Plant Ecology and Bioassay

Plant Ecology and Bioassay

• BSC 1005L – Life Science Lab

What is Ecology?

• Ecology is the study of interactions between organisms and their physical environment.
• Ecosystem Composition: An ecosystem comprises both biotic and abiotic components:
  • Biotic factors (living components): Bacteria, plants, fungi, animals.
  • Abiotic factors (non-living components): Rocks, soil, water, air, light, temperature.

Trophic Levels

• The hierarchy shows the nutritional relationships among organisms within an ecosystem and is primarily based on energy flow from the sun.
• Food Chain: Simple representation of the food relationship, often oversimplified.
• Food Web: More complex and accurate depiction representing multiple food chains.

Classification of Trophic Levels:

1. Producers: Organisms that make energy through photosynthesis.
2. Consumers:
   • Primary consumers: Herbivores.
   • Secondary consumers: Omnivores.
   • Tertiary consumers: Carnivores, some omnivores.
   • Quaternary consumers: Top predators.
3. Decomposers: Organisms that break down organic material, recycling energy back to producers.

Plant Defenses

• Primary producers, particularly plants and photosynthetic microorganisms, have developed various defense mechanisms to protect themselves in their habitat.

Defensive Strategies:

1. Physical Defenses:

   • Characteristics that harm herbivores or primary consumers (e.g., thorns on roses, spikes on hawthorn trees).
   • Goal: Prevent consumption of plant parts.

2. Chemical Defenses:

   • Secondary compounds produced by plants to deter herbivory (e.g., capsaicin in peppers).
   • Some compounds serve as warning signals to other plants.
   • Examples include cinnamon and tannin.

3. Indirect Defenses:

   • Recruitment of insects for defense (e.g., acacia trees attract ants).
   • Use of chemical attractants.

Evolution and Coevolution

• Evolution:
  • The change in organisms over time due to natural selection and genetic drift, leading to biodiversity and environmental adaptation.
• Coevolution:
  • The mutual influence on the evolution of two different species; interactions could be mutualistic or antagonistic.
  • Example: Herbivores evolving detoxification methods against plant toxins and then employing those toxins for their defense.

Bioassay

• Bioactive Compounds: Compounds affecting survival, growth, and reproduction of living organisms.
• Bioassay: Experimental method to screen for potential bioactive substances in a controlled environment.
  • Measurement of how potent a bioactive compound is based on its effect on living cells.
  • Applications: Development of antibiotics, cancer therapies, and environmental monitoring.

Example: Garlic

• Contains allicin, known for various therapeutic properties (antioxidant, antibacterial, antiviral).
• Used in lab activities to test its effectiveness against Bacillus cereus, a pathogenic bacterium.

Lab Activities Planned

• Activity A: Demonstrate the role of light in photosynthesis using spinach leaves.
• Activity B: Construct a food chain and identify its components.
• Activity C: Identify and label different defense strategies in plants.
• Activity D: Examine cytotoxic effects of plant compounds on bacterial cells using agar plates.
• Upcoming Assignments: Conservation poster and presentation, due next week.