Biology: Life and Physical Sciences - AIT's Version 7 Exam Review

Biological Systems and Organization

• Cellular Level

  • Fundamental unit of life.
  • Present in all living organisms (bacteria, fungi, protists, plants, animals).
  • Contains organelles, biomolecules, atoms, and subatomic particles.

• Tissue Level

  • Group of cells performing a unified function.
  • Example: Cardiac muscle tissue comprised of cardiac muscle cells.

• Organ Level

  • Composed of different tissues.
  • Examples: Heart, lungs, kidneys.

• Organ System Level

  • Group of organs working together.
  • Example: Digestive system (stomach, intestines, liver).

• Organism Level

  • Multiple organ systems functioning together.

Biological Hierarchy Levels

• Cell ➔ Tissue ➔ Organ ➔ Organ System ➔ Organism
• Practice Question: Correct order is cell, tissue, organ, organ system, organism.

Cell Theory

• Basic principles:
  • Cells are the fundamental unit of life.
  • All living organisms are composed of cells (unicellular or multicellular).
  • Cells arise from pre-existing cells.

Types of Cells

• Prokaryotes: Lack nucleus and membrane-bound organelles (bacteria, archaea).
• Eukaryotes: Have nucleus and membrane-bound organelles (fungi, protists, animals, plants).

Organelles and Their Functions

• Cell Membrane: Selective permeability for homeostasis.
• Cytoplasm: Jelly-like substance enveloping organelles.
• Ribosomes: Protein synthesis.
• Nucleus: Houses DNA, control center.
• Endoplasmic Reticulum (ER):
  • Rough ER: Protein synthesis.
  • Smooth ER: Lipid synthesis, detoxification.
• Golgi Apparatus: Packaging and distribution.
• Mitochondria: ATP production, "Powerhouse of the cell."
• Chloroplasts: Photosynthesis (in plants).
• Lysosomes: Digestion and waste removal.
• Vacuoles: Storage, maintaining pressure.

Cell Division: Mitosis vs. Meiosis

• Mitosis:

  • Produces two identical diploid cells.
  • Used for growth and repair.

• Meiosis:

  • Produces four genetically distinct haploid gametes (sperm and egg).
  • Two stages: Meiosis I and II.
  • Involves crossing over for genetic diversity.

Genetics and Heredity

• DNA Structure: Double helix, composed of nucleotides (A, T, C, G).
• Genes: Segments of DNA coding for traits.
• Chromosomes: DNA organized into structures.
• Regulatory Genes: Control gene expression.

RNA and Protein Synthesis

• RNA:

  • Single-stranded; types include mRNA, rRNA, tRNA.
  • Involved in protein synthesis.

• Protein Synthesis Processes:

  • Transcription: DNA to mRNA in nucleus.
  • Translation: mRNA to protein in ribosomes.

Genetic Variation

• Alleles: Different versions of a gene (dominant and recessive).
• Punnett Squares: Predict genetic outcomes.
• Monohybrid Crosses: Focus on single trait.
• Dihybrid Crosses: Involving two traits.
• Non-Mendelian Inheritance:
  • Incomplete Dominance: Blending traits.
  • Co-dominance: Both traits fully expressed.

Biomolecules

• Carbohydrates: Energy source, structure (glucose, cellulose).
• Lipids: Long-term energy storage, cell membrane structure.
• Proteins: Enzymes, structural roles, immune system.
• Nucleic Acids: Genetic information (DNA, RNA).

Infectious Agents

• Viruses: Not living, require host cells.
• Bacteria: Prokaryotic, diverse shapes and functions.
• Fungi: Eukaryotic, cell walls made of chitin.
• Protozoa: Eukaryotic, can cause diseases like malaria.
• Helminths: Parasitic worms, can cause infections.

Disease Transmission

• Direct Transmission: Physical contact or droplet spread.
• Indirect Transmission: Airborne, fomite, vector-borne.

Microscopy

• Light Microscopes: Common in classrooms, use light.
• Electron Microscopes:
  • Transmission EM: Internal structures.
  • Scanning EM: Surface structures.

This summary captures the key points and foundational concepts for the AIT's version 7 exam in life and physical sciences, particularly focused on biological systems, cell theory, genetics, infectious agents, and microscopy. Ensure to review each section thoroughly for a comprehensive understanding.