Principles of Organic Evolution and Origin of Life
1. Fundamentals of Evolutionary Biology
1. How can you determine the age of a fossil?
The age of a fossil is determined by radiocarbon (C-14) dating.
2. What is a protovirus?
A protovirus is viral DNA integrated into the genome of a host cell.
3. What were the raw materials used in Miller’s experiment?
The raw materials were methane, ammonia, hydrogen, and water vapour.
4. What is hidden hunger?
Hidden hunger is a condition caused by a deficiency of essential vitamins and minerals in the diet.
5. How are the ages of fossils calculated?
The ages of fossils are calculated by radiocarbon (C-14) dating.
6. Fill in the blank:
Archaeopteryx is a connecting link between reptiles and birds.
7. What is a gene pool?
The gene pool is the total collection of genes present in a population at a given time.
8. What are coacervates?
Coacervates are microscopic organic droplets formed by the aggregation of organic molecules, considered precursors of life.
9. What is meant by speciation?
Speciation is the process by which new species are formed from existing ones due to evolutionary changes.
10. Give an example of adaptive radiation:
Darwin’s finches of the Galapagos Islands.
2. Evolutionary Mechanisms and Theories
1. Explain the significance of mutation in evolution:
Mutation introduces new genetic variations. These variations are the raw materials of evolution and help in adaptation and the formation of new species.
2. The Hardy-Weinberg Principle:
The principle states that gene frequency remains constant in a population if no evolutionary forces act. Conditions include:
- No mutation
- No migration
- Large population
- Random mating
- No natural selection
Equation: p² + 2pq + q² = 1
3. What are coacervates?
Coacervates are microscopic aggregates of organic molecules surrounded by a thin membrane, considered precursors of living cells during chemical evolution.
4. Why is Archaeopteryx a connecting link?
Archaeopteryx shows reptilian characters (teeth, long tail) and avian characters (feathers, wings).
5. Modern Synthetic Theory of Evolution:
Combines Darwinism and Mendelian genetics:
1. Mutation creates variations.
2. Genetic recombination increases diversity.
3. Natural selection favours useful traits.
4. Genetic drift changes gene frequency.
5. Reproductive isolation leads to speciation.
3. Chemical Origin and Geological Evidence
1. Miller’s Experiment on Chemical Origin:
Miller and Urey simulated early Earth conditions using methane, ammonia, hydrogen, and water vapour. Electric sparks represented lightning. The formation of amino acids proved that organic molecules can be formed abiotically.
2. Forms of Speciation:
- Allopatric speciation
- Sympatric speciation
- Parapatric speciation
3. Life in Sea Water:
Sea water provided a stable environment for chemical reactions. Early life forms like cyanobacteria and algae originated in oceans, supported by marine fossil evidence.
4. Chemical vs. Biological Origin:
- Chemical: Life arose from chemicals via abiotic processes (supported by Miller’s experiment).
- Biological: Life arose from pre-existing life (biotic process, not scientifically accepted).
5. Geological Time Scale:
A chronological record of Earth’s history. It helps determine evolutionary sequences, correlate fossils with time periods, and study the origin and extinction of species.
4. Advanced Evolutionary Concepts
1. Darwinian Theory Basis:
1. Overproduction of offspring
2. Limited resources
3. Struggle for existence
4. Variation among individuals
5. Natural selection and survival of the fittest
2. Homologous vs. Analogous Organs:
- Homologous: Same origin, different function (e.g., forelimbs of man and whale). Indicates divergent evolution.
- Analogous: Different origin, same function (e.g., wings of bird and insect). Indicates convergent evolution.
3. Recapitulation Theory:
States that ontogeny recapitulates phylogeny (embryonic development repeats evolutionary history). Example: Human embryo shows gill slits like fishes.
4. Genetic Drift and Migration:
- Gene Migration: Movement of individuals/genes between populations.
- Genetic Drift: Random change in gene frequency in a small population (e.g., Founder effect).