Solutions of Heredity and Evolution Lakhmir Singh Manjit Kaur LAQ, MCQ and HOTS Pg No. 210 Class 10 Biology
34A. Name the scientist who gave the theory of origin of life on earth. What is this theory?
Answer
→ (A) The theory of origin of life on earth was given by J.B.S Haldane.
The theory states that life developed from simple inorganic molecules (methane, ammonia hydrogen sulphide). Haldane said that the conditions on earth at that time including lightning converted these simple inorganic mol.to complex organic molecules that joined together to form the first primitive life forms.
34B. How are those species which are now 'extinct’ studied?
Answer
→ (B) Those species that are now extinct are studied by excavating (digging the earth) and studying their fossils.
35. What do you understand by the term 'evolution'? State Darwin's theory of evolution.
Answer
→ Any change in the heritable characteristics of biological population over successive generation is known as Evolution.
Darwin’s theory of evolution – Natural Selection
Variation occurs within a population. Although Species produce a great number of offspring yet the population number remains the same. This constancy in the population number is because of the struggle for resources like food, shelter etc. This Is known as struggle for existence. It favors the fit individuals which survive and reproduce and eliminates the unfavorable ones. This is Natural Selection. These variations accumulate together and they form a new species over time.
36A. Explain the terms 'analogous organs' and 'homologous organs' with examples.
Answer
→ (A) Analogous organs are organs that are similar in function but have different basic structure which means that they have different origin. For example- Wings of a bird and wings of a bat are analogous organs which have same function of flying but have different basic structure of wings.
Homologous organs are organs that have different functions but have similar basic structure i.e. they have common origin. For example- Forelimbs of man and Forelimbs of frog are similar in structure but they perform completely different functions. Forelimbs of frog are used to prop up at front ends while at rest whereas forelimbs of human are used for grasping.
36B. In what way is analogous organ evidence for evolution?
Answer
→ (B) Analogous organs have similar functions but different origins. Presence of analogous organisms in individuals provides evidence for convergent evolution wherein different organisms with different origins evolve to perform similar functions to adapt to similar environmental niches.
37A. Define 'speciation'. Explain how speciation occurs.
Answer
→ (A) Speciation is the formation of new and different species from existing species in the course of evolution. Speciation occurs when a population gets separated geographically.
37B. Will geographical isolation be a major factor in the speciation of a self-pollinating plant species? Give reason for your answer.
Answer
→ (B) No, geographical isolation will not be a major factor in the speciation of a self-pollinating species because self-pollinating plants do not require any other plant to reproduce. Hence, No new gene variants will be introduced into the population and thus there will be no evolution of new species
38A. Define 'natural selection'.
Answer
→ (A) Natural Selection – This theory was given by evolutionist Charles Robert Darwin
Natural selection is a process by which organisms that are better adapted to the environment with their characteristics- survive, reproduce and pass their characteristics to their offspring and organisms that are not adapted well to the environment do not survive much due to the requirements that they fail to accomplish and hence their characteristics are not passed on.
38B. "Only variations that confer an advantage to an individual organism will survive in a population". Do you agree with this statement? Give reason for your answer.
Answer
→ (B) Yes; only variations that confer advantage to an individual organism will survive in a population.
For example- In a population of red beetles, some sudden variation in reproduction produces a green colored beetle. Red beetles are a easy source of prey as they can be easily spotted on the green bushes. The green colored beetle that was produced by a variation could mix up with the green bushes and protect itself from being a prey to predator. If the variation that has occurred in the color of the beetle was blue, then it would have been of no advantage to help in surviving, as it would be easily open to predation like the red beetles.
Multiple Choice Questions (MCQs)-Pg-210
39. 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 Chimpanzee is more common in evolutionary terms. Since it’s a African ape and human beings and modern African apes have had common ancestors, chimpanzee is more common in evolutionary terms.
40. The human species has genetic roots in:
A. America
B. Africa
C. Australia
D. Antarctica
Answer
→ Africa
This is because studies show that human and Modern African Ape shared a common ancestor millions of years ago. So, humans are believed to have evolved in Africa.
41. Which of the following gas was not present in early earth atmosphere?
A. Ammonia
B. Oxygen
C. Hydrogen sulphide
D. Methane
Answer
→ Oxygen
Due to the absence of free oxygen, the organic molecules remain unspoiled and reacted to produce new and more complex organic compounds.
42. A gradual change, over a long period, in a form of life is known as :
A. Erosion
B. Evolution
C. Revolution
D. Evaluation
Answer
→ Evolution
Evolution is a phenomenon that brings about continuous and orderly changes in nature. It is a change through time in physical or biological world.
43. Scientists believe that all life originated in:
A. The sea
B. The soil
C. The ground
D. The air
Answer
→ The sea
It is believed that life originated about 3.5bya in sea, near deep sea hydrothermal vents.
44. According to scientists, aves have evolved from:
A. Mammals
B. Amphibians
C. Reptiles
D. Arthropods
Answer
→ Reptiles
Aves have evolved from reptiles. Archaeopteryx lithographica is a connecting link between reptiles and aves. The fossil bird was of the size of crow and had both reptilian and avian characters.
45. The theory of evolution of species by natural selection was given by:
A. Mendel
B. Darwin
C. Dalton
D. Lamarck
Answer
→ Darwin
Charles Robert Darwin wrote a book ‘Origin of Species’ in which he gave The theory of Evolution of species by Natural Selection.
46. The term 'father of genetics' is used for the scientist:
A. Morgan
B. Mendel
C. Darwin
D. Marie Curie
Answer
→ Mendel
Gregor Johann Mendel is known as the father of genetics. He worked on Pea plant and discovered the fundamental laws of inheritance.
47. One of the following traits cannot be inherited. This one is:
A. Color of eyes
B. Color of skin
C. Size of body
D. Nature of hair
Answer
→ Size of body
Size of body cannot be inherited because it depends on division capability of somatic cells and physical efforts also. The rest are inherited through gametes.
48. Only one of the following characteristic of the parents can be inherited by their children. This one is:
A. Deep scar on chin
B. Snub nose
C. Technique of swimming
D. Cut nose
Answer
→ Snub nose
This is because the rest of them cannot be inherited as they are related to somatic cell characteristics and learning. Only snub nose can be inherited as its trait would be carried in the gene.
49. The organs which perform different functions but have the same basic structure are known as:
A. Homologous organs
B. Analogous organs
C. Homolytic organs
D. Analytic organs
Answer
→ Homologous organs
These organs are similar in their basic structure but they perform different functions. For example- Forelimbs of bird are used for flying, whereas forelimbs of man are used for grasping (i.e. they have same basic structure of bones but perform different functions.)
50. The organs which perform similar functions but have different basic structure are called:
A. Asymmetric organs
B. Analogous organs
C. Homologous organs
D. Homophonic organs
Answer
→ Analogous organs
These organs perform similar functions but have different basic structure. For example- Wing of an insect and wing of a bird perform the same function of uplifting the body in air but their basic structure is totally different.
51. Wing of an insect and forelimb of a bird are:
A. Analogous organs
B. Analeptic organs
C. Homologous organs
D. Homophobic organs
Answer
→ Analogous organs
Wing of an insect and forelimb of a bird help them to lift their body up in the air but their basic structure is totally different, so they are analogous organs.
52. 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 years ago
C. The fossil position in the layers of earth is not related to its time of extinction
D. Time of extinction cannot be determined.
Answer
→ The extinction of organism has occurred thousands of years ago.
Fossils are formed in sedimentary rock which is formed in layers by the deposition and pressure of sediments on top of each other thus the oldest layers are on the bottom, and the youngest layers are on the top.
53. Which of the following statement is incorrect with respect to variations?
A. All variations in a species have equal chance of survival
B. Change in genetic composition results in variations
C. Selection of variations by environmental factors forms the basis of evolutionary process
D. Variations are the minimum in asexual reproduction
Answer
→ All variations in a species have equal chances of survival.
This is incorrect because nature follows survival of the fittest. If variation in a species does not let the organism adapt to surroundings it would not survive for long whereas the species that will be able to adapt to surroundings will survive.
54. One of the following traits of the parents cannot be passed on to their future generations. This trait is:
A. Cleft chin
B. Pointed chin
C. Scarred chin
D. Broad chin
Answer
→ Scarred chin
This trait cannot be passed from parents to future offspring because chin gets scarred when the somatic cells of the chin are damaged and it is not a trait that is transferred genetically.
55. Some dinosaurs had feathers although they could not fly but birds have feathers that help them to fly. In the context of evolution, this means 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
→ Birds have evolved from reptiles
Reptiles had feathers but could not fly. Over time evolution kept on taking place and with evolution the body size changed and feathers got the ability to help in to flying. Reptiles kept on evolving and their evolution led to the formation of birds which could use feathers for flying. Thus birds have evolved from Reptiles.
56. Select the incorrect statement from the following:
A. Frequency of certain genes in a population changes over several generations resulting in evolution
B. Reduction in the weight of an organism due to starvation is genetically controlled
C. Low weight parents can have heavy weight progeny
D. Traits which are not inherited over generations do not cause evolution.
Answer
→ Reduction in the weight of an organism due to starvation is genetically controlled.
This statement is incorrect/false. Reduction in weight due to starvation is a result of less amount of food consumed and is not genetically controlled.
57. 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
→ New species may be formed if DNA undergoes significant changes in germ cells and Chromosome number changes in the gamete.
If DNA undergoes changes in germ cells that will cause mutations and if chromosome number changes in the gamete it will lead to lethal consequences; both of these changes will lead to formation of new species.
58. According to the evolutionary theory, formation of a new species is 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
→ Accumulation of variations over several generations
Variations when accumulate will lead to natural selection and natural selection is based on survival of the fittest. So, a new species is formed when nature starts selecting species that can survive well.
59. The presence of which of the following types of organs in two animals indicates that they are not derived from a common ancestor?
A. Homologous organs
B. Excretory organs
C. Analogous organs
D. Reproductive organs
Answer
→ Analogous organs
These organs have different origins i.e. they are not derived from common ancestor, but they perform similar functions. For example- Wings of insect and bat.
60. The presence of which of the following types of organs in two organisms indicates that they are derived from the same ancestor?
A. Analogous organs
B. Respiratory organs
C. Digestive organs
D. Homologous organs
Answer
→ Homologous organs
Homologous organs have different functions but they have basic structure of bones which means they have the same ancestor. For example-forelimbs of frog and forelimbs of man. Both have a similar basic structure of bones but forelimbs or frog are used to prop up at front ends when at rest, whereas forelimbs of man are used for grasping.
61. One of the following has not been produced from wild cabbage by the process of artificial selection. This one is:
A. Kohlrabi
B. Cabbage
C. Spinach
D. Kale
Answer
→ Spinach
Kohlrabi, cabbage and kale have been produced from Wild cabbage (Brassica oleracea) by the process of artificial selection.
62. The fossil trilobite was originally:
A. An arthropod
B. An invertebrate
C. A reptile
D. Ave
Answer
→ An arthropod
Trilobite is a fossil group of marine arthropods.
63. One pair of organs in the following animals is not homologous. This is:
A. Forelimbs in humans and lizard
B. Forelimbs in lizard and frog
C. Wings in butterfly and bat
D. Wings in bat and bird
Answer
→ Wings in butterfly and bat
Wings in butterfly and bat are analogous. They have similar functions i.e. flying but they have different ancestors from which they evolved so the pair is not homologous.
64. The wings of a housefly and the wings of a sparrow are an example of:
A. Analogous organs
B. Vestigial organs
C. Respiratory organs
D. Homologous organs
Answer
→ Analogous organs
Wings of a housefly and wings of a sparrow are analogous organs since they have similar function which is flying but they have evolved independently in each lineage separately after diverging from an ancestor without wing.
Questions Based on High Order Thinking Skills (HOTS)-Pg-211
65. Some of the important fossils which have been studied are those of organisms X, Y and Z. X were marine arthropods which were common between 400 to 600 million years ago. Y were the invertebrate animals (molluscs) with a flat, coiled, spiral shell which lived in the sea about 180 million years ago. Z are the extinct carnivorous or herbivorous reptiles which appeared on the earth about 250 million years ago and became extinct about 65 million years ago. What are X, Y and Z?
Answer
→ Marine arthropods whose fossils have been studies are known as Trilobites.
Ammonites are the extinct molluscs with flat, coiled spiral shape shell millions of years ago but are now extinct.
Carnivorous animals that appeared about 250mya and disappeared 65 mya are none other than Dinosaurs, as we all know dinosaur disappeared 65mya.
So, X- Trilobites; Y- Ammonites; Z- Dinosaurs.
66. The farmers have been cultivating a food plant X for over two thousand years and have produced as many as five entirely different looking vegetables A, B, C, D and E from it.
(a) What could the plant X be?
(b) What are A, B, C, D and E?
(c) What is the process of evolution involved in this example known as?
Answer
→ (a) X- Wild Cabbage (Brassica oleracea) is made to produce 5 different varieties of vegetables by artificial selection.
(b) These 5 different looking vegetables are Cabbage, Kohlrabi, Kale, Broccoli, and Cauliflower.
67. There are five animals A, B, C, D and E. The animal A uses its modified forelimbs for flying. The animal B uses its forelimbs for running whereas the animal C uses its forelimbs for grasping. The animal D can live on land as well as in water and uses its forelimbs to prop up the front end of its body when at rest. The animal E which respires by using spiracles and tracheae uses wings for flying but its wings are analogous to the modified forelimbs of animal A.
(a) What could the animals A, B, C, D and E be?
(b) Why are the forelimbs of animals A, B, C and D called homologous organs ?
(c) What does the existence of homologous organs in animals A, B, C and D tell us about their ancestors?
(d) Why are the modified forelimbs of animal A and the wings of animal E called analogous organs?
(e) State whether animals A and E have a common ancestor or not.
Answer
→ (a)Animals A, B, C, D and E could be sparrow, Lizard, human, frog, insect.
(b) Forelimbs of Bird, lizard, human and frog are called homologous organs because their basic structure of bones is similar but they perform different functions. This means that they have had a common ancestor and with time they adapted themselves according to the requirements.
(c) The existence of homologous organs in animals A, B, C, D tell us that since they have similar basic structure of origin, they have a common ancestor.
(d) Modified forelimbs of Bird and wings of Insect are called analogous organs because they have different basic structure but they perform similar functions. Bird uses its forelimbs to fly; similarly insect uses its wings to fly. Because their basic structure of origin is different so they do not have a common ancestor.
(e) No, Animals having analogous organs do not have a common ancestor because their basic structure of origin is different.
68. X, Y, and Z are three animals. The animal X can fly but animal Y can only run on ground or walls. The forelimbs of animals X and Y have the same basic design but they are used for different purposes such as flying and running respectively. The animal Z became extinct a long time ago. The study of fossils of Z tells us that it had some features like those of X and some like those of Y. In fact, Z is said to form a connecting link in the evolutionary chain of X and Y.
(a) What could the animals X, Y and Z be?
(b) What name is given to the forelimbs like those of X and Y which have the same basic design but different functions?
(c) Name one feature in which Z resembled X.
(d) Name one feature in which Z resembled Y.
(e) Which is the correct evolutionary chain involving X, Y and Z: X Z Y or YZ X?
Answer
→ (a) Bird, lizard and dinosaur; Birds can fly ; Lizards can walk on walls; Dinosaurs can fly as well as walk too)
(b) Homologous organs. (Organs that have same structure but different function)
(c) Feathered Wings as in birds
(d) Tail as in reptiles
(e) YZ X?
69. A population of red beetles lives in green bushes in a garden. Once during the process of breeding, a green beetle is produced.
(a) State whether the change in color of beetle is a process of evolution or not.
(b) Can the new color of green beetle be passed on to its next generations?
(c) What will be the advantage (if any) of the green color to the beetle?
(d) State whether the production of green color involved a change in genetic material or not.
Answer
→ (a) Yes; the change in color of beetle is a process of evolution which might have occurred to adapt to certain environmental condition.
(b) Yes; the color of green beetles can be passed on to the next generation through genes.
(c) The green color will protect the beetle from predation as it will help the beetle hide in the bushes.
(d) Yes; it involved a change in genetic material because unless and until the gene responsible for color gets some changes, no new color can be produced than the original one.
70. The organs P and Q of two animals have different structures but similar functions. On the other hand, the two organs R and S of two other animals have the same basic structure but different functions.
(a) What are the organs like P and Q known as?
(b) Name the organs like P and Q. Also name the animals which have such organs.
(c) What are the organs like R and S called?
(d) Name the organs like R and S. Also name the animals which have such organs.
Answer
→ (a) These organs that have different basic structure but perform similar functions are known as analogous organs. So organs P and Q are analogous organs.
(b) Wings of a Butterfly and wings of a sparrow; wing of an insect and wing of a bird.
(c) These organs that have similar basic structure but perform different functions are known as homologous organs. So organs R and S are homologous organs
(d) Forelimbs; Forelimbs of a frog and forelimbs of human are homologous.