Biology Revision Flashcards

Abiotic Factors

• Non-living components affecting ecosystems:
  • Light Intensity: Affects photosynthesis and behavior of organisms.
  • Wind Direction: Influences temperature and moisture.
  • Oxygen / CO2 Availability: Essential for respiration and photosynthesis.
  • Water Availability: Crucial for survival; limits biodiversity in droughts.
  • Temperature: Affects metabolic rates and species distribution.
  • Shelter: Provides protection and breeding sites for organisms.
  • Salinity: Affects organism health, particularly in aquatic environments.

Biotic Factors

• Living components affecting ecosystems:
  • Competition: For resources like food, shelter, and mates.
  • Predators: Impact on prey population dynamics.
  • Mates: Availability affects reproduction success.
  • Consumers: E.g., herbivores eat plants, carnivores eat other animals.
  • Food Availability: Determines population sizes.
  • Parasites: Organisms that live on others for nutrients.
  • Pathogens: Microorganisms causing diseases.
  • Pollinators: Facilitate plant reproduction.

Food Chains and Food Webs

• Food Chain: Linear sequence of organisms where each is eaten by the next.
• Food Web: Complex network showing interdependencies among species; promotes biodiversity and ecosystem stability.
• Energy flow:
  • Producers → Primary Consumers → Secondary Consumers → Tertiary Consumers
• Energy transfer efficiency is low due to losses (waste, respiration).

Biodiversity

• Definition: Variety of life forms; essential for a resilient ecosystem.
• Benefits of biodiversity:
  • More species contribute to ecosystem stability and resilience against change.
  • Forests help absorb CO2, thus regulating climate.
• Threats: Deforestation, pollution.
• Prevention: Conservation efforts, reforestation, and sustainable farming practices.

Adaptations

• Types of adaptations in organisms:
  • Morphological: Structural features (e.g., camouflage, body shapes).
  • Physiological: Internal processes (e.g., tolerance to extremes, life cycles).
  • Behaviours: Actions like migration to optimize survival.
• Example: Fennec Fox adaptations include large ears for cooling.

Quadrat Sampling

• Used in ecological studies to estimate species abundance and distribution.
  • Steps:
  • Set up a grid using measuring tapes.
  • Use random coordinates to place quadrats.
  • Count species within each quadrat.
  • Calculations:
  • Percentage Cover = \frac{\text{no. of squares covered by species}}{\text{total no. of squares in quadrat}} \times 100
  • Total Population Size = \frac{\text{total area}}{\text{area sampled}} \times \text{no. of organisms counted}

Decomposition

• Process where dead organic matter is broken down by bacteria and fungi.
• Conditions for effective decomposition:
  • Sufficient oxygen, moisture, and warm temperatures.
• Result: Nutrient-rich compost that can serve as fertilizer.

The Carbon Cycle

• Processes:
  • Photosynthesis: Plants absorb CO2 to create glucose, storing carbon.
  • Respiration: Release of CO2 through the breakdown of glucose.
  • Combustion: Burning fossil fuels releases CO2 into the atmosphere.
  • Decomposition: Returns carbon to the atmosphere from dead organisms.

The Water Cycle

• Steps of the water cycle:
  1. Evaporation: Water from various surfaces turns to vapor.
  2. Condensation: Water vapor cools and forms clouds.
  3. Precipitation: Water released from clouds in rain, snow, etc.
  4. Percolation: Water moves through soil.
  5. Transpiration: Plants release water vapor.
• Impacts of Human Activity: Deforestation disrupts transpiration leading to altered rainfall patterns.

Influence of Environmental Changes

• Environmental changes affect ecosystems:
  • Water Availability: Variations impact survival (droughts, floods).
  • Temperature: Seasonal changes can affect migration and breeding.
  • Atmospheric Gases: Fluctuations impact plant growth and respiration.

Levels of Organization in Biology

1. Cells:
   • Basic unit of life; multicellular organisms have specialized cells.
2. Tissues:
   • Groups of similar cells performing a specific function.
3. Organs:
   • Composed of tissues working together for a task.
4. Systems:
   • Groups of organs collaborating for a function.
5. Organisms:
   • Complete living entities.

Cell Structure and Function

• Key Organelles:
  • Nucleus: Stores genetic information.
  • Cell Membrane: Controls substances in/out of cell.
  • Mitochondria: Site of energy production.
  • Ribosomes: Protein synthesis.
  • Vacuoles: Storage.
  • Chloroplasts: Site of photosynthesis.
  • Cell Wall: Provides structural support (in plants).

Cell Differentiation

• Process allowing cells to become specialized for specific functions; vital for multicellular organisms.
• Examples:
  • Sperm Cells: Adapted for locomotion, contains enzymes for fertilization.
  • Root Hair Cells: Specialized for water absorption.
  • Muscle Cells: Designed for contraction and energy production.
  • Nerve Cells: Specialized for signal transmission.

Key Processes in Plants

• Transpiration: Movement of water from roots through xylem to leaves; influenced by multiple environmental factors (light, temperature, humidity).
• Translocation: Movement of sugars through phloem; requires energy for active transport.

Experimentation in Plant Water Uptake

• Potometer Experiment: Measures water uptake by tracking air bubble movement related to evaporation from leaves.

Structure of Leaves and Functions

• Upper Epidermis: Protects leaf; allows light entry.
• Wax Cuticle: Reduces water loss.
• Mesophyll: Main site for photosynthesis.
  • Palisade Mesophyll: Primarily responsible for photosynthesis.
  • Spongy Mesophyll: Allows gas exchange.
• Lower Epidermis: Controls stomatal movement for gas exchange.

Light and Electron Microscopes

• Light Microscopes:
  • Advantages: Cheaper, portable, living specimens.
  • Disadvantages: Lower magnification and resolution.
• Electron Microscopes:
  • Advantages: Higher magnification and resolution.
  • Disadvantages: Expensive, complex, samples must be dead.