MULTIPLE CHOICE QUESTIONS
1. A pure dominant pea plant producing round — yellow seeds is crossed with pure recessive pea plant producing wrinkled — green seeds. The number of plants bearing round — green seeds in the F1 generation of Mendel‘s experiment is (April 2019)
(A) 0 (B) 1 (C) 3 (D) 9
Ans: (A) 0
2. Observe the table which shows contrast forms of pea plants
(A) gGAa (B) GgAa (C) GgAA (D) Ggaa
Ans: (D) Ggaa
3. If a round green seeded pea plant [ RRyy ] is crossed with wrinkled yellow seeded pea plant [ rrYY ], the seeds produced in F1 generation are (July 2021)
(A) round and green seeds
(B) round and yellow seeds
(C) wrinkled and yellow seeds
(D) wrinkled and green seeds
Ans: (B) round and yellow seeds
4. Homologous organs (July 2021)
(A) have same structure and perform same function
(B) have same structure and perform different functions
(C) have different structures and perform same function
(D) have different structures and perform different functions
Ans: (B) have same structure and perform different functions
5. The experiences of an individual during its lifetime cannot be passed on to its progeny because, they are (July 2021)
(A) inherited traits
(B) acquired traits
(C) dominant traits
(D) recessive traits
Ans: (B) acquired traits
6. Tall pea plants having round seeds ( TTRR ) are crossed with dwarf pea plants having wrinkled seeds ( ttrr ). The progeny obtained in F1 generation is (Sep 2021)
(A) Tall plants having wrinkled seeds
(B) Dwarf plants having round seeds
(C) Tall plants having round seeds
(D) Dwarf plants having wrinkled seeds
Ans: (C) Tall plants having round seeds
7. Analogous organs have (Sep 2021)
(A) same structure and perform same function
(B) different structures and perform different functions
(C) different structures and perform same function
(D) same structure and perform different functions
Ans: (C) different structures and perform same function
8. The genotypic ratio of F2 generation of Mendel‘s monohybrid cross experiment is (Sep 2021)
(A) 3 : 1 (B) 1 : 2 : 1
(C) 2 : 1 (D) 9 : 3 : 3 : 1
Ans: (B) 1 : 2 : 1
ONE MARK QUESTIONS
1. What are fossils ? (April 2019)
Ans. The preserved traces of the living organisms are called fossils.
2. Name the factors responsible for speciation. (June 2019)
Ans. : Natural selection Variations Geographical isolation.
3. The gene for brown coloured hair is recessive that of gene for black coloured hair. What is the hair colour of a person who has inherited a gene for brown coloured hair from mother and black coloured hair from father ? (April 2020)
Ans. : Black coloured hair
4. When a tall ( TT ) pea plant is crossed with a dwarf ( tt ) pea plant, represent the result obtained in F2 generation of monohybrid cross with the help of checker board and mention the ratio of varieties of plants. (April 2022)
Ans:
5. What is the sex of a child born by receiving X chromosome from father ? (June 2022)
Ans. : Female child / baby girl
TWO MARKS QUESTIONS
1. Explain the two methods to estimate the age of fossils. (Sep 2020)
Ans. :
★ Relative method: If we dig into the earth, the fossils we find closer to the earth‘s surface are more recent than the fossils we find in deeper layers.
★ By detecting the ratios of different isotopes of the same element in the fossil material.
2. Can the wing of butterfly and the wing of bat be considered as Analogous organs ? If yes, why ? If no, why ? (June 2022)
Ans. :
★ Yes, these structures are considered as Analogous organs.
★ Because the wing of butterfly and wing of bat both are useful for flight.
★ But their basic design / origin are not same.
3. Mention the tools used for tracing the evolutionary relationships between the organisms.
Ans. : .
★ Excavating
★ Time-dating
★ Studying fossils
★ Determining
DNA sequences
THREE MARKSQUESTIONS
1. (i) How does relative method help to determine the age of fossils ?
(ii) Experiences of an individual during its life time cannot direct evolution.‖ Why ?
(iii) Chromosomes inherited from the father determines the sex of a child.‖ Explain. (June 2019)
Ans. : (i) Gives the information that, fossils which are closer to the surface are most recent than those in deeper layers.
(ii) Change in non-reproductive tissues cannot be passed on to the DNA of germ cells. Experiences gained by the organism is not transferred to the DNA and cannot be transferred to the next generation. ( Any one )
(iii) All children will inherit an X chromosome from mother. Child who inherit an X chromosome from father will be a girl. Child who inherit an Y chromosome from father will be a boy.
2. Mendel crossed plants bearing red flowers ( RR ) with the plants bearing white flowers ( rr ) and produced progeny from them. The plants with red flowers obtained in F1 generation were different from the plants with red flowers of parental generation. Why ? Explain with reasons. (Sep 2020)
Ans. :
★ In parent generation, plant bearing red flowers has both the dominant traits RR. In parent generation, plant bearing white flowers has both the recessive traits rr.
★ F1 generation plant inherits one copy of dominant trait ( red ) and one copy of recessive trait (white ) from the parental plants Rr. But only the dominant trait ( red ) is expressed.
3. a) Mention any four main factors that lead to the rise of new species.
b) The experiences of an individual acquired during its lifetime cannot be passed on to its progeny. Give reason. (April 2022)
Ans:
a) Factors responsible for the rise of new species :
★ Geographical isolation
★ Natural selection
★ Inheritance of traits
★ Genetic drift / gene flow
★ Variation / mutuation / changes in DNA.
b) Change in non-reproductive tissues cannot be passed on to the DNA of germ cells.
4. What are fossils ? Mention the methods of estimation of dating fossils and explain briefly. (April 2022)
Ans:
Preserved traces of living organisms in deep layers of the earth.
Methods :
i) Relative method : The fossils we find closer to the surface are more recent than fossils we find in deeper layers.
ii) Determining the time period by using isotopes ( Carbon dating ) Detecting the ratios of different isotopes of same element in the fossil material.
5. An individual organism cannot pass the experiences acquired during its life time to the progenies of the next generation. Explain this concept with the help of an illustration. (June 2022)
Ans. :
★ Change in non-reproductive tissues cannot be passed on to the DNA of the germ cells.
★ For example, if we breed a group of mice all their progeny will have tails, as expected. Now, if the tails of these mice are removed by surgery in each generation, the tailless mice produce tailed progeny.
★ Because, removal of the tail cannot change the genes of the germ cells of the mice.
6. Pure short‘ pea plant is crossed with pure tall‘ pea plant. Represent the results obtained in F2 generation with the help of checker board and mention the ratio of the types of plants obtained. (June 2022)
Ans:
Result of F2 generation :
Ratio obtained in F2 generation :
Tall : dwarf 3 : 1
OR
Pure tall : tall : Pure dwarf 1 : 2 : 1
7. a) How did Mendel identify the tall trait as dominant and short trait as recessive traits in the experiments conducted on plants?
b) Give illustration to prove that, the complicated organ such as eye evolved in stages. ( State Level Preparatory 2023)
Ans:
★ When plants with two contrasting characteristics are crossed each other , the characteristics appeared in first generation were called dominant (i.e. tall plants) and the characteristics that did not appear were called recessive ( i.e. short plants).
★ eyes of flatworms are simple and exist in the form of eyespots. Eyespots are light-sensitive cells which can detect light.
★ As evolution progressed, comparatively larger and mobile organisms evolved. They required better vision for predation. Hence, from the basic design of eyes, more complex forms evolved.
8. Tall pea plant producing red flowers ( TT RR ) is crossed with short pea plant producing white flowers ( tt rr ).
i) Mention the type of plants produced from these plants in the F1 generation.
ii) Write the ratio of plants obtained in the F2 generation by crossing the plants of F1 generation and name the varieties of plants obtained. (April 2023)
Ans:
ii) Ratio = 9 : 3 : 3 : 1
Types of plants
a) 9-Tall — Red flowers producing pea plants
b) 3-Tall — White flowers producing pea plants
c) 3-Short — Red flowers producing pea plants
d) 1-Short — White flowers producing pea plant
9. Analyse the situations given below. Answer the questions given :
Situation 1 : The number of green grasshoppers in a green zone has been increasing from one generation to another generation.
Situation 2 : The number of brown grasshoppers in the same green zone has been reducing.
Here, a) Where could genetic drift be happened more ? Why ?
b) How can natural selection be considered as an important factor in organic evolution? (April 2023)
Ans:
a) In situation (1)
because, natural selection is positive. Among the organisms of new generation of green grasshoppers new combinations in genetic material have been accumulating and genetic drift increases.
b) In situation (2)
because, natural selection is not positive. Due to this, the number of brown grasshoppers is reduced and may disappear in future. So the natural selection is an important event.
FOUR MARKS QUESTIONS
1. (i) Write the differences between homologous organs and analogous organs.
(ii) Write the differences between the sex chromosomes of man and sex chromosomes of woman.
(iii) Sex of a child is determined by the father. How ? ( April 2019)
Ans:
(i) Differences between homologous organs and analogous organs
★ Woman has a perfect pair of sex chromosomes, both called X. bat.
★ Man has a normal sized chromosome X and another short sized chromosome Y.
(iii) A child who inherits X chromosome from her father will be a girl and a child who inherits Y chromosome from his father will be a boy. Both the girl and the boy inherit only X chromosome from the mother. Therefore sex of a child is determined by the father.
2. The plant bearing round yellow coloured ( RrYy ) seed are self pollinated with the same plant. Represent the result obtained in the F2 generation of dihybrid cross with the help of a checker board. Mention the varieties of plants obtained in F2 generation. (April 2020)
Ans :
The plants obtained are
Round yellow — 9 ,
Wrinkled yellow — 3 ,
Round green — 3
Wrinkled green — 1
3. What is evolution ? Explain the three evidences for evolution. (April 2020)
Ans : Phenomenon of gradual change of organisms from simple form into complex form in a long period is called evolution.
Three evidences are :
i) Homologous organs :
★Provide the information that organisms of different species might be evolved from common ancestor.
ii) Analogous organs :
★Provide the information that though the organs of different organisms perform same function, they may not have same function but they may not be evolved from common ancestor.
iii) Fossils :
★ They help to study evidence and missing link between different species.
★ They help to understand the sequence of evolution and help in classification of organisms.
FIVE MARKS QUESTIONS
1. a) Tall pea plant (TT) is crossed with short pea plant (tt). What type of the plants will obtain in F1 generation? Write the genetic make up of this progeny.
b) Forelimbs of frog, wings of bird, wings of bat, forelimbs of lizard pair them as analogous and homologous organs. Give reason for your pairing. (KSEEB MQP 2023)
Ans : a)
★ Tall plants will be obtained in F1 generation.
★ genetic make up of this progeny is- Tt
b)
IMPORTANT QUESTIONS
1. How does the creation of variations in a species promote survival?
Ans :
★ The variations provide stability to the population of various species by preventing them from getting wiped out during adverse conditions.
★ The natural environment also changes, and variations in species which become suited to the environment help it to survive.
2. How do Mendel‘s experiments show that traits may be dominant or recessive?
Ans : When plants with two contrasting characteristics are crossed each other , the characteristics appeared in first generation were called dominant (i.e. tall plants) and the characteristics that did not appear were called recessive (dwarf i.e. plants).
3. How do Mendel‘s experiments show that traits are inherited independently?
Ans : When tall-round seeded plant is crossed with short-wrinkle seeded plant , we find new combinations in F2 progenies like tall-wrinkle seeded and short-round seeded plants . This shows that the tall/short trait and the round seed/wrinkled seed trait are independently inherited.
4. What are the different ways in which individuals with a particular trait may increase in a population ?
Ans :
★ If it gives the benefit of survival through natural selection.
★ Due to a sudden increase in a particular trait in a population, i.e., by genetic drift.
5. Traits acquired during the life-time of an individual is not inherited . Explain with suitable example.
Ans: The traits acquired during the life-time are changes in the non-reproductive cells of the organisms and are not capable of being passed on to the next generation. If a rat accidently lost its tail or we remove it intentionally , this is an acquired character. But this character does not inherited because all progenies of rat are born with tail
6. What are fossils ? What do they tell us about the process of evolution ?
Ans: Fossils : Fossils are the remains or traces of a dead organism. These are formed through the formation of sedimentary rocks. They provide following information on the process of evolution.
1. They tell about the gradual development of complex structured organisms from simple structured organisms.
2. It is known through them that birds are evolved from reptiles.
7. Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species ?
Ans: Humans may be slightly different in different races of people, but there is no reproductive isolation. Reproductive isolation differentiates one species from the other. Human beings may be different in size, colour and looks , they can marry among themselves and produce fertile offspring.
8. In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a better‘ body design ? Why or why not ?
Ans: Bacteria is a primitive organism as they came into being very early in evolution. But these organisms are still surviving in the present conditions after millions of years. This is because they have adapted well to the changing environment over these years. Same is the case for all other organisms like spiders, fishes and chimpanzees which have adapted to their environment and have survived. Therefore, all the organisms which exist have a body design which is better as it is suited to their environment.
9. 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 ?
Ans: No, many of the times the variations are not advantageous to an individual organism but still survive in a population, e.g., take the case of free ear lobe and attached ear lobe.
Sometimes , variation may be advantageous or disadvantageous to an individual.
Ex : feather coloration in peacock is advantageous as it is used attract the opposite sex. But it is disadvantageous as it is recognised by the predators.
10. The human hand, cat paw and horse foot, when studied in detail show the same structure of bones and point towards a common origin. (a) What do you conclude from this ? (b) What is the term given to such structures ?
Ans :
(a) All have originated from same ancestor
(b) These structures are called homologous organs
11. No two individuals are absolutely alike in a population. Why ?
Ans : Variation occur in the DNA due to the Crossing-over and Recombination during the DNA copying process. Hence, no two individuals are absolutely alike in a population.
12. Write the differences between Acquired traits and Inherited traits.
Ans:
No comments:
Post a Comment