Cell 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
Mammalian Adaptations: Locomotion, Metabolism, and Reproduction
L8 – Mammalian Locomotion I: Terrestrial Adaptations
- Cursorial: Running adaptation characterized by long limbs and reduced digits (e.g., pronghorn, cheetah).
- Advantages of Cursorial Locomotion: Increased range, successful migration, and endurance in predator–prey interactions.
- Cursorial Adaptations: Longer distal limbs, reduced or fused bones, and loss of the clavicle.
- Horse Evolution: Extreme digit reduction resulting in a single toe, optimizing efficient endurance.
- Ricochetal: Bipedal hopping utilizing
Core Concepts of Life Science and Biology Fundamentals
Photosynthesis: The Process of Life
- Equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (light + chlorophyll)
- Location: In chloroplasts (mainly leaf cells).
- Purpose: Converts light energy into chemical energy (glucose).
- Reactants: Carbon dioxide (from air), water (from roots).
- Products: Glucose (used/stored), oxygen (released).
- Uses of Glucose:
- Respiration (energy)
- Stored as starch
- Cellulose (cell walls)
- Fats and oils (seeds)
- Proteins (with nitrates)
- Limiting Factors: Light intensity, temperature, CO₂ concentration,
Fundamentals of Biology: Cells, Tissues, and Organ Systems
Seven Characteristics of Life
- All living things are highly organized entities composed of one or more cells.
- Use energy for their metabolic activities.
- Respond to environmental stimuli.
- Regulate the internal environment to maintain relatively constant internal conditions (homeostasis).
- Grow and develop.
- Pass genetic material through reproduction.
- Adapt to their environment through evolution.
Biological Levels of Organization
- Cell (e.g., human blood cell)
- Tissue (e.g., human skin tissue)
- Organ and Organ System
Prostaglandins: Synthesis, Functions, and Clinical Roles
Introduction to Prostaglandins
Prostaglandins are a group of physiologically active lipid compounds that have diverse, hormone-like effects in animals. Unlike classical hormones, they are not secreted from a gland and do not travel to a distant site but are synthesized at the site where they are needed.
Discovered by: Ulf von Euler in 1935 in human semen, who thought they originated from the prostate gland (hence the name).
Classification: Prostaglandins belong to a broader group of bioactive lipids