General Biology: Core Concepts and Practice Questions

Introduction to the Science of Life

Characteristics of Living Things

Biology is the study of living organisms and their interactions with the environment. All living things share certain characteristics that distinguish them from non-living matter.

• Organization: Living things are organized into cells, tissues, organs, and systems.

• Metabolism: All organisms carry out chemical reactions to obtain and use energy.

• Homeostasis: The ability to maintain stable internal conditions.

• Growth and Development: Organisms grow and develop according to specific instructions coded in their DNA.

• Reproduction: Living things produce offspring, passing on genetic information.

• Response to Stimuli: Organisms respond to environmental changes.

• Evolution: Populations of organisms change over time through adaptation and natural selection.

The Chemistry of Life

Organic Molecules and Their Classes

Organic molecules are the building blocks of life, primarily composed of carbon, hydrogen, oxygen, and nitrogen.

• Carbohydrates: Provide energy and structural support. Example: Glucose ($C_6H_{12}O_6$).

• Lipids: Store energy and make up cell membranes. Example: Phospholipids.

• Proteins: Perform a variety of functions including catalysis (enzymes), structure, and transport. Example: Hemoglobin.

• Nucleic Acids: Store and transmit genetic information. Example: DNA and RNA.

Properties of Water

Water is essential for life due to its unique properties.

• Cohesion: Water molecules stick together due to hydrogen bonding.

• Adhesion: Water molecules stick to other surfaces.

• High Specific Heat: Water can absorb a lot of heat before changing temperature.

• Solvent Properties: Water dissolves many substances, facilitating chemical reactions.

The Cell: The Fundamental Unit of Life

Cell Types

Cells are the basic units of life. There are two main types:

• Prokaryotic Cells: Lack a nucleus and membrane-bound organelles. Example: Bacteria.

• Eukaryotic Cells: Have a nucleus and membrane-bound organelles. Example: Plant and animal cells.

Cell Structures and Functions

• Nucleus: Contains genetic material (DNA).

• Ribosomes: Site of protein synthesis.

• Mitochondria: Powerhouse of the cell, site of cellular respiration.

• Chloroplasts: Site of photosynthesis in plant cells.

• Cell Membrane: Controls movement of substances in and out of the cell.

• Cell Wall: Provides structure and protection in plant cells.

• Vacuole: Stores water and nutrients in plant cells.

Cell Transport Mechanisms

Cells regulate the movement of substances across their membranes through various transport mechanisms.

• Passive Transport: Movement of substances without energy input. Includes diffusion, osmosis, and facilitated diffusion.

• Active Transport: Movement of substances against a concentration gradient, requiring energy (ATP).

Energy and Life

Photosynthesis and Cellular Respiration

Organisms obtain energy through photosynthesis and cellular respiration.

• Photosynthesis: Process by which plants convert light energy into chemical energy. Occurs in chloroplasts.

  • Equation: $6CO_2 + 6H_2O + light \rightarrow C_6H_{12}O_6 + 6O_2$

• Cellular Respiration: Process by which cells break down glucose to produce ATP.

  • Equation: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP$

Chromosomes and Inheritance

Genetic Material and Cell Division

• DNA: The molecule that carries genetic information.

• Chromosomes: Structures within cells that contain DNA.

• Mitosis: Cell division resulting in two identical daughter cells.

• Meiosis: Cell division producing gametes with half the number of chromosomes.

DNA: The Molecule of Life

Structure and Function

• Double Helix: DNA consists of two strands forming a double helix.

• Nucleotides: Building blocks of DNA, each containing a sugar, phosphate, and nitrogenous base.

• Replication: DNA copies itself before cell division.

Darwinian Evolution

Natural Selection and Adaptation

• Natural Selection: Process by which organisms better adapted to their environment survive and reproduce.

• Adaptation: Traits that improve an organism's chances of survival.

Biodiversity

Classification of Life

• Domains: Bacteria, Archaea, Eukarya.

• Kingdoms: Protista, Fungi, Plantae, Animalia.

Human Body Systems

Major Organ Systems

• Circulatory System: Transports nutrients and oxygen.

• Respiratory System: Facilitates gas exchange.

• Digestive System: Breaks down food for energy.

• Nervous System: Controls body functions and responses.

Ecology

Levels of Organization

• Organism: Individual living thing.

• Population: Group of organisms of the same species.

• Community: All populations in a given area.

• Ecosystem: Community plus the non-living environment.

• Biosphere: All ecosystems on Earth.

Energy Flow and Food Webs

• Producers: Organisms that make their own food (plants).

• Consumers: Organisms that eat other organisms.

• Decomposers: Break down dead material.

Tables and Data Interpretation

Example Table: Comparison of Cell Types

Feature	Prokaryotic Cell	Eukaryotic Cell
Nucleus	Absent	Present
Membrane-bound Organelles	Absent	Present
Size	Smaller	Larger
Examples	Bacteria	Plants, Animals

Example Table: Levels of Ecological Organization

Level	Description
Organism	Single living individual
Population	Group of same species in an area
Community	All populations in an area
Ecosystem	Community plus non-living environment
Biosphere	All ecosystems on Earth

Additional info:

• Some content was inferred and expanded for completeness, including definitions and examples.

• Tables were recreated based on common biology comparisons and classifications.