Evolution and Fossils Quiz

Key Biological Concepts

• Fossils: Preserved remains of ancient plants and animals. Buried in sediments like sand and mud.
• Paleontology: Scientific study of prehistoric life, using fossil analysis.
• Archaeopteryx: An extinct bird-like dinosaur, exhibiting characteristics of both reptiles and birds. It had feathers, wings, and hollow bones, but also teeth, a bony tail, and reptilian-like legs. Fossils are found in rocks from the late Jurassic Period.
• Homologous Structures: Similar anatomical structures in different organisms, indicating shared ancestry but potentially different functions.
• Analogous Structures: Structures having similar functions but different evolutionary origins and anatomical structures, not indicating a recent common ancestor.
• Vestigial Structures: Anatomical parts with reduced or no apparent function, but evident in ancestor species. Examples include the hip bones in whales and wisdom teeth in humans.
• Molecular Similarities: Similarities in DNA (98-99% between humans and chimps), amino acid sequences, and pseudogenes are evidence of evolutionary relationships. Pseudogenes are non-functional segments of DNA showing evolutionary similarities between species.
• Evolutionary Relationships (Evolution): Species evolve gradually over time.

Darwin's Theory of Natural Selection

• Species Vary Globally: Species in similar habitats around the world act similarly, even if distantly related. Examples include Rheas and ostriches.
• Species Vary Locally: Related organisms in different environments within a region can show variations depending on the specific environment. Galapagos tortoises showcase this.
• Darwin's Theory: All present-day species are descendants from ancestral species, changing over time via natural selection.
• Natural Selection: Organisms with traits better suited for an environment are more likely to survive and reproduce, passing their traits to offspring.
• Stabilizing Selection: Favors average traits. Extreme traits are less advantageous.
• Directional Selection: Extreme traits are advantageous. The population shifts towards the extreme trait over time. Examples include antibiotic resistance in bacteria.
• Disruptive Selection: Extreme traits on both ends are favoured over the average trait, leading to the development of two distinct groups.

Modern Synthesis/Evolutionary Mechanisms

• Genetic Drift: Random changes in allele frequencies, more pronounced in smaller populations, impacting genetic variation. Examples include the founder effect and the bottleneck effect.
• Gene Flow: Movement of alleles between different populations through the migration of individuals, increasing genetic diversity in recipient populations.
• Mutations Random genetic changes in DNA

Speciation

• Prezygotic Barriers: Barriers preventing mating and fertilization.
• Behavioral Isolation: Species exhibit different mating rituals/signals.
• Temporal Isolation: Different species reproduce during different times of the day or year/seasons.
• Habitat Isolation: Species occupy different habitats, preventing contact for mating.
• Mechanical Isolation: Species have incompatible reproductive organs, preventing mating.
• Gametic Isolation: Gametes (sperm and egg) from different species cannot fuse.
• Postzygotic Barriers: Barriers preventing the hybrid zygote from developing into a fertile individual.
• Hybrid Inviability: The zygote fails to develop.
• Hybrid Sterility: The hybrid is infertile (e.g., a mule).
• Hybrid Breakdown: First-generation hybrids are fertile, but later generations lose fertility.
• Allopatric Speciation: Geographic isolation leads to speciation (e.g., populations separated by mountains or bodies of water).
• Sympatric Speciation: Speciation occurs in the same geographic region (e.g., due to different ecological niches).
• Peripatric Speciation: A small population becomes isolated at the edge of a larger population.
• Parapatric Speciation: Populations diverge along an environmental gradient.

Types of Evolution

• Divergent Evolution: Related species evolving different traits and adaptations in different environments.
• Convergent Evolution: Unrelated species evolving similar traits in similar environments due to adaptations.
• Parallel Evolution: Related species evolving similar traits independently.
• Adaptive Radiation: Rapid diversification of a single lineage into multiple new species to fill various ecological roles.

Biodiversity

• Taxonomy: The science of naming, defining, and classifying groups of biological organisms based on shared characteristics.

Prokaryotes

Prokaryotes include bacteria and archaea.

• Structure and Function: They lack a nucleus and membrane-bound organelles. They have a cell membrane, cell wall, plasmids, and ribosomes.
• Cell Shapes: Spherical (cocci), rod-shaped (bacilli), spiral (spirochaetes).
• Reproduction: Binary fission.
• Gram-positive vs. Gram-negative: Differences in cell wall structure, which affects staining behaviour.
• Important Processes: Photosynthesis, cellular respiration, and fermentation.

Viruses

• Structure: Viruses contain genetic material (DNA or RNA) enclosed in a protein coat (capsid).
• Characteristics: Viruses require a host cell to reproduce; they are not considered living organisms.
• Lytic cycle: Viruses reproduce using the host's machinery.
• Lysogenic cycle: Viral DNA integrates into host DNA, lying dormant.

Protists

• Diversity: Eukaryotic organisms that are not plants, animals or fungi.
• Movement: Flagella, cilia, and pseudopodia.
• Energy Acquisition: Heterotrophic or autotrophic (photosynthetic)
• Reproduction: Asexual through binary fission or budding and sexual reproduction

Fungi

• Structure: Consist of a network or filaments called hyphae (unicellular or multicellular).
• Nutrient Acquisition: Fungi secrete enzymes that break down organic matter and absorb nutrients.
• Reproduction: They can reproduce sexually and asexually.
• Mycorrhizae: Symbiotic relationships between fungi and plant roots.

Eukaryotic Cells

• Structure: Possess a defined membrane-bound nucleus and organelles.
• Cell Division: Mitosis or meiosis

Prokaryotic Cells

• Structure: Lack a nucleus and membrane-bound organelles.
• Cell Division: Binary fission.