Early Earth Life Origins and Biological Classification
Part 5: Early Earth, Origin of Life, and Evolution
Characteristics of Early Earth & Prebiotic Simulation
Early Earth lacked oxygen and an ozone layer, resulting in high UV radiation, noxious gases, frequent electrical storms, and abundant water.
The prebiotic simulation (1950s) recreated these early Earth conditions in the lab, leading to the formation of amino acids—the basic building blocks of life. This supports the chemical evolution hypothesis.
Hypotheses for the Origin of Life
- Chemical Evolution
Key Concepts in Evolutionary Biology and Genetics
Key Evolutionary and Genetic Concepts
Fixism
Belief that all species were created as we see them today. Species are therefore immutable.
Lamarckism
Evolutionary theory proposed by Lamarck. It considers that living beings change throughout their lives as a result of the use or disuse of organs. Body modifications acquired are transmitted to the offspring. Also called evolutionism.
Genotype
The combination of specific alleles of a cell of an individual for the full genome, or more often, a particular gene.
Read MorePlant-Based Contaminant Cleanup: Phytoremediation Principles
What Is Phytoremediation?
The term phytoremediation combines two Latin words: “plant” and “remedy.” It is defined as the use of plants to metabolize, immobilize, or transfer and detoxify contaminants. It removes toxic substances from the soil through their natural metabolic pathways. It is a low-cost, sustainable, and aesthetically friendly remedy that removes elemental contaminants from the environment.
When Was Phytoremediation Identified?
People first discovered metal-tolerant plants in
Understanding Chromosomes and Genetic Inheritance
Chromatin: DNA-protein complex forming chromosomes. Centromere: Constriction point on a chromosome where spindle fibers attach. Telomere: Repetitive DNA at chromosome ends prevents degradation. Chromatid: One of two copies of a replicated chromosome. Homologous Chromosomes: Chromosome pairs (one from each parent) with the same genes but different alleles. Histones: Proteins that DNA wraps around to form nucleosomes in eukaryotic cells.
Cell Cycle and Division
Interphase:
Period between cell divisions.
Read MoreCell Structure, Function, and Division Fundamentals
Biology Exam Revision: Chapters 1, 2, 3
Prokaryotes and Eukaryotes
- Prokaryote
- A single-celled organism made up of prokaryotic cells. They do not contain membrane-bound organelles. Examples: bacteria, archaea.
- Eukaryote
- A single-celled or multicellular organism made up of eukaryotic cells. They contain membrane-bound organelles. Examples: protists, fungi, plants, animals.
Organelles in Plant and Animal Cells
- Nucleus: Double membrane-bound organelle; contains genetic material (DNA, RNA).
- Endoplasmic Reticulum
Ecosystem Nutrient Cycling and Global Biodiversity Conservation
Nutrient Cycling and Ecosystem Dynamics
The Origin and Movement of Mineral Nitrogen (N)
Nutrients generally move among organisms. The **origin of mineral N** involves converting atmospheric N₂ into mineral forms (NH₄⁺, NO₃⁻) through:
- Biological fixation (by bacteria in roots or soil)
- Lightning fixation
- Industrial fixation (fertilizers)
N Cycling Steps:
- Plant uptake and incorporation (mineral → organic N)
- Resorption before leaf fall (retranslocating nutrients)
- Decomposition of litterfall (organic