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

Gas Exchange Mechanisms in Diverse Species

The Chinook salmon, European honey bee, and brown bear demonstrate striking diversity in gas exchange adaptations, each optimized for their distinct environments and metabolic demands. The salmon's counter-current gill system, enhanced by protective gill rakers and unidirectional water flow controlled by the operculum, maximizes oxygen extraction from water—critical for its energy-intensive migrations—but renders it dependent on constant water movement.

Comparative Respiratory Systems

In contrast, the honey bee's tracheal system, featuring spiracles that regulate airflow and air sacs for oxygen storage, enables direct, rapid oxygen delivery to flight muscles, though this system limits body size and... Continue reading "Gas Exchange Adaptations in Salmon, Bees, and Bears" »

Active Transport

Active transport moves substances across membranes from lower to higher concentration, against the concentration gradient. This process requires cellular energy (ATP) and a carrier protein.

The substance binds to the carrier protein's receptor site on one side of the membrane. ATP changes the protein's shape, releasing the substance on the other side. Active transport occurs only in living, respiring cells.

Factors influencing active transport:

• ATP Production: Increased ATP production increases active transport rate.
• Temperature and Oxygen: These affect respiration and ATP production, thus impacting transport rate.
• Mitochondria: Cells with more mitochondria have higher transport rates due to increased ATP production.
• Poisons: Respiratory

The Human Circulatory and Respiratory Systems

Key Components and Functions

1. The Diaphragm's Role in Respiration

The diaphragm separates the thoracic cavity (containing the heart, lungs, and ribs) from the abdominal cavity. It plays a crucial role in respiration. As the diaphragm contracts, the volume of the thoracic cavity increases, drawing air into the lungs.

2. Arteries: Transporting Oxygenated Blood

Arteries are large, thick-walled, muscular blood vessels that carry oxygenated blood away from the heart.

• Pulmonary Arteries: Carry deoxygenated blood from the heart to the lungs.
• Umbilical Arteries: Paired arteries (one for each half of the body) found in the abdominal and pelvic regions. They supply deoxygenated blood from the fetus to the placenta

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

Fundamentals of Biopsychology

1. Nature and Scope of Biopsychology

Biopsychology is the scientific study of the biological basis of behavior.

It is an interdisciplinary field that combines principles from psychology, biology, neuroscience, and medicine.

Key Focus Areas:

• Focuses on how the brain, hormones, and nervous system affect behavior and cognition.
• Applications include understanding mental disorders, learning, memory, and emotional responses.
• Example: Studying the stress response involves analyzing both hormonal (endocrine) and neural mechanisms.
• Relevance: Essential for clinical psychology, neurorehabilitation, and pharmacology.

2. Structure and Function of a Neuron

Neurons are the basic functional units of the nervous system.

Parts and Functions:

Definitions of Respiration

• Respiration: The biochemical process of breaking down glucose to release energy (ATP).
• Respiratory System: The biological system responsible for gas exchange (O₂ intake, CO₂ output).

Aerobic and Anaerobic Respiration

• Aerobic Respiration: Occurs with oxygen, yielding high energy (38 ATP).
• Anaerobic Respiration: Occurs without oxygen, yielding low energy (2 ATP), and producing lactic acid or ethanol + CO₂.

Principles of Gas Exchange (Diffusion)

Gas exchange occurs by diffusion across moist surfaces. The surfaces must meet specific criteria:

• Must be thin, moist, and highly vascularized.
• Surface area must be large relative to body size.

Note: These three features (thin, moist, vascularized) are critical for effective gas... Continue reading "Animal Respiration: Mechanisms of Gas Exchange and Ventilation" »

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: