InteractionsSubtitle

Introduction

• All organisms need energy to sustain life. Each activity that organisms do in ecosystems requires energy.

• Plants, some kind of bacteria, and algae are capable of converting energy from the sun into chemical energy and store it as food. This group of organisms is called producer. The process is called photosynthesis, it uses H2O, CO2 and sunlight.

• Plants excess glucose is converted into starch and is stored in their body.

• People and organisms eat plants , and chemical energy from food is transferred to their bodies. Organisms that consume food for their energy supply are called consumers.

• Scientists assigned organisms in ecosystem to a specific level called the Trophic level.

• Energy moves from one trophic level to another. This means that energy flows from one organism to another organism

Trophic Structure

Energy transfer within an ecosystem, represented by a pyramid diagram

• At each trophic level, some energy is available as food for the next level

• Each level decreases in size, 90% of energy lost through life processes-respiration, movement and excretion

• Only 10% available as food, number of living organisms decreases as trophic levels increase

• Producers/autotrophs - first layer, produce their own food through photosynthesis(green plants)

• Primary consumers -eat the producers(herbivores)

• Secondary consumers - consume the herbivores(carnivores)

• Tertiary consumers - top predators that eat secondary consumers

Activity 1 – How do you identify the component of a food chain in an ecosystem?

• Q1. What are the organisms found in the surrounding area of Monfort Bat Cave?

• Answer: Plants – durian trees, other trees

• Animals – bats, crows, rats, pythons, monitors lizards, dogs, cats

• Q2. What groups of organisms are considered producers?

• Answer: The durian trees and other trees are the producers, providing food for the bats.

• Q3. What part of the durian trees and other trees served as food for the bats?

• Answer: Nectar and fruits served as food for the bats.

• Q4. The population of cave-dwelling bats is declining because they are being eaten by other organisms. What are these organisms that feed on bats?

• Answer: Crows, rats, python, monitor lizards, cats, dogs, humans are organisms that feed on bats.

• Q5. Among the organisms that feed on bats, are there organisms that possibly feed on the predators of bats?

• Answer: Yes

• Q6. Categories of organisms living in Monfort Bat Cave

• Producers – Durian trees, Other trees

• 1st Order Consumer – bats

• 2nd Order Consumer – crows, rats, python, monitor lizard, cats, dogs, humans

Food Chain

• Energy from the sun Durian Tree Bats Python

• Food chain shows the flow of energy from one organism to another.

• In most ecosystem, energy does not follow simple straight paths because individual animals often feed at several trophic levels.

Food Chain• A food chain is a transfer of energy from the sun in

sequence, for example, from green plants (convert energy from the sun into chemical energy), to animals that eat plants, to animals that eat other animals. The feeding of one organism, upon another in a series of energy transfers is known as a food chain.

• Biomass or energy

• Decomposers act on dead organisms and change these into simple nutrients which plants can use again.

Interconnected food chains comprise this simplified food web in a forest. Many organisms, excluding the decomposers, such as bacteria and fungi are not shown in this food web.

In marine environment, food chains begin with microscopic algae called phytoplankton. Zooplankton eat algae, in turn are eaten by small fishes, crustaceans and a variety of sea animals

The food web shows decomposing the decomposers consisting of bacteria and fungi.Without decomposers, will producers and consumers stay alive? Why?Without producers, will consumers stay alive? Why?

Activity 2 – Making Food Webs

• Think of the food your family ate for supper last night. Make a food web based on your meal. Remember , your food web must have producers, consumers and decomposers.

• Q1. To which group of organisms do you belong?

• Answer: Consumer

• Q2. Which trophic level do you occupy?

• Answer: Definitely, humans occupy the top trophic level in the food web.

• Q3. Which group of animals has the greatest biomass? Which has the greatest energy?

• Answer: The producers, plankton that are producers– greatest biomass and energy

• Q4. Which group of organisms has the least biomass? Which has the least energy?

• Answer: The top consumer, humans have the least biomass and energy.

• Q5. What happens to the amount of biomass from the bottom to the top of the pyramid?

• Answer: The amount of biomass decreases at each succeeding level from the bottom to the top of the pyramid.

Food Web• A food web shows the complex feeding

interrelationships between organisms in an area. It consists of interconnected food chains.

• A food chain or food web can be arranged in the form of a pyramid. A pyramid of biomass shows the decreasing amount of matter or tissue while an energy pyramid depicts the decreasing amount of energy. The greatest amount of biomass or energy is at the base of the pyramid. The amount of biomass or energy decreases towards the top.

• While matter is recycled in ecosystems, energy flows only in one direction 1st order from producer to consumer to 2nd order consumer.

• People are the top consumers in many food webs. To increase food production, they use methods which may disrupt food chains or food webs. They have to learn how to make decisions to correct these mistakes.

Biomass and Energy

• Biomass is the total mass of organisms in a food chain or food web. Not all plants and animals at one level are eaten by organisms at the next level. Some parts of plants or animals are not edible. Only about 10 % of biomass and energy are being transferred to the next level. 90% of energy and biomass consumed by the previous level.

Activity 3 – Meat Eaters vs. Plant Eaters

•Q1. How much biomass of chicken can 5000 kg of corn support?

• Answer: 500 kg

•Q2. How much biomass of humans can the chickens support?

• Answer: 50 kg

• Q3. How much biomass of humans can 5000 kg of corn support?

• Answer: 500 kg

• Q4. Which is more efficient in converting biomass of producers to biomass of consumers – plant eater or a meat eater? Give an explanation.

• Answer: Plant eater, the same biomass of producers (corn) can support a greater biomass of consumers (humans) than if one were an animal. If each person has a mass of 50 kg; 5000 kg of corn can support 10 plant eaters with a total mass of 500 kg and only 1 meal eats with mass of 50 kg.

• Q5. What gas do plants produce that animals use?

• Answer: Oxygen

• Q6. What gas do animals produce that plants use?

• Answer: Carbon Dioxide

• Q7. Describe one way by which the following practices may disrupt a food chain or food web

a) monoculture

b) use of insecticides

c) use of fertilizers

Definition

• Monoculture - practice of growing just one crop: the practice of growing a single crop in a field or larger area.

• Insecticide - insect poison: a chemical substance used to kill insects.

• Herbicide – weedkillers : chemical substance for killing unwanted plants: a chemical preparation designed to kill plants, especially weeds, or to inhibit their growth.

• Pesticide - The chemical agents called pesticides include herbicides (for weed control), insecticides, and fungicides.

• Fertilizers- natural or synthetic chemical substance or mixture used to enrich soil so as to promote plant growth.

• Monoculture – deprive many animals of their food and home. When land is converted to (for example) rice farms, sugar farms and coconut farms, animals move to other places. Insects who only eat monocrops remain in the area. Some soil microorganisms depend on specific plants for food, without it cycling of nutrients is disturbed

• Herbicides and Insecticides – destroy other organisms including beneficial insects and soil microorganisms which help in decay. Insecticides move up the pyramid and accumulate in the body of organisms. The greatest concentration is found in the top consumers.

• Chemical Fertilizers – Continuous and uncontrolled use may increase soil acidity, destroying soil structure. Fertilizers may run off to rivers, ponds and lakes, which may cause death to these bodies of water. Fertilizers will increase growth of algae and other water plants. They cover water’s surface and block the passage of oxygen, which will lead to the death of fishes and other aquatic animals

10 item exam•5 points Explain the Water Cycle

•5 points Explain the Nitrogen Cycle