BT101 Midterm Merged PPT Handouts Lectures 1-75

Lecture 1 What is ecosystem

Ecosystem

Community of living organisms in conjunction of its non-living components Non-living components Interaction as a system between both components Population is group of individuals belonging to same species occupying same space in particular time. Community is group of populations occupying same space in particular time.

Control of Ecosystem

External

Climate, topography

Internal

Types of species, population size, disease, gene pool, reproduction rate. External factors are independent of internal factors.

Biome

Distinct biological communities Formed in response to specific external factors in that environment Internal factors are controlled by feedback loop

Example:

Population size is controlled by availability of resources. Ecosystem – a dynamic entity Subjected to disturbances and recovery (succession)

Flow of Energy in Ecosystem

• Living organisms can use many forms of energy, but not heat

Lecture 2

Introduction of energy dynamics in ecosystem. Use of energy by organisms. Type of useable energy

Energy

Energy exists in several different forms

1. Light
2. Chemical-bond energy
3. Motion
4. Heat

All organisms need energy to function

Principles

Energy is neither created nor destroyed in the biosphere. Organisms cannot convert heat to any of the other forms of energy. They only convert some chemical-bond or light energy to heat. Earth is an open system having constant and equal exposure to light. Plants use light energy in photosynthesis. They convert light energy into chemical bond energy. Animals use chemical bond energy to make organic molecules. Light and chemical-bond energy are partially converted to heat at every step. Heat is radiated into outer space at invisible infrared wavelengths. Earth’s incoming and outgoing flows of radiant energy must be equal for global temperature to stay constant. Concept of producers. Types of producers. Photosynthesis. Chemosynthesis

Autotrophs

Synthesis of the organic compounds of their bodies from inorganic precursors such as:

• CO2, H2O, NO3

using energy from an abiotic source

• Light
• inorganic oxidation

reactions

Types of Autotrophs

1. Photoautotrophs

Photosynthetic organisms Examples: plants, algae, and cyanobacteria Photosynthesis 6CO2 + 6H2O —> C6H12O6 + 6O2 Main input of free energy into the biosphere

2. Chemoautotrophs

Occurs in dark habitats. They obtain energy by means of inorganic oxidation reactions. Convert toxic molicules into glucose Example: Microbes, mussels

Concept of consumers. Types of consumers · • Producers · Lecture 3 · • Consumers · Lecture 4