Key Concepts in Biology GCSE

Cell Structure:
- Prokaryotic vs. Eukaryotic cells
- Organelles: nucleus, mitochondria, ribosomes, chloroplasts, cell membrane, cell wall (in plants)
Cell Functions:
- Respiration, protein synthesis, photosynthesis (in plants), and transport mechanisms (diffusion, osmosis).

DNA Structure: Double helix, nucleotides (adenine, thymine, cytosine, guanine).
Chromosomes: 23 pairs in humans, loci, and alleles.
Inheritance: Dominant and recessive traits, Punnett squares, phenotypes vs. genotypes.

Theory of Evolution: Proposed by Charles Darwin; survival of the fittest.
Adaptation: Organisms' traits that enhance survival in specific environments.
Speciation: Process by which new species arise.

Ecosystems: Interactions between organisms and their environment; food chains and webs.
Biomes: Different ecosystems (tundra, rainforest, desert).
Biodiversity: Importance of genetic, species, and ecosystem diversity.

Organ Systems:
- Circulatory (heart, blood vessels)
- Respiratory (lungs, gas exchange)
- Digestive (stomach, intestines)
- Nervous (brain, nerve cells)
Homeostasis: Maintaining stable internal conditions (temperature, pH, hydration).

Photosynthesis: Process by which plants convert sunlight into energy; occurs in chloroplasts.
Plant Structures: Roots, stems, leaves, flowers; their functions in nutrient uptake, support, and reproduction.
Transport Systems: Xylem (water transport) and phloem (nutrient transport).

Pollution: Air, water, and soil pollution effects on health and ecosystems.
Conservation: Strategies to protect endangered species and habitats.
Sustainability: Practices aimed at meeting present needs without compromising future generations.

Experiments: Importance of hypothesis, variables, controls, and data collection.
Safety: Lab safety rules and proper handling of equipment and chemicals.
Data Analysis: Interpreting graphs, charts, and statistical data.

Prokaryotic cells lack a nucleus and membrane-bound organelles; eukaryotic cells have a nucleus and organelles such as mitochondria and chloroplasts.
Essential organelles include the nucleus (controls cell activities), mitochondria (powerhouse of the cell), ribosomes (protein synthesis), chloroplasts (photosynthesis in plants), cell membrane (regulates entry and exit of substances), and cell wall (provides structure in plants).
Key functions: respiration (energy production), protein synthesis (creating proteins), photosynthesis (light energy conversion in plants), diffusion (movement of molecules from high to low concentration), and osmosis (water movement across membranes).

DNA has a double helix structure formed by nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G).
Humans have 23 pairs of chromosomes, with specific locations called loci; variations at these loci are known as alleles.
Inheritance includes dominant traits that express in the presence of a recessive allele; Punnett squares model genetic crosses to predict offspring traits; phenotypes (observable traits) differ from genotypes (genetic makeup).

Charles Darwin proposed the theory of evolution based on natural selection, where organisms best adapted to their environment survive and reproduce.
Adaptation refers to traits that improve an organism's ability to survive and thrive in its environment.
Speciation is the process through which new species develop, often as a result of environmental pressures and genetic divergence.

Ecosystems consist of living organisms interacting with their physical environment, structured by food chains that show energy flow.
Major biomes include tundra, rainforest, and desert, each characterized by specific climate conditions and biodiversity.
Biodiversity encompasses genetic diversity (variation within species), species diversity (variety of species within a habitat), and ecosystem diversity (variety of habitats).

Organ systems:
- Circulatory system includes the heart and blood vessels for transport of nutrients and gases.
- Respiratory system involves the lungs, facilitating gas exchange.
- Digestive system processes food in the stomach and intestines.
- Nervous system consists of the brain and nerve cells, controlling bodily functions and responses.
Homeostasis is the regulation of internal conditions such as temperature and pH, essential for optimal cellular function.

Photosynthesis occurs in chloroplasts, enabling plants to convert sunlight into chemical energy (glucose).
Plant structures include roots (nutrient uptake), stems (support), leaves (photosynthesis), and flowers (reproduction).
Plants have transport systems: xylem carries water from roots to leaves, while phloem distributes nutrients produced during photosynthesis.

Pollution types include air, water, and soil, adversely affecting health and ecosystems.
Conservation strategies aim to protect endangered species and preserve their natural habitats for ecological balance.
Sustainability focuses on practices that fulfill current needs while ensuring resources for future generations.

Scientific experiments require forming a hypothesis, controlling variables, and systematic data collection to validate results.
Safety in laboratories includes following rules for handling equipment and chemicals to prevent accidents.
Data analysis techniques involve interpreting graphs, charts, and statistical data to draw meaningful conclusions.

Effective revision techniques include using flashcards, creating mind maps, and practicing with past exam papers for familiarity.
Understanding key biological terminology and definitions is essential for clear communication of concepts.
Time management is critical; scheduling study sessions ensures sufficient coverage of all topics in preparation for exams.