bio midterm review

Midterm Review Notes

Topics Covered in the Midterm

  • Scientific Method

  • Cells

  • Cell Theory

  • Life Functions

  • Transport (Passive & Active)

  • Body Systems

  • Cellular Respiration

  • Photosynthesis

  • Natural Selection

Scientific Method

  • Problem: The issue or question that prompts investigation.

  • Question: The specific inquiry derived from the problem.

  • Research: Background information gathered to inform the hypothesis.

  • Hypothesis: A statement or proposed answer to the problem, typically structured as: "If… then…".

  • Experiment Design and Performance:

    • Independent Variable (IV): The variable that is manipulated in the experiment.

    • Dependent Variable (DV): The variable measured as the data in response to the IV.

    • Control Group: The group that does not receive the IV; serves as a baseline for comparison.

    • Constants: Factors that remain unchanged across both the experimental and control groups (everything except the IV).

  • Data Collection: Gather and organize data using tables and graphs to enhance clarity.

  • Data Analysis: Review the collected data to draw valid conclusions.

  • Improving Validity: Make results more valid by

    • Repeating the experiment.

    • Using a large sample size.

Experiment Components

  • Control vs. Experimental Group:

    • Control group lacks the independent variable; aids in comparison.

    • Experimental group receives the independent variable for testing.

  • Independent Variable: Should only be one per experiment for accurate results.

  • Dependent Variable: Represents the collected data and outcomes.

  • Constants vs. Control:

    • Constants: These are factors that remain unchanged in both groups.

    • Control Group: A baseline for comparison that does not undergo changes to the IV.

Graphing Data

  • Use even intervals for graph scales (skipping lines must be consistent).

  • Independent Variable: Plotted on the X-axis.

  • Dependent Variable: Plotted on the Y-axis (e.g., time, plant height, mice weight gain).

Data Tables and Charts

  • Critical for organizing data and facilitating valid conclusions.

  • Visualizations: Graphs illustrate data trends and patterns but do not increase data accuracy.

Life Functions of Cells

  • Essential processes necessary for cells to maintain life:

    • Respiration: Production of ATP in mitochondria.

    • Regulation: Coordination of systems within the body.

    • Excretion: Removal of metabolic wastes from the cell.

  • Metabolism: The collective sum of all life functions working together.

  • Homeostasis: Maintenance of a stable internal environment; examples include:

    • Shivering/sweating for temperature regulation.

    • Insulin regulating blood glucose levels.

    • Guard cells regulating water loss.

    • Disruptions in homeostasis can result in sickness or death.

Feedback Mechanisms

  • Mechanisms that help maintain homeostasis by influencing one substance's level to manage another.

  • Types of Feedback Mechanisms:

    • Positive Feedback: Increases levels or activity.

    • Negative Feedback: Decreases levels or activity to maintain balance.

  • Examples of Feedback Mechanisms:

    • Blood Glucose Regulation: Insulin and glucagon from the pancreas maintain glucose levels by storing and releasing glucose from the liver.

    • Thermoregulation: Changes in blood vessel diameters release or conserve heat.

    • Osmoregulation: Kidney adjustments affect water balance in blood.

    • Carbon Dioxide Regulation: Elevated CO2 levels result in increased heart and breathing rates.

Cellular Composition

  • Cells: The smallest unit of life; fundamental components of all living organisms.

Cell Theory

  • Principles of Cell Theory:

    1. Cells arise only from pre-existing cells.

    2. Cells are the basic structural and functional units of organisms.

    3. Cells perform life functions.

  • Exceptions to Cell Theory:

    • Viruses: Do not classify as true cells; lack organelles and can only reproduce inside a host cell.

    • Mitochondria and Chloroplasts: Capable of self-replication.

Types of Cells

  • Cell Types:

    • Prokaryotic: Cells without a nucleus (e.g., bacteria).

    • Eukaryotic: Cells with a nucleus (e.g., plants, animals, fungi).

    • Organisms:

      • Bacteria: Prokaryotic, heterotroph.

      • Protista: Eukaryotic, varies.

      • Fungi: Eukaryotic, heterotroph.

      • Plants: Eukaryotic, autotroph.

      • Animals: Eukaryotic, heterotroph.

Organelles and Their Functions

  • Nucleus: Stores the cell's hereditary material and regulates cellular activities.

  • Mitochondria: Site of ATP production through cellular respiration.

  • Ribosomes: Locations for protein synthesis.

  • Cell Membrane: Regulates the entrance and exit of materials; facilitates cellular communication via receptors.

Organization of Multicellular Organisms

  • Hierarchy from Smallest to Largest:

    • Organelles

    • Cells

    • Tissues

    • Organs

    • Organ Systems

    • Organism

Interactions Among Organelles

  • Examples of Interactions:

    • The nucleus directs protein synthesis by sending instructions to ribosomes.

    • Vacuoles merge with the cell membrane to excrete waste through exocytosis.

Cell Receptors

  • Cell Communication: Hormones bind to specific chemical receptors; only target cells with matching receptors are affected.

Transport in Cells

  • Passive Transport:

    • Requires no ATP; molecules move from high to low concentration until equilibrium is achieved.

    • Examples include diffusion and osmosis.

    • Small molecules (e.g., O2, CO2, H2O, amino acids, glucose) pass through cell membranes due to their size.

  • Active Transport:

    • Requires ATP; molecules move against their concentration gradient (from low to high concentration).

    • Example: Phagocytosis (cell eating).

Circulatory Links

  • Circulation and Respiration: Oxygen enters the respiratory system and is circulated via red blood cells (RBCs).

  • Excretion Link: Transport of wastes to kidneys via the circulatory system for excretion.

  • Digestion and Circulation: Nutrients are absorbed in the small intestine and delivered to the liver through the bloodstream.

Heterotrophic Digestion

  • Organisms process organic molecules for cellular entry.

  • Key Absorption Sites:

    • Stomach: Alcohol & drugs.

    • Small Intestine: Amino acids, fatty acids, glycerol.

    • Large Intestine: H2O & vitamins.

Autotrophic Photosynthesis

  • Occurs in chloroplasts and requires CO2, energy (sunlight), and H2O, producing glucose and O2.

  • Linkage to Cellular Respiration: Oxygen produced during photosynthesis is utilized in cellular respiration for ATP production.

  • Photosynthesis Reaction:
    extWater+CarbonDioxide<br>ightarrowextGlucose+Oxygenext{Water + Carbon Dioxide} <br>ightarrow ext{Glucose + Oxygen}

Metabolic Processes

  • Sequence of Metabolic Functions:

    1. Digestion

    2. Diffusion (intestine to blood to cells)

    3. Cellular Respiration

Human Respiration and Its Links

  • Exercise: Increased respiration rate for enhanced oxygen transport to muscles for ATP synthesis.

  • Circulation: Oxygen intake is circulated through the body.

  • Excretion: CO2, a waste from respiration, is expelled through the lungs.

Cellular Respiration

  • Process that converts energy from glucose into ATP.

  • Can occur with or without oxygen:

    • Aerobic respiration (in mitochondria) generates significantly more ATP.

  • Respiration Reaction:
    extGlucose+Oxygen<br>ightarrowextCarbonDioxide+Water+ATPext{Glucose + Oxygen} <br>ightarrow ext{Carbon Dioxide + Water + ATP}

Immune System Mechanisms

  • Utilizes phagocytosis and antibody production to mark and destroy pathogens.

  • Key Terms:

    • Allergy: Response to allergens (non-harmful).

    • Pathogen: Disease-causing microbe.

    • Vaccine: Inactive pathogen that stimulates WBC antibody production for future protection.

Shape-Specific Functions of Molecules

  • Molecules function based on their specific shapes; this includes:

    • Antibodies

    • Enzymes

    • Hormones

    • Neurotransmitters

  • Antigens: Harmful substances found on RBCs.

  • Receptors: Bind specific substances that influence cell behavior.

Biochemistry of Molecules

  • Carbohydrates:

    • Composed of simple sugars (end in -ose); provide energy.

    • Examples: Cellulose (plant cell walls), glycogen (stored in liver), glucose (pass through membranes).

  • Proteins:

    • Composed of amino acids (end in -ine); key structural and functional molecules.

    • Role: Hormones, enzymes, antibodies; bind to receptors based on their shape.

  • Lipids:

    • Provide energy and structure for cell membranes; composed of glycerol and fatty acids, which can also pass through membranes.

  • Nucleic Acids:

    • DNA: The genetic material.

    • RNA: Synthesized from DNA; essential for protein production.

Natural Selection

  • Proposed by Charles Darwin, states that organisms with favorable traits are more likely to survive and reproduce.

  • Survival of the Fittest: The best-suited organisms survive within their environment.

  • Industrial Revolution Example:

    • Tree bark changed from light to dark; tree species with darker colors thrived post-revolution.

Evolutionary Concepts

  • Populations evolve rather than individuals;

  • Sources of Genetic Variation:

    1. Sexual Reproduction: Contributes to genetic diversity.

    2. Mutations: Random genetic changes, usually neutral or harmful.

    3. Genetic Engineering: Deliberate manipulation of genetic material.

  • Evolutionary Implications:

    • Variation leading to change results in evolution.

    • Lack of variation with change results in extinction.

    • Stability occurs without change or variation.