NCERT Exemplar Solution Class 10 Science Chapter 9 Heredity and Evolution
NCERT Exemplar Solution Class 10 Science Chapter 9 Heredity and Evolution all Questions Answer Solution. NCERT Exemplar Class 10 Science Chapter 9 Solution PDF.
NCERT Exemplar Solution Class 10 Science Chapter 9: Overview
NCERT Exemplar Solution Class 10 Science Chapter 9 |
|
Board |
NCERT |
Topic |
Exemplar Problem Solution |
Class |
10 |
Subject |
Science |
Chapter |
9 |
Chapter Name |
Heredity and Evolution |
Multiple Choice Questions
1.) Exchange of genetic material takes place in
(a) vegetative reproduction
(b) asexual reproduction
(c) sexual reproduction
(d) budding
Answer: Answer is C.
2.) Two pink colored flowers on crossing resulted in 1 red, 2 pinkand 1 white flower progeny. The nature of the cross will be
(a) double fertilisation
(b) self-pollination
(c) cross fertilisation
(d) no fertilisation
Answer: Answer is C.
3.) A cross between a tall plant (TT) and short pea plant (tt) resultedin progeny that were all tall plants because
(a) tallness is the dominant trait
(b) shortness is the dominant trait
(c) tallness is the recessive trait
(d) height of pea plant is not governed by gene ‘T’ or ‘t’
Answer: Answer is A.
4.) Which of the following statement is incorrect?
(a) For every hormone there is a gene.
(b) For every protein there is a gene.
(c) For production of every enzyme there is a gene.
(d) For every molecule of fat there is a gene
Answer: Answer is D.
5.) If a round, green seeded pea plant (RR yy) is crossed with wrinkled,yellow seeded pea plant, (rr YY) the seeds produced in F1 generation are
(a) round and yellow
(b) round and green
(c) wrinkled and green
(d) wrinkled and yellow
Answer: Answer is C.
6.) In human males all the chromosomes are paired perfectly exceptone. This/these unpaired chromosomes is/are
(i) large chromosome
(ii) small chromosome
(iii) Y-chromosome
(iv) X-chromosome
(a) (i) and (ii) (b) (iii) only
(c) (iii) and (iv) (d) (ii) and (iv)
Answer: Answer is C.
7.) The maleness of a child is determined by
(a) the X chromosome in the zygote
(b) the Y chromosome in zygote
(c) the cytoplasm of germ cell which determines the sex
(d) sex is determined by chance
Answer:Answer is B.
8.) A zygote which has an X-chromosome inherited from the fatherwill develop into a
(a) boy
(b) girl
(c) X- chromosome does not determine the sex of a child
(d) either boy or girl
Answer: Answer is B. X chromosome inherit from father to girls and vice vera.
9.) Select the incorrect statement
(a) Frequency of certain genes in a population change over severalgenerations resulting in evolution
(b) Reduction in weight of the organism due to starvation isgenetically controlled
(c) Low weight parents can have heavy weight progeny
(d) Traits which are not inherited over generations do not causeevolution
Answer: Answer is B.
10.) New species may be formed if
(i) DNA undergoes significant changes in germ cells
(ii) chromosome number changes in the gamete
(iii) there is no change in the genetic material
(iv) mating does not take place
(a) (i) and (ii) (b) (i) and (iii)
(c) (ii), (iii) and (iv) (d) (i), (ii) and (iii)
Answer: Answer is A.
11.) Two pea plants one with round green seeds (RRyy) and anotherwith wrinkled yellow (rrYY) seeds produce F1 progeny that haveround, yellow (RrYy) seeds. When F1 plants are selfed, the F2progeny will have new combination of characters. Choose the newcombination from the following
(i) Round, yellow
(ii) Round, green
(iii) Wrinkled, yellow
(iv) Wrinkled, green
(a) (i) and (ii) (b) (i) and (iv)
(c) (ii) and (iii) (d) (i) and (iii)
Answer: Answer is B.
12.) A basket of vegetables contains carrot, potato, radish and tomato.Which of them represent the correct homologous structures?
(a) Carrot and potato
(b) Carrot and tomato
(c) Radish and carrot
(d) Radish and potato
Answer: Answer is C.
13.) Select the correct statement
(a) Tendril of a pea plant and phylloclade of Opuntia arehomologous
(b) Tendril of a pea plant and phylloclade of Opuntia are analogous
(c) Wings of birds and limbs of lizards are analogous
(d) Wings of birds and wings of bat are homologous
Answer: Answer is D.
14.) If the fossil of an organism is found in the deeper layers of earth,then we can predict that
(a) the extinction of organism has occurred recently
(b) the extinction of organism has occurred thousands of yearsago
(c) the fossil position in the layers of earth is not related to its timeof extinction
(d) time of extinction cannot be determined
Answer: Answer is B.
15.) Which of the following statements is not true with respect tovariation?
(a) All variations in a species have equal chance of survival
(b) Change in genetic composition results in variation
(c) Selection of variants by environmental factors forms the basisof evolutionary processes.
(d) Variation is minimum in asexual reproduction
Answer: Answer is D.
16.) A trait in an organism is influenced by
(a) paternal DNA only
(b) maternal DNA only
(c) both maternal and paternal DNA
(d) neither by paternal nor by maternal DNA
Answer: Answer is C.
17.) Select the group which shares maximum number of commoncharacters
(a) two individuals of a species
(b) two species of a genus
(c) two genera of a family
(d) two genera of two families
Answer: Answer is A.
18.) According to the evolutionary theory, formation of a new speciesis generally due to
(a) sudden creation by nature
(b) accumulation of variations over several generations
(c) clones formed during asexual reproduction
(d) movement of individuals from one habitat to another
Answer: Answer is B.
19.) From the list given below, select the character which can beacquired but not inherited
(a) colour of eye
(b) colour of skin
(c) size of body
(d) nature of hair
Answer: Answer is C.
20.) The two versions of a trait (character) which are brought in by themale and female gametes are situated on
(a) copies of the same chromosome
(b) two different chromosomes
(c) sex chromosomes
(d) any chromosome
Answer:Answer is A.
21.) Select the statements that describe characteristics of genes
(i) genes are specific sequence of bases in a DNA molecule
(ii) a gene does not code for proteins
(iii) in individuals of a given species, a specific gene is located on aparticular chromosome
(iv) each chromosome has only one gene
(a) (i) and (ii) (b) (i) and (iii)
(c) (i) and (iv) (d) (ii) and (iv)
Answer: Answer is B.
22.) In peas, a pure tall plant (TT) is crossed with a short plant (tt). Theratio of pure tall plants to short plants in F2 is
(a) 1 : 3
(b) 3 : 1
(c) 1 : 1
(d) 2 : 1
Answer: Answer is B.
23.) The number of pair (s) of sex chromosomes in the zygote of humans is
(a) one (b) two(c) three (d) four
Answer: Answer is A.
24.) The theory of evolution of species by natural selection was given by
(a) Mendel(b) Darwin(c) Morgan (d) Lamarck
Answer: Answer is B.
25.) Some dinosaurs had feathers although they could not fly but birdshave feathers that help them to fly. In the context of evolution thismeans that
(a) reptiles have evolved from birds
(b) there is no evolutionary connection between reptiles and birds
(c) feathers are homologous structures in both the organisms
(d) birds have evolved from reptiles
Answer: Answer is D.
Short Answer Questions
26.) How is the sex of a newborn determined in humans?
Answer: Human contains 23 pairs of chromosome. 23 pairs means 46 chromosomes are present in humans. Out of these 23 pair of chromosomes the 22 pairs are autosomes which are body chromosomes, which decide appearance of the body such as height, color and pigmentation etc. The 23rd pair chromosome called as sex chromosome which determines the sex of individual. The male have XY chromosome whereas female have XX chromosomes. The Y chromosome in male determines the sex of offspring.
27.) Do genetic combination of mothers play a significant role indetermining the sex of a new born?
Answer: No, sex of the new born is determined by genetic material or Y chromosome of father.
28.) Mention three important features of fossils which help in the study of evolution.
Answer: Three important features of fossils which help in the studyof evolution
1) From the fossils the scientist can determine the age time period in which they lived.
2) Fossils can get information about the existence of some extinct species.
3) These fossils can be preserved for future use.
29.) Why do all the gametes formed in human females have an Xchromosome?
Answer: Humans have 23 pair of chromosomes in which 23rd pair determines the sec of individual either male or female, therefore in 23rd chromosome there is presence of two sets of X chromosomes.
30.) In human beings, the statistical probability of getting either a maleor female child is 50 : 50. Give a suitable explanation.
Answer: Humans have 23 pair of chromosomes. Out of these 23 pairs 22 pairs are autosomes and 1 pair is of sex chromosome. In male sex chromosome is XY and in female sex chromosome is XX. The Y chromosome in male determines the sex of individual. So on the basis of transmission of Y chromosome to the next generation, determines the sex of new born. There are 50-50 % chances of male or female.
31.) A very small population of a species faces a greater threat of extinctionthan a larger population. Provide a suitable genetic explanation.
Answer: A very small population of a species faces a greater threat of extinction than a larger population. Because during inbreeding also there is increase in small number of species. There are certain factors which are responsible for extinction such as environmental conditions, food scarcity etc.
32.) What are homologous structures? Give an example. Is it necessarythat homologous structures always have a common ancestor?
Answer: The homologous structure can be defined as the organs which are similar in their structure but have different functions are called as homologous structures. For example: The wings of birds and bat are most common homologous structure and the homologous structure have common ancestor.
33.) Does the occurrence of diversity of animals on earth suggest theirdiverse ancestry also? Discuss this point in the light of evolution.
Answer: Yes, the occurrence of diversity of animals on earth suggest theirdiverse ancestry also. Because animals have huge diversity on earth, and every animal have evolved from a single origin, but according to their habitat such as feeding, place they have modified into another structures, therefore the diversity of animals on earth suggest their diverse ancestry.
34.) Give the pair of contrasting traits of the following characters inpea plant and mention which is dominant and recessive
(i) yellow seed (ii) round seed
Answer: The yellow and round seeds are dominant over green and wrinkled seeds.
35.) Why did Mendel choose pea plant for his experiments?
Answer:
1) It has short life span.
2) Pea plant is easy to grow and handle.
3) Fertilization can be self or cross.
4) It requires less space.
5) From the experiment pure line can be obtained.
36.) A woman has only daughters. Analyse the situation geneticallyand provide a suitable explanation.
Answer: The sex of new born will be determined by father’s chromosomes. If father transmits X chromosome then it will be girl child if father transmits a Y chromosome then it will be a boy child. Therefore women sex chromosome don’t have a significant role in determination of sex of child.
Long Answer Questions
37.) Does geographical isolation of individuals of a species lead toformation of a new species? Provide a suitable explanation.
Answer:Yes, geographical isolation of individuals of a species lead toformation of a new species because if due to barrier of environment one population is divided into two, but after certain years that precious one population can be regarded as two different population due to adaptation in their structure.
38.) Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved thanbacteria? Provide a suitable explanation.
Answer: Bacteria have a simpler body plan when compared with humanbeings. It means that human beings are more evolved thanbacteria because bacteria are single celled prokaryotic structure which lacks true nucleus, whereas the humans are multicellular eukaryotic organism which have their modified organs.
39.) All the human races like Africans, Asians, Europeans, Americansand others might have evolved from a common ancestor. Provide afew evidences in support of this view.
Answer:All the human races like Africans, Asians, Europeans, Americansand others might have evolved from a common ancestor, because due to geographical barrier all humans get separated in other geographical location but in general all he humans have common ancestor so due to environmental condition, their niche, feeding habitat all have some sort of different features.
40.) Differentiate between inherited and acquired characters. Give oneexample for each type.
Answer:
acquired characters | Inherited characters |
1)The traits which are not transmitted from parents. | 1) The traits which are passing from one generation to the next generation. |
2) The characteristics may develop the environment or habitat surrounding us. | 2) The physical characteristics develop in individual from their parents. |
3) They are called as non heritable changes. | 3) They are called as heritable changes. |
4)For example: laugh, cry and learned behavior. | 4) For example: Appearance of hair, shape of the nose, height of the bone etc. |
41.) Give reasons why acquired characters are not inherited.
Answer: An acquired traits can be defined as the characteristics which are not under genetic control. The traits are not transmitting from one generation to the next generation, instead that acquired during life called as acquired traits. For example: Laugh, cry, life stye of organisms are not transmitted from generation to generation. These characteristics which we gain or receive from our surrounding. Therefore acquired characters are not inherited.
42.) Evolution has exhibited a greater stability of molecular structurewhen compared with morphological structures. Comment on thestatement and justify your opinion.
Answer: Evolution has exhibited a greater stability of molecular structurewhen compared with morphological structures. As the molecular structure contain genetic material such as DNA, RNA or protein formation, but there is great similarity in every molecular aspect.
43.) In the following crosses write the characteristics of the progeny
Cross Progeny
(a) RR YY x RR YY
Round, yellow Round, yellow Round, yellow
(b) Rr Yy x Rr Yy Round yellow, round green, wrinkled
Round, yellow Round, yellow Yellow, wrinkled green.
(c) rryy x rryy
wrinkled, green wrinkled, green Wrinkled green
(d) RR YY x rryy
Round, yellow wrinkled green Round yellow
44.) Study the following cross and showing self pollination in F1, fill inthe blank and answer the question that follows
Parents RRYY x rryy
Round, yellow wrinkled, green
F1 — Rr Yy x ?
Round, yellow
Answer: Self crossing means the crossing with itself F1 generation that is RrYy.
45.) In question 44, what are the combinations of character in the F2progeny? What are their ratios?
Answer:
46.) Give the basic features of the mechanism of inheritance.
Answer: The humans reproduce sexually. The sexual method or reproduction means involvement and fusion of gametes and 2 parents are present. Every living organism on earth have their own unique genetic material and study of this genes called as genetics. Every offspring in some sense is similar to their parents. This similarity is arise due to heredity. The heredity can be defined as transmission of characteristics from one generation to the next generation. So in heredity the characters are transmitted means offspring have similar kind of characteristics to those of parents. The characteristics such as color and height etc. These characteristics are called as traits. This is called as inheritance.
47.) Give reasons for the appearance of new combinations of charactersin the F2 progeny.
Answer: Heredity the characters are transmitted means offspring have similar kind of characteristics to those of parents. The characteristics such as color and height etc. These characteristics are called as traits.
Traits can be defined as particular characteristics of living organisms. It determines the genetic makeup of living organisms. The question is from 2 parents which characteristics transmitted to offspring. These traits are appearing due to genes which are present in the chromosome. The gene is the basic unit of heredity. Therefore, the traits on the basis of expression are divided into 2 types such dominant and recessive.
1) Dominant trait: The characteristics which will express in offspring even in presence of recessive traits. It is denoted by capital letters. For example: BB and Bb in both of the situations, the dominant character is expressing.
2) Recessive trait: The characters which are expressed only in 25 % chances. The characters which are suppressed due to presence of dominant characters. It is denoted by small letters. For example: bb in this situation both the characters are recessive so, will only express in homozygous condition.
As we know the offspring does not look exactly like parents, some differences are always present, such differences are called variations.