Biology: Cell Transport and Photosynthesis

Cell Transport

• Simple diffusion: Movement of molecules from high to low concentration, no energy required. Examples include oxygen and carbon dioxide across cell membranes.
• Facilitated diffusion: Movement of molecules from high to low concentration, assisted by transport proteins; still no energy required. Examples include glucose transport.

Photosynthesis

• Process: Plants use light energy to convert carbon dioxide and water into glucose (sugar) and oxygen.
• Equation: 6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂
• Location: Chloroplasts (specifically, chlorophyll) in plant cells.
• Importance: Produces food for the plant and oxygen for the atmosphere.

Cellular Respiration

• Process: Breakdown of glucose to release energy in the form of ATP (adenosine triphosphate). A crucial energy-production process for all living cells.
• Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP)
• Types: Aerobic (requires oxygen) and anaerobic (without oxygen).

Animal vs. Plant Cells

• Animal Cells: Typically lack cell walls, chloroplasts, and large central vacuoles.
• Plant Cells: Possess cell walls, chloroplasts, and a large central vacuole for storage and support.

Tonicity (Hypertonic, Hypotonic, Isotonic)

• Hypertonic: Solution with higher solute concentration compared to the cell. Water moves out of the cell, potentially causing it to shrink.
• Hypotonic: Solution with lower solute concentration compared to the cell. Water moves into the cell, potentially causing it to swell or burst.
• Isotonic: Solution with equal solute concentration to the cell. Water movement is balanced in both directions, maintaining cell shape.

Enzymes

• Biological catalysts: Speed up chemical reactions in living organisms.
• Specificity: Each enzyme catalyzes a specific reaction.
• Active site: Region of the enzyme where the substrate binds.
• Factors affecting enzyme activity: Temperature, pH, and substrate concentration.

Biomolecules

• Carbohydrates: Provide energy; composed of carbon, hydrogen, and oxygen.
• Lipids: Store energy, insulation; composed of carbon, hydrogen, and oxygen.
• Proteins: Build cells, control reactions; composed of amino acids.
• Nucleic acids: Store genetic information; composed of nucleotides.

Independent and Dependent Variables

• Independent variable: The factor the researcher manipulates.
• Dependent variable: The factor the researcher measures.

Control vs. Experimental Groups

• Control group: Used for comparison; receives no treatment or a standard treatment.
• Experimental group: Receives the treatment being tested.