KSEEB Solutions for Class 10 Science Chapter 9 Heredity and Evolution

Students can Download Science Chapter 9 Heredity and Evolution Questions and Answers, Notes Pdf, KSEEB Solutions for Class 10 Science helps you to revise the complete Karnataka State Board Syllabus and to clear all their doubts, score well in final exams.

Karnataka State Syllabus Class 10 Science Chapter 9 Heredity and Evolution

KSEEB Class 10 Science Heredity and Evolution Intext Questions and Answers

Question 1.
If a trait A exists in 10% of a population of an asexually reproducing species and a trait B exists in 60% of the same population, which trait is likely to have arisen earlier?
Answer:
Trait B is likely to have arisen earlier as it is present in more individuals of the population, it takes much time for a character to spread vastly through reproduction, generations after generations in a population.

Question 2.
How does the creation of variations in a species promote survival?
Answer:
Some variations enable some individuals to adapt better in this ever-changing environment. Thus the advantageous variations of species promote its survival. Ex: Bacteria that can withstand heat will survive better in a heatwave.

Question 3.
How does variations occur in offsprings?
Answer:
Variations are generated due to small inaccuracies in, DNA copying at the of cell division.

Question 4.
How do Mendel’s experiments show that traits may be dominant or recessive?
Answer:
When mendel cross pollinated pure tall pea plants with pure short pea plants all the F₁ generation plants were tall. When mendel self pollinated F₁, tall plants, he got both tall and short plants in the ratio 3:1 in F₂ generation. That means short character was present in F₁ tall plants but it was suppressed and only trait of tallness was expressed. Mendel proposed that in a pair of dissimilar traits, one dominates the other (Tallness in the F₁) and hence called the dominant trait while the other one is recessive

Question 5.
How do Mendel’s experiments show that traits are inherited independently?
Answer:
A tall plant with round seeds and a short plant with wrinkled seeds were crossed by Mendel. All of the F₁progeny plants were tall and had round seeds. Tallness and round seeds were thus dominant traits. When F₁ progeny were self pollinated a mixture of tall plants with round seeds, short plant with wrinkled seeds, tall plants with wrinkled seeds and short plants with round seeds were formed. Thus, the tall/short trait and the round seed / wrinkled seed trait were inherited independently.

Question 6.
A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?

Answer:
No, we cannot ascertain which blood group is dominant.

Question 7.
How is the sex of the child determined in human beings?
Answer:
In human beings out of 23 pairs of chromosomes present, 22 pairs are exactly same in both males and females; these are autosomes which determine the characters. The 23 rd pair of chromosomes is called sex chromosomes. A pair of X – chromosomes are present in the female. Whereas in male the pair consist an X – chromosome and a shorter Y – chromosome. All children will inherit an X – chromosome from their mother regardless of whether they are boys or girls A child who inherits an X chromosome from her father will be a girl and one who inherits a Y chromosome from the father will be a boy.

Question 8.
What are the different ways in which individuals with a particular trait may increase in a population?
Answer:
If a variation occurs in a population, that makes the organism better adapted to survive in the prevailing natural conditions, then the trait would be selected naturally and individuals with that trait may increase in the population through reproduction.

Question 9.
Why are traits acquired during the lifetime of an individual not inherited?
Answer:
Change in non – reproductive tissues cannot be passed on to the DNA of the germ cells. Therefore traits acquired during the lifetime of an individual are not inherited.

Question 10.
Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?
Answer:
Variations are very important for better survival chances of a species. Smaller numbers lead to lesser variants. A natural calamity like forest fire or outbreak of disease kills off the small numbers of surviving tigers and their genes will be lost forever.

Question 11.
What factors could lead to the rise of a new species?
Answer:
Accumulation of inheritable variations favorable to the existing natural environment, geographical isolation of sub-populations, natural selection,(genetic drift, change in the number of chromosomes are the factors that could lead to speciation.

Question 12.
Will geographical isolation be a major factor in the speciation of a self-pollinating. plant species? Why or why not?
Answer:
Geographical isolation is not a major factor in the speciation of a self- pollinating plant species because stigma is pollinated by the pollen grains coming from the same plant.

Question 13.
Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?
Answer:
Geographical isolation is not a major factor in the speciation of an asexually reproducing organism A single parent is enough to pass on the genetic substance to offsprings. The offspring are exact copies of their parent, thus geographical isolation has no effect on asexually reproducing organisms.

Question 14.
Give an example of characteristics being used to determine how close two species are in evolutionary terms.
Answer:
Study of homologous organs is used to determine the common ancestry .of two species. Fossils of some dinosaurs show that they had feathers, although they could not fly. Birds must have later adapted the feathers to fly. This example helps us to know that birds are closely related to reptiles. ( Dinosaurs were reptiles).

Question 15.
Can the wing of a butterfly and the wing of a bat be considered homologous organs? Why or why not?
Answer:
No. wings of a butterfly and the wings of a bat are not anatomically similar structures though they perform same functions. They are analogous organs.

Question 16.
What are fossils? What do they tell us about the process of evolution?
Answer:
All preserved traces of living organisms are called fossils. Fossils tell us that life-forms varied over time and certain life forms were restricted to certain geographical time – spaces. Hence, new forms of life must have arisen at different times in the history of earth.

KSEEB Class 10 science Heredity and Evolution Textbook Exercise Questions and Answers

Question 1.
A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as
(a)TTWW
(b) TTww
(c)TtWW
(d)TtWw
Answer:
(c) TtWW

Question 2.
An example of homologous organs is
(a) our arm and a dog’s fore-leg.
(b) our teeth and an elephant’s tusks.
(c) potato and runners of grass.
(d) all of the above.
Answer:
(d) all of the above.

Question 3.
In evolutionary terms, we have more in common with
(a) a Chinese school-boy.
(b) a chimpanzee.
(c) a spider.
(d) a bacterium.
Answer:
(a) a Chinese school-boy.

Question 4.
A study found that children with light- coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?
Answer:
We can say that light eye colour trait is dominant because only dominant traits are expressed in the first generation. (F, generation).

Question 5.
How are the areas of study – evolution and classification – interlinked?
Answer:
Evolution and classification are linked in many ways. Classification of organisms is based on relative similarities and differences among organisms. The more resemblances two species share, the more closely they are related. The differences in between them are due to adaptations to different types of environment.

Question 6.
Explain the terms analogous and homologous organs with examples.
Answer:
The organs which are similar in appearance and perform similar functions but quite different in their origin and development are analogous organs. Ex : Sweet potato (root modification) and potato (modified stem) Homologous organs are organs which have common origin and are built on the same fundamental pattern, but they may have similar or different appearance due to varied functions. Ex: The patterns of bones of forelimbs in man, bat, whale and cheetah.

Question 7.
Outline a project which aims to find the dominant coat colour in dogs.
Answer:
A black homozygous male is mated with a brown homozygous female. If all the pups born are black then the dominant coat colour is black. Only dominant trait appears in F₁, generation.

Question 8.
Explain the importance of fossils in deciding evolutionary relationships.
Answer:
A study of fossils in different sedimentary layers indicates. The geological period in which they existed. Fossils represent extinct organisms, some of them resemble modem organisms. This indicates that existing life forms have evolved from common ancestors.Ex: The fossils of archeopteryx explain about how birds have evolved from reptiles.

Question 9.
What evidence do we have for the origin of life from inanimate matter?
Answer:
In 1953, S.L.Miller and Harold. C. Urey devised an experiment to simulate the primitive earth conditions in a laboratory scale. At high temperature, sparks were passed through a mixture of gases to simulate lightning. At the end of a week organic molecules such as amino acids were formed. Millers experiment proved that life originated from non- living molecules.

Question 10.
Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?
Answer:
Sexual reproduction gives rise to more viable variations than asexual reproduction.
This occurs through

• Random separation of homologous chromosomes during gamete formation.
• Exchange of hereditary material between homologous chromosomes during formation of gametes.

Sexually reproducing organisms evolve in each succeeding generations to adapt themselves better to changing conditions.

Question 11.
How is the equal genetic contribution of male and female parents ensured in the progeny?
Answer:
Genetic material in most organisms is present in pairs of chromosomes (diploid). During meiosis, gametes are formed where only one set of chromosomes gets incorporated into each gamete. (Haploid) When the gametes from male and female parents fuse with each other during sexual reproduction, the normal complement is restored.

Question 12.
Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?
Answer:
No, this is not necessarily true, there are numerous variations that have no function but yet organisms persist.

Multiple choice questions:

Question 1.
One who arrived at law of inheritance was
a) G.T. Mendel
b) Charles Darwin
c) Homosapiens
d) Newton
Answer:
a) G.T. Mendel

Question 2.
The deceudants from wild cabbage are
a) Couliflower
b) Broccoli
c) Cabbage
d) All of these
Answer:
d) All of these

Question 3.
Fossil is
a) Impressions of a hard body part of an organisms on sand or any material
b) Record of euidance that organisms once lined
c) both (a) and (b)
d) Neither (a) nor (b)
Answer:
c) both (a) and (b)

Question 4.
Dianossurs are not found today. But we can find their
a) Eggs
b) Houses
c) Fossils
d) Legs
Answer:
c) Fossils

Question 5.
Limbs of a frog, lizard, bird, human are
a) Analogous
b) Homologus
c) Analogous and Homologous
d) Homosapiens
Answer:
b) Homologus

KSEEB Class 10 Science Heredity and Evolution Additional Questions and Answers

Question 1.
Define a gene determination is regulated by
Answer:
A section of DNA that provides information for one protein is called the gene for that protein.

Question 2.
Give an example where sex environmental factors is regulated by environmental factors.
Answer:
In alligators, the temperature determines gene for that protein the sex of the developing eggs.

Question 3.
Individuals can change sex, as we can see in animals like.
a) Honey bee
b) Sparrow
c) Snail
d) Shark.
Answer:
c) Snail

Question 4.
What is a chromosome?
Answer:
Chromosome is the microscopic threadlike structures in the cell that carries hereditary information in the form of genes.

Question 5.
Write the expanded form of DNA.
Answer:
Deoxyribo nucleic acid.

Question 6.
Define Heredity.
Answer:
The transmission of structural, functional and behavioural traits from one generation to another is termed as heredity.

Question 7.
Name the plant on which Mendel performed his experiments.
Answer:
Garden pea (Pisum sativum)

Question 8.
State the law of Dominance.
Answer:
It states that one of the factors of a dissimilar pair dominates the other (recessive) resulting in the expression of only one of the parental characters in the F₁ generation.

Question 9.
State the principle of segregation.
Answer:
The separation, of two alleles during gamete formation and the restoration of paired conditions during random fertilization is called the principle of segregation.

Question 10.
Sketch the schematic representation of inheritance of a single trait over two generations.
Answer:

Question 11.
Genetic information is carried out by a long chain of molecules made up of
a) Enzymes
b) DNA
c) aminoacids
d) Glucose.
Answer:
b) DNA

Question 12.
A pair of contrasting characters is called ……………
a) Genotype
b) Phenotype
c) Allele
d) Genes
Answer:
c) Allele

Question 13.
In at eros Tt X Tt, the percentage of offsprings produced having the same phenotype as parents would be
a) 50%
b) 100%
c) 25%
d) 75%
Answer:
a) 50%

Question 14.
Define species.
Answer:
A group of individual organisms with fundamental similar characters, which can interbreed among themselves is referred to as species.

Question 15.
Illustrate with an example how fossils were formed.
Answer:
If a dead insect gets caught in hot mud, for example it will not decompose quickly, and the mud will eventually harden and retain the impression of the body parts of the insect. Such preserved traces of living organisms form fossils

Question 16.
What is evolution?
Answer:
Evolution is the generation of diversity and the shaping of diversity by environmental selection.

Question 17.
A bats wing and a cats paw are examples of …………….
a) Homologous organs
b) Vestigeal organs
c) Primitive organs
d) Analogous organs
Answer:
Homologous organs.

Question 18.
Sweet potato and potato are examples of ………………
a) Homologous organs
b) Primordial organs
c) Vestigial organs
d) Analogous organs.

Question 19.
How can we calculate the age of fossils?
Answer:
The age of fossils is calculated by detecting the ratios of different isotopes of the same ‘ element in the fossil material.

Question 20.
Taking example of wild cabbage, explain how dissimilar – looking structures evolve from a common ancestor.
Answer:
Man has been cultivating wild cabbage over more than two thousand years. Different vegetables have been. generated from it by artificial selection. They are as follows:

• Cabbage having leaves with short distances between them.
• Broccoli with arrested flower development.
• Cauliflower was made selecting sterile flowers.
• Kale selected for larger leaves.
• Kohlrabi was selected for swollen parts.

Question 21.
A husband has 46 chromosomes his wife has 46 chromosomes. Then why don’t their offspring have 46 pair of chromosomes which is obtained by the fusion of male and female gamete support your answer with a neat illustrate?
Answer:
At the stage of gamete formation meiosis occurs as a result each gamete receivers half no. chrosomes of the parent. So when male gamate (sperm) fuses with egg original no. of chrosomes of the parent received by the zygote.

Illustration:

Question 22.
How variations occurs in sexual reproduction.
Answer:

• Due to error in D.N.A copying
• Due to favorable and unfavorable conditions.

Question 23.
Which of the following traits can not be passed to the progeny? Justify your answer.
a) Rudimentary eye of mouse.
b) Absence of tail in a mouse [after surgical removed]
c) Low weight of a starning beetle
Answer:
The following trait can not be passed on the progeny. Because these traits do not cause change in Genes [D.N.A] of the germ eyes and hence can not be passed to the progeny.

Question 24.
Where are the Genes located? What is the chemical nature of Genes.
Answer:
Genes are located in specific position on a chrosomes.
Chemically gene is a segment of D.N.A consisting of specific sequence of the nucleotides.

Question 25.
Explain whether the traits like eye colour or height is generally inherited or not.
Answer:
Eye colour or height trait can not be changed because they are controlled by the Genes.