Principles of Ecology Chapter 2

Student Performance Standards SB4. Students will assess the dependence of all organisms on one another and the flow of energy and matter within their ecosystems. – A. Investigate the relationships among organisms, populations, communities, ecosystems, and biomes. – B. Explain the flow of matter and energy through ecosystems by: Arranging components of a food chain according to energy flow. Comparing the quantity of energy in the steps of an energy pyramid. Explaining the need for cycling of major nutrients (C, O, H, N, P). – C. Relate plant adaptations, including tropisms, to the ability to survive stressful environmental conditions.

Essential Question How does energy flow and matter cycle through an ecosystem?

Chapter 2, Section 1: Organisms and Their Relationships Ecologists study different species in their natural environment. Organisms depend on living and nonliving factors in their environment for survival. Things like: – Food sources, and – Shelter Ecology is the study of how living things interact with one another and with their environment.

The Biosphere The portion of Earth that supports life. Biotic factors – the living (and once living) factors in an organisms environment. – Organisms need other organisms to reproduce. – Organisms depend on other living things for food. Abiotic factors – the non-living factors in an organisms environment that are necessary for its survival. – Temperature, air, sunlight, soil type, water, rocks, etc.

Ecosystems are Open Systems! Ecosystems are not isolated from each other. They do not have clear boundaries. Things move from one ecosystem to another. Example: A green turtle that lives off the shores of Miami, Florida swims 90 miles to an island off the coast of Cuba to lay her eggs every summer. She travels from one ecosystem to another.

Levels of Organization The biosphere is large and complex so ecologists organize living things into levels: – Organism – an individual living thing. – Species – a group of organisms that can mate to produce fertile offspring. – Population – all of the members of a species that live in the same place at the same time. – Community – groups of different species that live in the same place and interact with each other. hill.com/sites/ /student_view0/unit1/chapter2/co ncepts_in_motion.html#

ORGANISM

Ecosystem Interactions A habitat is an area where an organism lives. A habitat might be a single tree for an organism (like the bug in the picture below). Or it could be a coral reef, or a rainforest, or a desert. What other types of habitats are there?

Chapter 2, Section 2: Flow of Energy in Ecosystems Organisms cannot survive without a constant source of energy. You are a living organism. You get your energy from the foods you eat. Many of the foods you eat come from plants. Where do plants get their energy from?

Life Depends on the Sun When energy from the sun enters an ecosystem, plants use the sunlight to make sugar molecules in a process called photosynthesis: Solar energy + carbon dioxide + water = sugar molecules (called carbohydrates), and oxygen

Flour Production Wheat Products: Pizza Dough Pretzels Breads Pasta Cookies Cakes

Photosynthesis Equation: 6CO 2 6H 2 O Solar energy C 6 H 12 O 6 6O 2 carbohydrate

The Flow of Energy from Plants to Animals:

When animals eat a plant……. Some of the energy is transferred from the plant to the animal. Organisms use this energy to move, grow, and reproduce.

From Producers to Consumers A producer is an organism that makes its own food. – Also called autotrophs – organisms that collect energy from sunlight or inorganic substances to produce food. – Plants, bacteria, algae – In places where sunlight is unavailable, some bacteria use hydrogen sulfide and carbon dioxide to make organic molecules as food.

From Producers to Consumers A consumer is an organism that gets its energy from eating other organisms. – Also called heterotrophs. Clover plant > Rabbit > Coyote Name the producer. Name the consumer.

4 Types of Consumers: 1. Herbivores – consumers that eat only producers – Rabbits, sheep, cows, deer, grasshoppers, etc. 2. Carnivores – consumers that eat other consumers. (lions, hawks) 3. Omnivores – eaters of plants and animals. – Bears, pigs, cockroaches, humans 4. Detritivores – eat fragments of dead matter returning nutrients to soil, air, and water where nutrients can be reused by organisms (worms and aquatic insects). – Decomposers – similar to detritivores, are consumers that break down dead organisms by releasing digestive enzymes (fungi and bacteria).

What are Detritivores? Centipedes, woodlice, earthworms, are a few examples.

Models of Energy Flow Ecologists often use models to show the flow of energy through an ecosystem. The following models are simplified representations of the flow of energy: Food Chains Food Webs Ecological Pyramids

Food Chain

Food Web Energy flow in an ecosystem is more complex than energy flow in a simple food chain. A food web shows many feeding relationships that are possible in an ecosystem:

Ecological Pyramids An ecological pyramid is a diagram that can show the relative amounts of energy, biomass, or numbers of organisms at each trophic level in an ecosystem. – Energy Pyramid – Biomass Pyramid – Pyramid of Numbers

Energy Pyramids Times

Trophic Levels Each step through which energy is transferred is called a trophic level: – Primary – Secondary – Tertiary – Quaternary Each time energy is transferred from one organism to another, some of the energy is lost as heat and less energy is available to organisms at the next level.

Chemical Equation for Cellular Respiration: 6CO 2 6H 2 Oenergy C 6 H 12 O 6 6O 2 Cellular Respiration: Carbohydrates + oxygen = carbon dioxide + water + energy

How Energy Loss Affects an Ecosystem: The decreased amount of energy at each trophic level affects the organization of an ecosystem. – Because so much energy is lost at each level, there are fewer organisms at the higher trophic levels.

Biomass Pyramid Biomass – the total mass of living matter at each trophic level. In a pyramid of biomass, each level represents the amount of biomass consumed by the level above it.

Pyramid of Numbers