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Understanding Life and Physical Sciences

Apr 23, 2025

AIT's Version 7 Exam: Life and Physical Sciences

Biological Systems

  • Levels of Organization
    • Cellular Level: Fundamental unit of life across all organisms.
    • Tissues: Formed by cells working together, e.g., cardiac muscle tissue.
    • Organs: Composed of tissues, e.g., heart, lungs, kidneys.
    • Organ Systems: Collaboration of organs, e.g., digestive system.
    • Organisms: Result from interconnected organ systems.
    • Additional levels: Population, community, ecosystem, biomes, biospheres.

Questions on Biological Organization

  1. Hierarchy Order: Cells → Tissues → Organs → Organ Systems → Organisms
  2. Organ Systems and Organism Relationship: Multiple organ systems work together to ensure survival.

Cell Theory and Types

  • Cell Theory Principles
    • Cells as fundamental life units.
    • Composed of cells, single (unicellular) or multiple (multicellular).
    • Cells arise from pre-existing cells.
  • Prokaryotes vs. Eukaryotes
    • Prokaryotes: No nucleus, e.g., bacteria.
    • Eukaryotes: Has nucleus, e.g., fungi, protists, animals, plants.

Organelles and Functions

  • Cell Membrane: Selective permeability; maintains homeostasis.
  • Cytoplasm: Jelly-like, supports organelles.
  • Cytoskeleton: Provides structural support and movement.
  • Ribosomes: Protein synthesis, found in both prokaryotes and eukaryotes.
  • Nucleus: Contains DNA, control center in eukaryotes.
  • Endoplasmic Reticulum (ER)
    • Rough ER: Ribosome-studded, protein synthesis.
    • Smooth ER: Lipid synthesis, detoxification.
  • Golgi Apparatus: Modifies, sorts, and packages proteins.
  • Mitochondria: ATP production through cellular respiration.
  • Chloroplasts: Photosynthesis in plant cells.
  • Lysosomes: Digestive enzymes for breaking down materials.
  • Vacuoles: Storage, more predominant in plant cells.

Mitosis vs. Meiosis

  • Mitosis
    • Somatic cell formation.
    • Results in two genetically identical diploid cells.
  • Meiosis
    • Produces gametes (sperm and egg).
    • Results in four genetically unique haploid cells.
    • Involves crossing over (genetic variation).

Phases of Mitosis and Meiosis

  • Mitosis Key Phases
    • Prophase: Chromosomes condense.
    • Metaphase: Chromosomes align at cell center.
    • Anaphase: Chromatids pulled to opposite ends.
    • Telophase: New nuclear envelopes form.
  • Meiosis (Two Rounds)
    • Prophase I: Homologous chromosomes pair, crossing over occurs.
    • Metaphase I & II: Homologous chromosomes and chromatids align.
    • Anaphase I & II: Homologous chromosomes and chromatids separate.
    • Telophase I & II: Nuclear envelopes reform, leading to cell division.

Genetics

  • DNA Structure
    • Double helix, composed of nucleotides (sugar, phosphate, base).
    • Base Pairing: Adenine-Thymine, Cytosine-Guanine.
  • Genes and Chromosomes
    • Genes as DNA segments coding for proteins.
    • Chromosomes are DNA-protein complexes.
  • Gene Expression
    • Regulatory Genes: Control expression of other genes.
    • RNA Types: mRNA (messenger), tRNA (transfer), rRNA (ribosomal).
  • Transcription and Translation
    • Transcription: DNA to mRNA.
    • Translation: mRNA to protein synthesis at ribosome.

Heredity

  • Genotype vs. Phenotype
    • Genotype: Genetic makeup (e.g., Homozygous, Heterozygous).
    • Phenotype: Physical traits and characteristics.
  • Punnett Squares
    • Tool for predicting genotypic and phenotypic outcomes.
  • Non-Mendelian Inheritance
    • Incomplete Dominance: Blending of traits.
    • Co-Dominance: Both traits expressed equally.

Biomolecules

  • Carbohydrates: Energy source, structural roles (e.g., glucose, cellulose).
  • Lipids: Long-term energy storage, membrane structure, hormones.
  • Proteins: Structural support, enzymes, immune function.
  • Nucleic Acids: Genetic information (DNA, RNA).

Infectious Agents

  • Viruses: Non-cellular, require host for replication.
  • Bacteria: Prokaryotic cells, various shapes (cocci, bacilli).
  • Fungi: Eukaryotic, reproduce via spores.
  • Protozoa: Eukaryotic, often unicellular, cause diseases like malaria.
  • Helminths: Multicellular parasites (e.g., worms).

Disease Transmission

  • Modes
    • Direct Transmission: Direct contact, droplet spread.
    • Indirect Transmission: Airborne, fomite (object), vector-borne.

Microscopy

  • Types of Microscopes
    • Light Microscope: Basic visualization.
    • Electron Microscope: High detail, internal (TEM) or surface (SEM) structures.
  • Key Concepts
    • Magnification and Resolution: Important for observing specimens.

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