1st Achievement Test: Origin of Life Theories

Six major theories explain life's origin: Divine Creation, Abiogenesis, Biogenesis, Catastrophism, Cosmozoic, and Eternity of Life.
Divine Creation Theory: Life created by a supernatural being; no evolution involved; all organisms created in their present form.
Objections include lack of experimental evidence and fossil evidence indicating diverse emergence timelines.
Abiogenesis Theory: Suggests life arose spontaneously from non-living materials; exemplified by Van Helmont's claim of mice arising from a dirty shirt.
Biogenesis Theory: Life comes only from pre-existing living things; substantiated by experiments from:
- Francisco Redi: Showed maggots in uncovered meat jars proved life did not originate from meat.
- Lazarro Spallanzani: Found microbial growth in unsealed broth, indicating microorganisms come from other life.
- Louis Pasteur: Used swan-necked flasks to demonstrate that air-borne contaminants led to microbial growth.
Theory of Catastrophism: Life originated through cycles of catastrophic geological events; lacks experimental support and relies on hypothetical concepts.
Cosmozoic Theory: Life exists due to microorganisms from space (panspermia); lacks details on spores and their journey to Earth.
Theory of Eternity of Life: Suggests life has always existed and will continue indefinitely; also known as Steady State Theory.

Living organisms are made of cells and possess the ability to respond to their environment.
Atom: Smallest unit of matter.
Molecule: Formed when atoms bond; examples include proteins, lipids, carbohydrates, nucleic acids (like DNA).
Organelle: Functional structures within cells; mitochondria and chloroplasts are key examples.
Cell: Basic unit of life; classified into prokaryotic (e.g., bacteria) and eukaryotic cells (e.g., plants, humans).
Tissue: Groups of similar cells performing specific functions; includes epithelial, connective, muscle, and nervous tissues.
Organ: Collection of tissues working together for a common purpose.
Organ System: Groups of organs that work together.
Organism: Any living entity made up of various systems.
Population: Group of the same species in a specific area.
Community: Multiple species interacting within a habitat.
Ecosystem: Interactions among organisms and their environment.
Biosphere: Global sum of all ecosystems, representing regions of life on Earth.

1590: Creation of the compound microscope by Zacharias and Hans Janssen, allowing magnified observations of cells.
1665: Robert Hooke coins the term "cells" while examining cork under a microscope.
1674: Anton Van Leeuwenhoek first observes live cells, describing Spirogyra as "animalcules."
1838: Matthias Schleiden declares that plants consist of nucleated cells, foundational to cell theory.
1839: Theodor Schwann attributes cell structure as the foundational unit of animals, adding to cell theory.
1855: Rudolf Virchow introduces the idea that all cells arise from pre-existing cells, completing the cell theory.
Principles of Cell Theory:
- All living things are composed of one or more cells.
- The cell is the basic unit of life.
- All cells originate from pre-existing cells.

Bacteria: Single-celled organisms without a nucleus or membrane-bound organelles.
Cell Wall: Provides shape and protection, made of peptidoglycan for mechanical strength.
Capsule: Polysaccharide cover that protects from drying and host immune responses.
Cytoplasm: Site of cellular growth, metabolism, and genetic material replication.
Plasma Membrane: Semi-permeable barrier regulating the entry and exit of substances.
Ribosomes: Sites for protein synthesis and targets for antibiotics.
Flagella: Hair-like structures for locomotion, aiding movement.
Pili: Hair-like projections for adhesion and gene transfer through conjugation.
Plasmid: Circular DNA that allows DNA exchange among bacteria.
Nucleoid: Irregular region containing DNA without a membrane.

Plasma Membrane: Phospholipid bilayer regulating substance transport, characterized by hydrophilic heads and hydrophobic tails.
Endoplasmic Reticulum: Modifies proteins and synthesizes lipids; exists in rough (with ribosomes) and smooth (without ribosomes) forms.
Cytoplasm: Fluid region essential for metabolic processes.
Ribosomes: Critical for synthesizing proteins used across multiple cellular functions.
Golgi Bodies/Apparatus: Sorts and packages proteins and lipids for distribution.
Peroxisomes: Involve in oxidation reactions to break down fatty acids and amino acids.
Mitochondria: Energy-producing organelles responsible for ATP generation through cellular respiration.
Cytoskeleton: A protein network that maintains cell shape and organizes organelles.
Nucleus: Governs cell activities and houses DNA; includes nuclear envelope, nucleoplasm, and nucleolus (ribosomal RNA synthesis).
Lysosomes: Contain enzymes for digestion and breakdown of waste material; known as "suicide bags" due to their role in cellular self-destruction when necessary.
Plant Cell Structures:
- Cell Wall: Protects and provides structure, made of cellulose.
- Chloroplast: Site of photosynthesis containing chlorophyll.
- Vacuole: Regulates water concentration and stores nutrients.