# Lesson Notes By Weeks and Term - Senior Secondary 1

Energy transformation in nature

TERM – 2ND TERM

WEEK FIVE

Class: Senior Secondary School 1

Age: 15 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Biology

Topic: ENERGY TRANSFORMATION IN NATURE

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. Describe how energy is transformed in nature
2. State the two laws thermodynamics

iii. Discuss the applications of the two laws of thermodynamics to ecological phenomena

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS:  Videos, loud speaker, textbook, picture

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

 PRESENTATION TEACHER’S ACTIVITY STUDENT’S ACTIVITY STEP 1 INTRODUCTION The teacher explains how energy is transformed in nature Students pay attention STEP 2 EXPLANATION Teacher guide students to state the two laws of thermodynamics Students pay attention and participate STEP 3 DEMONSTRATIO N Teacher explains the applications of the two laws thermodynamics to ecological phenomena Students pay attention and participate STEP 4 NOTE TAKING The teacher writes a summarized note on the board The students copy the note in their books

NOTE

ENERGY TRANSFORMATION IN NATURE

Energy undergoes various transformations in nature. For example, sunlight is converted into chemical energy through photosynthesis in plants. This stored energy is then transferred through the food chain as organisms consume each other. Eventually, some energy dissipates as heat, contributing to Earth's overall heat budget. Additionally, natural processes like water cycle and weather patterns involve energy transformations. Understanding these transformations helps explain the dynamic balance within ecosystems.

Energy loses in the ecosystem

Energy losses occur in ecosystems through various processes. As energy moves through trophic levels in a food chain, not all of it is transferred to the next level. Energy is lost as heat during metabolic processes, such as respiration, and as organisms excrete waste. Each trophic level receives only a fraction of the energy from the level below it.

The second law of thermodynamics dictates that energy transformations are never 100% efficient, leading to entropy and energy dissipation. This is why ecosystems have a pyramid-like structure, with fewer individuals at higher trophic levels.

NOTE:  energy losses in ecosystems occur as heat, metabolic processes, and waste, contributing to the overall inefficiency of energy transfer between trophic levels.

Laws of thermodynamics

The laws of thermodynamics are fundamental principles that govern the behavior of energy in physical systems.

1. First Law of Thermodynamics (Conservation of Energy):

The first law of thermodynamics states that energy cannot be created or destroyed in an isolated system. The total energy of a system remains constant; it can only change forms. In simple terms, it's the law of conservation of energy.

Application to ecological phenomena

The first law of thermodynamics has several applications in ecological phenomena:

i. Energy Flow in Ecosystems: The law explains how energy flows through ecosystems. Solar energy is captured by plants through photosynthesis, converted into chemical energy, and then transferred to herbivores, carnivores, and decomposers in a series of trophic levels. The total energy within the system remains constant, adhering to the first law.

ii. Metabolic Processes: Organisms within ecosystems undergo metabolic processes that involve the conversion of energy from food into usable forms. The first law is evident in these processes, as the energy obtained from consuming other organisms is used for growth, reproduction, and other life-sustaining activities.

iii. Energy Budgets: The first law helps ecologists analyze energy budgets within ecosystems. By accounting for the energy inputs (e.g., sunlight) and outputs (e.g., heat, work done), researchers can understand how energy is distributed and utilized by different components of the ecosystem.

iv. Conservation of Energy in Ecological Systems: The law reinforces the concept of energy conservation in ecological systems. Understanding that the total energy content remains constant allows ecologists to track energy transformations and predict the outcomes of various ecological processes.

2. Second Law of Thermodynamics: This law has two parts:

- Entropy: The total entropy (measure of disorder or randomness) of an isolated system tends to increase over time. This implies that systems naturally move towards a state of greater disorder.

- Heat Flow: Heat energy tends to flow from hot to cold objects, and not the other way around spontaneously. This aspect relates to the irreversibility of certain processes.

Application to ecological phenomena

The second law of thermodynamics, particularly the concept of entropy, has several applications in ecological phenomena:

1. Entropy and Ecosystem Dynamics: The second law implies that natural processes tend to increase entropy, leading to greater disorder or randomness. In ecosystems, this is evident in the constant cycling of nutrients and the transformation of energy. Ecological systems evolve toward states of increased complexity and diversity, which aligns with the tendency towards higher entropy.
2. Energy Transfer Efficiency: The law underscores the limitations in energy transfer efficiency between trophic levels in food webs. As energy flows through the food chain, each transfer results in some energy being lost as heat. This inefficiency contributes to the hierarchical structure of ecosystems, where energy becomes more dispersed and disorder increases.
3. Decomposition and Nutrient Cycling: Decomposition of organic matter by microorganisms is a process driven by the second law. It involves the breakdown of complex organic compounds into simpler forms, increasing the disorder within the system. This process is essential for nutrient cycling and maintaining ecosystem function.
4. Climate and Heat Transfer: The second law influences the heat transfer processes in ecosystems. Heat tends to flow from warmer to cooler regions, influencing climate patterns and affecting the distribution of organisms within ecosystems.

EVALUATION: 1. State the first law of thermodynamics and identify 3 of it's applications to ecological phenomena

1. Stat the second law of thermodynamics and identify its applications to ecological phenomena.
2. Describe how energy is lost in the ecosystem

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively