Biology Chapter 1: Evolution

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Questions and Answers

What term did Darwin use to describe characters like the type of beak in finches, which had diversified structurally and functionally from the same original type?

homologous characters

Natural selection led to the evolution of diverse forms of __________ found in nature.

species

What did Darwin observe about the variations in finches' beaks on the Galapagos Islands?

The variations were only in coat color.

The variations were due to differences in leg size.

The variations were most prominent in the type of beaks. (correct)

The variations were only in wing length.

Artificial selection by humans is intentional and involves breeding organisms with preferable traits.

True Signup and view all the answers

Match the following parts of plants with their respective functions:

Stem (Tendril) = Reproduction Stem (Thorn) = Protection Stem (tuber) = Food storage Root = Absorption of nutrients Signup and view all the answers

Where have dinosaur fossils been found in India?

Narmada valley Signup and view all the answers

What habitat were dinosaurs found in, according to the text?

Narmada valley Signup and view all the answers

Dinosaurs were present on earth from around 2000 to 600 lakh years ago.

True Signup and view all the answers

During the time of dinosaurs, several plants similar to those found nowadays like algae, fern, moss, cycads, and _ were present.

gingko Signup and view all the answers

Match the following naturalists with their contributions: Charles Darwin and Alfred Russell Wallace

Charles Darwin = Proposed the theory of evolution Alfred Russell Wallace = Contributed to the theory of evolution Signup and view all the answers

Name the process through which modern breed of pet dog was acquired.

Artificial selection Signup and view all the answers

Forelimbs of dog and sheep are for walking, whale for swimming and that of bat for flying. All these are examples of:

Homologous Signup and view all the answers

Which of the following are analogous structures?

Wings of bat and butterfly Signup and view all the answers

While proposing his theory, Darwin was influenced by:

The observations of his voyage Signup and view all the answers

A group of organisms which can interbreed sexually producing viable off-springs is known as ____________.

species Signup and view all the answers

Difference among beaks of finches show the ____________ among them.

variation Signup and view all the answers

Some bacteria can grow in the medium containing streptomycin (antibiotic). The reason behind this is ____________.

antibiotic resistance Signup and view all the answers

Study Notes

Evolution

Hundreds of lakhs of species exist on earth, with some known, some unknown, and some extinct.
Fossil remains provide evidence of extinct species, such as dinosaurs, which were present on earth from 2000 to 600 lakh years ago.
Dinosaurs were of various types, including carnivores, herbivores, bipeds, and quadrupeds, and their size ranged from 50 cm to 40 meters.

Habitat and its Effect

Habitat is a place where the basic needs of an organism are fulfilled, including food, reproduction, and safety.
The availability of resources in a habitat affects the population of a species.
If resources are adequate, the population of a species may increase, while a decline in resources may lead to extinction.

Graphs and Population Growth

The rate of population growth is not always the same as the rate of growth of food resources.
Uncontrolled population growth can lead to a shortage of food resources, resulting in control measures such as natural disasters or deaths due to competition for resources.
The graph shows that the amount of food resources has an effect on the rate of population growth.

Darwin and his Findings

Charles Darwin, a naturalist, proposed the theory of evolution, which revolutionized scientific thought.
Darwin's observations during the voyage of the HMS Beagle, including the diversity of living organisms and the influence of nature on diversity, led to his theory of evolution.

Voyage of the Beagle and Darwin's Experience

Darwin traveled around the world on the HMS Beagle, studying and gathering information about natural phenomena, habitats, and organisms.
He observed that organisms have adapted to their environments and that there is a struggle for life everywhere.

Darwin's Observations

Darwin observed food chains and webs, where organisms (predators) feed on others (prey).
He found fossils of aquatic organisms and observed changes in land forms over time.
He collected and observed different organisms, including specimens of the existing forms, and compared them with fossils of the past.

Galapagos Islands

Darwin collected fossils and specimens of organisms on the Galapagos Islands, which helped him to study and compare forms of present organisms with those of the past.
He observed variations in finches, including differences in beak shape and size, which were related to their food habits.

Homologous Characters

Homologous characters are characters that indicate similar origins but have diverse functions, such as the type of beak in finches.
Examples of homologous characters can be seen in plants, such as stems that have different functions, and in animals, such as the forelimbs of humans, dogs, and birds.

Selection and Evolution

Darwin suggested that a process of natural selection, similar to artificial selection, occurs in nature, resulting in the evolution of one form to another.
Natural selection is not an intentional process, but rather a result of the environment and the presence of diverse organisms.
The process of natural selection can lead to the evolution of new species.### Evolution
Evolution is the process by which organisms or species become better suited to their environment through variations in populations.
Theory of Evolution suggests that organisms evolved from pre-existing organisms and selective processes in nature occurred spontaneously and non-intentionally, giving rise to diverse forms of species on Earth.
Variations found in organisms lead to diversity in their ability to survive in nature, and those with greater ability to survive have more chances of evolving.

Artificial Selection

Artificial selection is the process of selection of desirable characters of organisms by humans.
Examples of artificial selection include the evolution of different varieties of rice, wheat, vegetables, and fruits.

Theory of Evolution by Darwin and Wallace

Darwin and Wallace together suggested that:
- Variations found in organisms lead to diversity in their ability to survive in nature.
- New varieties of organisms may emerge suddenly from pre-existing ones due to natural calamities.
- Various organisms have had similar ancestors, and the evolutionary relationship can be represented by a branched tree diagram.
- Variations are found in populations of organisms, and only some variations pass on from one generation to the next.
- Populations of organisms that have advantageous variations grow more profusely, affecting the population composition.

Process of Speciation

Adaptation is the process of change by which organisms or species become better suited to their environment.
Speciation is the process of evolution where organisms vary so much that they are not able to interbreed.
The process of speciation can be fast due to natural calamities or slow otherwise.

Biological Species Concept

A group of organisms that can interbreed sexually producing viable offspring is known as a species.
This definition of species is considered as the biological species concept.

Key Terms

Evolution of organisms
Speciation
Adaptation
Natural selection
Artificial selection
Fossils
Homologous characters
Analogous characters

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This quiz covers the basics of evolution, including the diversity of species on Earth.