Biology: Photosynthesis and Plant Functions

Definition of Organic Compounds

  • Organic Compounds: Typically contain carbon and hydrogen.
  • Example: Glucose
    • Chemical formula: $C6H{12}O_6$.
  • Inorganic Example: Carbon dioxide ($CO_2$) is not organic because it lacks hydrogen.

Autotrophs

  • Autotrophs: Organisms that can produce their own food.
    • Definition breakdown: "Auto" means self, and "troph" refers to feeding.
    • Function: They convert substances like carbon dioxide into glucose through photosynthesis.

Photosynthesis

  • Photosynthesis Equation: 6CO<em>2+6H</em>2O+extSunlightightarrowC<em>6H</em>12O<em>6+6O</em>26CO<em>2 + 6H</em>2O + ext{Sunlight} ightarrow C<em>6H</em>{12}O<em>6 + 6O</em>2
    • Reactants: Carbon dioxide ($CO2$) and water ($H2O$) using sunlight.
    • Products: Glucose ($C6H{12}O6$) and oxygen ($O2$).
  • Importance: Plants are primary producers; 99.9% of life on Earth relies on photosynthesis for energy.

Plant Cells

  • Structures in Plant Cells:
    • Cell Membrane: Made of a phospholipid bilayer.
    • Cell Wall: Composed of cellulose.
    • Organelles: Include nucleus, central vacuole, mitochondria, and chloroplasts.
  • Chloroplasts vs. Mitochondria:
    • Chloroplasts: Sites for photosynthesis.
    • Mitochondria: Sites for cellular respiration.
    • Plants can perform both processes, while humans only perform cellular respiration.

Chloroplast Structure

  • Chloroplast Layers:
    • Composed of two phospholipid bilayers (outer and inner membrane).
    • Contains thylakoids, which can stack to form granum.
    • Houses chlorophyll, the pigment for capturing sunlight.

Light Spectrum

  • Visible Spectrum: Small part of the overall electromagnetic spectrum that humans can see.
    • Ranges from purple and blue (short wavelengths, high energy) to red (long wavelengths, lower energy).
  • Chlorophyll: Absorbs red and blue light, reflects green light (thus plants appear green).

Protecting Against UV Radiation

  • Methods:
    • Wearing sunglasses to protect the eyes from UV rays.
    • Using sunblock to prevent skin damage and reduce risk of skin cancer due to UV exposure.

Comparisons of Pigments

  • Chlorophyll (plant) vs. Hemoglobin (animal):
    • Hemoglobin carries oxygen and carbon dioxide in the blood, contains iron ($Fe$).
    • Chlorophyll absorbs sunlight, contains magnesium ($Mg$) instead of iron.

Nutritional Sources of Minerals

  • Iron Sources: Red meat, fish, and certain vegetables (like parsley).
  • Magnesium Sources: Leafy greens such as spinach or kale, often consumed for health benefits.