General Biology: Midterm 1 Practice Questions Study Guide

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Genetic Variation and Natural Selection

Role of Genetic Variation in Populations

Genetic variation is essential for populations to adapt to changing environments. It provides the raw material for natural selection to act upon, allowing certain traits to become more common if they confer a survival advantage.

Genetic Variation: Differences in DNA among individuals within a population.
Natural Selection: The process by which individuals with advantageous traits survive and reproduce more successfully.
Example: Brown beetles become more common after a forest fire because their coloration provides better camouflage, increasing their survival rate.

Biomolecules: Structure and Function

Identification of Biomolecules

Biomolecules are organic molecules essential for life, including lipids, proteins, amino acids, and nucleotides. Recognizing their structures is fundamental in biology.

Lipid: Hydrophobic molecules, such as fats and oils.
Polypeptide: Chains of amino acids forming proteins.
Amino Acid: Building blocks of proteins, containing an amino group, carboxyl group, and side chain.
Nucleotide: Monomers of nucleic acids, composed of a sugar, phosphate group, and nitrogenous base.
Example: The structure shown in the question is a nucleotide, as it contains a phosphate group, a sugar, and a nitrogenous base.

Protein Structure and Interactions

Types of Interactions in Protein Tertiary Structure

The tertiary structure of proteins is stabilized by various interactions between amino acid side chains (R groups).

Peptide Bonds: Covalent bonds between amino acids (primary structure).
Hydrogen Bonds: Form between backbone groups and some side chains.
Disulfide Bonds: Covalent bonds between cysteine residues.
Hydrophobic Interactions: Nonpolar side chains cluster away from water.
Example: Hydrophobic interactions between R groups are crucial for protein folding.

Metabolism and Energy

Spontaneity of Chemical Reactions

Spontaneous reactions occur without external energy input and are driven by changes in free energy.

Gibbs Free Energy (): Determines whether a reaction is spontaneous.
Spontaneous Reaction: (negative free energy change).
Equation:
Example: Glucose breakdown is spontaneous because it releases energy ( is negative).

Enzymes and Catalysis

Function of Enzymes

Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required.

Activation Energy: The energy needed to start a reaction.
Enzyme Action: Enzymes do not change the free energy of a reaction but make it proceed faster.
Example: Enzymes in metabolism allow reactions to occur rapidly at body temperature.

Cell Structure and Cytoskeleton

Cytoskeletal Elements and Their Functions

The cytoskeleton provides structural support and enables movement within cells. It consists of microfilaments, microtubules, and intermediate filaments.

Microfilaments: Composed of actin, involved in cell movement and shape.
Microtubules: Tubulin-based, important for cell division and intracellular transport.
Intermediate Filaments: Provide mechanical strength.
Example: Amoeboid movement uses actin filaments to extend pseudopodia.

Cellular Respiration and Energy Production

Role of Mitochondria and Tubulin

Mitochondria are the site of cellular respiration, producing ATP. Tubulin is essential for microtubule formation and cell movement.

Mitochondria: Powerhouse of the cell, generates ATP.
Tubulin: Protein forming microtubules, necessary for cell structure and movement.
Example: Loss of cytoplasmic tubulin impairs cell movement and shape.

Microbial Nutrition and Classification

Types of Microorganisms Based on Energy and Carbon Sources

Microorganisms are classified by how they obtain energy and carbon.

Phototrophs: Use light as an energy source.
Chemotrophs: Use chemicals as an energy source.
Autotrophs: Use CO2 as a carbon source.
Heterotrophs: Use organic compounds as a carbon source.
Example: A chemoheterotroph obtains energy from chemicals and carbon from organic sources.

Antibiotic Resistance and Natural Selection

Evolution of Antibiotic-Resistant Bacteria

Antibiotic resistance arises when bacteria evolve mechanisms to survive exposure to antibiotics, often due to natural selection.

Antibiotic: Substance that kills or inhibits bacteria.
Natural Selection: Antibiotic-resistant bacteria survive and reproduce, passing resistance genes to offspring.
Example: Introduction of a new antibiotic selects for resistant strains in a bacterial population.

Enzyme Inhibition

Types of Enzyme Inhibition

Enzyme inhibitors reduce or block enzyme activity, affecting metabolic pathways.

Competitive Inhibition: Inhibitor competes with substrate for active site.
Noncompetitive Inhibition: Inhibitor binds elsewhere, changing enzyme shape.
Feedback Inhibition: End product inhibits an earlier step in the pathway.
Example: HIV drugs may act as competitive inhibitors, blocking the active site of viral enzymes.

Temperature Effects on Biological Systems

Impact of High Fever on Children

High body temperature can disrupt normal cellular processes and protein structure, posing health risks.

Protein Denaturation: High temperatures can break bonds, altering protein structure and function.
Metabolic Rate: Increased temperature raises metabolic rate, potentially leading to rapid weight loss.
Example: Prolonged high fever in children can be dangerous due to increased breakdown of proteins and altered metabolism.

Summary Table: Types of Microbial Nutrition

The following table summarizes the classification of microorganisms based on their energy and carbon sources.

Type	Energy Source	Carbon Source	Example Organism
Photoautotroph	Light	CO2	Plants, Cyanobacteria
Chemoautotroph	Chemicals	CO2	Nitrifying bacteria
Photoheterotroph	Light	Organic compounds	Some bacteria
Chemoheterotroph	Chemicals	Organic compounds	Animals, Fungi, Most bacteria

Key Equations

Gibbs Free Energy:
Spontaneity: Reaction is spontaneous if

Additional info:

Some explanations and examples have been expanded for clarity and completeness.
Table entries and definitions are inferred from standard General Biology curriculum.