(i) This idea was developed by Oparin (1922) and Haldane (1929). They proposed that with the conditions prevailing on earth, life arose by a series of sequential chemical reactions.

(ii) The first form of life could have come from pre-existing non-living inorganic molecules which gave rise to formation of diverse organic molecules which are transformed into colloid system to produce life.

(iii) The modern concept on chemical evolution regarding origin of life was accepted.

(a) The views on the origin of life has been putforth as

(i) Special creation

(ii) Spontaneous generation (Abiogenesis)

(iii) Biogenesis

(iv) Extraterrestrial or Cosmic origin

(v) Chemical Evolution of Life

(b) J.W. Harshberger

(i) No. These animals cannot be grouped together. Only the presence of eyes is not a factor to group animals together.

(ii) The interrelationship of the organism must be supported by evidence from other disciplines of biology.

(iii) Octopus and cockroach belong to phylum Arthropoda. (Invertebrates) Frog belongs to phylum Chordata. (Vertebrates).

(iv) Based on the presence of a single character, animals cannot be grouped to establish a common evolutionary origin.

(i) Fossils are evidence of ancient life forms or ancient habitats which have been preserved by natural process.

(ii) Fossil records show that the evolution has taken a gradual process from simple to complex organism.

(iii) The origin of modern birds is supported by the evidences from paleontology.

Yes. he is correct.

Reason:

(i) Because they are analogous organs.

(ii) The wings of a dragon fly and crow look similar and perform similar functions but they have different origin and developmental pattern.

(i) The age of fossils is determined by radioactive elements present in it.

(ii) They may be carbon, uranium, lead or potassium. It is used in paleobotany and anthropology for determining the age of human fossils and manuscripts.

Radioactive carbon (C¹⁴) dating method :

(i) This method was discovered by W.E. Libby (1956).

(ii) Carbon consumption of animals and plants stops after death and since then, only the decaying process of C occurs continuously.

(iii) The time passed since death of a plant or animal can be calculated by measuring the amount of C¹⁴ present in their body.

(i) Archaeopteryx is the oldest known fossil bird.

(ii) It is considered to be a connecting link between reptiles and birds. It had wings with feathers, like a bird. It had long tail, clawed digits and conical teeth, like a reptile.

(i) When there is a change in the environment, the animals respond to the change.

(ii) They develop adaptive structures. The characters developed by the animals during their life time, in response to the environmental changes are called acquired characters.

(iii) Lamarck's use and disuse theory states that if an organ is used constantly, the organ develops well and gets strengthened. When an organ is not used for a long time, it gradually degenerates.

(iv) Degenerated wing of kiwi is an example for organ of disuse.

Degeneration of wings in kiwi is due to disuse of wings over generations since they have learns to walk on land for all their needs. This is an acquired character in response to their habitat. According to Lamarck such characters are passed to the off springs by inheritance.

Lamarck's theory of evolution was published in Philosophic Zoologique' in the year 1809. It is popularly known as Theory of inheritance of Acquired Characters' or Use and Disuse theory" or Lamarckism.

Principles of Lamarckism

(i) Internal vital force

Living organisms or their component parts tend to increase in size continuously. This increase in size is due to the inherent ability of the organisms.

(ii) Environment and new needs

A change in the environment brings about changes in the need of the organisms. In response to the changing environment, the organisms develop certain adaptive characters. The adaptations of the organisms may be in the form of development of new parts of the body.

(iii) Use and disuse theory

Lamarck's use and disuse theory states that if an organ is used constantly, the organ develops well and gets strengthened. When an organ is not used for a long time, it gradually degenerates. The degenerated wing of Kiwi is an example for organ of disuse.

(iv) Theory of Inheritance of acquired characters

When there is a change in the environment, the animals respond to the change. They develop adaptive structures. The characters developed by the animals during their life time, in response to the environmental changes are called acquired characters. According to Lamarck, the acquired characters are transmitted to the offspring by the process of inheritance.

The process of formation of fossil in the rocks is called fossilization.

Common methods of fossilization includes

(i) Petrifaction

(ii) Mold and Cast

(iii) Preservation

(iv) Compression

(v) Infiltration

(i) A plant fossil is any preserved part of a plant that has died long back.

(ii) A replica of a plant is preserved in sedimentary rocks by mold and cast fossilization method.

(iii) Original remains can be preserved in ice or amber (tree sap).

(iv) They protect the organisms from decay. The entire plant is preserved.

Overproduction :

• Living beings have the ability to reproduce more individuals and form their progeny.

• They have the capacity to multiply in a geometrical manner.

• It increases reproductive potential leading to overproduction.

Struggle for existence :

• Overproduction causes a geometric ratio of increase in population.

• The space to live and food available for the organisms remain the same.

• It creates competition among the organisms. They struggle for food and space.

Three types of struggle :

• Intraspecific struggle.

• Interspecific struggle.

• Environmental struggle.

Variations :

• Variation is a characteristic feature of all plants and animals.

• Small variations are important for evolution.

• Darwin's favourable variations are useful to the organism.

• Unfavourable variations are harmful or useless to the organism.

Survival of the fittest or Natural selection:

• During the struggle for existence, organisms which can Overcome the challenging situation, survive and adapt to the surrounding environment.

• Organisms which are unable to face the challenges, are unfit to survive and disappear.

• The process of selection of organisms with favourable variation is called as natural selection.

Origin of species : Darwin states, new species originates by the gradual accumulation of favourable variations for a number of generations.

(i) Ethnobotany is the study of a region's plants and their practical uses through the traditional knowledge of the local culture of people.

(ii) The term Ethnobotany was coined by J. W. Harshberger in 1895 to include the study of plants used by the primitive and aboriginal people.

Importance of Ethnobotany:

(i) It provides traditional uses of plant.

(ii) It gives information about certain unknown and known useful plants.

(iii) The ethnomedicinal data will serve as a useful source of information for the chemists, pharmacologists and practitioners of herbal medicine.

(iv) Tribal communities utilize ethnomedicinal plant parts like bark, stem, roots, leaves, flower bud, flowers, fruits, seeds, oils, resins, dyes, gum for the treatment of diseases like diarrhoea, fever, headache, diabetes, jaundice, snakebites, leprosy, etc.

(i) Astrobiology/ Exobiology is the science which looks for the presence of extraterrestrial life in the universe.

(ii) Astrobiology deals with the origin, evolution and distribution of life in the universe and to investigate the possibility of life in other world.

Paleobotany is derived from Greek words paleon that means old" and botany the study of plants. It is the branch of Paleontology that deals with recovery and identification of plant remains of geological past.

(i) It was given by Ernst Haeckel.

(ii) According to this theory, ontogeny recapitulates Phylogeny.

(iii) The stages of development of the individual animal repeats the evolutionary history of the entire race of the animal.

The reappearance of ancestral characters in some individuals is called atavism. Presence of rudimentary tail in new born babies, presence of thick hair on the Human body are examples of atavism.

(i) According to this theory life originated spontaneously from lifeless matter.

(ii) It was believed that fishes originated from mud, frogs from moist soil and insects from decaying matter.

Extraterrestrial or Cosmic origin: Sone scientists still believe that life came from outer space. This states that units of life called spores (Panspermia) were transferred to different planets including Earth. This is still an idea of some Astronomers.

Vermiform appendix, Nictitating membrane, Caudal Vertebra and Coccyx.

Gradual change occurring in living organisms over a period of time is called evolution. The theories of evolution as proposed by Lamarck and Darwin.