Key Concepts in Biology

Cell Theory:
- All living organisms are composed of cells.
- Cells are the basic unit of life.
- All cells arise from pre-existing cells.
Types of Cells:
- Prokaryotic: No nucleus, smaller, simpler (e.g., bacteria).
- Eukaryotic: Nucleus present, larger, complex (e.g., plant and animal cells).
Cell Organelles:
- Nucleus: Contains genetic material (DNA).
- Mitochondria: Powerhouse, site of ATP production.
- Ribosomes: Protein synthesis.
- Endoplasmic Reticulum: Protein and lipid synthesis (Rough ER has ribosomes; Smooth ER does not).
- Golgi Apparatus: Modifies, sorts, and packages proteins.

DNA Structure:
- Double helix made of nucleotides (adenine, thymine, cytosine, guanine).
Gene Expression:
- Transcription: DNA to RNA.
- Translation: RNA to protein.
Mendelian Genetics:
- Law of Segregation: Alleles segregate during gamete formation.
- Law of Independent Assortment: Genes for different traits are inherited independently.

Natural Selection:
- Survival of the fittest; traits beneficial for survival and reproduction are passed on.
Speciation:
- Formation of new and distinct species through processes like geographic isolation or reproductive isolation.
Evidence of Evolution:
- Fossil records, comparative anatomy, molecular biology, and biogeography.

Levels of Organization:
- Individual, Population, Community, Ecosystem, Biome, Biosphere.
Energy Flow:
- Producers (autotrophs) convert sunlight into energy (photosynthesis).
- Consumers (heterotrophs) obtain energy by eating other organisms.
Biogeochemical Cycles:
- Water cycle, carbon cycle, nitrogen cycle, and phosphorus cycle.

Homeostasis:
- Maintaining a stable internal environment despite external changes.
Systems:
- Circulatory: Transports nutrients and oxygen.
- Respiratory: Facilitates gas exchange.
- Digestive: Breaks down food for nutrient absorption.
- Nervous: Processes information and coordinates responses.

Photosynthesis:
- Process by which plants convert sunlight into chemical energy (glucose).
- Takes place in chloroplasts.
Plant Structures:
- Roots: Absorb water and nutrients.
- Stems: Support and transport.
- Leaves: Main site of photosynthesis.

Microorganisms:
- Bacteria: Prokaryotic, diverse functions (e.g., decomposition, nitrogen fixation).
- Viruses: Non-living entities, require host cells to replicate.
- Fungi: Eukaryotic, decomposers, can be unicellular (yeasts) or multicellular (molds).

Genetic Engineering:
- Techniques like CRISPR to manipulate genes.
Applications:
- Medicine (gene therapy, vaccines), agriculture (GMOs), and environmental science (bioremediation).

Cell Theory: Living organisms are made of cells, which are the basic unit of life, and all cells originate from pre-existing cells.
Types of Cells:
- Prokaryotic cells lack a nucleus, are smaller, and simpler, exemplified by bacteria.
- Eukaryotic cells possess a nucleus, are larger and more complex, examples include plant and animal cells.
Cell Organelles:
- Nucleus houses genetic material (DNA).
- Mitochondria produce ATP, serving as the cell's powerhouse.
- Ribosomes are responsible for protein synthesis.
- Endoplasmic Reticulum (ER) is involved in protein (Rough ER with ribosomes) and lipid synthesis (Smooth ER without ribosomes).
- Golgi Apparatus modifies, sorts, and packages proteins for transport.

DNA Structure: Comprises a double helix formed by nucleotides adenine, thymine, cytosine, and guanine.
Gene Expression:
- Transcription converts DNA into messenger RNA (mRNA).
- Translation synthesizes proteins from mRNA.
Mendelian Genetics:
- Law of Segregation states that alleles separate during gamete formation.
- Law of Independent Assortment indicates that different traits' genes are inherited independently.

Natural Selection: Concept where advantageous traits for survival and reproduction are conveyed to future generations.
Speciation: New species arise from mechanisms like geographic or reproductive isolation.
Evidence of Evolution: Supported through fossil records, comparative anatomy, molecular biology, and biogeographical studies.

Levels of Organization: Ranges from individual organisms to populations, communities, ecosystems, biomes, and the biosphere.
Energy Flow:
- Autotrophs (producers) transform sunlight into chemical energy through photosynthesis.
- Heterotrophs (consumers) derive energy by consuming other organisms.
Biogeochemical Cycles: Includes essential cycles like water, carbon, nitrogen, and phosphorus cycles.

Homeostasis: The body's ability to maintain a stable internal environment despite external changes.
Body Systems:
- Circulatory system: Transports nutrients and oxygen throughout the body.
- Respiratory system: Engages in gas exchange between the body and the environment.
- Digestive system: Breaks down food to absorb nutrients.
- Nervous system: Processes information and coordinates bodily responses.

Photosynthesis: Plants convert sunlight into chemical energy, primarily glucose, occurring in chloroplasts.
Plant Structures:
- Roots absorb water and nutrients from the soil.
- Stems provide support and transport nutrients and water.
- Leaves are the main sites for photosynthesis, harnessing sunlight.

Microorganisms:
- Bacteria: Prokaryotic organisms with diverse roles including decomposition and nitrogen fixation.
- Viruses: Non-living entities that replicate only within host cells.
- Fungi: Eukaryotic decomposers, existing as unicellular (yeasts) or multicellular (molds) forms.

Genetic Engineering: Techniques like CRISPR are employed for gene manipulation.
Applications: Includes advancements in medicine (gene therapy, vaccines), agriculture (genetically modified organisms), and environmental science (bioremediation).

Emphasize understanding concepts over mere memorization.
Utilize diagrams to visualize complex processes, such as cellular respiration and food chains.
Reinforce learning through quizzes and flashcards.