Biology: Sustainability, Photosynthesis, and Consumers

Sustainability

• A system or process is sustainable if it can be continued indefinitely without depleting energy or materials
• Sustainable yields are a key component of forestry and fishery practices
• Harvesting trees or fish at a rate exceeding their natural growth rate is unsustainable
• Sustainable ecosystems recycle nutrients, maintain species diversity, and use solar energy sustainably

Producers and Photosynthesis

• Plants are producers and convert sunlight to chemical energy through photosynthesis
• Photosynthesis: 6CO2 + 6H2O → C6H12O6 + 6O2
• Chlorophyll absorbs light energy to split water molecules, releasing oxygen and creating glucose
• Glucose is used for plant growth, storage (starch, oils), and to form other organic molecules

Consumers

• Consumers obtain energy by consuming other organisms
• Cellular respiration breaks down glucose for energy: 6O2 + C6H12O6 → 6CO2 + 6H2O
• Only a small fraction of consumed food is converted to body tissue, the rest is used for energy or waste

Detritus Feeders and Decomposers

• Detritus is mostly cellulose, a major source of food for decomposers and detritus feeders
• Decomposers (e.g., bacteria, fungi) use oxygen to break down organic matter, releasing nutrients, water, carbon dioxide, and heat
• Termites have symbiotic relationships with microbes in their gut to digest cellulose

Food Chain and Food Web

• Food Chains represent linear flow of energy from producers to consumers
• Food Webs reflect more complex feeding relationships, where organisms can occupy multiple trophic levels

Biotic Potential vs Environmental Resistance

• Biotic Potential: the ability of populations to increase under ideal conditions
• Factors Affecting Biotic Potential:
  • Reproduction rate
  • Generation time
  • Length of reproductive period
  • Survival rates of offspring
• Environmental Resistance: factors limiting population growth
  • Predation
  • Competition
  • Parasitism and Disease
  • Lack of resources (food, water, shelter)

Carrying Capacity

• Carrying Capacity: the maximum population size a particular environment can support over a long period
• Factors Affecting Carrying Capacity:
  • Food availability
  • Water supply
  • Shelter
  • Climate
  • Predator and prey relationships

Modern Industrialized Agriculture

• Modern Agriculture relies heavily on machinery, fertilizers, pesticides, and high-yielding crop varieties
• Increased efficiency has led to increased food production but also environmental consequences
• Consequences of Modern Agriculture:
  • Reliance on fossil fuels for machinery
  • Land use change (loss of forests and wetlands)
  • Water depletion and pollution from irrigation and fertilizer runoff
  • Pest resistance to pesticides
  • Genetic erosion (loss of biodiversity)

Animal Farming and its Environmental Consequences

• Animal farming has a significant impact on land use, resource consumption, and environmental pollution
• Factory-style farming:
  • High grain consumption for livestock feed
  • Manure management issues
  • Pollution from animal waste
  • Greenhouse gas emissions (methane)

Effects of Animal Farming

• Rangeland degradation
• Loss of biodiversity
• Climate change from methane emissions
• Nutrient pollution from animal waste

Subsistence Farming

• Small-scale farming practiced for local food production and consumption
• Often relies on traditional techniques such as crop rotation and animal manure
• Can have a minimal environmental impact if practiced sustainably

Cultural Eutrophication

• Accelerated eutrophication caused by human activities
• Nutrient enrichment of water bodies due to agricultural runoff, sewage disposal, industrial waste
• Leads to algal blooms, oxygen depletion, and ecosystem degradation

This quiz covers key concepts of sustainability, the role of producers in photosynthesis, and the function of consumers in energy transfer within ecosystems. Understand how sustainable practices benefit our environment, how plants convert sunlight into energy, and how consumers derive energy from other organisms. Test your knowledge of these fundamental ecological principles.