Test: Evidences of Organic Evolution - Grade 12 MCQ

• During the voyage of Darwin, he visited the Galapagos island.
• There, he came across different varieties of species. He saw the variations in the modification of beaks of finches.

The reptiles and the aves belong to the vertebrates. Archaeopteryx is a connecting link between reptiles and birds as it possesses characteristics of both birds and reptiles. Archaeopteryx possessed a long tail, teeth in jaws, long neck with cervical vertebrae, all are reptilian characters. Like birds, it had wings and beak. It was warm blooded. 

Vestigial organs are degenerate, non-functional and rudimentary organs correspond to fully developed and functional organs of related organism. Third molar (wisdom teeth), plica semilunaris and pyramidalis muscles are vestigial organs. Epiglottis is not a vestigial organ in man. Epiglottis is the structure that prevents the entry of food into respiratory tract during swallowing in man.

 There are about 100 vestigial organs in human being like rudimentry ear muscles (much developed in have elephant and cow) third molar, coccyx (4-5 coccygeal vertebrae) scalp muscle, vermiform appendix, nictitating membrane, ear pinna muscle is vestigial but ear functional bone in man, olecranon process is related to nervous system.

Vestigial organs are those organs which are non-functional in the possessor but were functional in their ancestors and in related animals. Human beings possess many vestigial organs like nictitating membrane in the eye, vermiform appendix at the end if caecum, coccyx and tail muscles, non-functional muscles of the pinna, wisdom teeth, segmental muscle of abdomen and nipples in males.

The name of Charles Darwin and his famous book The Origin of Species will forever be linked with the Galapagos Islands. Although he was only in the Galapagos for five weeks in 1835, it was the wildlife that he saw there that inspired him to develop his Theory of Evolution.

Paleontology is the branch of biology that studies the forms of life that existed in former geologic periods, mainly by studying fossils. It is the study of the history of life on earth, as reflected in the fossil record. Fossils are the remains or traces of organisms (plants, animals, fungi, bacteria and other single-celled living things) that lived in the geological past and are preserved in the crust of the earth. 

• It was from the seed-eating finches, many other altered forms of beak arose enabling them to be insect, cactus or fruit eaters.
• This led to the discovery of Adaptive radiation.
• Darwin’s finches are one of the best examples of this process.

Evolution is the gradual changes occurring over generations after generations, during which different species of plants, animals, birds and insects gradually change some of their physical characteristics. These changes include the different aspects of life like genetic drift, mutation, natural selection, thought and technology.The main factors responsible for the evolutionary changes are certain environmental changes and predation pressures.

Prototheria are mammals that lay eggs. They have several characters similar to reptiles like they have one opening for excretion and reproduction. They are also similar to reptiles in some aspects of their skeletons. Notably, their legs are on the sides of their bodies rather than underneath them. This results in a reptile-like gait. Hence, option D is correct.

Homologous organs - Homologous organs are organs of different organisms, which are dissimilar externally but similar in origin and in fundamental structural plan. e.g. hand of man and wing of bird. There are other organs called analogous organs which are similar in function and external appearance, but dissimilar in origin and structural plan.

The only explanation for homologous organs is that these animals are the diverging descendants of the common ancestor. Homologous characteristics help to identify an evolutionary relationship between apparently different species.

The insects the mouth parts comprise labrum,mandibles and maxilla (representing similar origin and structure) but they have different functions.
Function of mouth in-
Cockroaches - biting and chewing
Honey bee - chewing and lapping
Mosquito - piercing and sucking.
Evidently,the same structure is developed along different divergent evolution and these structures are Homologous.

The “wisdom teeth,” or last molars, are in man approaching a vestigial condition, since they generally do not appear until relatively late, between the ages of twenty and thirty years, and in many persons are never cut at all. In a large percentage of individuals, they are useless, and they often become impacted and have to be removed surgically.

The theory of recapitulation, also called as the biogenetic law or embryological parallelism often expressed in Ernst Haeckel's phrase "ontogeny recapitulates phylogeny" is a largely discredited biological hypothesis that in developing from embryo to adult, animals go through stages resembling or representing successive stages in the evolution of their remote ancestors. While examples of embryonic stages show that molecular features of ancestral organisms exist, the theory of recapitulation itself has been viewed within the field of developmental biology as a historical side-note rather than as dogma. 

Therefore, the correct answer is option B.

Analogous organs are the organs of different animals which have different basic structure but perform same function. For example, the wing of a bird and the wing of a butterfly have different structures but they perform similar function so they are analogous organs.

Euglena is a connecting link between animals and plants. Nutrition in Euglena is mixotrophic, when the light is available it is photosynthetic, in darkness, it is saprophytic absorbing food from surrounding water.

Penguins are birds that cannot fly, but are excellent swimmers, which is why they spend a lot of time in the water. Out of 18 penguin species, only 3 species live exclusively in Antarctica, while the rest are scattered in many places around the Southern Hemisphere

Neopilina is a connecting link between annelids and molluscans. It is the only segmented mollusc. It has a cup shaped shell like that of limpet. Its visceral mass is divided into five segments, each with a pair of shell muscles, gills, auricles,  and nephidia.

The evolutionary term descent with modification is most often associated with human evolution, but it is actually a more general term than that would suggest. Simply put, descent with modification means that traits are passed down from generation to generation and sometimes undergo changes or modifications over time. These changes may be caused by natural selection or even a mutation of DNA. It is a theory of organic evolution.

Lycaenops was a mammal-like reptile. It is considered a missing link between reptiles and mammals. Laying shelled eggs is a characteristic of birds and reptiles. Having hair, teats on body and cloaca are characteristics of animals. So, particular animal has shelled eggs, hair and teats on the body and has cloaca, it may be a connecting link between reptiles and mammals. Thus, option C is correct and other options are wrong.

Homologous organs are structures or organs of different animals that evolved from a common ancestor (similar developmental origin) but differ in their functions. On the other hand, analogous organs are structures that evolved independently (different developmental origin) in two different species of organisms to serve a similar function. The wings of a butterfly and a bird have a similar function of flying but they are anatomically different in origin.

If a starfish possess 6 arms instead of 5, it is an example of variation [variation is any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences (genotypic variation) or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation)]. Variation may be shown in physical appearance, metabolism, fertility, mode of reproduction, behaviour, learning and mental ability and other obvious or measurable characters. Metamorphosis is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Biogenesis is the production of new living organisms or organelles and evolution is change in heritable traits of biological populations over successive generations.

The organs which have different embryonic origin but perform same function are called as analogous organs, e.g., wings of bat and insects. The organs which have same embryonic origin but adapted to perform different functions are known as homologous organs, e.g., wing of bat and forelimb of humans.

The first theory of evolution was proposed by Jean Baptiste de Lamarck Lamarckism proposed, Some internal forces are present in all organisms. Due to  the presence of these forces, the organism has the tendency to increase the size of their organs or the entire body.
Environment influences all type of organisms. Changing environment give rise to new needs. New needs or desires produce new structure and change habits of the organism.
If an organ is constantly used, it would be better developed whereas disuse of organ results in its degeneration.
So, the correct option is 'Lamarck'.

Fossilization occurs after an organism dies and only affects hard body parts, such as bones and shells. Soft flesh, scales, and feathers will not become fossils, although, imprints of these parts are sometimes made. In order for fossilization n to occur three things must happen. First, an organism dies.

Fossil 'X' can be considered to have evolved earlier than fossil 'Y' if fossil 'X' is found in lower stratum of undisturbed sedimentary rock than 'Y'. Fossils are preserved forms of living organisms that really existed on earth. Presence of 'X' in lower stratum indicates that it existed of 'X' in lower stratum indicates that it existed much before than 'Y'. 

The Mesozoic era is called the age of reptiles(golden) because this is when dinosaurs dominated the Earth. When a mass extinction occurred, it killed off all of the dinosaurs and was one of the largest in the history of the Earth.

Answer:

Fossils are dated by:

• Amount of radioactive carbon compound: Fossils can be dated using a method called radiocarbon dating, which measures the amount of radioactive carbon compound (carbon-14) present in the fossil. This method is used to determine the age of organic materials up to approximately 50,000 years old.

Other options:

• Amount of calcium residue: The amount of calcium residue in a fossil is not used to determine its age.


• Association with other mammals: While the association with other mammals can provide information about the environment and ecosystem in which the fossil was found, it does not directly date the fossil.


• Structure of bones: The structure of bones can provide information about the anatomy and characteristics of the organism, but it does not directly date the fossil.

Therefore, the correct answer is b. Amount of radioactive carbon compound.

Life was not possible in Azoic era because it was the first era on earth and the temperature and climate was not favorable of living creatures.

Evolution leads to changes in the characteristics of a living organism according to the changing environmental conditions with time. This change creates variations which are inherited from one generation to the other. The modification leads to shifting of simpler structures into complex structures due to evolutionary changes and helps to adapt in harsh conditions. For example two-chambered heart of fishes turned to three chambered in amphibians and three to four chamber in reptiles which ends on completely modified four-chambered heart in man.

So, the correct answer is option C.