The Private Life of Plants - Biology Topic 3

Advantages of Plants Living on Land:

1. Direct and undiluted sunlight for easier photosynthesis.

2. Absence of land predators at the time allowed for more growth space and time.

Plant Characteristics:

• Movement: Plants grow towards stimuli like light and water (e.g., sunflowers follow the sun).

• Respiration: Continuous release of energy from glucose created during photosynthesis.

• Sensitivity: Shoots bend towards sunlight; roots grow down due to gravity.

• Growth: Plants grow mainly at the roots and shoots' tips.

• Reproduction: Most reproduce sexually; some asexually.

• Excretion: Waste products include oxygen (day) and carbon dioxide (night) through stomata.

• Nutrition: Makes own food (glucose) via photosynthesis; absorbs minerals from the soil.

Plant Classification:

• Plant Kingdom: All plants belong to this group, which is subdivided into phyla.

  • Bryophytes: ~23,000 species, small leaves, no stems, thrive in damp areas.

  • Ferns: ~15,000 species, larger leaves with spores for reproduction, no flowers.

  • Gymnosperms: ~1,000 species, conifers with seeds in cones, woody stems.

  • Angiosperms: ~350,000 species, flowering plants that attract pollinators.

Flower Parts:

• Female Parts (collectively: carpel): stigma, style, ovary, ovule.

• Male Parts (collectively: stamen): anther, filament.

• Neutral Parts: petals, sepals, stem, roots.

Pollination:

• Self Pollination: Pollen fertilizes ovules from the same flower or plant, no genetic variation.

• Cross Pollination: Pollen from one plant fertilizes another, introducing genetic variation.

Pollination Adaptations:

• Wind Pollinated Plants: Basic green color, no strong odors, exposed seeds.

• Bee Pollinated Plants: Blue/yellow flowers, strong odors, landing pads for bees.

• Bird Pollinated Plants: Bright colors (reds/oranges), tubular flowers, small odors.

• Butterfly Pollinated Plants: Pink/lavender flowers, strong odors, landing pads.

• Fly Pollinated Plants: Dark brown/purple flowers, smell like rotten meat, funnel-shaped.

• Bat Pollinated Plants: No bright colors, strong aromas, bell-shaped flowers.

Seed Benefits:

1. Protects embryos from drying out, damages, and ensures a steady food supply.

2. Dispersing seeds prevents competition among offspring and encourages species spread.

Nutrition Classification:

• Heterotrophs: Require other organisms for nutrition.

• Autotrophs: Produce their own food through photosynthesis.

Photosynthesis:

• Word Equation: Carbon dioxide + water -> glucose + oxygen.

• Chemical Equation: 6CO2 + 6H2O -> C6H12O6 + 6O2 (in presence of light and chlorophyll).

• Useful Product: Glucose; waste product: oxygen (for respiration).

Testing for Substances:

• Benedict's Test: Detects sugars (glucose).

  • Colors indicate sugar levels (Blue: none, Green: trace, Yellow: low, Orange: moderate, Red: high).

• Iodine Test: Detects starch.

  • Yellow/Brown: negative; Blue/Black: positive (starch present).

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