Biology

Lesson 1: Definition and Scope of Ecology

🌱 Ecology – Definition
 Ecology is the study of relationships between organisms and their environment.
 It looks at:
o Living things (biotic factors) → e.g., animals, plants, microorganisms.

o Non-living things (abiotic factors) → e.g., soil, temperature, water, light.

 Example: A butterfly visiting a flower for nectar.

🌍 Scope of Ecology
Biological Spectrum / Hierarchy of Life (PCTOOOPCEB)
Think of it as levels of organization in biology:
1. Particle (atoms, molecules)
2. Cell
3. Tissue
4. Organ
5. Organ system
6. Organism
7. Population
8. Community
9. Ecosystem → basic unit of ecology (living + nonliving interactions)
10.Biosphere → largest level, all ecosystems on Earth
⚠️Note: Sequence cannot be rearranged; each level depends on the other.

🔑 Key Points
 Ecosystem: Interactions between organisms and their environment (includes population,
community, habitat, and abiotic factors).
 Biosphere: Global realm of life; captures and stores solar energy to sustain life.
 Interdependence: No organism lives completely alone; all rely on each other and their
environment.

📝 Sample Test Prep

Test 1: Matching Type
Match terms with correct descriptions (examples):
 Population → group of same species in one area
 Community → different species living together
 Ecosystem → living + nonliving interactions
 Biosphere → all life on Earth
Test 2: Practice Questions
1. Define ecology in your own words (3 sentences).
o Ecology is the study of how living things interact with each other and their
environment.
o It involves both living and nonliving factors.

o These interactions are important for survival and balance in nature.

2. Draw the Biological Spectrum (PCTOOOPCEB) from smallest to largest. Show arrows to
indicate connection.

Lesson 2: Ecosystems

🌍 The Ecosystem
 The biosphere is the part of Earth where life exists:
o Atmosphere → air

o Hydrosphere → water

o Lithosphere → land

 Ecosystem = all living (biotic) and nonliving (abiotic) things in a given area + their
interactions.
🌱 Examples of Ecosystems
1. Aquarium – plants, fish, snails, sand, pebbles, water, caretaker
2. Grassland – grass, earthworms, insects, bacteria, soil, sunlight, water
3. Pond – aquatic plants, animals, and environmental factors
4. Forest – trees, soil, rain, decomposed leaves, animals, etc.
5. Earth as a whole can also be viewed as one big ecosystem.

🔑 Components of an Ecosystem
1. Biotic (Living)
 Plants, animals, fungi, bacteria
2. Abiotic (Non-living)
 Soil, substratum, light, rainfall, nutrients, temperature, water
👉 Both are essential for balance and survival.

🌱 Roles of Biotic Components

Producers (Autotrophs)
 Green plants, phytoplankton
 Make food through photosynthesis (CO₂ + H₂O + sunlight → glucose + O₂)
 Convert inorganic → organic matter (proteins, fats, carbs)
 Form the base of the food chain
Consumers (Heterotrophs)
 Depend on producers or other consumers for food
 Types:
o Herbivores – plant eaters

o Carnivores – animal eaters

o Omnivores – eat both (e.g., humans)

 Release CO₂ + H₂O during respiration, which plants reuse

Decomposers (Bacteria & Fungi)
 Feed on dead plants & animals
 Break down materials → recycle nutrients to soil and environment
 Called the “janitors of nature”
 Without them, ecosystems would not recycle matter

📝 Sample Test Prep

1. Define an ecosystem.
o An ecosystem is the interaction of living and nonliving things in a specific area.

2. Give two examples of ecosystems and explain their interactions.

 Pond Ecosystem: Aquatic plants like algae provide food and oxygen for fish and snails.
Animals use the water and also release waste, which decomposers break down to recycle
nutrients.
 Forest Ecosystem: Trees provide shelter and food for animals, while dead leaves decompose to
enrich the soil. Animals like birds and insects help in pollination and seed dispersal, keeping the
forest balanced.

3. Differentiate producers, consumers, and decomposers.

 Producers (Autotrophs): Make their own food through photosynthesis (e.g., green
plants, phytoplankton).
  Consumers (Heterotrophs): Depend on other organisms for food (herbivores,
carnivores, omnivores).
 Decomposers: Break down dead organisms and return nutrients to the soil
(bacteria, fungi).
4. Explain why decomposers are important in the ecosystem.
 Decomposers are important because they recycle nutrients back into the
environment. Without them, dead plants and animals would pile up and soil would
lose fertility. By breaking down organic matter, decomposers make nutrients
available again for plants, which supports the entire food chain.

Lesson 3: Effects of Abiotic Factors

🌱 Abiotic Factors in Ecosystems

Abiotic = non-living environmental factors that influence living organisms.
Main factors: Soil, Water, Light, Temperature, Wind

🟤 Soil
 Definition: Upper layer of Earth’s crust affected by plants and animals.
 Composition: Rock particles + humus (decayed organic matter) + roots, bacteria,
earthworms.
 Importance:
o Habitat for organisms

o Anchors plants, prevents erosion

o Provides water & nutrients (organic & inorganic)

o Supplies air for roots & decomposers

💧 Water
 In Plants:
o 40–60% of trees, ~90% of herbaceous plants

o Maintains metabolism (protoplasm), structural support (turgor pressure)

o Transports nutrients, cools environment via transpiration

 In Animals:
o ~70% of body composition

o Functions in cooling, circulation, structural support

 Water Loss Effects:

o Overheating, blood thickening, waste buildup, slower metabolism

 Adaptations in Desert Animals:

o Get water from plants, large ears to release heat, burrowing to avoid evaporation

☀️Light
 Role: Main energy source for ecosystems; affects both plants & animals
  Effects on Plants:
o Needed for photosynthesis

o Influences flowering (photoperiodism):

 Short-day plants (e.g., tobacco, chrysanthemum)

 Long-day plants (e.g., sunflower, daisy)
o Light penetration in water limits plant growth (phytoplankton near surface)

 Indirect Effects:
o Animals depend on plants for food

o Vitamin D production in animals under UV light

o Bird migration triggered by changing day length

Temperature
 Importance: Affects metabolism, water balance, and survival range (0°C–50°C for most
organisms)
 Plants:
o High temp + low water → wilting, enzyme failure

o Adaptations: thick bark, cuticle, small leaves

o Low temp → physiological drought (roots can’t absorb water)

o Cold adaptations: creeping growth, cushion plants, hairy stems (Arctic poppy)

 Animals:
o Warm-blooded (homeothermic): Birds & mammals regulate body temp (fat, fur,
sweating, panting)
o Cold-blooded (poikilothermic): Fish, reptiles, amphibians rely on environment
(basking, hiding)
 Risk: Above 45°C → protein damage → death (land: dehydration; water: oxygen shortage)

💨 Wind
 Direct Effects on Plants:
o Can uproot plants, break branches, restrict growth → plants grow shorter in windy
areas
 Reproductive Role:
o Pollination and seed dispersal by wind

📝 Practice Question (½ crosswise, 5 pts each)

Q: Discuss the effects of abiotic factors that make up the ecosystem to living organisms.
A (Key Points):
 Soil: Provides nutrients, water, habitat, and anchorage for plants.
 Water: Essential for metabolism, structure, transport, cooling in plants and animals.
 Light: Enables photosynthesis, controls flowering, affects animal behavior (migration,
Vitamin D).
 Temperature: Regulates metabolism; influences adaptations; extremes cause stress or
death.
 Wind: Can damage plants but helps in pollination and seed dispersal.