S6 - Q4 - Unit 2 Introduction: Ecosystems

Interactions, Energy, and Dynamics

            📚 Science
                            🎓 Grade 6
                                        ⏱️ 30 minutes
                    

Learning Objectives

Distinguish between biotic and abiotic factors in an ecosystem and give examples of each.
Trace the flow of energy through a food chain and explain why only about 10% of energy passes to each successive level.
Identify and describe the major types of ecological relationships: predation, mutualism, competition, parasitism, and commensalism.

            Progress
            7 sections
        

1
Unit hook and vocabulary
                            ~3 minutes                        

Unit question: How do living things depend on each other and on their nonliving surroundings to survive?

Every organism on Earth is part of an ecosystem: a community of living things interacting with each other and with the physical environment around them. In this unit, we explore how energy moves through ecosystems and how organisms shape one another's survival.

                📖
                Key vocabulary            

ecosystem - biotic factor - abiotic factor - producer - consumer - decomposer - food chain - food web - energy pyramid - predation - mutualism - competition - parasitism - commensalism

2
Biotic vs. abiotic factors
                            ~6 minutes                        

Biotic vs. Abiotic Factors

                Biotic vs. Abiotic FactorsTwo-column comparison: Biotic (living) factors on the left include plants, animals, fungi, and bacteria. Abiotic (nonliving) factors on the right include sunlight, water, soil and minerals, and temperature.Biotic (Living)PlantsAnimalsFungiBacteriaAny living organismAbiotic (Nonliving)SunlightWaterSoil / MineralsTemperatureAny nonliving factor            
Two-column diagram. Left column labeled Biotic (Living) in dark green lists: Plants, Animals, Fungi, Bacteria, with the note 'any living organism.' Right column labeled Abiotic (Nonliving) in dark blu...

Every ecosystem contains two categories of factors:

- Biotic factors are all the living components of an ecosystem: plants, animals, fungi, bacteria, and any other organism.
• Abiotic factors are the nonliving physical and chemical components: sunlight, water, soil composition, temperature, air, and pH.

Biotic and abiotic factors interact constantly. The amount of sunlight (abiotic) determines which plants can grow (biotic). Those plants then determine which animals can survive in that ecosystem. Remove any key factor and the whole system shifts.

3
Check your understanding 1
                            ~3 minutes                        

                💡
                Check your understanding 1: Biotic vs. abiotic            

Answer questions Q-6L-1 and Q-6L-2 before moving on.

Question 1

Which of the following is a biotic factor in a forest ecosystem?

The amount of rainfall each year
The temperature in January
An oak tree
The mineral content of the soil

Question 2

Producers are organisms that make their own food using energy from the Sun.

4
Energy flow through food chains
                            ~7 minutes                        

Energy Flow in a Food Chain

                Energy Flow in a Food ChainFood chain: Sun provides energy to Grass (Producer), which is eaten by a Grasshopper (Primary Consumer), which is eaten by a Frog (Secondary Consumer), which is eaten by a Hawk (Tertiary Consumer). About 10 percent of energy passes at each step; 90 percent is lost as heat.SunEnergyProducer(Grass)PrimaryConsumer(Grasshopper)SecondaryConsumer(Frog)TertiaryConsumer(Hawk)~10% of energy passes to each next level~90% is lost as heat at every step            
Horizontal food chain showing energy flowing from the Sun to Grass (Producer), then to a Grasshopper (Primary Consumer), then to a Frog (Secondary Consumer), then to a Hawk (Tertiary Consumer). Arrows...

Energy enters most ecosystems from the Sun. Here is how it moves:

- Producers (also called autotrophs) capture sunlight and convert it to food through photosynthesis. Examples: grasses, trees, algae.
• Primary consumers eat producers. Examples: grasshoppers, rabbits, deer.
• Secondary consumers eat primary consumers. Examples: frogs, foxes.
• Tertiary consumers eat secondary consumers. Examples: hawks, sharks.
• Decomposers break down dead organisms and return nutrients to the soil. Examples: fungi, bacteria.

The 10% rule: Only about 10% of the energy at one trophic level passes to the next. The rest is lost as heat. This is why food chains rarely have more than four or five levels.

5
Ecological interactions
                            ~5 minutes                        

Organisms in an ecosystem interact in several ways. The key relationships to know:

RelationshipWho benefits?Example
PredationPredator eats preyHawk eats a mouse
MutualismBoth organisms benefitBees pollinate flowers; flowers give bees nectar
CompetitionNeither benefits fullyTwo deer competing for the same territory
ParasitismParasite benefits, host is harmedTick feeding on a deer
CommensalismOne benefits, other is unaffectedBarnacles on a whale

Relationship	Who benefits?	Example
Predation	Predator eats prey	Hawk eats a mouse
Mutualism	Both organisms benefit	Bees pollinate flowers; flowers give bees nectar
Competition	Neither benefits fully	Two deer competing for the same territory
Parasitism	Parasite benefits, host is harmed	Tick feeding on a deer
Commensalism	One benefits, other is unaffected	Barnacles on a whale

These interactions shape population sizes, energy flow, and the structure of ecosystems over time.

6
Check your understanding 2
                            ~4 minutes                        

                💡
                Check your understanding 2: Energy flow and interactions            

Answer questions Q-6L-3 and Q-6L-4 before the exit ticket.

Question 3

What happens to most of the energy at each level of a food chain?

It is permanently stored in the organisms at that level
It is lost as heat and is not passed on
It doubles as it moves to the next level
It is recycled directly back to the Sun

Question 4

Match each ecological relationship with its correct description.

Predation

Mutualism

Parasitism

Competition

7
Exit ticket
                            ~2 minutes                        

                💡
                Exit ticket            

Complete Q-6L-5 and Q-6L-6 to wrap up today's lesson.

Question 5

Organisms that make their own food through photosynthesis are called ______. They occupy the first trophic level in every food chain.

Word Bank:

                                                    producers
                                                    consumers
                                                    decomposers
                                                    predators
                                            

Question 6

Bees collect nectar from flowers, and in doing so they transfer pollen that helps flowers reproduce. What type of ecological relationship is this?

Parasitism
Predation
Commensalism
Mutualism