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Inside Questions of Lakhmir Singh Manjit Kaur Class 10 Biology Chapter 4 ‘Heredity And Evolution’.
|Chapter Name||Heredity And Evolution|
(1) What is called Characters or traits?
Ans. A recognizable feature of a human being like height, complexion, shape of hair color of eyes and shape of nose and chin are called characters or traits.
(2) Define heredity.
Ans. The transmission of characters from the parents to their offsprings is called heredity.
(3) Name the male gamete.
(4) Name the female gamete.
(5) Define variation.
Ans. The off springs are never a true copy of the parents. In fact no two individuals are exactly alike and the members of any species differ from one another in some characters or the other. These differences are known as variation.
(6) Write one example of variation found in human population.
Ans. The free earlobes and attached earlobes are the two variation found in human population.
(7) Write the great advantage of variation.
Ans. The great advantage of variation to a species is that it increases the chances of its survival in a changing environment.
(8) Define Chromosome.
Ans. Chromosomes is a thread like structure in the nucleus of a cell formed of DNA which carries the genes.
(9) Define Gene.
Ans. Genes are actually units of heredity which transfer characteristics from parents to their offsprings during reproduction.
(10) How many pairs of chromosomes does a normal cell of human body contains?
Ans. A normal cell of human body contains 23 pairs of chromosomes.
(11) Define dominant gene.
Ans. The gene which decides the appearance of an organism even in the presence of an alternative gene is known as dominant gene.
(12) Define recessive gene.
Ans. The gene which can decide the appearance of an organism only in the presence of another identical gene is called recessive gene.
(13) Define phenotype.
Ans. The characteristics which is visible in a organism is called its phenotype.
(14) What is called first filial generation or F1 Generation.
Ans. When two parents cross to produce progeny, then their progeny is called first filial generation or F1 generation.
(15) Define second filial generation or F2 generation.
Ans. When the first generation progeny cross among themselves to produce second generation progeny then this progeny is called second filial generation or F2 generation.
(16) Name the first scientist who make a systematic study of patterns of inheritance which involved the transfer of characteristics from parents to progeny.
Ans. Gregor Mendel.
(17) Mendel chose pea plants for studying inheritance. Give reason.
Ans. This is because pea plants had a number of clear cut differences which were easy to tell apart.
(18) Who do you know by the term hybrid?
Ans. A new form of plant resulting from a cross or breeding of different varieties of a plant is known as a hybrid.
(19) What is Monohybrid?
Ans. When we breed two pea plants having one contrasting characteristic each to obtain new plants then it is called a monohybrid cross.
(20) What is dihybrid cross?
Ans. If we breed two plants having two contrasting characteristics to obtain new plants then it is called dihybrid cross.
(21) Define Mendel’s first law of Inheritance.
Ans. According to Mendels the characteristics of an organism are determined by internal factors which occur in pairs. Only one of pair of such factors can be present in a single gamet.
(22) Define Mendel’s second law of inheritance.
Ans. According to Mandel’s second law of inheritance In the inheritance of more than one pair of traits in a cross simultaneously the factors responsible for each pair of traits are distributed independently to the gamets.
(23) What do the progeny of a tall plant with round seeds and a short plant with wrinkled seeds look like? Why?
Ans. The progeny of a tall plant having round seeds crossed with short plants having wrinkled seeds are all tall plants having round seeds. This is because tallness and round shape of seeds are dominant traits. On the other hand shortness and wrinkled shape of seeds are recessive traits.
(24) What happens when F1 progeny obtained above are used to produce F2 progeny by self pollination?
Ans. When F1 progeny are cross bred by self pollination then will get four type of progeny in the F2 generation . Of these four types of progeny two types will have traits like parents and the other two will have new combinations of traits. Thus
(a) Some F2 progeny will be tall plants with round seeds (9).
(b) Some F2 progeny will be tall plants with wrinkled seeds (3).
(c) Some F2 progeny will be short plants with round seeds (3).
(d) Some F2 progeny will be short plants with wrinkled seeds (1).
(25) How are characteristics transmitted to progeny?
Ans. The characteristics or traits of parents are transmitted to their progeny through genes present on their chromosomes during the process of sexual reproduction.
(26) John having blood group A marries Soniya having blood group O and they have a child. What will be the blood group of the child?
Ans. The answer to this question depend on wheather the blood group A of John has gene conmbination IAIA or IAIO
When the blood group A has genotype IAIA . In this case the genotype of man’s blood is IAIA and that of Soniya’s blood is IOIO. So the child will have blood group A.
When the blood group A has genotype IAIO , Here the genotype of John’s blood is IAIO and that of Soniya’s blood is IOIO. So in this case there is an equal chance that the genotype of child’s blood can be either IAIO or IOIO. That’s why there is an equal chance of the child acquiring blood group A or blood group O.
(27) What is sex determination?
Ans. The process by which the sex of a person is determined is called sex determination.
(28) What is sex chromosomes?
Ans. The chromosomes which determine the sex of a person are called sex chromosomes.
(29) Who is responsible for the sex of the baby. Write details.
Ans. Father is responsible for the sex of the baby. We know that father has XY chromosomes and mother has XX chromosomes. If the father contributes X chromosomes at fertilization through his sparms, the baby born will be a girl. On the other hand If the father gives Y chromosome thein the baby born will be boy.
Mother has only one type of chromosomes X but the father has Two types XY. So its totally depends on father.
(30 What is called acquired trait? Give example.
Ans. A trait of an organism which is not inherited but develops in response to the environment is called an acquired trait.
Ex. Swimming is an acquired trait. It is not present by birth. In other words the technique of swimming is not inherited from parents. It is learnt by the person himself.
(31) What is called inherited trait?
Ans. A trait of an organism which is caused by a change in its genes is called an inherited trait.
(32) What is the actual mean of inherited traitrs?
Ans. Inherited traits actually mean the characteristics which we receive from our parents.
(33) What is evolution?
Ans. Evolution is the sequence of gradual changes which take place in the primitive organisms over millions of years in which new species are produced.
(34) Write an example briefly of evolution.
Ans. Pterosaur is an ancient flying reptile which lived on the earth about 150 million years ago. The development Pterosaur is an example of evolution.
It began life as a big lizard which could just crawl on land. Over million of years small folds of skin developed between its feet which enabled it to glide from tree to tree.
Over many many generations spread over millions of years the folds of skin and the bones and muscles supporting them grew to form wings which could make it fly. In this way an animal which crawled on ground evolved into a flying animal. This evolution led to the formation of a new species.
(35) Write some of the important which provide evidence for evolution.
Ans. Some of the important sources which provide evidences for evolution are follows:-
(i) Homologous organs.
(ii) Analogous organs
(36) Define Homologous organs, Analogous organs, Fossils
Ans. Homologous organs:- Those organs which have the same basic structure but different functions called homologous organs.
Example:- the forelimbs of a man, a lizard, a bird and a bat seem to be built from the same basic designs of bones but they perform different functions.
Analogous organs:- Those organs which have different basic structure but have similar appearance and perform similar functions are called analogous organs.
Example: The wings of an insect and a bird have different structures but function is similar.
Fossils:- The remains of dead animals or plants that lived in the remote past are known as fossils.
Example: a fossil bird called Archaeopteryx looks like a bird but it has many other feature which are found in reptiles.
(37) Give one example in where animal fossil was found.
Ans. In the desert buries under the sand.
(38) About how many years old the estimation of the age of ammonite fossils have told us.
Ans. About 180 million.
(39) Name the scientist who gave the theory of evolution.
Ans. Charles Darwin.
(40) Name the book in where Charles Robert Darwin gave the theory of evolution.
Ans. The origin of species.
(41) Describe Darwin’s theory of evolution.
Ans. Darwin’s theory of evolution can be described as follows:
(i) Within any population there is natural variation. Some individuals have more favorable variations than others.
(ii) Even though all species produce a large number of offsprings, populations remain fairly constant naturally.
(iii) Due to the struggle between members of the same species and different species for food, space and mate.
(iv) the struggle for survival within populations eliminates the unfit individuals. The fit individuals possessing favourable variations survive and reproduce.
(v) The individuals having favourable variations pass on these variations to their progeny from generation to generation.
(vi) These differenciency when accumulated over a long period of time then it will lead to the origin of a new species.
(42) What is Natural selection?
Ans. Natural selection is the process of evolution of a species whereby characteristics which help individual organisms to survive and reproduce are passed onto their offspring and those characteristics which do not help are not passed on.
(43) Define speciation.
Ans. The process by which new species develop from the existing species is known as speciation.
(44) Write two important factors which could lead to the rise of a new species.
Ans. Genetic drift caused by drastic changes in the frequencies of a particular genes by chance alone.
Variation caused in individuals due to natural selection.
(45) Name the ancestors of human beings.