Selina Textbook Solutions: Structure of Chromosomes, Cell Cycle and Cell Division | Biology Class 10 ICSE PDF Download

 Page 1


 
                   
EXERCISE: 1 
A.  MULTIPLE CHOICE TYPE 
(Choose the best option out of the four alternatives a, b, c, and d) 
Question 1:  
The Chromatin material is formed forms of  
(a) DNA only  
(b) DNA and histones  
(c) Histones only 
(d) Nucleotides 
Solution 1: 
 (b) DNA and Histones 
 
 
Question 2:  
The term “chromosomes” literally means 
(a) Inherited bodies 
(b) Twisted threads 
(c) Coloured bodies 
(d) Shining threads 
Solution 2: 
(c) Coloured bodies 
 
 
B. VERY SHORT ANSWER TYPE: 
 
Questions 1:  
1. Name the following: 
a) The repeating components of each DNA strand lengthwise. 
b) The complex 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 a nucleotide. 
Solution 1:  
(a) Nucleotides. 
(b) Nucleosome. 
(c) Hydrogen Bond. 
(d) Phosphate, Sugar and Nitrogenous base. 
 
 
 
Class X Chapter 1 - Cell Cycle, Cell Division and Structure Of Chromosomes  Biology 
_____________________________________________________________________________ 
Page 2


 
                   
EXERCISE: 1 
A.  MULTIPLE CHOICE TYPE 
(Choose the best option out of the four alternatives a, b, c, and d) 
Question 1:  
The Chromatin material is formed forms of  
(a) DNA only  
(b) DNA and histones  
(c) Histones only 
(d) Nucleotides 
Solution 1: 
 (b) DNA and Histones 
 
 
Question 2:  
The term “chromosomes” literally means 
(a) Inherited bodies 
(b) Twisted threads 
(c) Coloured bodies 
(d) Shining threads 
Solution 2: 
(c) Coloured bodies 
 
 
B. VERY SHORT ANSWER TYPE: 
 
Questions 1:  
1. Name the following: 
a) The repeating components of each DNA strand lengthwise. 
b) The complex 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 a nucleotide. 
Solution 1:  
(a) Nucleotides. 
(b) Nucleosome. 
(c) Hydrogen Bond. 
(d) Phosphate, Sugar and Nitrogenous base. 
 
 
 
Class X Chapter 1 - Cell Cycle, Cell Division and Structure Of Chromosomes  Biology 
_____________________________________________________________________________ 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
C. SHORT ANSWER TYPE: 
 
Question 1:  
What is the difference between chromatin fibre and chromosome? 
Solution 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? 
Solutions:  
Rungs of DNA ladder is made of nitrogenous bases which includes Adenine (A), Guanine 
(G), Cytosine (C) and Thymine (T). 
 
 
Question 2:  
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. 
Solution 2:  
(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. 
 
 
D. LONG ANSWER TYPE: 
 
Question 1:  
What is a nucleosome? 
 
Page 3


 
                   
EXERCISE: 1 
A.  MULTIPLE CHOICE TYPE 
(Choose the best option out of the four alternatives a, b, c, and d) 
Question 1:  
The Chromatin material is formed forms of  
(a) DNA only  
(b) DNA and histones  
(c) Histones only 
(d) Nucleotides 
Solution 1: 
 (b) DNA and Histones 
 
 
Question 2:  
The term “chromosomes” literally means 
(a) Inherited bodies 
(b) Twisted threads 
(c) Coloured bodies 
(d) Shining threads 
Solution 2: 
(c) Coloured bodies 
 
 
B. VERY SHORT ANSWER TYPE: 
 
Questions 1:  
1. Name the following: 
a) The repeating components of each DNA strand lengthwise. 
b) The complex 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 a nucleotide. 
Solution 1:  
(a) Nucleotides. 
(b) Nucleosome. 
(c) Hydrogen Bond. 
(d) Phosphate, Sugar and Nitrogenous base. 
 
 
 
Class X Chapter 1 - Cell Cycle, Cell Division and Structure Of Chromosomes  Biology 
_____________________________________________________________________________ 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
C. SHORT ANSWER TYPE: 
 
Question 1:  
What is the difference between chromatin fibre and chromosome? 
Solution 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? 
Solutions:  
Rungs of DNA ladder is made of nitrogenous bases which includes Adenine (A), Guanine 
(G), Cytosine (C) and Thymine (T). 
 
 
Question 2:  
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. 
Solution 2:  
(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. 
 
 
D. LONG ANSWER TYPE: 
 
Question 1:  
What is a nucleosome? 
 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
Solution 1:  
Nucleosome is basic structural unit of DNA. Each strand of DNA winds around a core of eight 
histone molecules. This core can be imagined like a football, around which a long rope is 
wound with one or two loops. Each such complex structure is called a nucleosome. A single 
human chromosome may have about a million nucleosomes. 
 
 
Question 2: 
What are genes? 
Solution 2: 
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. 
 
 
E. STRUCTURED / APPLICATION / SKILL TYPE: 
 
Question 1:   
Given below is a schematic diagram of a portion of DNA. 
 
 
 
 
 
 
 
 
(a) How many strands are shown in the  pic? 
(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, 3 collectively. 
Solution 1:  
(a) 2 
(b) 2 on each strand 
(c) 1- Phosphate, 2- Sugar, 3- Nitrogen Base, 4- Hydrogen Bond, 5 – Base 
(d) Nucleotide 
 
 
 
Page 4


 
                   
EXERCISE: 1 
A.  MULTIPLE CHOICE TYPE 
(Choose the best option out of the four alternatives a, b, c, and d) 
Question 1:  
The Chromatin material is formed forms of  
(a) DNA only  
(b) DNA and histones  
(c) Histones only 
(d) Nucleotides 
Solution 1: 
 (b) DNA and Histones 
 
 
Question 2:  
The term “chromosomes” literally means 
(a) Inherited bodies 
(b) Twisted threads 
(c) Coloured bodies 
(d) Shining threads 
Solution 2: 
(c) Coloured bodies 
 
 
B. VERY SHORT ANSWER TYPE: 
 
Questions 1:  
1. Name the following: 
a) The repeating components of each DNA strand lengthwise. 
b) The complex 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 a nucleotide. 
Solution 1:  
(a) Nucleotides. 
(b) Nucleosome. 
(c) Hydrogen Bond. 
(d) Phosphate, Sugar and Nitrogenous base. 
 
 
 
Class X Chapter 1 - Cell Cycle, Cell Division and Structure Of Chromosomes  Biology 
_____________________________________________________________________________ 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
C. SHORT ANSWER TYPE: 
 
Question 1:  
What is the difference between chromatin fibre and chromosome? 
Solution 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? 
Solutions:  
Rungs of DNA ladder is made of nitrogenous bases which includes Adenine (A), Guanine 
(G), Cytosine (C) and Thymine (T). 
 
 
Question 2:  
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. 
Solution 2:  
(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. 
 
 
D. LONG ANSWER TYPE: 
 
Question 1:  
What is a nucleosome? 
 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
Solution 1:  
Nucleosome is basic structural unit of DNA. Each strand of DNA winds around a core of eight 
histone molecules. This core can be imagined like a football, around which a long rope is 
wound with one or two loops. Each such complex structure is called a nucleosome. A single 
human chromosome may have about a million nucleosomes. 
 
 
Question 2: 
What are genes? 
Solution 2: 
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. 
 
 
E. STRUCTURED / APPLICATION / SKILL TYPE: 
 
Question 1:   
Given below is a schematic diagram of a portion of DNA. 
 
 
 
 
 
 
 
 
(a) How many strands are shown in the  pic? 
(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, 3 collectively. 
Solution 1:  
(a) 2 
(b) 2 on each strand 
(c) 1- Phosphate, 2- Sugar, 3- Nitrogen Base, 4- Hydrogen Bond, 5 – Base 
(d) Nucleotide 
 
 
 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
Question 2:  
The three sketch (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? …… 
 
 
 
 
 
 
 
 
 
Solution 2:  
B, C and A. 
 
 
EXERCISE: 2  
MULTIPLE CHOICE TYPE: 
(Choose the best option out of the four alternatives a, b, c and d) 
Question 1:  
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 
Solution 1:  
(c) Both ovary and testis 
 
Question 2: 
In which one of the following options the two stages of mitosis have been given in correct 
sequence? 
(a) Prophase, anaphase 
(b) Metaphase, telophase  
(c) Anaphase, telophase 
(d) Telophase, anaphase 
Solution 2:  
(c) Anaphase, telophase 
 
Page 5


 
                   
EXERCISE: 1 
A.  MULTIPLE CHOICE TYPE 
(Choose the best option out of the four alternatives a, b, c, and d) 
Question 1:  
The Chromatin material is formed forms of  
(a) DNA only  
(b) DNA and histones  
(c) Histones only 
(d) Nucleotides 
Solution 1: 
 (b) DNA and Histones 
 
 
Question 2:  
The term “chromosomes” literally means 
(a) Inherited bodies 
(b) Twisted threads 
(c) Coloured bodies 
(d) Shining threads 
Solution 2: 
(c) Coloured bodies 
 
 
B. VERY SHORT ANSWER TYPE: 
 
Questions 1:  
1. Name the following: 
a) The repeating components of each DNA strand lengthwise. 
b) The complex 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 a nucleotide. 
Solution 1:  
(a) Nucleotides. 
(b) Nucleosome. 
(c) Hydrogen Bond. 
(d) Phosphate, Sugar and Nitrogenous base. 
 
 
 
Class X Chapter 1 - Cell Cycle, Cell Division and Structure Of Chromosomes  Biology 
_____________________________________________________________________________ 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
C. SHORT ANSWER TYPE: 
 
Question 1:  
What is the difference between chromatin fibre and chromosome? 
Solution 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? 
Solutions:  
Rungs of DNA ladder is made of nitrogenous bases which includes Adenine (A), Guanine 
(G), Cytosine (C) and Thymine (T). 
 
 
Question 2:  
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. 
Solution 2:  
(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. 
 
 
D. LONG ANSWER TYPE: 
 
Question 1:  
What is a nucleosome? 
 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
Solution 1:  
Nucleosome is basic structural unit of DNA. Each strand of DNA winds around a core of eight 
histone molecules. This core can be imagined like a football, around which a long rope is 
wound with one or two loops. Each such complex structure is called a nucleosome. A single 
human chromosome may have about a million nucleosomes. 
 
 
Question 2: 
What are genes? 
Solution 2: 
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. 
 
 
E. STRUCTURED / APPLICATION / SKILL TYPE: 
 
Question 1:   
Given below is a schematic diagram of a portion of DNA. 
 
 
 
 
 
 
 
 
(a) How many strands are shown in the  pic? 
(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, 3 collectively. 
Solution 1:  
(a) 2 
(b) 2 on each strand 
(c) 1- Phosphate, 2- Sugar, 3- Nitrogen Base, 4- Hydrogen Bond, 5 – Base 
(d) Nucleotide 
 
 
 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
Question 2:  
The three sketch (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? …… 
 
 
 
 
 
 
 
 
 
Solution 2:  
B, C and A. 
 
 
EXERCISE: 2  
MULTIPLE CHOICE TYPE: 
(Choose the best option out of the four alternatives a, b, c and d) 
Question 1:  
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 
Solution 1:  
(c) Both ovary and testis 
 
Question 2: 
In which one of the following options the two stages of mitosis have been given in correct 
sequence? 
(a) Prophase, anaphase 
(b) Metaphase, telophase  
(c) Anaphase, telophase 
(d) Telophase, anaphase 
Solution 2:  
(c) Anaphase, telophase 
 
Class X Chapter 2 – Cell Cycle, Cell Division and Structure of Chromosomes  Biology 
_____________________________________________________________________________ 
Question 3: 
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 
Solution 3:  
(c) DNA 
 
 
B. VERY SHORT ANSWER TYPE: 
 
Question 1: 
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? 
Solution 1:  
Cell A: 2 
Cell B: 4 
 
 
Question 2: 
Match the events given in column A with the phase in mitotic cell division in column B  
Column ‘A’ Column ‘B’ 
a) Chromosomes get arranged in a 
horizontal plane at the equator. 
Prophase  
b) Daughter chromosomes move to 
the opposite poles of a spindle. 
 
Anaphase 
c) Chromosomes become visible as 
fine long threads.  
Metaphase 
d) Chromosomes lose their 
distinctiveness and gradually 
become transformed into a 
chromatin network.  
Telophase 
Solution 2: 
(a) Metaphase 
(b) Telophase 
(c) Prophase 
(d) Anaphase