Structure of Chromosomes Cell Cycle and Cell division ICSE Class-10 Selina Concise Biology Solutions Chapter-2. We Provide Solutions of Progress Check , MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type Questions and Structured / Applications / Skill Type Questions of Exercise-2 Structure of Chromosomes Cell Cycle and Cell division. Visit official Website CISCE for detail information about ICSE Board Class-10.
| Board | ICSE |
| Publications | Selina Publishers PVT LTD |
| Subject | Concise Biology |
| Class | 10th |
| writer | HS Vishnoi |
| Chapter-2 | Structure of Chromosomes Cell Cycle and Cell division |
| Topics | Solutions of MCQs, Short ,Descriptive and Structural Questions |
| Edition | 2021-2022 |
Structure of Chromosomes Cell Cycle and Cell division ICSE Class-10 Selina Concise Biology Solutions Chapter-2
-: Select Topics :-
E. STRUCTURED/APPLICATION/SKILL TYPE
Note :- Before Viewing Concise Solutions of Chapter-2 Structure of Chromosomes Cell Cycle and Cell division . Read the whole chapter carefully with figure. Make a self written notes including following point.
Focus on Mitosis and its stages. A basic understanding of Meiosis (Stage not in Syllabus ) homologous chromosomes and crossing over leading to variations. Significance and major differences between mitotic and meiotic division
A. MULTIPLE CHOICE TYPE of Structure of Chromosomes Selina Biology for ICSE Class-10
Page-19
(Choose the best option out of the four alternatives a, b, c and d)
Question 1
The chromatin material is formed of
(a) DNA only
(b) DNA and Histones
(c) Histones only
(d) Nucleotides
Answer 1
(b) DNA and Histones
Question 2
The term “chromosomes” literally means
(a) Inherited bodies
(b) Twisted threads
(c) Coloured bodies
(d) Shining threads
Answer 2
(c) Coloured bodies
Question 3
The number of chromosomes in a certain type of cell division is halved. This kind of cell division occurs in
(a) only testis
(b) only ovary
(c) both ovary and testis
(d) all body cells
Answer 3
(c) both ovary and testis
Question 4
In which one of the following options the two stages of mitosis have been given in correct sequence?
(a) Prophase, metaphase, telophase, anaphase
(b) Prophase, metaphase, anaphase, telophase
(c) Anaphase, telophase, prophase, metaphase
(d) Telophase, anaphase, prophase, metaphase
Answer 4
(c) Anaphase, telophase, prophase, metaphase
Question 5
Synthesis phase in the cell cycle is called so for the synthesis of more of
(a) RNA
(b) RNA and proteins
(c) DNA
(d) Glucose
Answer 5
(c) DNA
B. VERY SHORT ANSWER TYPE Structure of Chromosomes Chapter-2 Concise Biology Selina Solutions
page-19
Question 1
Name the following:
(a) The repeating components of each DNA strand lengthwise.
(b) The complex structure consisting of DNA strand and a core of histones.
(c) The type of bond which joins the complementary nitrogenous bases.
(d) The three components of nucleotide.
Answer 1
(a) – Nucleotides.
(b) – Nucleosome.
(c) – Hydrogen Bond.
(d) – Phosphate, Sugar and Nitrogenous base.
Question 2
Imagine one cell (A) has undergone one mitotic division and another cell (B) has completed its meiotic division. How many cells would the two produce?
Cell A: ……………………….
Cell B:………………………..
Answer 2
Cell A: 2
Cell B: 4
Question 3
| Column ‘A’ | Column ‘B’ |
| (a) Chromosomes become arranged in a horizontal plane at the equator.
(b) Daughter chromosomes move to the opposite poles of a spindle (c) Chromosomes become visible as fine long threads. (d) Chromosomes lose their distinctiveness and gradually become transformed into a chromatin network |
Anaphase
Prophase Telophase Metaphase |
Answer 3
(a) – Metaphase.
(b) – Telophase.
(c) – Prophase.
(d) – Anaphase.
Question 4
Fill in the blanks.
(a) DNA replicates in the …………. of the cell cycle.
(b) Mitosis occurs in our …………. cells.
(c) Mitosis produces two daughter cells, whereas meiosis produces ………… daughter cells.
(d) Meiosis occurs only in …………. cells.
(e) Modern humans have 46 chromosomes. Their sperms and eggs will have ………. chromosomes each.
(f) During the pairing of chromosomes in meiosis, the ………… chromosomes come to lie side by side.
Answer 4
(a) DNA replicates in the synthesis (S) phase of the cell cycle.
(b) Mitosis occurs in our somatic (body) cells.
(c) Mitosis produces two daughter cells, whereas meiosis produces four daughter cells.
(d) Meiosis occurs only in reproductive cells.
(e) Modern humans have 46 chromosomes. Their sperms and eggs will have 23 chromosomes each.
(f) During the pairing of chromosomes in meiosis, the homologous chromosomes come to lie side by side.
C. SHORT ANSWER TYPE Cell Cycle Selina ICSE Class-10 Biology
Page-19
Question 1
What is the difference between chromatin fibre and chromosome?
Answer 1
Chromatin fibre is unfolded, uncondensed, extended DNA. It is only visible when cell under goes division whereas chromosomes are condensed DNA and they are visible when the cell is divided.
Question 2
What are the rungs of the “DNA ladder” made of?
Answer 2
Rungs of DNA ladder is made of nitrogenous bases which includes Adenine (A), Guanine (G), Cytosine (C) and Thymine (T).
Question 3
Correct the following statements if there is any mistake.
(a) The four nitrogenous bases in the DNA are Guanine, Thiamine, Adrenaline and Cytosine.
(b) Genes are specific sequences of bases on a chromosome.
(c) A nucleotide is composed of a sulphate, a sugar (pentose) and a nitrogenous base.
(d) Nucleosomes are groups of cysteine molecules surrounded by DNA strands.
(e) If there are 46 chromosomes in a cell there will be 23 chromatin fibres inside the nucleus during interphase.
Answer 3
(a) The four nitrogenous bases in the DNA ladder are Guanine, Thymine, Adenine and Cytosine.
(b) Genes are specific sequences of nucleotides on a chromosome.
(c) A nucleotide is composed of a phosphate, sugar (pentose) and a nitrogenous base.
(d) Nucleosomes are groups of histone molecules surrounded by DNA strands.
(e) If there are 46 chromosomes in a cell there will be 46 chromatin fibres inside the nucleus during interphase.
Descriptive Type
Selina Concise Biology Solutions ICSE Classs-10 Ch-2
Page-20
Question-1
Mention———-answer
(a) ……………
(b) ….
(c) ….
(d) …….
Answer-1
(a) T
(b) F
(c) F
(c) T
Question-2
(a) Chromosome
(b) Gene
(c) Cell division
(d) Chromatids
(e) Aster
Answer-2
(a) Chromosome–Chromosomes are highly condensed coiled chromatic fibres made of DNA which carries the hereditary material of the organisms.
(b) Gene–Gene is a structural and functional unit of heredity and variations. Genes are specific sequences of nucleotides on a chromosome that encode particular proteins which express in the form of some particular feature of the body. In other words, gene is the DNA segment of the chromosome and it controls the expression of characteristics
(c) Cell division:- Cell division happens when a parent cell divides into two or more cells called daughter cells. Cell division usually occurs as part of a larger cell cycle. All cells reproduce by splitting into two, where each parental cell gives rise to two daughter cells.
(d) Chromatids:-
- A chromatid is one of two strands of a copied chromosome.
- Chromatids that are joined together at their centromeres are called sister chromatids. These chromatids are genetically identical.
- Chromatids are formed in both the cellular division processes of mitosis and meiosis
(e) Aster :- Asters are radial microtubule arrays found in animal cells. These star-shaped structures form around each pair of centrioles during mitosis. Asters help to manipulate chromosomes during cell division to ensure that each daughter cell has the appropriate complement of chromosomes
Question-3
Give reason
a) Gamete must be produce by meiosis for sexual reproduction
(b) why is meiosis refer as as reductional division
(c) The children of same parent how ever similar are different each other in certain aspect
Answer-3
(a) Gametes must be produced by meiosis for sexual reproduction because the numbers of chromosomes are reduced to half during meiosis and then the normal diploid numbers of chromosomes are regained during the process of fertilization.
(b) meiosis refer as as reductional division:- Meiosis is a type of cell division in which each daughter cell receives half set of chromosomes. Hence, in meiosis, haploid daughter cells (n) are formed from a diploid parent cell (2n). Since the chromosome number is halved in the daughter cells, meiosis is also known as reductional division.
(c) The answer to why this happens has to do with our genes and how they are passed on. … And that each parent passes only half of their genes to their child. And that the half that gets passed down is random. All of this together ensures that each child ends up with a different, unique set of gene
Question 4
Difference between following pair
(a) Cytokinesis and Karyokinesis
(b) DNA and RNA
(c) Nucleosome and Nucleotide
(d) Centrosome and centromere,
(e) Haploid and diploid
Answer 4
(a) Cytokinesis and Karyokinesis
| Karyokinesis | Cytokinesis |
| Karyokinesis means the process of division of the nucleus. |
Cytokinesis means the process of division of cytoplasm.
|
| The nucleus gets divided into two daughter nuclei. |
The cytoplasm, cell organelles and the nuclei divide and are passed on to daughter cells equally.
|
| It can occur with or without cytokinesis. |
It is dependent on karyokinesis.
|
(b) DNA and RNA
| DNA (Deoxyribonucleic acid) | RNA (Ribonucleic acid) |
| It is a long polymer. It has a deoxyribose and phosphate backbone having four distinct bases: thymine, adenine, cytosine and guanine. | Is a polymer with a ribose and phosphate backbone with four varying bases: uracil, cytosine, adenine and guanine. |
| It is located in the nucleus of a cell and in the mitochondria. | It is found in the cytoplasm, nucleus and in the ribosome. |
| It has 2-deoxyribose. | It has Ribose. |
| DNA is functional is the transmission of genetic information. It forms as a media for long-term storage. | RNA is functional is the transmission of the genetic code that is necessary for the protein creation from the nucleus to the ribosome. |
| The DNA is a double-stranded molecule that has a long chain of nucleotides. | The RNA is a single-stranded molecule which has a shorter chain of nucleotides. |
(c) Nucleosome and Nucleotide
A nucleotide is composed of a phosphate, sugar (pentose) and a nitrogenous base. Nucleosomes are groups of histone molecules surrounded by DNA strands.
(d) Centrosome and centromere,
| Centrosome | Centromere |
| It is an organelle of the animal cell. | It is a non-stainable part of chromo-some at which two chromatids join. |
| It contains two centrioles which move towards the opposite poles and forms spindle fibres during cell division | It provides attachment of spindle fibres during cell division. |
(e) Haploid and diploid
A haploid cell is a cell that contains one complete set of chromosomes. Gametes are haploid cells that are produced by meiosis whereas a diploid cell is a cell that contains two sets of chromosomes. One set of chromosomes is donated from each parent.
Question 5
Enumerate the various changes that occur in the nucleus of the cell during anaphase of mitotic division
Answer 5
During anaphase:
The two sister chromatids of each chromosome separate and are drawn apart towards the opposite poles.
Question 6
Name and explain the various stages of the cell cycle.
Answer 6
Stages of the cell cycle:
- Non-dividing interphase
- Dividing mitotic phase or M phase
Interphase:
In interphase, cells grow in size and volume and prepare for the next cell division.
It is divided into three phases:
- First growth phase (G1):RNA and proteins are synthesised, and the volume of the cytoplasm increases.
- Synthesis phase (S):DNA is synthesised and chromosomes are duplicated.
- Second growth phase (G2):RNA and proteins continue to be synthesised.
Mitosis:
Mitosis is the division of somatic cells in which two identical daughter cells are produced by the division of one parent cell.
It consists of the following phases:
- Karyokinesis: It is the division of the nucleus during cell division.
- Cytokinesis: It is the division of the cytoplasm during cell division.
Karyokinesis:
It occurs in four phases:
- Prophase: During prophase, chromatinfibres condense and thick chromosomes are visible. The nucleolus and nuclear membrane disappear. A pair of centrioles duplicates. The spindle apparatus starts forming.
- Metaphase: Chromosomes are arranged on the metaphase plate or equatorial plane.
- Anaphase: The centromere divides, and the sister chromatids separate from each other. Spindlefibres contract and pull chromatids towards opposite poles.
- Telophase: Spindle apparatus disappears. Chromosomes become thin and turn into chromatinfibres. Nuclear membranes and nucleoli reappear.
Cytokinesis:
- The furrow continues to deepen in the cell, and it finally divides the cytoplasm forming two new daughter cells.
- In plant cells, a cell plate appears at the equatorial plane.
E. STRUCTURED / APPLICATION / SKILL TYPE Structure of Chromosomes Cell Cycle Cell Division
Page-20
Question 1
Given below is a schematic diagram of a portion of DNA.
(a) How many strands are shown in the diagram?
(b) How many nucleotides have been shown in each strand?
(c) Name the parts numbered 1,2,3,4 and 5 respectively.
(d) Name the DNA unit constituted by the parts 1, 2 and 3 collectively.
Answer 1
(a) 2
(b) 2 on each strand
(c) 1- Phosphate,2- Sugar, 3- Bases,4- Hydrogen Bond,5 – Base
(d)Nucleotide
Question 2
The three sketches given below (A, B and C) are intended to represent the replication of DNA. What should be their correct sequence starting with the first and ending with the last? ………..
Answer 2
B, C and A.
Question 3
The diagram below represents a stage during cell division. Study the same and then answer the questions that follow:
(a) Name the parts labelled 1, 2 and 3.
(b) Identify the above stage and give a reason to support your answer.
(c) Mention where in the body this type of cell division occurs.
(d) Name the stage prior to this stage and draw a diagram to represent the same.
Answer 3
(a)
1 – Centromere
2 – Spindle fibres
3 – Chromatids
(b) The stage described in the diagram is the late anaphase of mitosis in an animal cell. The stage can be identified by the presence of separated chromatids which are found at the two poles of the cell. The appearance of the furrow in the cell membrane classifies the stage as the late anaphase.
(c) The division is mitotic division and this kind of cell division occurs in all the cells of the body except for the reproductive cells.
(d) The stage before anaphase is metaphase.
Question 4
Draw a labelled diagram to show the metaphase stage of mitosis in an animal cell having ‘6’ chromosomes.
Answer 4
Question 5
The diagram given below represents a certain phenomenon which occurs during meiosis. Name and explain the phenomenon by using the terms – homologous chromosomes, chromatids, and crossing-over.
Answer 5
The exchange of chromatids between homologous chromosomes is called crossing-over. This is the process by which the two chromosomes of a homologous pair exchange equal segments with each other.
Crossing over occurs in the first division of meiosis. At that stage each chromosome has replicated into two strands called sister chromatids. The two homologous chromosomes of a pair synapse, or come together. While the chromosomes are synapsed, breaks occur at corresponding points in two of the non-sister chromatids, i.e., in one chromatid of each chromosome.
Since the chromosomes are homologous, breaks at corresponding points mean that the segments that are broken off contain corresponding genes, i.e., alleles. The broken sections are then exchanged between the chromosomes to form complete new units, and each new recombined chromosome of the pair can go to a different daughter sex cell. It results in recombination of genes found on the same chromosome, called linked genes that would otherwise always be transmitted together.
Question 6
Given below is a diagram representing a stage during mitotic cell division in an animal cell. Examine it carefully and answer the questions which follow.
(a) Identify the stage. Give one reason in support of your answer.
(b) Name the cell organelle that forms the ‘aster’.
(c) Name the parts labelled 1, 2 and 3.
(d) Name the stage that follows the one shown here. How is that stage identified?
(e) Mention two points of difference between mitosis and meiosis with regard to:
(i) The number of daughter cells produced.
(ii)The chromosome number in the daughter cells.
Answer 6
(a) Late prophase. Because the nuclear membrane and nucleolus have disappeared.
(b) Centrioles.
(c)
1 – Centromere
2 – Chromatids.
3 – Spindle fibre.
(d) Metaphase. The centromeres of chromosomes are drawn to the equator by equal pull of two chromosomal spindle fibres that connects each centromere to the opposite poles, forming a metaphasic plate.
(e)
| Mitosis | Meiosis |
| (i) Two daughter cells are produced. | (i) Four daughter cells are produced. |
| (ii) It is equational division i.e. the number of chromosome in the daughter cells or parent cells remains the same. | (ii) It is reductional division i.e. the number of chromosomes is reduced to half in the daughter cells. |
Question 7
Given below are three diagrammatic sketches (A, B and C) of one and the same particular phase during mitotic type of cell division.
(a) Identify the phase …………..
(b) What is the diploid number of chromosomes shown in them? …………….
(c) Identify whether these are animal cells or plant cell? Give reasons.
A ……………..
B ……………..
C ……………..
Answer 7
(a) Metaphase.
(b) 4.
(c)
A – Animal
B – Animal
C – Plant
Question 8
Shown below are four stages (A, B, C, D) (not in sequence) of a certain kind of cell division.
(a) Is it a plant cell or an animal cell? Give two reasons ………….
(b) Is it undergoing mitosis or meiosis? ………………
(c) What should be the correct sequence of these four stages among themselves? ………………
(d) Name the stage that should precede the earliest of these stages…………..
(e) Draw the stage named above inside the blank space provided.
Answer 8
(a) This is an animal cell because:
(i) The outline is circular (in plants it would be angular {rectangular or polygonal}) and cell wall is absent.
(ii) Centrosomes on centrioles are present. (These are found only in animal cells)
(b) Mitosis.
(c) B, C, D, A.
(d) Interphase.
(e)
Question 9
Given below is a diagram representing a stage during mitotic cell division. Study it carefully and answer the questions that follow.
(a) Is it a plant cell or an animal cell? Give a reason to support your answer.
(b) Identify the stage shown.
(c) Name the stage that follows the one shown here. How is that stage identified?
(d) How will you differentiate between mitosis and meiosis on the basis of the chromosome number in the daughter cells?
(e) Draw a duplicated chromosome and label its parts.
Answer 9
(a) It is a plant cell because centrioles are not shown in the diagram.
(b) Prophase
(c) Metaphase. Chromosomes arrange themselves on the metaphase or equatorial plate.
(d) Difference between mitosis and meiosis based on the chromosome number in daughter cells:
| Mitosis | Meiosis |
| Chromosome number remains the same as that of parent cells. | Daughter cells receive only half the number of chromosomes from parent cells. |
(e) Duplicated chromosome:
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