1. Complete the following diagram.
Answer:_
2. Read the following statements and justify the same in your own words with the help of suitable examples.
a. Human evolution began approximately 7 crore years ago.
Answer:_
The statement that human evolution began approximately 7 crore years ago is based on scientific evidence from the field of paleoanthropology, which studies the origins and development of human beings. This evidence includes the discovery and analysis of fossils, as well as genetic and cultural data.
One example of this evidence is the discovery of a fossilized skull in eastern Africa that is estimated to be around 7 million years old. This skull, known as the Sahelanthropus tchadensis, has a mix of characteristics that are seen in both apes and early human ancestors, leading scientists to believe that it represents a transitional form between the two.
Another example is the discovery of the Orrorin tugenensis fossils, dated to about 6 million years ago, which also suggested to be a transitional form between apes and human ancestors.
Additionally, genetic studies have shown that the human genome is highly similar to that of chimpanzees and gorillas, with the last common ancestor between humans and chimpanzees lived around 6-7 million years ago.
All of these examples support the idea that human evolution began around 7 crore years ago and that the process of evolution has led to the development of the modern human species.
b. Geographical and reproductive isolation of organisms gradually leads to speciation.
Answer:_
Geographical and reproductive isolation are two factors that can lead to the gradual formation of new species. Geographical isolation occurs when a physical barrier, such as a mountain range or a body of water, separates a population of organisms from other populations of the same species. This separation can prevent interbreeding between the populations, leading to the development of distinct genetic characteristics over time.
Reproductive isolation, on the other hand, refers to mechanisms that prevent interbreeding between different populations or species even when they are geographically close to each other. This can be due to differences in mating rituals, timing, or physical characteristics that prevent successful mating between individuals.
An example of geographical isolation leading to speciation is the case of the Galapagos finches, also known as Darwin’s finches. These finches are a group of closely related birds that live on the Galapagos Islands. Over time, the different finch populations on the different islands have adapted to their specific environments, leading to the formation of different species. For example, the beak size and shape of the finches have evolved to better suit the different types of food available on each island.
An example of reproductive isolation leading to speciation is the case of the North American red fox and the arctic fox. These two fox species live in the same geographic region, but they have different mating rituals and physical characteristics that prevent them from interbreeding. As a result, they have developed distinct genetic characteristics over time, leading to the formation of two separate species.
In conclusion, both geographical and reproductive isolation can lead to the gradual formation of new species through the process of speciation. The isolation can lead to the development of distinct genetic characteristics over time which ultimately lead to the formation of different species.
c. Study of fossils is an important aspect of study of evolution
Answer:_
The study of fossils is an important aspect of the study of evolution because it provides evidence of the existence and diversity of past life forms. Fossils are the remains or traces of ancient organisms that have been preserved over time. They can include bones, teeth, shells, footprints, and even impressions of soft tissues. By studying these fossils, scientists can infer information about the appearance, behavior, and ecology of extinct organisms, as well as the evolutionary relationships between different species.
Fossils can also provide information about the geologic history of the Earth. By studying the rock layers in which fossils are found, scientists can infer information about the environment and climate of the past, as well as the age of the fossils. The study of fossils in this way is called stratigraphy.
An example of how fossils have helped to understand the evolution is the case of horse. Fossils of horse-like animals have been found that date back more than 50 million years. By studying these fossils, scientists have been able to infer information about the evolution of the horse. They have observed that horse’s body, teeth, and foot structures have changed over time, with early horse species having multiple toes and later horse species having just one. This change in the number of toes is evidence of the gradual evolution of horse species over time.
Another example is the study of dinosaurs fossils. Dinosaurs lived on Earth around 65 million years ago and went extinct. Scientists study the fossils of dinosaurs to understand their physical features, behavior and how they lived, and how they relate to the modern animals.
In conclusion, the study of fossils is a crucial aspect of understanding evolution. It provides a glimpse into the past, which helps scientists understand the diversity and evolution of life forms. Fossils give us a glimpse of the evolution of different species over time and how they are related to the present-day organisms. It helps scientists to understand the geologic history of the Earth and the changing environment.
d. There is evidence of fatal science among chordates
Answer:-
There is evidence of parallel evolution among chordates, a group of animals that includes fish, amphibians, reptiles, birds, and mammals. Parallel evolution occurs when different species independently evolve similar characteristics in response to similar environmental pressures. This can result in the development of similar adaptations in different groups of organisms, even if they are not closely related.
An example of parallel evolution among chordates is the development of limbs. Limbs are a defining characteristic of chordates and are found in many different groups of animals, including fish, amphibians, reptiles, birds, and mammals. However, the limbs of these different groups of animals have evolved independently, in response to similar selective pressures, such as the need for mobility on land. This has resulted in the development of similar structures, such as a shoulder girdle, a humerus, and a radius and ulna, in different groups of chordates.
Another example of parallel evolution among chordates is the development of jaws. Jaws are a defining characteristic of fish and are found in many different groups of fish, such as sharks and bony fish. The jaws of these different groups of fish have evolved independently, in response to similar selective pressures, such as the need for food. This has resulted in the development of similar structures, such as a skull, a jaw bone, and teeth in different groups of fish.
In conclusion, parallel evolution is the development of similar adaptations in different groups of organisms in response to similar environmental pressures. This can occur among chordates, a group of animals that includes fish, amphibians, reptiles, birds, and mammals. The examples of the development of limbs and jaws in different groups of chordates are the evidence of parallel evolution. It is a fascinating phenomenon that highlights the power of natural selection to shape the diversity of life on Earth.
3. Complete the statements by choosing correct options from bracket.
(Gene, Mutation, Translocation, Transcription, Gradual development, Appendix)
a. The causality behind the sudden changes was understood due to — — principle of Hugo de Vries.
b. The proof for the fact that protein synthesis occurs through — — was given by George Beadle and
Edward Tatum.
c. Transfer of information from molecule of DNA to mRNA is called as — — — process.
d. Evolution means — — — –.
e. Vestigial organ — — — present in human body is proof of evolution.
Answer:_
a. The causality behind the sudden changes was understood due to mutation principle of Hugo de Vries.
b. The proof for the fact that protein synthesis occurs through transcription was given by George Beadle and Edward Tatum.
c. Transfer of information from molecule of DNA to mRNA is called as transcription process.
d. Evolution means gradual development.
e. Vestigial organ appendix present in human body is proof of evolution.
4. Write short notes based upon the information known to you.
a. Lamarckism
Answer:-
b. Darwin’s theory of natural selection.
c. Embryology.
d. Evolution.
e. Connecting link.
Answer:_
a. Lamarckism is a theory of evolution proposed by French biologist Jean-Baptiste Lamarck in the early 19th century. It posits that organisms can pass on to their offspring the traits they acquire during their lifetime, in response to changes in their environment. This theory was later discredited by scientists, as it was later found that traits acquired during an organism’s lifetime could not be passed on to its offspring.
b. Darwin’s theory of natural selection is a theory of evolution proposed by Charles Darwin and Alfred Russel Wallace in the 19th century. It posits that organisms that are better adapted to their environment are more likely to survive and reproduce, passing on their advantageous traits to their offspring. Over time, this process can lead to the gradual evolution of new species. This theory is widely accepted by scientists as the main mechanism of evolution.
c. Embryology is the study of the development of organisms from the earliest stages of fertilization to the point at which they become fully formed. It is an important field of study in understanding the evolution of organisms. Embryological similarities between different groups of organisms can provide evidence of evolutionary relationships, and the study of embryonic development can also provide insight into how evolutionary changes have occurred.
d. Evolution is the process by which different species of organisms have developed and diversified over time. It is driven by natural selection, which acts on genetic variation in populations, leading to the survival of certain traits and the elimination of others. Over many generations, this process can lead to the gradual development of new species, as well as the extinction of existing ones.
e. Connecting link is a term used to describe an organism that shares characteristics with two or more groups of organisms and is thought to be an intermediate form between them. These organisms are considered as an evidence for evolution as they bridge the gap between different groups of organisms and provide a glimpse into the evolutionary history of those groups. Examples of connecting links include the extinct species of mammal-like reptiles, which share characteristics with both reptiles and mammals, and are thought to be an intermediate form between the two groups.
5. Define heredity. Explain the mechanism of hereditary changes
Answer:-
Heredity refers to the passing on of traits or characteristics from parents to their offspring through the genetic material. The genetic material that is responsible for heredity is DNA, which is found in the form of chromosomes in the cells of all living organisms.
The mechanism of hereditary changes is the process of transmitting the genetic information from one generation to the next. This process is carried out by the genetic material DNA, which carries the information of all the inherited characteristics. The DNA is composed of units called nucleotides, which are arranged in a specific sequence. This sequence is the code for all the inherited characteristics like eye color, hair color, height, etc.
The mechanism of hereditary changes can be broadly classified into two types: genetic and environmental.
- Genetic changes occur due to mutations in the DNA sequence, which can be caused by various factors such as errors in DNA replication, exposure to radiation or certain chemicals, or viral infections. These mutations can lead to changes in the genetic code and can result in the development of new traits or characteristics in the offspring.
- Environmental changes occur due to the influence of the environment on the expression of genes. These changes can be caused by various factors such as temperature, nutrition, and exposure to toxins. Environmental changes can result in changes in the way the genetic code is read, which can result in the development of new traits or characteristics in the offspring.
In summary, Heredity is the process of passing on genetic information from parents to their offspring and it can be caused by genetic and environmental changes.
6. Define vestigial organs. Write names of some vestigial organs in human body and write the names of those animals in whom same organs are functional.
Answer:_
Vestigial organs are organs or structures that have lost most or all of their original function in an organism, but are still present in the body. They are remnants of organs or structures that were once functional in an ancestor of the organism, but are no longer needed. Vestigial organs can provide evidence for evolution, as they demonstrate that the organism has changed over time, and is no longer using certain structures or organs that were once functional.
Some examples of vestigial organs in the human body include:
- Appendices: The appendix is a small, finger-shaped pouch that is located near the junction of the small and large intestine. It is a vestigial organ in humans, and its function is not clear. In some animals like rabbits, the appendix is much larger and serves as a fermentation chamber to aid in the digestion of tough plant materials.
- Wisdom Teeth: Wisdom teeth, also known as third molars, are located at the back of the mouth and are vestigial in humans because they are often removed due to lack of space in the jaw. In animals such as chimpanzees, however, wisdom teeth are functional and are used to chew tough, fibrous foods.
- Nictitating Membrane: A Nictitating membrane is a transparent or translucent eyelid that is found in some animals, including birds, reptiles, and fish. Humans have a vestigial nictitating membrane, known as the plica semilunaris, which is located at the inner corner of the eye, but it is not functional.
- Tailbone: The tailbone, also known as the coccyx, is a small, triangular bone at the base of the spine in humans, it is vestigial because humans no longer have a tail. In animals such as monkeys, the tail is functional and is used for balance and communication.
In summary, Vestigial organs are organs or structures that have lost most or all of their original function in an organism, but are still present in the body as a remnant of its ancestors. They are seen as evidence of evolution as they show that the organism has changed over time and no longer needs certain structures or organs that were once functional.
7. Answer the following questions.
a. How are the hereditary changes responsible for evolution?
Answer:- Hereditary changes, also known as genetic variation, are responsible for evolution because they provide the raw material for natural selection to act upon. Evolution is the process by which populations of organisms change over time, and genetic variation is the driving force behind this process.
Hereditary changes occur through several mechanisms, including mutation, gene flow, genetic drift, and recombination.
- Mutation: Mutation is a change in the DNA sequence that can result in a new allele, or variant of a gene. These mutations can be beneficial, neutral or harmful. Beneficial mutations can provide an advantage to the organism, increasing its chances of survival and reproduction. Over time, these beneficial mutations can accumulate in a population, leading to the evolution of new traits and characteristics.
- Gene flow: Gene flow is the movement of genes from one population to another, either through migration or the movement of individuals. Gene flow can introduce new alleles into a population, increasing genetic variation.
- Genetic drift: Genetic drift is the random fluctuation of allele frequencies in a population. This can result in the loss of alleles from a population, or the fixation of alleles, where one allele becomes the only allele present in the population. Genetic drift can also lead to the evolution of new traits and characteristics, but it is a more random process than natural selection.
- Recombination: Recombination is the process by which alleles are shuffled during the formation of sperm and eggs, creating new combinations of alleles. This can lead to the evolution of new traits and characteristics in a population.
Overall, hereditary changes introduce genetic variation into populations, and this variation is the driving force behind evolution. Natural selection, the process by which certain traits become more or less common in a population depending on their effect on the survival and reproduction of individuals, acts on this variation, leading to the evolution of new traits and characteristics over time.
b. Explain the process of formation of complex proteins.
Answer:_
1)Transcription is the process by which genetic information in DNA is used to synthesize a complementary RNA molecule. In the case of protein-coding genes, this RNA is called messenger RNA (mRNA) and carries the genetic code for the synthesis of a specific protein. The process of transcription involves the binding of RNA polymerase to the promoter region of a gene, followed by the separation of the DNA strands and the formation of a complementary RNA strand using the genetic code in the DNA as a template. Once the mRNA is synthesized, it is transported out of the nucleus and into the cytoplasm, where it is used as a template for protein synthesis during translation
2) Translation is the process by which the genetic code in mRNA is used to synthesize a specific protein. It occurs in the ribosomes of the cell and involves the binding of the mRNA to a ribosome, the alignment of transfer RNAs (tRNAs) carrying specific amino acids to the codons (groups of three nucleotides) in the mRNA, and the joining of the amino acids to form a protein.
The process of translation starts with the binding of the small subunit of the ribosome to the mRNA, which brings the codons of the mRNA into the ribosome’s active site. The next step is the binding of a tRNA carrying the correct amino acid to the codon in the mRNA. The tRNA is brought to the ribosome by the aid of an enzyme called aminoacyl-tRNA synthetase. This process is called charging of the tRNA. The ribosome catalyzes the formation of a peptide bond between the amino acid on the tRNA in the P site and the amino acid on the tRNA in the A site. This causes the tRNA in the P site to be released and the ribosome to move along the mRNA by one codon, bringing the next codon into the A site. This process continues until a stop codon is reached, at which point the ribosome releases the newly synthesized protein.
Translation is a highly regulated process, and the rate and efficiency of protein synthesis can be controlled by various factors such as the availability of mRNA and tRNAs, the activity of the ribosomes, and the presence of regulatory proteins. And this process of translation leads to the formation of complex proteins which play vital roles in the cell.
3) Translocation refers to the process by which a protein is moved from one cellular compartment to another or across a membrane. This can occur during or after protein synthesis and can be an essential step in the proper localization and function of a protein.
One example of translocation is the movement of a protein from the cytoplasm to the endoplasmic reticulum (ER) or the Golgi apparatus. This process is known as cotranslational translocation and occurs as the protein is being synthesized on the ribosome. As the protein is synthesized, it is passed through a channel in the ribosome called the translocon, which spans the ER or Golgi membrane. This allows the protein to be inserted into the lumen of the ER or Golgi, where it can be modified and sorted for transport to its final destination.
Another example of translocation is the movement of a protein from the cytoplasm to the nucleus. This process is known as nuclear import and requires the presence of specific signals on the protein called nuclear localization signals (NLS). These signals interact with nuclear import receptors on the nuclear membrane, allowing the protein to be transported across the membrane and into the nucleus.
Proteins can also be translocated across plasma membrane via specific signals on the protein called signal peptides. This process is called protein secretion and it is a way for the cell to communicate with the outside environment or other cells.
Overall, translocation is an important process that allows proteins to be properly localized and functional within the cell.
c. Explain the theory of evolution and mention the proof supporting it.
Answer:_
The theory of evolution is the scientific explanation for the diversity of life on Earth. It states that all living organisms have a common ancestry and that over time, through a process called natural selection, certain traits become more or less common in a population. This leads to the gradual development of new species over many generations.
The main mechanism of evolution is natural selection, which is the process by which certain traits become more or less common in a population based on their ability to help the organisms that possess them survive and reproduce. Traits that are beneficial in a particular environment are more likely to be passed on to future generations, while those that are not beneficial are less likely to be passed on. Over time, this leads to the gradual accumulation of small changes that can result in the formation of new species.
There is a vast amount of evidence supporting the theory of evolution. One of the most important pieces of evidence is the fossil record, which shows a clear progression of organisms over time. Fossils of extinct species that are similar to, but clearly distinct from, modern species provide strong evidence that these organisms are the ancestors of modern species.
Another important piece of evidence is the existence of vestigial structures in organisms. These are structures that have no function in the organism but resemble structures that are functional in other organisms. For example, the human appendix is a vestigial structure that resembles the cecum of other mammals, which plays a role in the digestion of plant matter.
Biogeography, the study of the distribution of living things, also supports the theory of evolution. The similarities and differences between the flora and fauna of different regions can best be explained by common ancestry with adaptation to local conditions.
Molecular biology also supports the theory of evolution. The study of the genetic code of different organisms has revealed that the genetic code is highly conserved among different species, with slight variations that can be explained by the evolutionary process. The genetic similarity between different organisms, such as the high degree of homology between the DNA of humans and other primates, is strong evidence of common ancestry.
Overall, the theory of evolution is supported by a wide variety of scientific evidence from many different fields of study, including paleontology, biogeography, anatomy, and molecular biology.
d. Explain with suitable examples importance of anatomical evidences in evolution
Answer:-
Anatomy is an important field of study in understanding the evolution of different species. The study of the structure and form of organisms, or their anatomy, can provide key insights into the evolutionary relationships between different groups of organisms.
One key example of anatomical evidence for evolution is the study of homologous structures. Homologous structures are structures in different organisms that have a similar underlying structure or function, but may have evolved to serve different purposes. For example, the forelimbs of mammals, birds, and reptiles are homologous structures. They all have a similar skeletal structure, with a humerus, radius and ulna, but they have evolved to serve different functions, such as grasping, flying, and crawling respectively. This is evidence that these structures have a common ancestor and have evolved over time to suit different environments.
Another important example is the study of vestigial structures. Vestigial structures are structures that have no function in an organism but resemble structures that are functional in other organisms. For example, the human appendix is a vestigial structure that resembles the cecum of other mammals, which plays a role in the digestion of plant matter. The existence of vestigial structures is evidence that the organisms that possess them have evolved from ancestors that possessed functional versions of those structures.
Anatomy also can provide evidence for convergent evolution, which is the process by which different organisms evolve similar structures independently. An example of this is the streamlined body shape of sharks and dolphins, which are not closely related, but both have evolved to be efficient swimmers in their environments.
Lastly, comparative anatomy is also a powerful tool to understand the evolution of different organisms. For example, the study of the internal organs and bones of mammals, birds, reptiles, and fish reveal that they share common ancestors, but have evolved in different ways over time to adapt to different environments.
Overall, anatomical evidence is an important field of study in understanding the evolution of different species and provides a way to study the historical relationships among different organisms and infer the evolutionary history of life on earth.
e. Define fossil. Explain importance of fossils as proof of evolution
Answer:-
A fossil is the preserved remains or traces of an organism that lived in the past. Fossils can include bones, shells, teeth, footprints, and even impressions of leaves and other plant material. Fossils can form in a variety of ways, but most commonly occur when an organism dies and its remains are buried in sediment, which then hardens into rock. Over time, the organic matter of the remains may be replaced by minerals, leaving a rock-like replica of the original organism.
Fossils are an important piece of evidence for the theory of evolution. They provide a record of the diversity and change of life on Earth over time, and they allow scientists to study the characteristics of extinct organisms and infer their evolutionary relationships to living organisms.
One of the most significant ways that fossils support the theory of evolution is by providing evidence of the gradual change of organisms over time. Fossils of extinct species that are similar to, but clearly distinct from, modern species provide strong evidence that these organisms are the ancestors of modern species. By studying the fossil record, scientists can see how different organisms have evolved over time, and how different groups of organisms are related to one another.
Fossils also provide evidence of the adaptive radiation, which is the process by which a single ancestor gives rise to a diverse array of descendant species that are adapted to different environments. For example, the fossil record of the horse shows a gradual increase in size and changes in the number and shape of teeth and toes, which reflect the adaptation to different habitats and diet during the time.
Fossils also provide a way to date the age of rocks and the time of evolution of different species. By studying the layers of rock in which fossils are found, scientists can infer the relative ages of different fossils and the time period in which they lived. This allows scientists to establish a chronological framework for the evolution of life on Earth.
In summary, fossils are an important piece of evidence for the theory of evolution. They provide a record of the diversity and change of life on Earth over time and allow scientists to study the characteristics of extinct organisms and infer their evolutionary relationships to living organisms. Fossils also provide evidence of the gradual change of organisms over time, adaptive radiation, and the time frame of evolution of different species.
f. Write evolutionary history of modern man.
Answer:_
The evolutionary history of modern humans, also known as Homo sapiens, can be traced back to Africa around 300,000 years ago. From there, our ancestors spread throughout the world, eventually replacing other human species such as Homo neanderthalensis and Homo erectus. The exact timeline and details of this process are still being studied and debated by scientists, but it is generally agreed that modern humans evolved from a common ancestor with chimpanzees and bonobos around 6 million years ago. Our species developed a larger brain, the ability to walk upright on two legs, and sophisticated communication and tool-making abilities. These developments likely gave our ancestors a survival advantage, allowing them to migrate out of Africa and into other parts of the world.