IGCSE Biology Video 91 Overview

Introduction

• Focus: Comprehensive review for IGCSE Biology, aiming for Grade 9
• Offers revision guides with perfect questions and answers
• Mrs. Grant's website for additional resources

Characteristics of Living Organisms

• Features: Movement, Respiration, Sensitivity, Nutrition, Excretion, Reproduction, Growth
• Non-living organisms like viruses lack these features

Cell Biology

• Animal and Plant Cells:
  • Shared organelles: Cell membranes, cytoplasm, nucleus, ribosomes, mitochondria
  • Plant-specific organelles: Cell wall, vacuole, chloroplasts

Functions of Organelles

• Nucleus: Controls cell activities
• Cytoplasm: Site of chemical reactions
• Cell Membrane: Controls entry and exit of substances
• Ribosomes: Protein synthesis site
• Cell Wall (plants): Made of cellulose, provides support
• Vacuole: Contains cell sap, maintains structure
• Chloroplasts: Contains chlorophyll, site of photosynthesis

Types of Cells

• Prokaryotes: Bacteria and viruses, no membrane-bound organelles
• Eukaryotes: Animal and plant cells, contain membrane-bound organelles
• Bacterial Cell Structure: Cell wall, nucleoid, plasmids, flagella
• Viruses: Non-living, pathogenic, simple structure

Microorganisms

• Pathogenic vs. Non-pathogenic Bacteria:
  • Pathogenic examples: Pneumococcus, tuberculosis
  • Useful bacteria: Lactobacillus bulgaricus
• Viruses: Always pathogenic, e.g., flu, HIV

Protists

• Algae, Chlorella: More plant-like
• Amoeba: More animal-like
• Plasmodium: Pathogenic, causes malaria

Fungi

• Structure similar to plant cells but with chitin cell walls
• Nutrition: Saprotrophic, extracellular digestion

Biological Classification

• Five Kingdoms: Plants, Animals, Protists, Bacteria, Fungi
• Carbohydrate storage varies: Glycogen in animals and fungi, starch in plants

Organization of Life

• Definitions:
  • Cell: Group of organelles
  • Tissue: Group of cells
  • Organ: Group of tissues
  • Organ System: Group of organs
  • Organism: Group of organ systems
• Human Organ Systems: Digestive, endocrine, reproductive, etc.

Enzymes

• Biological catalysts, speed up reactions
• Enzyme-substrate complex
• Digestive Enzymes:
  • Amylase: Starch to glucose
  • Protease: Proteins to amino acids
  • Lipase: Lipids to fatty acids and glycerol

Enzyme Activity

• Factors affecting activity:
  • Temperature: Optimum around 37°C, denatures at high temps
  • pH: Varies per enzyme, enzymes denature at extreme pH

Transport Mechanisms

• Diffusion: Movement from high to low concentration
• Osmosis: Movement of water, requires partially permeable membrane
• Active Transport: Movement from low to high concentration, requires energy

Plant Biology

• Photosynthesis:
  • Equation: CO2 + H2O → Glucose + O2
  • Limiting Factors: Light, CO2, temperature
• Leaf Structure: Adaptations for photosynthesis, layers such as waxy cuticle, epidermis

Nutrition

• Mineral Ions:
  • Nitrates: Protein synthesis
  • Magnesium: Chlorophyll production
• Deficiency Symptoms: Stunted growth, yellow leaves

Human Nutrition

• Balanced Diet: Carbohydrates, proteins, fats, vitamins, minerals, water, fiber
• Deficiency Diseases:
  • Kwashiorkor (protein), scurvy (vitamin C), rickets (vitamin D)

Respiration

• Aerobic Respiration:
  • Equation: Glucose + O2 → CO2 + H2O + Energy
• Anaerobic Respiration:
  • Produces lactate in muscles, ethanol in yeast

Circulatory System

• Heart and Blood Vessels:
  • Heart function: Double circulatory system
  • Blood vessels: Arteries, veins, capillaries
• Blood Components: Red blood cells, white blood cells, plasma, platelets

Excretion and Homeostasis

• Excretion in Humans: Sweat, urea, CO2
• Homeostasis: Maintaining internal environment

Coordination and Response

• Nervous System: Fast, localized, short-lived responses
• Endocrine System: Slow, widespread, long-lived responses

Reproduction

• Sexual vs. Asexual Reproduction: Genetic variation vs. clones
• Human Reproductive Systems: Structures and functions

Genetics

• Definitions: Gene, allele, genotype, phenotype
• Genetic Crosses: Punnett squares, pedigree analysis

Evolution and Natural Selection

• Darwin's Theory: Variation, survival of the fittest
• Antibiotic Resistance in Bacteria: Example of natural selection

Ecology

• Ecosystem Definitions: Population, community, habitat
• Food Chains and Webs: Producers, consumers, decomposers

Human Impact on Environment

• Eutrophication: Fertilizers causing aquatic ecosystem damage
• Greenhouse Effect: Greenhouse gases leading to global warming
• Acid Rain: From sulfur and nitrogen oxides

Use of Biological Resources

• Greenhouses: Controlled environments for crop yield
• Pesticides vs. Biological Control: Pros and cons

Genetic Engineering

• Insulin Production: Bacterial plasmids, recombinant DNA
• GM Crops: Traits like frost resistance, longer shelf life
• Transgenic Organisms: Genes transferred between species

This summary captures the essence of the lecture and can be used as a study guide to reinforce the important topics covered in IGCSE Biology.