Notes, summaries, assignments, exams, and problems for Biology

Biosystematics vs. Taxonomy: Defining Classification

Biosystematics and taxonomy are both fields focused on the classification of living organisms, but they differ in scope and approach. Taxonomy is the science of identifying, describing, naming, and classifying organisms, primarily based on observable characteristics. Biosystematics, on the other hand, is a broader field that encompasses taxonomy but also incorporates evolutionary relationships, genetic information, and ecological factors to understand the diversity of life.

Here's a more detailed breakdown:

The Scope of Taxonomy

• Focus: Identifying, describing, and classifying organisms based on shared characteristics.
• Key Aspects: Naming (nomenclature), describing physical traits, grouping organisms

Immunity Fundamentals

The ability to ward off disease through the body's defenses is called immunity.

Understanding Immunity Concepts

• Susceptibility

  Lack of resistance to a disease.

• Immunity Defined

  The ability to ward off disease.

• Genetic Resistance

  The inability of a pathogen to cause disease.

  • Genetic variation in an individual results in a lack of receptors for pathogen binding or other structures required by the pathogen.

• Innate Immunity

  Defenses against any pathogen.

  • Present at birth.
  • Comprises all body defenses that protect the body against any kind of pathogen.

• Adaptive Immunity

  Immunity or resistance to a specific pathogen.

  • Defenses (antibodies) against specific microorganisms.

Innate Immunity Activation

Innate immunity is activated by protein receptors... Continue reading "Understanding Innate Immunity: Body's First Defenses" »

Animal Classification

Vertebrates: Possess an endoskeleton and belong to the phylum Chordata. They are divided into 5 main groups:

• Mammalia (Mammals)
• Aves (Birds)
• Reptilia (Reptiles)
• Amphibia (Amphibians)
• Pisces (Fish)

Invertebrates: Often possess an exoskeleton or lack a backbone. Examples include:

• Cnidarians (e.g., jellyfish)
• Arthropods (e.g., insects, spiders)
• Molluscs (e.g., snails, clams)
• Worms (various phyla)

Kingdom Monera

Monera: Consists of prokaryotes (organisms lacking a true nucleus).

Plant Biology Basics

Vascularity refers to whether plants have specialized tissues (veins) for transporting water and nutrients.

• Xylem: Transports water and minerals upwards from the roots.
• Phloem: Carries glucose (food produced during photosynthesis) around the plant.

Week 1: The Heart

Purpose of the Cardiovascular System

To provide adequate blood flow to all tissues/organs according to immediate needs.

Heart Contractions

• Systole: Periods of contraction
• Diastole: Periods of relaxation

Note: The atria contract simultaneously, followed by simultaneous ventricular contraction.

Blood Vessels

• Arteries: Carry blood away from the heart.
• Veins: Carry blood towards the heart.

Intrinsic Conduction System

1. Sinoatrial (SA) Node (Pacemaker): Generates impulses in the right atrial wall. Depolarizes 80-100 times per minute, modified by the autonomic nervous system to approximately 75 times per minute.
2. Atrioventricular (AV) Node: Impulses pause here for 0.1 seconds, allowing the atria to complete contraction. Generates impulses 40-60

Cells are open systems – they exchange both matter and energy with their environment.

Cellular Open Systems: Examples of Exchange

• In: Water, oxygen, nutrients, solar energy (in plants)
• Out: Carbon dioxide, waste, thermal energy, kinetic energy

Cellular Needs and Organ System Functions

Surface Area to Volume Ratio (SA:V)

Cells work best with a high SA:V ratio (more membrane per unit of volume).

• Small cells = high SA:V → efficient transport
• Large cells = low SA:V → less efficient

SA:V Ratio Calculation Formulas

• Surface Area of cube:

Lymphocyte Migration and Immune Response

Lymphocytes constantly migrate through the blood and lymph, moving from one lymphoid organ to another. This process:

• Enhances the chance that an antibody will encounter its specific antigen.
• The spleen filters blood, while other lymphoid organs filter lymph.

Phagocytosis: A Non-Specific Innate Immune Response

Phagocytosis is the ingestion of microorganisms or particulate matter by a cell. It is performed by phagocytes, which are certain types of white blood cells or their derivatives.

Actions of Phagocytic Cells

1. Among the granulocytes, neutrophils are the most important phagocytes.
2. Enlarged monocytes transform into wandering macrophages and fixed macrophages.
3. Fixed macrophages are located in selected tissues

Local Inflammation

1. Occurs when bacteria enter a break in the skin.
2. Inflammatory reaction is initiated by nonspecific mechanisms of phagocytosis and complement activation.
3. Complement activation attracts phagocytes to the area.
4. As inflammation progresses, B cells produce antibodies against bacterial antigens.
5. Attachment of antibodies to antigens amplifies nonspecific responses because of complement activation.
6. Promotes phagocytic activity of neutrophils, macrophages, and monocytes (through opsonization).
7. In the inflamed area, leukocytes attach to the surface of endothelial cells.
8. Move by chemotaxis to the inflamed site.

• Neutrophils arrive first, then monocytes, then T cells.
  • Undergo extravasation (the entire process of movement of leukocytes from the bloodstream

Nervous and Endocrine Systems

The nervous system receives external and internal stimuli, interprets them, and decides an appropriate response. The response is executed by the effector organ or tissue. Nervous tissue is made up of cells called neurons.

Stimulus → Nervous System → Effectors → Muscles, Glands

Neuron Structure

• Cell body: The central part of the neuron.
• Dendrites: Extensions of the cell body. They receive the nerve impulse and transmit it to the cell body.
• Axon: A long fiber extending from the cell body. It transmits the nerve impulse to other neurons or effector cells.
• Myelin sheath: This layer protects the axon and increases the speed of the nerve impulse.
• Axon terminals: These are located at the end of the axon. They contain neurotransmitters,

Human Energy: The Aerobic Advantage

Humans, as members of the Animal Kingdom, primarily utilize aerobic cellular respiration for energy production. This vital process involves our cells using oxygen to efficiently break down glucose (sugar) into ATP, the fundamental energy currency our bodies require. This intricate process occurs within the mitochondria, famously known as the "powerhouse" of the cell.

Humans demand substantial energy for movement, cognitive functions, and growth, making aerobic respiration perfectly suited for our active lifestyle. Our ancestors similarly required high energy levels for hunting, long-distance travel, and complex thought, which likely explains our evolutionary reliance on this efficient method. The complete pathway,... Continue reading "Cellular Respiration: Fueling Life and Classifying Organisms" »

Anatomy, Pathology, and Lab Essentials

Bones: Rigid organs that make up the skeletal system of vertebrates, providing support and protection for the body’s organs.

Cranium: The part of the skull that protects the brain.

Backbone: Also known as the spine or vertebral column, a flexible and strong structure running along the center of the back, made up of small bones called vertebrae.

Skull: A bony framework enclosing the brain of a vertebrate.

Joints: The points where two or more bones, or a bone and cartilage, are attached in the body.

Ligaments: Short bands of tough, flexible fibrous connective tissues that connect two bones or cartilages, or hold joints together.

Cartilage: Firm, flexible connective tissue found in various forms, from which the... Continue reading "Anatomy, Pathology, and Lab Essentials: A Comprehensive Glossary" »