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Introduction to Archaea and Bacteria

  • Crenarchaeota
  • Korarchaeota
  • Euryarchaeota
  • Bacteria

Kingdoms of Life

  • Archaea
  • Bacteria
  • Eukaryota

Major Groups of Organisms

  • Kingdom Plantae
    • Autotrophic, multicellular eukaryotes
  • Proteins and Nucleic Acids
  • Cnidarians
  • Animalia

Specific Organisms

  • Vibrio
  • Spirillum
  • Bacillus
  • Coccals
  • Insects
  • Myriapods
  • Mollusks
  • Vertebrates

Plant Classification

  • Vascular
  • Nonvascular
  • Seedless
  • Gymnosperms
  • Angiosperms

Structures of Plants

General Characteristics

  • Plants are multicellular eukaryotes
  • Plants are autotrophic
    • Produce their own food via photosynthesis

Common Structures of Plants

Cuticle

  • Definition: A waterproof layer of wax covering the outside of leaves and stems.
  • Function: Prevents dehydration in plants.
  • Characteristic: Composed of waxes, which are hydrophobic in nature.

Stomata

  • Definition: Tiny holes in leaves.
  • Function: Allow entry of CO₂ and the exit of H₂O and O₂.
  • Guard Cells: Two cells surround each stoma that can regulate its opening and closing.
    • Open stoma allows gas exchange; closed stoma prevents water loss.

Transpiration

  • Definition: The loss of water vapor through open stomata.
  • Function: Facilitates water uptake from roots upwards through the plant.
    • Note: If conditions are too dry or too hot, stomata may close to prevent dehydration.

Cell Wall

  • Definition: A rigid layer outside the cell membrane that provides support and protection.
  • Composition: Primarily made of cellulose (a polysaccharide).
  • Pores: Allow nutrient, water, and hormone sharing between neighboring cells.

Photosynthesis

Chloroplasts

  • Definition: Organelles in plant cells where photosynthesis occurs.
  • Function: Contain chlorophyll, which is a green photosynthetic pigment located on thylakoids resembling stacks of pancakes.

Process of Photosynthesis

  • Light Absorption:
    • Chlorophyll absorbs blue and red light and reflects green light, causing plants to appear green.
  • Chemical Formula: 6 ext{CO}2 + 6 ext{H}2 ext{O} + ext{sunlight} ightarrow ext{C}6 ext{H}{12} ext{O}6 + 6 ext{O}2
    • CO₂ enters through stoma; water enters through roots.
    • Sugars produced (can be stored as starch or used in cellular respiration).
  • Byproducts:
    • Some O₂ is used in cellular respiration; excess is expelled as waste.

Cellular Respiration

  • Products: Photosynthesis products like sugars and oxygen are used in cellular respiration to generate energy (ATP).
  • Recycling: CO₂ produced in cellular respiration is recycled back into photosynthesis.
    • Chemical Process:
    • Photosynthesis:
      ext{Water} + ext{Sunlight energy} + ext{CO}2 ightarrow ext{Glucose} + ext{O}2
    • Cellular Respiration:
      ext{Glucose} + ext{O}2 ightarrow ext{CO}2 + ext{Water} + ext{ATP}

Chlorophyll vs Hemoglobin

  • Chlorophyll and hemoglobin share a structural similarity, hinting at a possible common ancestor for plants and animals.

Seasonal Changes in Plants

Autumn Leaf Change

  • Plants transition from green to red, orange, and yellow signals.
  • Mechanism: Light and temperature changes trigger the cessation of photosynthesis.
  • Process: Chlorophyll breaks down revealing previously hidden pigments like xanthophyll, carotene, and anthocyanin.

Light Absorption in Plants

  • Absorption characteristics of different pigments:
    • Chlorophyll a: Absorbs specific wavelengths of light (400-700 nm range).
    • Chlorophyll b: Assists chlorophyll a in capturing light energy.
    • Carotenoids: Absorb light energy and protect plants from damage.

Plant Reproduction

Alternation of Generations

  • Definition: An alternating pattern in plant reproduction between two stages:
    • Sporophyte Stage: Produces spores.
    • Gametophyte Stage: Produces gametes (male and female sex cells for fertilization).

Life Cycle of Ferns

  • Stages Include:
    • Sporangium
    • Spores
    • Mature gametophyte (produces sperm and egg)
    • Fertilization leads to the formation of a new sporophyte from the zygote.

Plant Responses to Stimuli

Phototropism

  • Definition: Growth towards light.
    • Observation: Unequal growth at plant tips leads to bending towards the light source.

Gravitropism

  • Definition: Roots grow following the gravity direction, while shoots grow in the opposite direction.

Thigmotropism

  • Definition: Growth response to touching an object (e.g., climbing plants).

Nastic Movements

  • Definition: Rapid responses to stimuli, such as touch (e.g., closing of Mimosa leaves upon contact).

Conclusion

  • Through various structures and functions, plants maintain their essential processes like photosynthesis, respond to environmental stimuli, and successfully reproduce.

  • Consideration: How plants adapt and respond to their environment represents a significant aspect of their survival and evolution.