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NCERT Solutions for Class 11 Biology Chapter 10 Cell Cycle and Cell Division is prepared to help students understand the intricate ideas of the chapter and prepare well for their final and entrance examinations. This chapter is important as it discusses how cells divide, grow, and reproduce, which forms the basis of the growth and development of all living organisms. It also gives knowledge about different biological processes like growth, repair, and reproduction. By NCERT Solutions, students can develop a solid understanding of biology. These detailed explanations, not only prepare for exams but are also made a foundation for higher learning in life sciences.
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If you are struggling with cell cycle and cell division, you've come to the right place. The NCERT Solutions for Class 11 are composed using easy and simple language, which makes it easier for students to understand important concepts with ease. The detailed answers to the questions are prepared by subject experts as per the latest CBSE curriculum, so they are extremely reliable for exam preparation.
Students can download the detailed explanations of the chapter from below:
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The detailed answers are given below:
Q1. What is the average cell cycle span for a mammalian cell?
Answer:
The average cell cycle span for a mammalian cell is 24 hours.
Q2. Distinguish cytokinesis from karyokinesis.
Answer:
The differences between cytokinesis and karyokinesis are as follows:
Cytokinesis | Karyokinesis |
The process of division of cytoplasm is called cytokinesis | The process of division of the nucleus is called karyokinesis |
Cytokinesis takes place after the end of the M-phase | Karyokinesis take place during the M-phase |
Q3. Describe the events taking place during the interphase.
Answer:
Interphase is the stage at which the cell makes preparations for division. It consists of three phases:
G1 phase: The cell increases in size, and synthesizes RNA, proteins, and molecules required for DNA replication. The cell determines whether to proceed in the cycle or enter a resting phase (G0).
S phase: The replication of DNA takes place, doubling the DNA but not changing the number of chromosomes. Duplicating begins in the centrosome.
G2 phase: The cell gets ready for mitosis by producing additional RNA, proteins, and organelles.
Q4. What is the Go (quiescent phase) of the cell cycle?
Answer:
G0 is a resting phase in which the cell halts dividing but doesn't die. These cells may re-enter the cycle if necessary. Example: Cells found in the root tip.
Q5. Why is mitosis called equational division?
Answer:
Mitosis is referred to as equational division since it gives rise to two daughter cells with the same amount of chromosomes as the parent cell.
Q6. Name the stage of the cell cycle at which one of the following events occurs:
(i) Chromosomes are moved to the spindle equator.
Answer:
During metaphase, the chromosomes move to the spindle equator and align themselves there.
Q6. Name the stage of the cell cycle at which one of the following events occurs:
(ii) Centromere splits and chromatids separate.
Answer:
During anaphase, the centromere splits and chromatids are separated. These chromatids after separation move to the opposite poles.
Q6. Name the stage of the cell cycle at which one of the following events occurs:
(iii) Pairing between homologous chromosomes takes place.
Answer:
The pairing between homologous chromosomes takes place during zygotene of prophase I of meiosis I. As a result of this pairing, bivalents are formed.
Q6. Name the stage of the cell cycle at which one of the following events occurs:
(iv) Crossing over between homologous chromosomes takes place.
Answer:
Crossing over between homologous chromosomes takes place during the pachytene of prophase I of meiosis I.
(a) synapsis
Draw a diagram to illustrate your answer.
Answer:
Synapsis- The process of the pairing of homologous chromosomes during the zygotene stage of prophase I of meiosis I is called synapsis. During synapse, a synaptonemal complex is formed by the homologous chromosome which is referred to as a bivalent or a tetrad.
(b) bivalent
Draw a diagram to illustrate your answer.
Answer:
Bivalent- it refers to the structure formed by a pair of synapsed homologous chromosomes.
(c) chiasmata
Draw a diagram to illustrate your answer.
Answer:
Chiasmata- These are points of attachment between homologous chromosomes during their separation in diplotene to the metaphase I stage of meiosis. Chiasmata are initially formed in the regions of crossing over between nonsister chromatids but later on, tend to shift sideways.
Q8. How does cytokinesis in plant cells differ from that in animal cells?
Answer:
The process of cytokinesis differs in plant and animal cells
Cytokinesis in plants | Cytokinesis in animals |
It occurs by the cell plate method | It takes place by the cleavage method |
The spindle persists during cytokinesis | The spindle starts to degenerate after anaphase |
The cell plate grows centrifugally | Cleavage takes place centripetally |
The new cell membrane is derived from vesicles of the Golgi apparatus | The new cell wall is derived from the endoplasmic reticulum |
Answer:
Q10. Distinguish the anaphase of mitosis from anaphase I of meiosis.
Answer:
Anaphase of mitosis | Anaphase I of meiosis |
Anaphase of mitosis involves splitting of each chromosome at the centromere into two sister chromatids which start moving towards the opposite poles. | Anaphase I of meiosis I involve the separation of homologous chromosomes, while the chromatids remain attached to their chromatids. |
Q11. List the main differences between mitosis and meiosis.
Answer: The major differences between mitosis and meiosis is discussed below in the table:
Mitosis | Meiosis |
It takes place in somatic cells | It takes place in germ cells |
The cells undergoing mitosis can be diploid or haploid | The cells that undergo meiosis cannot be haploid |
It involves a single division producing two daughter cells at the end | It involves two divisions that give rise to four daughter cells |
The daughter cells formed after mitosis are exactly similar to their parent cell | The daughter cells formed after meiosis are neither similar to the parent one nor to one another |
The number of chromosomes remains the same after meiosis | The number of chromosomes is reduced to half after meiosis. |
Mitosis helps in the multiplication of cells, healing and repair | Meiosis is involved in the formation of meiospores or gametes |
Answer:
Meiosis is significant because:
It produces gametes for sexual reproduction.
It maintains the chromosome number stable in the species.
It creates genetic variation by rearranging chromosomes.
It enables new characteristics to develop, helping in evolution.
It occasionally causes beneficial genetic mutations.
Q13. Discuss with your teacher about
(i) haploid insects and lower plants where cell division occurs
Answer:
In some lower plants and haploid insects such as drones of a honey bee, meiosis occurs in the zygote. This type of meiosis is called zygotic meiosis whereas this type of life cycle is called haplontic life cycle.
(ii) some haploid cells in higher plants where cell division does not occur.
Answer:
Synergids and antipodals are haploid cells in higher plants where cell division does not occur.
Q14. Can there be mitosis without DNA replication in 'S' phase?
Answer:
No, mitosis cannot occur without DNA replication during the S phase. Without copying DNA, the daughter cells will contain fewer chromosomes than required.
Q15. Can there be DNA replication without cell division?
Answer:
Yes, DNA can replicate without cell division. For instance, in polyteny, chromosomes replicate many times without the cell dividing, resulting in excess DNA.
(i) number of chromosomes (N) per cell
Answer:
The number of chromosomes decreases during anaphase I of meiosis I, when homologous chromosomes separate, resulting in daughter cells being haploid.
(ii) amount of DNA content (C) per cell
Answer:
DNA content doubles during the S phase since replication takes place. It reduces in anaphase II of meiosis, as sister chromatids move apart and halve the DNA content.
The important topics and subtopics of Cell Cycle and Cell Division are given below:
Significance of Mitosis | Significance of Meiosis |
Genetic Consistency | Genetic Variation |
Chromosome Number Maintenance | Chromosome Number Reduction |
Growth and Repair | Formation of Gametes |
Asexual Reproduction | Sexual Reproduction |
Single Cell Division | Two Cell Divisions |
Identical Daughter Cells | Diverse Offspring |
NCERT Solutions for Class 11: Subject-wise
Below are a few solved practice questions:
Q1. Write one feature about the G1 phase.
Answer:
The G1 phase, sometimes referred to as the gap 1 phase, is the initial stage of cell division. The cell is constantly growing, metabolically active, and produces proteins required for DNA replication.
Q2. What is a Bivalent of Meiosis-I?
Answer:
During meiosis, two homologous chromosomes couple up to produce a bivalent. When two homologous chromosomes pair, a bivalent comprises a total of four chromatids, since each chromosome is made up of two sister chromatids. They have two centromeres rather than four. This is because every chromosome has a single centromere.
Q3. What are the characteristics of Meiosis-I?
Answer:
The process of cell division known as mitosis produces two identical daughter cells when the chromosomes duplicate and are distributed equally. Each daughter cell has the same number of chromosomes as the parent cell, making them diploid. Consequently, the process of mitosis is referred to as equal division.
Q4. Where does Meiosis occur in an organism?
Answer:
In sexually reproducing animals, meiosis is a sort of cell division that reduces the number of chromosomes in gametes, also known as sex cells, such as eggs and sperm. Human body cells have two sets of chromosomes, one from each parent, making them diploid.
Q5. Write five features of anaphase-I of Meiosis.
Answer:
The five features of anaphase-I of Meiosis are:
Check the NCERT Books and NCERT Syllabus here:
The students should begin by understanding the key terms, such as interphase, mitosis, and meiosis, with the help of diagrams, before starting to solve the questions. The cell cycle can be broken down into different phases, and the sequence of the events should be revised carefully. Flowcharts and labelled diagrams should be used for better memory. By solving the exemplar problems, students can have an advanced understanding of the chapter. The Cell Cycle and Cell Division Class 11 Solutions have all the solved exercise questions, with to-the-point answers and necessary information. Finally, regular revision should be done to strengthen the concepts and boost exam confidence.
Studying concepts beyond the NCERT will definitely help in attaining conceptual clarity and will help answer application-based questions, especially for competitive exams or school exams. Some extra concepts that can be studied are:
Topics | NEET | NCERT |
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Cell Cycle: Division Phase or M-Phase (Mitotic or Meiotic Phase) | ✅ | ✅ |
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Stages of Meiosis Ⅰ - Telophase I, Cytokinesis I and Interkinesis | ✅ | ✅ |
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Below mentioned are the Chapterwise solutions:
Meiosis produces genetic diversity and ensures that offspring inherit the appropriate number of chromosomes from their parents.
In this phase, chromosomes along with their DNA replicates. The content of DNA doubles up, however, the number of chromosomes remains the same. After replication, the daughter chromosomes remain attached in the region of the centromere. The centrosome, if present begins to divide.
This phase is characterised by increased synthesis of RNA and proteins. The cell organelles undergo multiplication in this phase while the cell grows in size. G2 phase is also called a second growth phase or pre-mitotic gap phase.
Mitosis: Results in two identical cells, found in somatic (body) cells.
Meiosis: Forms four genetically unique cells containing half the number of chromosomes, takes place in reproductive cells.
The cell cycle provides growth, repair, and reproduction to organisms. It prevents the number of chromosomes in cells from being in error.
There are two main phases of the cell cycle:
Interphase – The cell is prepared for division.
M Phase (Mitotic Phase) – The cell divides.
Interphase permits the cell to increase in size, replicate DNA, and prepare for cell division. It makes sure that the daughter cells have complete genetic material.
G1 Phase: The cell increases in size, synthesizes proteins, and prepares for DNA replication.
S Phase: DNA is replicated but the chromosomes are not duplicated.
G2 Phase: The cell continues to grow, prepares for mitosis, and synthesizes proteins that are required.
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