cells.

2. Mitosis involves the division of a single diploid cell into two identical diploid cells, while meiosis involves the division of a single diploid cell into four haploid cells.

3. Mitosis results in the production of genetically identical daughter cells, while meiosis results in the production of genetically unique daughter cells.

4. Mitosis involves one round of DNA replication and two rounds of cell division, while meiosis involves one round of DNA replication and two rounds of cell division.

5. Mitosis involves the exchange of genetic material between the two daughter cells, while meiosis involves the exchange of genetic material between all four daughter cells.