Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries

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Kerala State Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries

Unraveling Genetic Mysteries Text Book Questions and Answers

Emergence Of Genetics

Genetics is the branch of science emerged at the beginning of the 20th century. It influences almost all areas of life like diagnosis, therapeutic and food production. Gregor Johann Mendel’s hybridization experiments in pea plants have led to the foundation of genetics. So he is considered as the father of Genetics.

Unravelling Genetic Mysteries Question 1.
What are the traits that were experimented by Mendel?
Answer:
The traits that were experimented by Mendel

  • Height of the plant (Tall – Dwarf)
  • Position of the flower (Terminal – Axial)
  • Shape of the seed (Round – Wrinkled)
  • Colour of the seed (Green-Yellow)
  • Colour of the flower (Purple, White)
  • Shape of the pod (Inflated – Constricted)
  • Colour of the fruit (Yellow-Green)

Experiments Of Mendel

Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 1

Guru Plant Genetic Question 2.
Which trait of the pea plant was considered in these experiments?
Answer:
Height of the pea plant was considered as the trait in this experiment.

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Unravelling Genetic Mysteries Question 3. What variant forms of the trait are considered here?
Answer:
Tall and dwarf are the variant forms of the trait considered here.

Guru Plant Genetic Question 4.
Which forms of the trait was expressed in the first generation?
Answer:
Tall is the trait was expressed in the first generation.

Biology Chapter 6 Question 5.
The following illustration showing hybridization experiment in pea plants using symbols for the factors that control traits.
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 2
Peculiarities of offsprings in the second generation
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 3
Mendel self-pollinated the plants obtained in the first generation and produced the second generation. Among the 1064 plants obtained in the second generation, 787 plants were tall and 277 plants were dwarf. The ratio of the result obtained is about 3:1

Statistics In Mendel’S Experiment

Question 6.
Complete the table
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 4
Answer:
a) Axial
b)3:1
c) Round
d) 3:1

Inferences of Mendel:

  • A trait is controlled by the combination of two traits.
  • One character is expressed (dominant character) and the other character remains hidden (recessive character) in the offspring first generation.
  • The character which remains hidden in the first generation appears in the second generation.
  • The ratio of the dominant character and recessive character in the second generation is 3:1

Gene – Allele:
The gene present in the chromosome of the nucleus determines the character. A gene that controls a trait has different forms. The different forms of a gene are called alleles. Generally, a gene has two alleles. When.we illustrate hybridization experiment, the allele that controls the dominant character that is expressed in the first generation is indicated by a capital letter and the allele that controls recessive character is indicated by a small letter.

Biology Chapter 6 Question 7.
Which are the alleles of a tall plant?
Answer:
‘TT are the alleles of a tall plant.

Question 8.
Which are the alleles of the dwarf planets?
Answer:
‘tt’ are the alleles of the dwarf planet.

Question 9.
How do the allele combination of the first generation differ from parental plants?
Answer:
The allele combination ‘Tt’ is responsible for the character height in first-generation instead of TT. One character is expressed and the other character remains hidden in the offsprings.

Kerala Genetics Question 10.
How can you differentiate alleles that control the dominant character and recessive character?
Answer:
The allele that controls dominant character generally indicated by capital letter and the allele that controls recessive character is indicated by a small letter.

Kerala Syllabus 8th Standard Textbooks 2017 Question 11. Observe the illustration showing the hybridization experiment conducted by Mendel on two traits namely height and color of flowers. Complete the illustration and table suitably based on the indicators, analyze illustration and write down inferences.
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 5
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 6
Tall, red flower TtRr
Self-pollination first-generation TtRr x TtRr
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 7

Kerala Syllabus 8th Standard Textbooks 2017 Question 12. What are the characters expressed in the offsprings of the first generation? Which are the recessive ones?
Answer:
Expressed characters – Tall and red flower
Recessive characters – Dwarf and white flower.

Question 13.
Are there new combination of characters different from parents appeared in the second generation? Which are they?
Answer:
Yes. New combination of characters different form parents appeared in the second generation. The appearance of new combination of characters in offsprings is due to the independent assortment of each character.
New combination of characters appeared in second generation

  • Dwarf, red flower plants
  • Tall, white flower plant

DNA (Deoxyribonucleic Acid)

Genetic Mysteries Question 14.
What are the peculiarities of double-helical model of DNA presented by Watson and Crick?
Answer:
James Watson and Francis Crick presented the double-helical model of DNA in 1953. As per the double-helical model, DNA contains two strands. Two strands of DNA are made of phosphate and pentose sugar and steps with nitrogen bases. The nitrogen bases are adenine, thymine, guanine, and cytosine.

Structure of DNA molecule

Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 8
DNA molecule contains two long strands with deoxyribose sugar, phosphate, and steps with nitrogen bases. Nitrogen bases are molecules that contain nitrogen and are alkaline in nature. The nitrogen bases are of four types. In DNA the bases adenine pairs with thymine and guanine pairs with cytosine. One deoxyribose sugar molecule one phosphate molecule and one nitrogenous base join together to form a nucleotide. Nucleotides are the basic unit of DNA. Since DNA has four kinds of nitrogen bases, DNA has four kinds of nucleotides.

Question 15.
Observe the illustration and complete its second strand.
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 9
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 10

Terminal Axial Question 16.
Compare the structure of DNA and RNA and complete the table.
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 11
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 12

How Do Genes Act?

Question 17.
Observe the following illustration and write down the inferences in the science diary.
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 13
Answer:
DNA does not participate directly in protein synthesis. RNA is the molecule that carries information form DNA to ribosomes and controls protein synthesis. This RNA is messenger of DNA, it is called messenger RNA or mRNA. Besides mRNA, there are tRNA (Transfer RNA) that carry amino acids to the ribosomes and rRNA (Ribosomal RNA) that are seen associated with ribosomes. Protein molecule is synthesized by the combined activities of all these molecules.

Question 18.
Prepare a flow chart of Protein synthesize.
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 14
There are 46 chromosomes in human beings. Of these 44 are somatic chromosomes and two are sex chromosomes. A somatic chromosome pair contains two identical chromosomes. Thus in human beings, there are 22 pairs of somatic chromosomes. Sex chromosomes are two types. They are called x chromosomes and y chromosomes. Females have 44 + xx and genetics of variation that of male 44 + XY.

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Genetics Of Variation

Crossing over in chromosomes: A source of variation:

Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 15
During the initial phase of meiosis, chromosomes pair and exchange their parts. This process is called crossing over. As a result of this, part of a DNA crosses over to become the part of another DNA. This causes a difference in the distribution of genes. When these chromosomes are transferred to the next generation, it causes the expression of new characters in offsprings.

Combination of Allele during fertilization:
When gametes undergo fusion, the combination of allele changes. This causes the expression of characteristics in offsprings that are different from parents. Thus fertilization causes variations int the next generation.

Mutation

Question 19.
What is mutation?
Answer:
Mutation is a sudden heritable change in the genetic constitution of an organism.

Question 20.
What are the causes of mutations?
Answer:
The defects in the duplication of DNA, certain chemicals and radiations.

Question 21.
What is the importance of mutations?
Answer:
Certain mutations are harmful and some are helpful for survival of the organisms. Mutations lead to variations in characters. Mutation has great relevance in evolution.

Is The Child – Male Or Female

Observe illustration and write down the inferences in the science diary.
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 16

Question 22.
Is there any difference in the number of chromosomes in male and female.
Answer:
No. In male and female, there is not any difference in the number of chromosomes. In men and women 46 chromosomes are present.

Question 23.
Which chromosome is different in male and female?
Answer:
Sex chromosome is different. The sex chromosome of female is are XX and in male are XY.

Question 24.
What is the possibility for the birth of a male or a female child? Discuss.
Answer:
The possibility for the birth of a male or a female child is more or less equal. If the X chromosomes in male unite with X chromosome in female the offspring will be female and if with the Y chromosome In female the offspring will be male.

Question 25.
Is it fair to criticize mothers who deliver only female- children. Substantiate your opinion scientifically.
Answer:
The XY chromosomes of the father determine whether the child is male or female. Child with XX sex chromosomes is female arid with XY sex chromosomes is made. So male sex chromosomes have greater importance than female sex chromosomes in sex determination. So the view of her husband and relatives is wrong.

Difference In Colour

Melanin, a pigment-protein imparts color to the skin. The difference in gene function is the reason for the color difference of skin. This is simply an adaption to live under sun.

Let Us Assess

Question 1.
The nitrogen base absent in RNA.
a) Admin
b) Thymine
c) Uracil
d) Cytosine
Answer:
b) Thymine

Question 2.
Arrange the stages of protein synthesis in the form of a flow chart.
1. Combines amino acid.
2. mRNA reaches ribosomes
3. mRNA is formed
4. Amino acids are carried to the ribosomes.
Answer:
mRNA is formed → mRNA reaches ribosomes → amino acids are carried to the ribosomes → combines amino acids.

Question 3.
Observe the hybridization experiment given below
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 17
a) Prepare an illustration of this hybridization experiment using symbols
b) Prepare an illustration for the second generation.
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 18
b) Parental plants (Self-pollination of first-generation) F2 → Gg × Gg
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 19

Extended Activities

Question 1.
‘ Prepare an excerpt including information on scientist who made contributions in the progress of genetics. (Hints – Gregor Johann Mendel, Walter, S. Sutton, Boveri, Friedrich Meischer, Johannsen, Avery, James Watson, Francis Crick, Marshall, Nirenberg, Har Gobind Khorana)
Answer:
Milestones in the History of Genetics
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 20

Question 2.
Prepare models of DNA and RNA using locally available materials and present them in a science exhibition.

Unraveling Genetic Mysteries More Questions And Answers

Question 1.
The father of genetics?
Answer:
Gregor Johann Mendel

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Question 2.
Mendel conducted the process of hybridization using one pair of contrasting characters. In all his experiments only one character was expressed. So which was the method he adopted to find out recessive character?
Answer:
Mendel self-pollinated the plants obtained as the first generation.

Question 3.
When Mendel conducted experiment using one pair of contrasting characters, the plants obtained in the F2 generation is was in ………. ratio.
Answer:
3:1

Question 4.
Find out the dominant characters in plants having TTRR, TTRr, TtRR, TtRr traits.
Answer:
All plants are tall with red flowers.

Question 5.
Hereditary factors which Mendel had described are now known as …………….
Answer:
Genes

Question 6.
What are genes?
Answer:
Genes are the specific units of DNA that control metabolic activities and responsible for the specific characters of any organism.

Question 7.
“Offsprings of the same parents show differences among themselves” Give reasons for this?
Answer:
During fertilization alleles from the chromosomes of gametes segregate and causes change in the allele combination. This change causes variations in the offsprings. So offsprings of the same parents also show differences.

Question 8.
When a woman gave birth to girl children in her consecutive deliveries, her husband and relatives blamed her. Evaluate this social situation and write your opinion.
Answer:
The XY chromosomes of the father determine whether the child is male or female. Child with XX sex chromosomes is female and with XY sex chromosomes is male. So male sex hormones have greater importance than female sex chromosomes in sex determination. So the view of her husband and relatives is wrong.

Question 9.
What is the possible ratio for the birth of a male or a female child? What is the reason for this?
Answer:
The possibility for the birth of a male or a female child is more or less equal. If the X chromosomes in male unite with X chromosome in female the offspring will be female and if with the Y chromosome in female the offspring will be male.

Question 10.
Which are the two types of nucleic acids?
Answer:
DNA, RNA

Question 11.
What is the figure shows?
Answer:
a) a DNA molecule
b) a RNA molecule
c) a nucleotide
d) a chromosome
Answer:
a) nucleotide

Question 12.
Identify the picture? From where is it seen?
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 21
Answer:
DNA molecule. DNA molecules are seen in chromosome.

Question 13.
Identify the nucleotides presented in DNA and RNA. Which factor help you to identify this?
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 22
B and C are nucleotides seen in DNA because the adenine and thymine are seen in DNA. A and C are nucleotide seen in RNA because Adenine and Uracil are seen in RNA.

Question 14.
Give examples for different kinds of RNA seen in the cell?
Answer:
mRNA(messenger RNA), tRNA (transfer RNA), rRNA (ribosomal RNA).

Question 15.
What is the following illustration represents?
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 23
Answer:
Protein synthesis of DNA.

Question 16.
Explain the role of mRNA in protein synthesis.
Answer:
DNA does not participate directly in protein synthesis. It unwinds and mRNA is synthesized which carries the information from DNA to ribosomes. Based on the information in mRNA protein is synthesized by proper adding amino acids.

Question 17.
Observe the diagram and find out the names of the labeled parts a. b and c.
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 24
Answer:
a) mRNA
b) Ribosomes
c) Protein molecule

Question 18.
Observe the figures and identify the process given below.
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 25
Answer:
Crossing over

Question 19.
‘ While some mutations are harmful, some of them are helpful.” Analyze the statement.
Answer:
This statement is correct. Certain mutations are harmful and some are helpful for survival of the organism. Mutations also lead to evolution.

Question 20.
‘‘Some specific processes during Meiosis helps to create variation in characters among organisms Analyse this statement and explain the process.
Answer:
Homologous chromosomes from father and mother pair exchange chromosomal material during meiosis. Tbi3 is “Crossing Over” in meiosis.

Question 21.
Diagrammatically represent with symbols the First generation of progenies of Tall and Dwarf pea plants when cross-pollinated as in Mendel’s first stage of Experiment (March 2015)
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 26

Question 22.
Observe the flow chart given below. (Model 2015)
Answer:
i) RNA is synthesized

ii) DNA unwinds

iii) RNA combines with ribosome

iv) RNA comes out through nuclear membrane.

v) Protein molecule is formed.

vi) Different amino acids are formed.

a) Arrange the flow orderly.
b) Identify the process.
Answer:
a) DNA unwinds

RNA Is synthesized

RNA comes out through nuclear membrane.

RNA combines with ribosome

Different amino acids are formed.

Protein molecule is formed
b) Protein synthesis or gene action

Question 23.
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 27
(Model 2014)
Observe the diagram Identify the process which occurs in Chromosomes during meiosis.
Answer:
Crossing over

Question 24.
A pea plant with genetic constitution TtRr (Tall plant which produces red flower) was subjected to self-pollination. The genetic constitution of some of the progenies obtained are given below.
Write the expressed character of the given progenies based on their genetic constitution. (Model 2014)
(a) TTRr
(b) ttrr
(c) ttRr
(d) Ttrr
Answer
a) TTRr – tall plant with red flower
b) ttrr – dwarf plant with white flower
c) ttRr – dwarf plant with red flower
d) Ttrr – tall plant with white flower

Question 25.
Mr. Rajan decided to divorce his wife by arguing that she is incapable to give birth to a boy child.
a) Can you agree with Mr. Rajan?
b) Give scientific explanation, to this problem with the help of an illustration showing the role of sex chromosomes in determining sex in human beings.
Answer:
a) I cannot agree with Rajan
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 28
Y chromosome from male decide the sex of child

Question 26.
Find the odd one. Write down the common feature of the others. (March 2014)
a) Bypass surgery, ECG, EEG, Pacemaker
b) Adenine, Cytosine, Thymine, Uracil
Answer:
a) EEG: Related with the treatment of heart diseases
b) Uracil: Nitrogen bases in DNA/Thymine: Nitrogen bases in RNA.

Question 27.
Gopalettan is trying to develop new varieties of pea plants in his garden. Given below is the illustration of the experiment which he conducted. Observe this and answer the questions that follow. (Model 2013)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 29
a) Which law of hereditary can be used to explain the reason of violet flowered plants in the F1 generation?
b) Among these, which are the dominant and recessive characters?
c) What will be the characters appearing in the F2 generation if the plants in the F1 generation are self-pollinated? In what ratio?
Answer:
a) Law of dominance. (When a pair of contrasting characters combines, only one character is expressed, while the other remains hidden.)
b) Dominant is violet and recessive is white.
c) Yellow and green seeds in 3:1 ratio.

Question 28.
Fill up the blanks in the table showing gene action in protein synthesis. (Model 2013)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 30
Answer:
a) RNA is being synthesized
b) RNA comes out through nuclear membrane
c) RNA1 combines with ribosomes

Question 29.
Rearrange B and C according to the data given in A. (Model 2013)

A Nucleic Acids B Sugar C Nitrogen Base
i) DNA Ribosome Uracil
ii) RNA Deoxyribose Amenin
Ribose Thymine

Answer:

A Nucleic Acids B Sugar C Nitroge Base
i) DNA Deoxyribose Thymine
ii) RNA Ribose Uracil

Question 30.
A portion of DNA molecule is shown below. Find out the missing nitrogen base pair from those given below. (Model 2012)
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Answer:
(b) C – G

Question 31.
The fusing of gametes during self-pollination of F1 in pea plants with two separate characters combined together were tabulated; (Model 2012)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 32
A) Fill up the blanks.
B) How many white-flowered plants will be formed if 16 pea plants in F2 generation were produced?
Answer;
A) (a) TtRR
(b) Ttrr
(c) ttRR
(d) ttrr
B) 4

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Question 32.
Given below is the illustration showing how sex determination is taking place in man. (March 2012)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 33
a) Observe the illustration and examine the 4 types of possible offsprings. Specify their sex chromosomes.
b) What are the inferences you arrive at from this illustration?
c) What is the probable ratio of formation of male child and female children in man ? Illustrate your answer.
d) Which are the sex-determining chromosomes in man?
Answer:
a) (i) and (iii) are female children having XX chromosomes
(ii) and (iv) are male children having XY chromosomes
b) The sex chromosomes of male determine the sex of a child. The probability of formation of male and female children is almost equal (1:1)
c) 1: 1
d) Male XY and female XX.

Question 33.
Using given indicators, construct RNA nucleotide and anyone DNA nucleotide. (March 2012)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 34
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 35

Unraveling Genetic Mysteries Questions & Answers

Question 1.
Find the word pair relationship and fill in the blanks appropriately. (Question Pool – 2017)
a) DNA: Thymine
RNA:……………..
b) Adenine: Thymine
Guanine:…………………
c) The character which is expressed: dominant
The character which remains hidden:……………
Answer:
a) Uracil
b) Cytosine
c) Recessive character

Question 2.
Given below are certain indicators exhibited by Anu in her slide presentation while conducting seminar on the topic ” Emergence of Genetics”. What explanations would you give for these indicators?
a) Heredity
b) Variation
c) Genetics
d) The father of Genetics
Answer:
a) Transmission of features of parent to offspring.
b) Features seen in offspring that are different from their parents.
c) The branch of science that deals with heredity and variation.
d) Gregor John Mendel

Question 3.
The note prepared by Shahana on Mendel’s inferences during the classroom analysis of Mendel’s hybridization experiment in pea plants, based on a single trait is given below. Analyze the statements in the note and correct those that are wrong ones.
a) A trait is controlled by a specific factor.
b) A character is expressed and the other remains hidden in the first generation.
c) The character that remains hidden, in the first generation does not appear in the second generation.
d) The ratio of characters in the second generation is 3: 1
Answer:
a) One trait is controlled by the combination of two factors.
b) The characters that remain hidden in the first generation appears in the second generation.

Question 4.
Fill in the blanks in the illustration given below. (Question Pool -2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 36
Answer:
A) tt
B) t
C) Tt
D) dwarf

Question 5.
Complete the flowchart illustrating the location of gene by using the information given in the box: (Question Pool – 2017)
nucleus, gene, DNA, cell, chromosome
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 37
Answer:
A – Cell
B – Nucleus
C – Chromosome
D – DNA

Question 6.
Analyze the article and answer the questions. The experiments performed by Gregor John Mendel in pea plants led to the emergence of a new branch of science that has today grown and expanded to a great extent. This branch of science has untravelled several mysteries regarding the similarities and variations found in the characters of organisms. (Question Pool – 2017)
a) Which branch of science does the article refer to?
b) List out any 4 traits selected by Mendel for performing hybridization in pea plants.
Answer:
a) Genetics
b) Height, colour of the seed, colour of the flower, shape of the seed, color of the fruit, shape of the pod

Question 7.
Observe the illustration given below and answer the questions. (Question Pool-2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 57
a) Identify the dominant character
b) How does the parental plant with green colored seed and the plant in the first generation differ in their alleles.
c) Describe alleles.
Answer:
a) Green
b) Alleles in parental plant – G, G Allele in the first generation – G, g
c) Different forms of a gene

Question 8.
Fill in the blanks in the illustration related to chromosomes in man. (Question Pool-2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 39
Answer:
A) Autosomes
B) 2
C) XY

Question 9.
Identify the word pair relationship and fill in the blanks: (Question Pool -2017)
Female : 44 + XX
Male: …………….
Answer:
44 + XY

Question 10.
Fill in the blanks in the illustration. (Question Pool-2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 40
Answer:
A. ggww
B. GW
C. Green colored round seed

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Question 11.
The indicators given below are about the plant in the first generation formed as a result of the hybridization between a tall plant with red flowers and a dwarf plant with white flowers. (Question Pool-2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 41
a) Identify the alleles in the plant related to the trait ’tallness’.
b) Identify the gametes formed from this plant.
Answer:
a) T, t
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 42

Question 12.
Complete the illustration of the second generation obtained from the hybridization in which two traits of a plant are considered. (Question Pool-2017)
Indicators:
Dominant character – Tallness, red color of flower Recessive character – Dwarfness, white color of flower
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 43
Answer:
A. TTRr
B. TtRr
C.TTRr
D. TtRr
E. TtRr
F. ttRR
G. ttRr
H. TtRr

Question 13.
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 44
Given below are some of the offspring obtained by self-pollinating the above plant. Analyze the offspring and answer the questions.
a) ttRr
b) ttRR
c) TTrr
d) ttrr
i) Identify the dominant characters in each of the offspring?
ii) What explanation would you give for the expression of characters in the offspring which were hidden in the parental plant?
Answer:
i. a) dwarf, red flower
b) dwarf, red flower
c) tall, white flower
d) dwarf, white flower
ii. The expression of characters in the offsprings which were hidden in the parental plant is due to the independent assortment of each character.

Question 14.
Analyze the illustration of a nucleotide molecule and answer the questions. (Question Pool-2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 45
a) Identify A and B in the illustration.
b) ‘Nucleotides are found in DNA alone’. What is your opinion regarding these statements? Substantiate.
Answer:
a) A – Phosphate
B – Sugar
b) 1. does not agree
2. Like DNA, RNA is also made up of nucleotides

Question 15.
Genes which are the specific units of DNA control the metabolic activities and are also responsible for specific characters. They control the process of protein synthesis. Binu has a doubt on the above note. (Question Pool – 2017)
‘Does the RNA have no role in protein synthesis?’ What explanation would you give to Binu’s doubt? Substantiate.
Answer:

  • RNA has role
  • DNA is not directly involved in protein synthesis
  • mRNA is formed from DNA.
  • mRNA that carries information from DNA, controls the protein synthesis
  • tRNA carries amino acids to ribosomes
  • rRNA associated with ribosomes also have a role in protein synthesis.

Question 16.
The components and features of nucleic acid are given below. Analyze them and complete the table. (Question Pool-2017)
a) ribose sugar
b) double helical shape
c) Uracil
d) one strand
e) deoxyribose sugar
f) thymine
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 46
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 47

Question 17.
Observe the nucleotide strands given below and answer the questions. (Question Pool-2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 48
a) Identify the strand that is found in DNA only.
b) Identify the strand that can be found in both DNA and RNA.
c) What is a nucleotide?
Answer:
a) B
b) A
c) A unit of sugar, phosphate and nitrogen base / Component of nucleic acid

Question 18.
The stages in the process of protein synthesis are given below. Prepare a flowchart using the stages. (Question Pool-2017)
a) tRNA carries different kinds of amino acids to the ribosome.
b) mRNA reaches outside the nucleus.
c) mRNA forms from DNA
d) Amino acids are added based on the information in mRNA
e) mRNA reaches ribosome.
f) Proteins are synthesized.
Answer:
c → b → e → a → d → f

Question 19.
A part of the article. Variations in ourself is given below: The features seen in offspring that are different form their parents are called variations. Certain processes taking place in the initial phase of meiosis are responsible for such variations. (Question Pool-2017)
a) Which process, as mentioned in the article, is responsible for variations?
b) How does this process bring about variations?
Answer:
a) Crossing over of chromosomes
b) 1. Part of a DNA crosses over to become the part of another DNA.
2. This causes difference in the distributions of genes
3. When these chromosomes are transferred to the next generation, new characters are expressed.

Question 20.
The process of crossing over of chromosomes that takes place in the initial phase of meiosis is illustrated below. Analyse-it and answer the questions. (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 49
a) Arrange the stages appropriately.
b) This process brings about variations in offspring. How?
Answer:
a) C, A, B
b) 1. Part of a DNA crosses Over to become the part of another DNA.
2. This causes difference in the distributions of genes.
3. When these chromosomes are transferred to the next generation, new characters are expressed.

Question 21.
Given below is an illustration regarding sex determination Observe the illustration and answer the questions. (Question Pool-2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 50
a) Complete A, B, C in the illustration.
b) What is the possibility of the formation of a male child or a female child? Explain.
Answer:
a) A) 44 + XY
B) 22 + X
C) 22+ Y
b) Equal chance. The number of male gametes with X chromosome and those with Y chromosome are equal.
Egg with the X chromosome has equal chance to combine with sperm having Y chromosome and those having X chromosome.

Question 22.
The practice of blaming those mothers who give birth to girl children exists even today. (Question Pool – 2017)
a) As a science student, how will you respond to this situation? Substantiate.
Answer:

  • No, it is wrong to blame the mother
  • The possibility of the birth of male or female child is equal.
  • The gender of the child is determined by the XY chromosome of the father.

Question 23.
The chromosomes from the father determine whether the child is male or female. Evaluate this statement on a scientific basis. (Question Pool-2017)
Answer:
Males have 2 types of sex chromosomes. (X, Y) Females have only one type of sex chromosome (X, X) Sex determination is based on the type of male gamete that fuses with the egg. If the male gamete with Y chromosome fuses with the egg, then male child is born, if the male gamete with X chromosome fuses with the egg, then female child is born.

Question 24.
Given below is a placard exhibited in a school rally organized ‘Against Racism’. It is not racial difference that makes the skin color different;
This is an adaptation to live under the sun.
a) How ; will you. explain the difference in skin color of people living in different parts of the world?
b) What attitude should be adopted by a scientifically enlightened society towards the idea in the placard? Substantiate.
Answer:
a) 1. Melanin, a pigment-protein imparts color to skin.
2. It is due to the difference in gene function,
b) 1. Skin color is an adaptation to live under the sun.
2. Races among making are only cultural.
3. Scientifically, all men are of the same race.
4. Consider all men as equal, without any racial difference.

Question 25.
Vipin wrote the following as situations that create variations in organisms. Choose the right ones. (Question Pool – 2017)
a) Mutation
b) Formation of mRNA
c) Crossing over of chromosomes
d) Action of rRNA
Answer:
a) Mutation
c) Crossing over of chromosomes

HSSLive.Guru

Question 26.
The components of nucleic acids are given below. Answer the questions through illustrations using these components: (Question Pool – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 51
a) Illustrate the nucleotide which is found only in RNA.
b) Illustrate the nucleotide which is found only in DNA.
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 52

Question 27.
Analyze the nitrogen bases given below and write the nitrogen base pairs found in DNA. (Question Pool-2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 53
Answer:
Thymine – Adenine.
Guanine – Cytosine

Question 28.
‘Gene itself is allele; allele itself is gene. (Question Pool – 2017)
Answer:
Statement is party correct.
Each character is controlled by pair factors called genes.
Different forms of a gene are called alleles. Generally, a gene has two alleles. ,
Alleles can be of the same type (TT) or different types (Tt).
If the alleles are of different types, only one trait represented by anyone of the alleles get expressed.

Question 29.
Offsprings may vary in characters from their parents.
a) What are reasons of this variation in the light of genetics?
b) How does the changes take place during meiosis cause variations in next generation?
c) How does the chemical substances and the radiations cause variation in characters?
Answer:
a) Crossing over and mutations.
b) When a part of a particular DNA become the part of another DNA, the sequencing of nucleotides in the DNA become differs and hence variation may occur in the offsprings.
c) Mutation may occur due to chemicals and radiations.

Question 30.
Observe the illustration related to Mendel’s experiment based on two contrasting characters.
a) Complete the illustration appropriately
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 54
b) What are the characters observed in the second generation?
Answer:
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 55
b) Tall with red flowers = 9
Tall with white flower = 3
Dwarf with red flowers = 3
Dwarf with white flowers = 1

Question 31.
The different stages of protein synthesis given below. Rearrange them appropriately. (Orukkam – 2017)
a) tRNA carries different types of amino acids.
b) mRNA come out from the nucleus.
c) mRNA is formed from DNA.
d) Amino acids are joined together based on the messages in mRNA.
e) mRNA reaches in ribosome.
f) Protein is synthesized.
Answer:
c → b → e → a → d → f

Question 32.
Observe the figure and answer the questions given below. (Orukkam – 2017)
Kerala Syllabus 10th Standard Biology Solutions Chapter 6 Unravelling Genetic Mysteries - 56
a) Name the process shown in the figure.
b) Write the importance of this process.
Answer:
a) Crossing over
b) Causes variation

Question 33.
Write the role of mRNA and tRNA in protein synthesis. (Orukkam – 2017)
Answer:
mRNA carries messages for protein synthesis from DNA to the ribosomes.
tRNA carries amino acids to ribosomes according to the message in the mRNA.

Question 34.
What is mutation? Write the reasons? (Orukkam – 2017)
Answer:
Mutation is a sudden heritable change occur in the genetic material (chromosomes)
Reasons: – Radiations, chemicals, changes in the replication of DNA.

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