NCERT Class 10 Science Chapter 9 Heredity and Evolution Extra Questions and Answers
Class 10 Science Chapter 9 Extra Inside Questions and Answers – Heredity and Evolution. Here in this Page Class X Students can Learn Extra Questions & Answer 9th Chapter Science fully Inside.
We Provided Here Heredity and Evolution Science Chapter 9 Long Answer Type Question, Multiple Choice Questions & Answer, Short Answer Type Questions (2 or 3 marks), and Very Short answer Type Question (1 marks) Solution.
Class 10 Science Chapter 9 Extra Question with Answer – Heredity and Evolution
Science Chapter 9 Heredity and Evolution Class 10 Inside 5 Marks, 3 marks, 2 Marks & And 1 Marks Important Questions and Answers.
a.) Solve the following mcqs
1.) Number of the successful variations are maximised by the process known as………………. reproduction.
a.) Asexual
b.) Sexual
c.) Vegetative
d.) None of the above
Ans. b. Sexual
Hint: Sexual reproduction serves as the source of variation.
2.) In asexual reproduction,……………………..individual reproduces.
a.) Single
b.) Double
c.) Triple
d.) Many
Ans. a. Single
Hint: only one parent is required for asexual reproduction.
3.) …………………………………are now called as genes.
a.) Factors
b.) Sector
c.) Arc
d.) Segments
Ans. a. Factors
Hint: Mendel used word factor for genes.
4.) Pea plant is………………………..
a.) Asexually reproducing
b.) Asexually reproducing
c.) All of the above
d.) None of the above
Ans. b. Sexually reproducing
Hint: pea plant requires two parents for seed formation. Hence, it is sexually reproducing.
5.) …………………is the source of information for making various types of proteins in the cell.
a.) Mitochondrial DNA
b.) Chloroplast DNA
c.) Cellular DNA
d.) Cellular RNA
Ans. c. Cellular DNA
Hint: Information present in Cellular DNA is the source of information for making various types of proteins in the cell.
6.) Each cell have ……………..copies of each chromosome inherited from both of his parents.
a) One
b) Two
c) Three
d) Four
Ans. two
Hint: one chromosome comes from mother and another from father hence each cell have two copies of each chromosome inherited from both of his parents.
7.) Women in human beings always have a ………………….pair of sex chromosomes.
a) Perfect
b) Imperfect
c) Uneven
d) Separate
Ans. a. Perfect
Hint: Womens have two X chromosomes hence they have perfect pair of sex chromosomes.
8.) The sex of the children will be determined by the sex chromosome they inherit from their……………
father
mother
brother
sister
ans. a. father
hint: father is responsible for determining the sex of child as it has two sets of sex chromosomes- X and Y.
b) ans. the following questions in short:
1.) What are the basis for evolutionary processes?
Ans. Selection of suitable variants by various environmental factors are the basis for evolutionary processes.
2.) What do heredity determines?
Ans. The hereditary determines the process by which traits and characteristics are inherited from one generation to the next.
3.) Who did experiments on pea plants?
And. Gregor Johann Mendel did experiments on pea plants.
4.) Define chromosome?
Ans. Chromosome are the single long thread of DNA.
In case you are missed :- Previous Chapter Extra Questions
5.) What do control traits?
Ans. factor which are now called as genes, controls traits in an individual.
6.) Define gene?
Ans. gene is a section of DNA which provides the information needed for making of a protein in the cell is called as the gene.
7.) How many pairs of chromosomes do human beings have?
Ans. humans have 46 chromosomes in total hence have 23 pairs of chromosomes.
8.) Which force operates in the selection of variation?
Ans. variation should be naturally selected in order for its survival in an individual.
9.) What do the specialised reproductive cells are called?
Ans. the specialised reproductive cells are called as germ cells.
10.) theory of evolution is proposed by whom?
Ans. Darwin is the proposer of theory of evolution.
q.3.) ans. the following questions
1.) Write down the genetic constitution of men and women?
Ans. human men have 22 pairs of autosomes along with XY sex chromosomes whereas human women have 22 pairs of autosomes along with XX sex chromosomes.
2.) Enlist the contrasting characters Mendel selected for his experimentation?
Ans. Mendel used a number of contrasting visible characters for his experiments on garden peas: round seeds /wrinkled seeds,
Tall pea plants /short pea plants,
White colour of flowers /violet colour of flowers
3.) What are homologous organs? Explain with examples?
Ans: Homologous organs are the organs which have the same structure but they perform different functions. For example- forelimbs of humans and forelimb of lizard have same internal structure but they both perform different functions.
4.) Why germ cells serve as vehicles for evolution than other body cells?
Ans. Change in the genetic constitution of tissues which are non-reproductive cannot pass on to the DNA of the germ cells of the same individual. Therefore the experiences and changes in his genetic constitution of an individual during its lifetime cannot be passed on to its progeny, and cannot direct the process of evolution.
5.) What do you understand by the term analogous organs? Explain.
Ans. Analogous organs are the organs which have different structure but performing similar function. For example, wings of birds and insects are different in structure and origin but perform a same function i.e. flying.
6.) Write a note on autosomes and sex chromosomes?
Ans. chromosomes can be categorised into two types as autosomes and sex- chromosomes. The chromosomes which determines the sex of the individual organisms are called as sex- chromosomes whereas the chromosomes who determines body characters other than the sex are called as autosomes.
4.) Ans. the following questions in details
1.) What are dominant and recessive traits? Mendel found which trait to be dominant and which to be recessive?
Ans. the trait which expresses itself even in the presence of its alternative allele is called as dominant trait. The trait which cannot express itself in the presence of its alternative form or it can express itself only in the absence of the alternative allele is called as recessive. Mendel with his experiments on pea plants found that plant with tall height are dominant over the dwarf pea plants. As tall plants were obtained even in the heterozygous conditions but dwarf did not.
2.) What is mean by speciation? What do you think is the probable cause of speciation?
Ans. origin of the new species from the pre- existing species over a passage of time can be termed as the speciation. Mutations occur during DNA replication which leads to different types of variations among the populations. This variations accumulate in the given population and passes to the next progeny and this carries out over a generation for a large passage of time. And this gives rise to the origin of new species called as speciation.
3.) Why do you think that fossil study is important when you are studying evolutionary history of an organism?
Ans. Fossils are important to study the process of evolution because they tell us about the past flora and fauna which we cannot see today. By studying fossil we can link the ancient flora and fauna with the one which we can see today. This helps us to establish the link between the two and trace evolutionary history.
4.) What phenotypic ratio Mendel got by crossing Tall pea plants with dwarf pea plants?
Ans. Mendel crossed homozygous tall pea plants with the homozygous dwarf pea plants and observed the progeny. F1 generation plants were also tall and dwarf in height but in a typical ration. He got 3 tall plants with 1 dwarf. Hence, the phenotypic ration becomes 3 tall: 1 dwarf.
5.) What will be sex of child if a sperm containing Y- chromosome fertilizes with an female gamete? Justify your decision.
Ans. if a sperm containing Y- chromosome fuses with the female gamete then a baby girl will be born. Because after fertilization, the genetic constitution of baby will be 44+XY which is the genetic constitution for a baby boy as human males are heterogametic and produce two types of gametes.
6.) Explain the process of fossilization?
Ans. When any organisms die, its body get decomposed and gets lost. But sometimes, the decomposition of the dead body does not occur due to environmental forces or it does not get sufficient time for decomposition. At that time, if that body gets trapped in a mud or a resin, it gets preserved as it is for a long period of time and thus forms fossil. This is the process of fossil formation also called as fossilization.
7.) Explain Mendel’s monohybrid cross in detail and comment on phenotypic and genotypic ratio he got?
Ans. Mendel conducted his experiments on the Pisum sativum or pea plant. To find out dominant and recessive traits in the plant, he selected and crossed homozygous tall (TT) pea plant with the homozygous dwarf (tt) pea plant and observed the next progeny. From this cross, it was observed that the F 1 generation is having all tall pea plants. After crossing F1 plants, he got tall plant again with some dwarf plants too. he calculated their ration and found that the phenotypic ratio was 3tall : 1 dwarf. But, genotypically, one plant was homozygous tall (TT), two plants were heterozygous tall (Tt) and one plant was homozygous dwarf (tt) so, the genotypic ratio was 1:2:1.
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