General Biology Exam 1 Study Guide: Scientific Method, Digestion, Membranes, and Cells

Exam 1 Study Guide: General Biology

Overview

This study guide covers key concepts and skills for Exam 1 in a General Biology course, focusing on the scientific method, biological themes, digestion and absorption, cell membranes, and cell structure. It includes definitions, processes, and analytical skills necessary for success in introductory biology.

Themes in Biology & The Scientific Method

Key Concepts and Skills

• Characteristics of Living Things: Living organisms share certain features such as organization, metabolism, homeostasis, growth, reproduction, response to stimuli, and adaptation.

• Scientific Method: A systematic approach to understanding the natural world through observation, hypothesis formation, experimentation, and analysis.

• Hypothesis: A testable explanation for an observation or question.

• Prediction: A logical statement about what will happen if the hypothesis is correct.

• Difference Between Hypothesis and Prediction: A hypothesis explains why something happens; a prediction states what will happen under specific conditions.

Analyzing Results

• Write a sentence describing results shown in a graph.

• Identify the major theme in biology illustrated by a research study.

• Define and control variables in experimental design.

• Describe trends in data presented in graphs or tables.

• Evaluate whether results are statistically significant (often using p-values).

• Distinguish between a result (what is observed) and an inference (interpretation of results).

Example: Experimental Design

• Given a description of an experiment, identify independent and dependent variables and graph their relationship.

Digestion & Absorption

Digestive System Structure and Function

• Alimentary Canal: The continuous tube from mouth to anus, including mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

• Accessory Organs: Organs such as the liver, pancreas, and gallbladder that aid digestion.

• Digestion: The breakdown of food into smaller molecules for absorption.

• Absorption: The uptake of nutrients by cells lining the digestive tract.

• Regions and Functions: Each region of the alimentary canal and accessory organs has specific roles in digestion, secretion, or absorption.

Key Processes

• Trace the path of food through the digestive system and describe the function of each region.

• List enzymes and secretions released into the mouth, stomach, and duodenum, and their functions.

• Describe the structure of the intestinal lining and how it increases surface area (e.g., villi, microvilli).

• Explain the absorption of biomolecules (carbohydrates, proteins, lipids) in the small intestine.

• Relate the structure of the alimentary canal to Fick's Law of Diffusion:

$J = -D \frac{dC}{dx}$ Where $J$ is the rate of diffusion, $D$ is the diffusion coefficient, $dC$ is the concentration difference, and $dx$ is the distance.

Example: Absorption Comparison

• Compare absorption of water, glucose, and amino acids in the small intestine.

Lipids & Cell Membranes

Types and Structure of Lipids

• Types of Lipids: Fat, phospholipid, steroid.

• Saturated vs. Unsaturated Fatty Acids: Saturated fatty acids have no double bonds; unsaturated have one or more double bonds.

• Phospholipids: Major component of cell membranes, with hydrophilic heads and hydrophobic tails.

• Steroids: Lipids with a characteristic four-ring structure (e.g., cholesterol).

Membrane Structure and Function

• Fluid Mosaic Model: Describes the cell membrane as a flexible layer made of lipid molecules interspersed with proteins.

• Selective Permeability: The membrane allows some substances to pass while blocking others.

• Transport Mechanisms:

  • Passive Transport: Movement of substances down their concentration gradient (diffusion, osmosis).

  • Facilitated Diffusion: Passive transport via membrane proteins.

  • Active Transport: Movement of substances against their concentration gradient using energy (e.g., Na+/K+ ATPase).

• Osmosis: Diffusion of water across a selectively permeable membrane.

• Carrier Proteins: Proteins that transport specific substances across the membrane.

• Channel Proteins: Form pores for specific molecules (e.g., aquaporins for water).

Example: Diffusion and Osmosis

• Given a scenario, predict the direction of water movement across a membrane.

Cells: Prokaryotic vs. Eukaryotic

Cell Structure Comparison

• Prokaryotic Cells: Lack a nucleus and membrane-bound organelles; DNA is in the nucleoid region (e.g., bacteria).

• Eukaryotic Cells: Have a nucleus and membrane-bound organelles (e.g., plants, animals, fungi, protists).

• Shared Characteristics: Both have a plasma membrane, cytoplasm, ribosomes, and genetic material.

Table: Prokaryotic vs. Eukaryotic Cells

Feature	Prokaryotic Cell	Eukaryotic Cell
Nucleus	No	Yes
Membrane-bound Organelles	No	Yes
Size	Small (1-10 μm)	Larger (10-100 μm)
Examples	Bacteria, Archaea	Plants, Animals, Fungi, Protists

Experimental Analysis and Graphing

Graphing and Data Interpretation

• Draw and interpret graphs showing relationships between variables.

• Identify independent and dependent variables in experiments.

• Summarize results from tables or graphs.

Example: Experimental Variables

• Given an experiment with light and dark arenas for mice, identify variables and graph the results.

Vocabulary and Key Terms

Important Terms to Know

• adaptation, alimentary canal, basal membrane, bile, cholecystokinin (CCK), diffusion, digestion, duodenum, enzyme, facilitated diffusion, gastrin, gastrointestinal cavity, hydrochloric acid, hydrolysis, hydrophilic, hydrophobic, hypertonic, hypotonic, ingestion, lipid, microvilli, osmosis, pepsin, peristalsis, phagocytosis, saturated fatty acid, secretion, selective permeability, tight junction, unsaturated fatty acid, channel protein, carrier protein, cholesterol, dehydration, ester linkage, osmolarity, phospholipid, prokaryote, eukaryote, plasmid, endocytosis, exocytosis.

Practice and Application

• Practice drawing and labeling diagrams (e.g., cell membranes, digestive system).

• Write definitions in your own words for key terms.

• Apply concepts to new scenarios, such as predicting the outcome of an experiment or explaining the function of a biological structure.