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Heredity and Evolution : Complete Set of Questions


This set of questions contains all the possible concepts
which could be asked in the examination

Q.1 Explain Heredity?

Transmission of characters from parents to offspring’s is known as heredity.

• Fertilized egg or zygote carries hereditary information.

• The zygote develops into a particular type of offspring only.

• Thus, eggs laid by a sparrow hatch into sparrows and a dog reproduce to give birth to pups only.


Q.2 What is the study of heredity and variation called?

The study of heredity and variation is called Genetics.


Q.3 Explain Variation?

Variation means some individual diversity in the organism of one generation from that of the parental generation.

• Variation passes from generation to generation.

• In sexual reproduction, both similarities and variation are clearly observed among the offspring’s of same parents.

• Due to variation, any two persons rarely show complete similarity.

 

Accumulation of Variation During Reproduction : -  

Q.4 Why is asexual reproduction not ideal for variations?

Asexual reproduction involves a single parent and is hence not ideal for facilitating variations. Organisms raised are exact copies of their parents and are known as clones. Due to their identical set of chromosomes, they exhibit no or very little variations. These variations may be either due to some environmental factors like light, scarcity of food, abundance of food, temperature etc or due to small inaccuracies in DNA copying (mutation). Out of these two factors, only mutations are heritable. But the quantum of variations would be too little and would take too many years to show effect.


Q.5 What is the source of genetic variation in asexually reproducing organisms?

The source of genetic variation in asexually reproducing organisms is mutation (inaccuracies in DNA replication).


Q.6 Variation useful for the survival of a species. Justify?

Variation is useful for the survival of species over time. If a population of reproducing organisms were suited to a particular niche and if the niche were drastically altered, the population could be wiped out. However, if some variations were to be present in a few individuals in these populations, there may be some chance of their survival.

E.g. : If the temperature of water increases by global warming, most bacteria would die. But a population of heat resistant bacteria could survive here. These few variants would be resistant to the heat and would survive and grow further.


Q.7 Why is sexual reproduction ideal for variations?

Sexual reproduction is ideal for facilitating variations because two parents are involved in it and there is formation and fusion of gametes. Due to crossing over and exchange of gene segments, off-springs show variations from their parents. They are not carbon copies of their parents. Due to recombination of parental genes, variations occur which are heritable.

 

Heredity 

Q.8 What is meant by inherited traits?

The characteristics or traits which are transmitted from the parents to the offspring’s are known as inherited traits. E.g. Height, skin colour, ability to roll tongue, haemophilia.


Q.9 What did Mendel propose?
Mendel proposed that for regulation of every character (in an organism) there is a pair of factors.


Q.10 What is a gene? How does it work?

Gene is a small segment of DNA on a chromosome occupying specific position in which is a hereditary determinant or unit of a biological function. Genes are passed from parents to offspring’s via chromosomes present in the nuclei of the parents’ gametes.

Genes function through the formation of specific proteins that serve as a structural or functional component required for expression of a character.


Q.11 Why did Mendel select pea plant in his experiment?

Mendel selected the pea plant for his experiments because -

•  Pea can be termed as biennial plant, i.e. two generations of a pea plant can grow in a given year. This means that mendel could get enough time to observe a larger number of generations.

•  Many easily identifiable and contrasting characters are present in pea plants.

•  Self fertilizing in nature and also cross bred experimentally.

•  Produce large number of offspring. 


Q.12  Who was gregor Mendel?

Gregor mendel is considered the father of Genetics. He was a monk, biologist and botanist born in Austria in 1822 and who died in 1884. His experiments consisted of crossing pea plants of distinct characteristics (size, color of the seeds, etc.), cataloging the results and interpreting them. The experiments led him to enunciate his laws, results published in 1886 with no scientific repercussion at that time. Only at the beginning of the 20th century, in 1902, 18 years after his death, were his merits broadly recognized.


Q.13 What is mono hybridism?

Mono hybridism is the study of only one characteristic in the crossing of two pure individuals (hybridization) for that characteristic.


Q.14 What is the condition for Mendel’s second law to be valid?

Mendel’s second law is only valid for genes located in different chromosomes. For genes situated in the same chromosome, i.e., linked genes (genes in linkage) the law is not valid since the segregation of these genes is not independent.


Q.15 What is the difference between dominant trait and recessive traits?

Dominant traits refers for the alternative of a character that expresses itself in the F1 generation. For example, Yy shows the dominant trait for yellow colour of seed. Seed is yellow even when single copy of dominant allele i.e., Y is present

Recessive trait means the trait, which is unable to express itself in the presence of the dominant trait. For example,  shows the recessive trait for green colour of the seed. It is expressed only when both the alleles are recessive i.e., y


Q.16 What constitutes the link between one generation and the next?

The hereditary information is transferred from parents to offspring through the gametes. So, gametes constitute the link between one generation and the next and pass on the paternal and maternal characters to the offspring.


Q.17 What is meant by alleles?

Alleles are pair unit factors that control the expression of a character.


Q.18 What is mono hybrid cross?

When only a single pair of contrasting or differentiating traits is considered in a cross (or inheritance of only one pair of contrasting traits is studied in a cross), it is called monohybrid cross, e.g ; When only a single pair of contrasting or differentiating traits is considered in a cross (or inheritance of only one pair of contrasting traits is studied in a cross), it is called mono hybrid cross.

e.g.

The two forms of the trait appear in F2 generation in ratio of three dominant to one recessive, 3 : 1. It is also called mono hybrid ratio.


Q.19 (a) What is genetics?

(b) Give the common name of plant on which Mendel performed his experiments.

(c) What for did Mendel use the term factors and what are these factors called now.

(d) What are genes? Where are the genes located?

(a) Genetics is the branch of biology that deals with the study of heredity and variation.

(b) Garden pea – Pisum sativum.

(c)  The units of inheritance of characters. These factors are now called as genes.

(d) Gene is a hereditary unit, a segment of DNA. It is located on a chromosome at a particular locus or position.


Q.20 What are the components of chromosome?

Each chromosome is double or replicated and consists of two thread like structures called chromatids attached to each other at centro mere.

Each chromatid has a number of dense areas arranged linearly which are known as chromomeres. They represent the areas of active genes.

Internally each chromosome has two spirally coiled threads called chromonemata embedded in matrix. These are DNA molecules.


Q.21 What is sex chromosome?

A chromosome which is associated with sex determination is called sex chromosome. There are 2 types of sex chromosomes- the X- chromosome and the Y- chromosome. Males possess one X and one Y chromosomes while females possess 2 X chromosomes.

Therefore, the sex of a child is determined by the inheritance of X or Y chromosome from the father

Parents         Male                           Female
Gametes         X Y                                X
Progeny          XX                                XY
Female          (50%)                         Male (50%)


Q.22 "The sex of the children is determined by what they inherit from their father and not from the mother." Justify.

The children inherit similar chromosomes (22 + X) from the mother but the sex of the children will depend on the chromosome they inherit from the father. If a child inherits (22 + X) chromosomes from the father that the child will be a girl but when a child inherits (22 + Y) chromosomes from the father then the child will be a boy.


Q.23 Difference between Genotype and Phenotype:


Q.24 What do you mean by sex determination?

The phenomenon determining whether the developing embryo will be a male or a female is known as sex determination.


Q.25 Describe the role of environmental factors in sex determination. 

  In some species, the sex determination is regulated by environmental factors.

•   For example, in turtle Chrysema Picta, high incubation temperature results into development of a female.

•   In a lizard, Agama agama, high incubation temperature results into development of a male.


Q.26 State Mendel’s Laws of Inheritance

Mendel on the basis of his observations of mono hybrid and dihybrid crosses in pea plants gave the following principles of inheritance-

(i) Law of Unit Characters- According to this law, all the traits are separate entities or units by themselves. Their inheritance is controlled by 'factors', now known as genes.

(ii) Law of Dominance - Each gene has more than one form of expression. These forms of expressions are called alleles or allelomorphs. Each pair of alleles will have a dominant allele and a recessive allele. In the presence of the dominant gene, the recessive gene will never express itself. Only if both the alleles are recessive, the recessive trait will be exhibited.

(iii) Law of Segregation - This is also called the law of purity of gametes. According to this law, the gametes are pure for a particular trait. This is because the alleles of a pair separate during gamete formation and again come together after fertilization. Therefore, in each gamete only either of the two alleles is present and it is pure for that trait..

(iv) Law of Independent Assortment - This law explains how more than one trait is inherited. According to this law, when there are two pairs of alleles, all four alleles assert themselves independently and are inherited independently.


Q.27 What is retro virus?

A virus with RNA as the genetic material instead of DNA. E.g., HIV is a retro virus.


Q.28 Explain the result of mono hybrid cross?

(i) Only one of the parental trait is observed in F1 progeny when two contrasting character of a trait is considered.

(ii) The trait which is seen in F1 hybrid is dominant one.

(iii) When F1 hybrid is self pollinated both the characteristics appear in ratio of 3:1 which shows that F1 hybrid has the traits of both characteristics.


Q.29 What is dihybrid cross? Mendel crossed the round and green seeded pea plants with the wrinkled and yellow seeded pea plants. Give the phenotypic ratio of Fgeneration.

A dihybrid cross is one in which two pairs of contrasting characters are taken at a time in this cross.


Q.30 How do traits get expressed?

(i) Chromosomes present in nucleus contain hereditary information.

(ii) Chromosomes are made up of DNA and protein. It’s important component is DNA.

(iii) Chromosomes occur in pair, one comes from mother and others from father.

(iv) Part of DNA responsible for a trait is called gene.

(v) A gene is expressed in the form of proteins. E.g. for tallness of a plant if proteins work efficiently a lot of hormone will be produced and the plant will be tall


Q.31 List the contrasting characters which were taken for experiments by mendel?

Mendel selected varieties that differed with respect to seven traits with easily distinguishable contrasting forms, i.e., he selected fourteen varieties as shown in the table given below


Q.32 How was it established that genes are located on the chromosomes?

In all the organisms, the number of chromosomes is fewer than the number of characteristic features, which are many. If 'genes' are responsible for a characteristic feature, they have to be certainly many more than the number of chromosomes. For example, in human beings, the total number of chromosomes is 23 pairs, but the total number of characters (genes) has been estimated to be between 30,000 to 40,000. This suggests that genes are located on the chromosomes


Q.33 Give example of animals in which sex is not genetically determined.

(i) snail-can change sex.

(ii) turtle-High incubation temperature leads to develop female offspring.

(iii) Lizard-High incubation temperature leads to develop male offspring


Q.34 What are auto somes and how are they different from sex chromosomes?


Q.35 What is a factor and who coined the term ?

The carriers of hereditary information were called factors. The term ‘factor’ was coined by Mendel.


Q.36 How did the Mendelian 'factors' acquire a change in the terminology? Who changed it?

The carriers of hereditary information were called 'factors' by Mendel. Wilhelm Johansson later called these factors genes.


Q.37 Explain the law of segregation by taking an example.

Law of segregation :

Paired factors responsible for a character segregate into gametes and are recombined at the time of fertilisation.

When a yellow seeded and green seeded plants are crossed, the F1 progeny are all yellow seeded. It indicates that yellow colour is dominant over green seed colour. When F1 plants are self pollinated, we get yellow and green seeded plants in the ratio of 3 :1  


Q.38 What is the reason that a male is called 'hetero gametic'?

A male is called hetero gametic because he forms two different types of gametes. One containing 'X' chromosome and the other containing 'Y' chromosome.


Q.39 Give an example of a plant showing sex determination.

Coccinia indica is a plant showing sex determination.

 

Evolution 

Q.40 Define evolution:

Evolution is a gradual and orderly process of change in the forms of life from simple to complex during the course of time that has given rise to the existing diversity of life.


Q.41 Who gave the concept of evolution?

Charles Darwin, a British naturalist gave the concept of evolution.


Q.42 What do you understand by natural selection?

Natural selection refers to increase in the frequency of genes, which results in evolution of populations that are better adapted to existing environment.


Q.43 What is meant by genetic drift?

Change in the frequency of some gene creating diversity without any adaptations caused by chance factor alone is called genetic drift.


Q.44 What are the two basic factors of evolution ?
Variation and heredity are the two basic factors of evolution. 


Q.46 Explain Darwin’s theory of evolution?

According to Darwin’s theory of evolution:

(i) There is natural variation within any population and some individuals have more favourable variations than others.

(ii) Population remains fairly constant even though all species produce a large number of off springs.

(iii) This is due to ‘competition’ or struggle for existence between same and different species.

(iv) The struggle for survival within population eliminates the unfit individuals and those with ‘favourable variations’ survive and pass on these variations to their progeny to continue. This is called natural selection.

(v) The  favourable variations are accumulated over a long time period leading to the origin of a new species.


Q.47 Describe the contribution of Lamarck?

Contribution of Lamarck :

(i) Lamarck proposed a theory called “The Theory of inheritance of Acquired Characters” to explain the origin and evolution of species.

(ii) The theory was explained in his book ‘Philosophic Zoologique.


Q.48 How do homologous organs provide evidence in support of evolution?

Homologous organs support evolution :

(i) The similarities of structure and origin of organs indicate that all vertebrates had common ancestors. For example, the forelimbs of humans, whale and bat show structural similarities but functional dissimilarities. Forelimbs in humans used for grasping or holding the things, in whale for swimming and in bat for flying.

(ii) All the organs and systems of the vertebrates show fundamental similarities i.e. homology, which indicate towards common ancestry. Thus, homologous point that organic evolution has taken place.


Q.49 Describe briefly four ways in which individuals with a particular trait may increase in a population.

The individuals with a particular trait may increase in a population in the following ways–

(i) Sufficient Food : By obtaining more food the individuals can increase in growth and reproduction.

(ii) Differential Reproduction : It gives an advantage to the individuals to survive and reproduce.

(iii) Variations : The useful variations help the individuals to adopt the environmental condition

(iv) Genetic Drift : The random change in the frequency of alleles in a population over successive generations due to error during DNA copying on the gametes


Q.50 Who explained the mechanism of origin of new species for the first time? How does new species arise according to his theory? What was his second observation?

Charles Darwin. New species arise by the slow accumulation of advantageous variations over a period of time. His second observation says that over population results in competition for food and shelter, ultimately leading to a struggle for existence among the members of a species.


Q.52 Differentiate between inherited and acquired traits.


Q.53 Which theory of evolution did Darwin give? Mention the limitation of Darwinism.

Darwin gave the Theory of Natural Selection.

Darwinism explains evolution with the help of variation but it does not explain how variation occurs. 


Q.54 The chromosomal number of the sexually producing parents and their offspring is the same." Justify this statement.

The first step in sexual reproduction is gamete formation. In this step, the number of chromosomes gets halved. Thus, each gamete receives half the number of chromosomes to that of somatic cells. During fertilisation, the fusion of male and female gametes takes place, which results in the number of chromosomes in the zygote to be equal to that of somatic cells. Thus, the chromosomal number of the sexually producing parents and their offspring is the same.


Q.55 “Evolution cannot be equated with progress”. Justify this statement.

Evolution cannot always be equated to progress because

• Evolution does not always lead to the formation of a new species.

• The newly formed species as a result of evolution may have complex organisation but cannot be considered 'better' to the earlier species.

• Evolution simply leads to diversification.

 

Speciation 

Q.56 What is speciation? What are the different ways in which it can occur?

The formation of a new species by evolution or any genetic modification of the previously existing species in a population is called speciation.

Few factors that affect speciation are

(a) Geographical isolation : - Geographical isolation is one of the factors which may lead to speciation. In this a group of individuals of a species may become geographically isolated from other members or species. So, both these groups grow in different environment and hence evolve to form a new species. Various factors which play an important role in this type of speciation are -

(i) Natural selection        

(ii) Genetic drift

(b) Hybridization : - Hybridization is a process by which new types of species come into existence as a result of mating of two distinct species. This process may lead to the existence of new species which is different from the parents. Hence, hybridization may result in speciation.


Q.57 What are the factors that give rise to a new species?

New species are produced as a result of

Mutations giving rise to new genetic variations

Genetic recombination during sexual reproduction provides wider variability for natural      selection to operate.

Natural selection of variants better adapted to the existing environment.

Genetic drift - random increase in the number of variants not having any selective advantage due to the change factor

Reproductive isolation of populations with different characters due to geographic or behavioural patterns.


Q.58 Define the term ‘species’:

A species can be defined as a group of similar organisms that can interbreed and produce fertile off springs.


Q.59 Define population:

Population is the group individuals of species living in a particular area.


Q.60 When a pesticide is sprayed on a population of insects, all insects do not get killed but few of them survive. Give reason. 

When a pesticide is sprayed on a field most of the insects are killed because they are sensitive to the pesticide. A few of the insects survive because they have variations which made them resistant against the pesticide, such that the pesticide has no effect on these insects.

 

Evolution and Classification 

Q.61 What is meant by characteristics? Give an example:

Characteristics are details of appearance or behaviour, i.e., a particular form or particular function in the body of an organism. For example, ability of plants to carry out photosynthesis.


Q.62 How do embryological studies provide evidence for evolution?

The similarities in embryonic development reinforce the idea of evolution from common ancestors. The sequence of embryonic development in different vertebrates shows striking similarities. Note chord and gill clefts appear in the embryos of all vertebrates.


Q.63 Difference between homologous and analogous organs with example


Q.64 Define Vestigial organs?

Vestigial organs are those organs, which are rudimentary and functionless in the evolved forms but are well developed and functional in the ancestral forms. Eg: Vermiform appendix in human beings.


Q.65 What are the basic characteristics for separation of major groups of organisms?

The basic characteristics for separation of major groups of organisms are -

1. Organisms of the cell, if it is prokaryotic or eukaryotic.

2. Organisation of the body(cell design), whether it is unicellular or multicellular.

3. If there is division of labour in the multicellular body.

4. Whether they can produce their own food by photosynthesis.

5. The way the organs of the body develop and become specialised.


Q.66 What is meant by hierarchy?

Hierarchy is the framework of classification in which the groups are arranged in the order of increasing or decreasing levels of similarities.


Q.67 Define Primitive and advanced organism:

Organisms that originated first and have not changed much during the course of evolution are called primitive or lower organisms. Primitive organisms have a simple body structure and ancient body design Eg., bacteria.

Organisms that originated later and have changed much during the course of evolution are called advanced organisms or higher organism. Advanced organisms have a complex body structure and organization. E.g., Primates.


Q.68 How has the method of artificial selection by humans helped in the evolution of different vegetables? Explain in brief giving an example.

Humans have developed different varieties of vegetables from a single wild cabbage by artificial selection some of these are as follows —

(i) Some farmers have wanted to select very short distances between the leaves and developed the present day cabbage.

(ii) Some farmers selected immature green flowers and developed the broccoli.

(iii)Some have selected the sterile flowers and developed the cauliflowers.

(iv) Some farmers selected the swollen part of the wild cabbage and developed the kohlrabi.

(v) Some of them have selected the larger leaves and developed Kale.

So, all these vegetables are descended from a common ancestor.


Q.69 What are fossils? What do they tell about the process of evolution?

The preserved traces or impressions of the body parts of living organisms are called fossils.

Since fossils reveal evolutionary relationships among different organisms, they are the proof of organic evolution.


Q.70 What is palaeontology? What is its importance?

Palaeontology is a branch of biology that deals with the study of fossils. It provides a direct evidence of evolution and is called a written document of evolution


Q.71 What is meant by molecular phylogeny?

Molecular phylogeny is the study of evolutionary relationship by comparing the DNA of different species.


Q.72 How the study of fossil is considered significant?

The study of fossil is considered significant because-

(i) Fossils provide direct evidence of past life.

(ii) These provide convincing proof of organic evolution.


Q.73 How do we know how old a fossil is?

The age of fossils can be determined by two ways-

(i) If we dig into the earth and start finding fossils, it can be assumed that the fissils closer to the surface are more recent to those found in deeper layers.

(ii) By detecting the ratio of different isotopes of the same element in the fossil materials


Q.74 Name the tools that are used to study human evolution:

The tools that are used to study human evolution are excavations, time dating and study of fossils, determining DNA sequences.


Q.75 Explain the importance of fossils in deciding evolutionary relationships:

Age of fossils can be found out by estimation of the depth of the layer of the rocks in which it is found.  It can be found out by the ratio of the isotopes in the fossil containing rocks. Thus, we can find out the types of organisms (plants, animals and microbes) that existed at a particular geological time and reconstruct the evolutionary process.


Q.76 Give the evidence that the birds have evolved from reptiles.

Fossils provide evidence of evolution. A fossil bird called Archaeopteryx, which lived in the Late Jurassic Period around 148–150 million years ago, had feathered wings like that of birds and a long bony tail, jaws with sharp teeth and various skeletal features like that of reptiles. Thus, Archaeopteryx is considered a connecting link between reptiles and birds.
Some dinosaurs had feathers that provide them insulation in cold weather; however, they could not fly using those feathers. Birds seem to have later used feathers to fly. This, of course, means that birds are very closely related to reptiles because dinosaurs were reptiles. Hence, it suggests that birds have evolved from reptiles.


Q.77 Insects, octopus, planaria and vertebrates possess eyes. Can we group these animals together on the basis of eyes that they possess ? Justify your answer giving reason.

While making groups, we need to decide the characteristics that are responsible for the more fundamental differences among organisms. The characteristics that account for the broadest divisions among living organisms should be independent of any other characteristics in their effects on the forms and structural functions of organisms like cellularity, mode of nutrition and nature of cell.
Insects, octopus and planaria are invertebrates. They cannot be grouped together with vertebrates, as they lack an internal skeleton with a backbone. Also, all of them belong to different phyla on the basis of different characteristics they possess. Just on the basis of one characteristic, i.e., presence of eyes, these organisms cannot be grouped together. 

 

Evolution Should Not Be Equated with Progress 

Q.78 Describe the human evolution.

The modern humans are called Homo sapiens. Many scientific investigations have shown that the modern humans evolved in Africa. 

Few thousand years ago some ancestors left Africa while other stayed back. The residents spread across Africa and the migrants spread across the planet from Africa to West Asia, Central Asia,  Eurasia, South Asia, Indonesia,  Australia and America. They went forwards and backwards with groups separating from each other, or sometime coming together.  Like all other species, they were also living their lives to the best of their ability.


Q.79 A blue colour flower plant denoted by BB is crossbred with that of white colour flower plant denoted by bb.

(a) State the colour of flower you would expect in their F1 generation plants.

(b) What must be the percentage of white flower plants in F2 generation if flowers of F1 plants are self-pollinated?

(c) State the expected ratio of the genotypes BB and Bb in the F2 progeny.

Blue colour flower plant:- BB

White colour flower plant:- bb

The cross involved is as follows:

(a) In F1 generation, all plants will have blue flower.

(b) In the F2 generation, 25% of flowers are white in color.

(c) The ratio of the genotypes BB and Bb in the F2 generation would be 1(BB) : 2(Bb).


Q.80 If we pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we now self-cross the pea plant of F1 generation, then we obtain pea plants of F2 generation.

(a) What do the plants of F2 generation look like?

(b) State the ratio of tall plants to dwarf plants in F2 generation.

(c) State the type of plants not found in F1 generation but appeared in F2 generation, mentioning the reason for the same.

When a pure breeding tall pea plant is crossed with a pure breeding dwarf pea plant

(a) All the plants in the F1 generation appear tall.

(b) The ratio of tall pea plant to dwarf pea plants is 3 (tall) : 1 (dwarf).

(c) The dwarf plant does not appear in the F1 generation but appears in the F2 generation because the progeny produced in the F1 generation were heterozygous (Tt). Hence, when they were selfed for obtaining the F2 generation, dwarf plants were also formed in the progeny. The cross involved in as follows

 

Value Based Question:

Q.1 A village recorded highest cases of atrocities against women the health officer of the village organised a skit to convey the fact that women should not be punished for the birth of a girl child. They should be given due respect in society. The villagers were greatly motivated.

(i) What is the method of sex determination in humans? 

(ii) What are the sex chromosomes in males? 

(iii) What value was the officer trying to highlight through the skit? 

1. Sex is determined at the time of fertilisation and the two sexes are produced in approximately equal numbers. A human male has XY sex-chromosomes and produces two types of sperms (heterogametic). Either with X-chromosome or with Y-chromosome.

A human female has XX sex-chromosomes and produce ova of one type (homogametic) all with X-chromosomes.

Parents Male                                   Female

Gametes         X Y                                X

Progeny          XX                                XY

                     Female (50%)           Male (50%)

2. The sex chromosomes in male is a X and a Y chromosome.

3.  (i) Awareness   (ii) Social Responsibility   (iii) Concern for women


Q.2 Anita had a huge scar on her cheek after she met with an accident during her school days. She is worried if her baby would inherit the scar she had acquired. Her doctor, a sincere medical practitioner explained and successfully convinced Anita.

(i) What are acquired traits?

(ii) How is it different from inherited traits?

(iii) Mention the values the doctor exhibits.

1. Traits which are acquired due to interaction with the environment are called acquired traits. Acquired traits are not inheritable. For example; if a boxer develops bulging biceps, it does not mean that his son would be borne with bulging biceps.

2. 

3.  (i)  Awareness            

(ii)  Social responsibility    

(iii) Professional ethics


Q.3 Mita observed that her grandmother was preparing a family tree. On enquiring why it was done, she explained that it was necessary to know our roots as we have inherited many traits from our ancestors. She also mentioned that many family values and traditions are no longer followed as joint families had disappeared?

(i) Who are the earliest members of human species? 

(ii) Where have the earliest members emerged?

(iii) What values do you think children would learn in a joint family?

(i) The earliest documented members of the genus Homo are Homo habilis, which evolved around 2.3 million years ago

(ii) Africa

(iii) 1.  Sharing and caring   2. Respect for elders 3. Concern for others 4. Knowledge of any genetic disorders in the family 



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