Test: Organic Evolution - UPSC MCQ

Organic evolution refers to the process of change in living organisms over time. It involves the gradual development of species through genetic variation, natural selection, and adaptation to changing environments.

Charles Darwin proposed the theory of natural selection in his book "On the Origin of Species" published in 1859. His theory revolutionized the understanding of how species evolve and adapt to their environments.

Adaptation is the primary driving force behind natural selection. Organisms that are better adapted to their environment have a higher chance of surviving and reproducing, passing on their advantageous traits to future generations.

Convergent evolution occurs when unrelated species develop similar traits or characteristics due to similar environmental pressures. Bats and birds both having wings is an example of convergent evolution.

The term "survival of the fittest" was coined by Herbert Spencer, an English philosopher, in his work "Principles of Biology." Although often associated with Charles Darwin, Spencer introduced the term before Darwin included it in later editions of his book.

Speciation is the process by which new species arise from existing ones. It occurs when populations become reproductively isolated and accumulate enough genetic differences to be considered distinct species.

The fossil record provides evidence for the common ancestry of different species. Fossils show the existence of organisms that lived in the past and help scientists trace the evolutionary history of various species.

An analogous structure refers to structures that have similar functions but different evolutionary origins. The human arm and whale flipper are examples of analogous structures as they both serve the function of locomotion in different lineages.

Natural selection is the process by which individuals with traits that increase their chances of survival and reproduction are more likely to pass on their genes to the next generation. It is the primary mechanism of evolution.

Wisdom teeth, appendix, and the tailbone (coccyx) are examples of vestigial structures in humans. These structures have lost their original function over time but are still present in our bodies.

Biogeography is the study of the geographic distribution of species. It examines the patterns of species diversity and the factors influencing the distribution of organisms across different regions.

The process of genetic change in a population over time is known as microevolution. It involves changes in allele frequencies within a population, often driven by natural selection, genetic drift, gene flow, or mutation.

Jean-Baptiste Lamarck proposed the concept of inheritance of acquired characteristics. He suggested that traits acquired by an organism during its lifetime could be passed on to its offspring, an idea that was later disproven by scientific research.

The age of the Earth is estimated to be approximately 4.6 billion years based on radiometric dating of rocks and minerals. This estimation provides evidence for the vast timescale over which life has evolved on our planet.

Homologous structures refer to similar structures found in different species that share a common ancestor. These structures may have different functions but are derived from the same ancestral structure.

The study of the similarities and differences in the DNA sequences of different species is known as molecular biology. It provides insights into evolutionary relationships and genetic similarities among organisms.

Genetic recombination is not a mechanism of evolution but rather a process that occurs during sexual reproduction. Genetic drift, gene flow, and genetic isolation are mechanisms that can lead to evolutionary changes in populations.

The bottleneck effect refers to a sudden reduction in the size of a population, leading to a loss of genetic variation. This reduction can occur due to a natural disaster, disease outbreak, or other events that drastically reduce the population's size.

Prezygotic isolation refers to barriers that prevent the formation of a zygote (fertilized egg) between two different species. Two bird species having different mating calls is an example of prezygotic isolation.

Comparative embryology is the study of the development and changes in organisms before they are born or hatched. It examines the similarities and differences in the early stages of development among different species.