Biology

• Levels of Organization within Organisms

  • Organelles
  • Cells
  • Tissues
  • Organs
  • Systems
• Organelles


  Subcellular structures that perform specific functions within cells
• Cells


  Basic structural and functional units of living organisms
• Tissues


  Groups of cells that work together to perform a specific function
• Organs


  Structures composed of different tissues that work together to carry out specific functions
• Systems


  Collections of organs that cooperate to perform complex physiological functions
• Cell Structures


  • Nucleus
  • Cytoplasm
  • Cell Membrane
  • Cell Wall
  • Mitochondria
  • Chloroplasts
  • Ribosomes
  • Vacuole
• Nucleus


  Contains genetic material and controls cell activities
• Cytoplasm


  Gel-like substance that fills the cell and houses organelles
• Cell Membrane


  Selectively permeable barrier that encloses the cell and regulates the passage of substances
• Cell Wall


  Rigid outer layer found in plant cells, providing structural support
• Mitochondria


  Organelles responsible for energy production through cellular respiration
• Chloroplasts


  Organelles found in plant cells that carry out photosynthesis
• Ribosomes


  Structures involved in protein synthesis
• Vacuole


  Membrane-bound sacs that store water, nutrients, and waste materials
• Functions of Cell Structures

  • Nucleus
  • Cytoplasm
  • Cell Membrane
  • Cell Wall
  • Mitochondria
  • Chloroplasts
  • Ribosomes
  • Vacuole
• Nucleus


  Controls cell activities and contains genetic information
• Cytoplasm


  Site of various cellular processes and houses organelles
• Cell Membrane


  Controls the movement of substances in and out of the cell
• Cell Wall


  Provides structural support and protection in plant cells
• Mitochondria


  Produces energy (ATP) through cellular respiration
• Chloroplasts


  Carry out photosynthesis, converting light energy into chemical energy
• Ribosomes


  Synthesise proteins
• Vacuole


  Stores water, nutrients, and waste materials
• Similarities and Differences in Plant and Animal Cells

  • Both have a cell membrane, cytoplasm, and nucleus
  • Plant cells have a cell wall, while animal cells do not
  • Plant cells have chloroplasts for photosynthesis, while animal cells do not
  • Plant cells often have larger vacuoles than animal cells
• Cell differentiation


  The process by which unspecialized cells become specialised to perform specific functions
• Cell differentiation plays a crucial role in the development of multicellular organisms
• Specialised cells enable the formation of different tissues, organs, and systems, allowing for complex physiological processes
• Advantages and Disadvantages of Using Stem Cells in Medicine

  • Advantages: Stem cells have the potential to differentiate into various cell types and can be used for tissue regeneration and repair. They offer hope for treating diseases and injuries.
  • Disadvantages: Ethical concerns regarding the use of embryonic stem cells. The potential for immune rejection if stem cells are derived from another individual. The risk of tumour formation if stem cells are not properly controlled.
• Photosynthesis


  Carbon dioxide + Water + Light energy → Glucose + Oxygen
• Photosynthesis is important as it produces oxygen, which is essential for aerobic respiration and the survival of organisms. It also provides a source of organic molecules and energy for the food chain.
• Photosynthesis (balanced chemical equation)

  6CO2 + 6H2O + light energy → C6H12O6 + 6O2
• Factors Affecting the Rate of Photosynthesis

  • Carbon Dioxide Concentration
  • Light Intensity
  • Temperature
• Leaves have a flat and thin structure with a large surface area to maximise light absorption. They contain chloroplasts for photosynthesis. The presence of stomata allows for gas exchange (CO2 uptake and O2 release) and water vapour loss (transpiration).
• Mineral Ions Required for Plant Growth

  • Magnesium
  • Nitrate
• Magnesium ions


  Needed for the synthesis of chlorophyll
• Nitrate ions


  Necessary for the formation of amino acids and proteins
• Phloem


  Vascular tissue responsible for transporting organic nutrients, such as sucrose and amino acids, throughout the plant
• Phloem moves these substances from the leaves (site of production) to other parts of the plant, including growing regions and storage organs.
• Xylem


  Vascular tissue that transports water and dissolved mineral ions from the roots to the rest of the plant