2nd Year NotesBiology class 12th

2nd Year Biology Chapter 24 Evolution

2nd Year Biology Chapter 24 Evolution Question And Answer

Short and Simple Question And Answer

Q 1. What are the sources of hydrogen for reducing CO2 in the first photosynthetic organism?

Ans. The first photosynthetic organism likely used hydrogen sulfide as a source of hydrogen to reduce carbon dioxide into sugars.

Q 2. What is known as the endosymbiont hypothesis?

Ans. The endosymbiont hypothesis suggests that eukaryotic cells evolved when anaerobic prokaryotes ingested small aerobic bacteria, which were then stabilized inside the host cell instead of being digested.

Q 3. What was the second idea of Lamarck called?

Ans. Lamarck’s second idea was called the “inheritance of acquired characteristics,” suggesting that modifications acquired during an organism’s lifetime could be passed on to its offspring.

Q 4. What was an important turning point for evolutionary theory?

Ans. The birth of population genetics was an important turning point for evolutionary theory, emphasizing genetic variation within populations and the significance of quantitative characters.

Q 5. How does natural selection occur?

Ans. Natural selection occurs through the interaction between the environment and inherent variability within a population.

Q 6. What is the Hardy-Weinberg theorem?

Ans. The Hardy-Weinberg theorem states that the frequencies of alleles and genotypes in a population’s gene pool remain constant over generations unless acted upon by factors other than sexual recombination.

Q 7. What is non-random mating?

Ans. Non-random mating occurs when individuals with specific genotypes mate with each other more often than expected on a random basis.

Q 8. What was Darwin’s theory of evolution mainly based on?

Ans. Darwin’s theory of evolution was mainly based on evidence from the geographical distribution of species and the fossil record.

Q 9. Who was Darwin’s predecessor that developed a comprehensive model for explaining how life evolves?

Ans. Jean Baptiste Lamarck (1744-1829) was Darwin’s predecessor who developed a comprehensive model of evolution.

Q 10. What is a spirochete?

Ans. A spirochete is a flexible, helical bacterium with periplasmic flagella.

Q 11. Define biogeography?

Ans. Biogeography is the study of the geographical distribution of life on Earth, aiming to explain factors influencing where species live.

Q 12. What are fossils?

Ans. Fossils are the remains, impressions, or traces of organisms from a previous geological age.

Q 13. Define embryology?

Ans. Embryology is the study of animal development, covering the period from a fertilized egg to the formation of major organs.

Q 14. What is molecular biology?

Ans. Molecular biology is the study of the biochemical structures and functions of organisms at the molecular level.

Q 15. What does evolution refer to?

Ans. Evolution refers to the processes responsible for transforming life on Earth from its earliest forms into the diverse array of species observed today.

Q 16. What is the concept of special creation?

Ans. The concept of special creation suggests that all living organisms were specifically and separately created in their present forms.

Q 17. What is the concept of evolution?

Ans. The concept of evolution proposes that organisms can change and give rise to new species over time.

Q 18. What did Darwin observe about the finches of the Galapagos Islands?

Ans. Darwin observed that the Galapagos finches comprised 13 distinct types, each appearing as a different species, with some unique to specific islands and others shared among islands.

Q 19. What did Lamarck propose about the use and disuse of organs?

Ans. Lamarck argued that organs extensively used to adapt to the environment would become stronger and larger, while unused organs would deteriorate.

Q 20. What was Darwin’s idea about the origin of species?

Ans. Darwin proposed that new species could gradually arise from ancestral forms through the accumulation of adaptations to different environments. Geographical barriers would separate the two populations over many generations until they became distinct species.

Q 21. What was Alfred Wallace’s contribution to the theory of natural selection?

Ans. Alfred Wallace independently developed a theory of natural selection that was similar to Darwin’s. Their work was jointly presented to the Linnaean Society of London in 1858.

Q 22. Define the theory of natural selection?

Ans. The theory of natural selection posits that nature selects organisms with inherited characteristics that best fit their environment while eliminating those that do not.

Q 23. What is Neodarwinism?

Ans. Neodarwinism asserts that new species evolve due to significant genetic variation within populations and natural selection.

Q 24. What indicates that prokaryotes are ancestors of all life?

Ans. Evidence from biochemistry, molecular biology, and cell biology suggests that prokaryotes are ancestors of all life and predicts that bacteria preceded all eukaryotic life in the fossil record.

Q 25. What are homologous structures?

Ans. Homologous structures are anatomical signs of evolution resulting from common ancestry, such as similar forelimbs in various species (e.g., cat, bat, horse, whale).

Q 26. What are vestigial organs?

Ans. Vestigial organs are historical remnants of structures that once had essential functions in ancestors but are no longer necessary. Examples in humans include the vermiform appendix.

Q 27. Name some vestigial structures in humans?

Ans. Ear muscles, nictitating membrane, vermiform appendix, and coccyx are vestigial structures in humans.

Q 28. Differentiate between homologous and analogous organs?

Ans. Homologous organs are structurally similar but functionally different, demonstrating divergent evolution (e.g., forelimbs of various animals). Analogous organs are functionally similar but structurally different, indicating convergent evolution (e.g., wings of bats, birds, and insects).

Q 29. Differentiate between natural selection and artificial selection?

Ans. Natural selection arises from the interaction between the environment and inherent population variability, whereas artificial selection involves human-driven selective breeding of domesticated plants and animals.

Q 30. What is a population?

Ans. A population is a group of interbreeding individuals of the same species within a shared geographic area.

Q 31. Define species?

Ans. A species is a group of individuals capable of interbreeding in nature.

Q 32. What is a gene pool?

Ans. A gene pool is the total collection of genes within a population at a given time, including all alleles at all gene loci in all individuals.

Q 33. Define the Hardy-Weinberg theorem?

Ans. The Hardy-Weinberg theorem states that allele and genotype frequencies in a population’s gene pool remain constant over generations unless influenced by factors other than sexual recombination.

Q 34. What is the Hardy-Weinberg equation used for?

Ans. The Hardy-Weinberg equation is used to calculate allele and genotype frequencies in populations at equilibrium.

Q 35. What factors affect gene frequency?

Ans. Factors influencing gene frequency include mutation, migration, genetic drift, non-random mating, and selection.

Q 36. Differentiate between endangered and threatened species?

Ans. An endangered species is at risk of imminent extinction throughout its range, while a threatened species is likely to become endangered in the near future.

Q 37. What are hydrothermal vents?

Ans. Hydrothermal vents are hot springs found deep in the ocean, where life may have originated.

Q 38. Name five species declared extinct in Pakistan?

Ans. The species declared extinct in Pakistan include the Cheetah, Tiger, Asian lion, Indian rhino, Crocodile, and Cheer pheasant.

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