Plant Biology Notes

Plant Structure

  • Roots:

    • Anchor the plant.

    • Absorb and transport water and mineral salts.

    • Store food.

    • Monocot and dicot root anatomy differ (epidermis, cortex, endodermis, pericycle, pith, xylem, pholem, root hairs).

  • Stem:

    • Supports leaves for sunlight capture.

    • Supports flowers and fruits.

    • Transports water, minerals, and sugar.

    • Stores food.

    • Monocot and dicot stem anatomy differ (vascular bundle arrangement).

  • Leaf:

    • Photosynthesis.

    • Transpiration.

    • Veins transport water and nutrients.

    • Leaf anatomy: cuticle, epidermis, mesophyll (palisade and spongy), stomata, guard cells, vascular bundles (xylem, phloem).

  • Flower:

    • Reproductive structure for seeds and fruit.

    • Appear at specific life cycle stages.

Photosynthesis

  • Process by which plants make carbohydrates using light energy.

  • Occurs in palisade mesophyll tissue within chloroplasts.

  • Chloroplasts contain chlorophyll to trap light energy.

  • 6CO2 + 6H2O   —> C6H12O6 + 6O2

  • Glucose can be: used for respiration, stored as starch, converted to sucrose, used to make cellulose and react with magnesium to form chlorophyll, or react with nitrates to form protein

  • Starch presence indicated by blue/black color.

  • Oxygen gas produced if photosynthesis occurs

Transport in Plants

  • Xylem:

    • Transports water and mineral salts from roots to plant parts.

    • Composed of dead cells forming long tubes with thick, woody walls.

    • Provides mechanical support.

  • Phloem:

    • Transports sucrose and amino acids from leaves to plant parts.

    • Composed of living cells forming long tubes with separating walls.

  • Transpiration:

    • Water evaporation from leaves.

    • Water moves from soil to root hair cells by diffusion.

    • Xylem transports water and minerals.

    • Stomata facilitate water evaporation and gas exchange.

    • Factors increasing transpiration: high temperature, high light intensity, faster air movement, lower humidity.

  • Sugar Transport

    • Glucose produced in leaves is transported by phloem.

    • Phloem transports glucose to shoots for growth and roots for starch storage.