Origins of Life on Earth - AP Biology
- What does the endosymbiotic theory explain?
- Origin of eukaryotic cells from prokaryotes. Organelles originated as symbiotic bacteria.
- Identify the process by which prokaryotes exchange genetic material.
- Horizontal gene transfer. Allows rapid spread of beneficial mutations.
- Which theory suggests that life can arise from non-living matter?
- Spontaneous generation (historical theory). Disproven theory that life emerges from non-living matter.
- Identify the process by which simple organic molecules form more complex polymers.
- Polymerization. Links monomers into chains through condensation reactions.
- What is the main energy source considered in the 'iron-sulfur world' hypothesis?
- Chemical reactions at hydrothermal vents. Mineral catalysis could drive early metabolism.
- Which experiment demonstrated the synthesis of organic compounds from inorganic precursors?
- Miller-Urey experiment. Simulated early Earth conditions to test abiogenesis.
- What is the oldest known form of life on Earth?
- Prokaryotic microbes. Simple single-celled organisms without nuclei.
- What are protobionts?
- Aggregates of abiotically produced molecules. Early cell-like structures before true living cells.
- What is the 'RNA world' hypothesis?
- Hypothesis that RNA was the first self-replicating molecule. RNA preceded DNA/protein systems in early evolution.
- Identify the type of chemical reaction crucial for forming complex organic molecules.
- Condensation reactions. Remove water to form bonds between organic molecules.
- Which molecule is considered a likely candidate for the first genetic material?
- RNA. Can both store information and catalyze reactions.
- What is the significance of the Urey-Miller experiment in abiogenesis?
- Showed organic molecules can form from inorganic precursors. Demonstrated abiotic synthesis of organic compounds.
- What role do coacervates play in hypotheses about the origin of life?
- Model for primitive cell-like structures. Membrane-bound droplets that could concentrate molecules.
- What is the function of nucleotides in early life forms?
- Monomers of nucleic acids like RNA and DNA. Store genetic information and enable replication.
- What did Aleksandr Oparin propose about the origin of life?
- Life arose from a primordial soup. Early hypothesis about chemical origin of life.
- Which molecule is central to the metabolic processes of all known life?
- ATP (adenosine triphosphate). Universal energy currency for cellular processes.
- What is the main hypothesis for the origin of life on Earth?
- Abiogenesis is the primary hypothesis. Life arising naturally from non-living matter without divine intervention.
- What is the significance of the 'iron-sulfur world' hypothesis?
- Proposes life originated on mineral surfaces. Metal sulfides could catalyze early biochemical reactions.
- What is the primary source of energy for early autotrophs?
- Sunlight. Drove photosynthesis in early life forms.
- Which modern theory refutes spontaneous generation?
- Biogenesis. Life only comes from pre-existing life.
- What is the primary challenge for the abiogenesis hypothesis?
- Formation of self-replicating systems. Must explain how molecules began copying themselves.
- What is the role of amino acids in the origin of life?
- Building blocks of proteins. Essential components for enzymatic and structural functions.
- What is the importance of the Hadean eon in Earth's history?
- Formation and stabilization of Earth's crust. When Earth's surface first solidified from molten state.
- Identify a key piece of evidence for the endosymbiotic theory.
- Mitochondria and chloroplasts have their own DNA. Shows organelles were once independent organisms.
- Which molecule is essential for the formation of cell membranes?
- Phospholipids. Form lipid bilayers that create cellular boundaries.
- What is the significance of ribozymes in the study of the origins of life?
- Ribozymes are RNA molecules with catalytic functions. Supports RNA world hypothesis - RNA can store info and catalyze.
- What is the significance of cyanobacteria in Earth's history?
- Produced oxygen through photosynthesis. Changed atmosphere from reducing to oxidizing.
- What did the Miller-Urey experiment use to simulate early Earth conditions?
- Electric sparks and a mixture of gases. Mimicked lightning and primitive atmosphere composition.
- What term refers to the idea that life originated elsewhere and arrived on Earth?
- Panspermia. Alternative to abiogenesis - life originated elsewhere in space.
- What is the significance of stromatolites in the study of early life?
- Fossilized microbial mats, evidence of early life. Ancient structures showing early microbial communities.
- What is an autotroph?
- An organism that produces its own food. Doesn't depend on other organisms for nutrition.
- Identify the scientist who disproved spontaneous generation.
- Louis Pasteur. Used controlled experiments with sterilized flasks.
- Which component of the atmosphere protects Earth from ultraviolet radiation?
- Ozone layer. Blocks harmful UV radiation from reaching surface.
- What is chemiosmosis?
- Process of ATP generation via proton gradient. Uses proton gradients to synthesize ATP.
- What is the main characteristic of self-replicating molecules?
- Ability to catalyze their own synthesis. Essential for evolution and inheritance of traits.
- State one method used to date the origins of life on Earth.
- Radiometric dating. Uses radioactive decay to determine age of rocks/fossils.
- What gas was notably absent in Earth's early atmosphere?
- Oxygen. Reducing atmosphere was necessary for organic synthesis.
- Name the location on Earth where life is hypothesized to have originated.
- Hydrothermal vents. Provide energy and chemical gradients for life processes.
- What does the term 'LUCA' stand for?
- Last Universal Common Ancestor. Hypothetical ancestor of all current life forms.
- What is the role of clay minerals in the origin of life?
- Catalysts for polymerization of organic molecules. Mineral surfaces can concentrate and organize molecules.