BIOLOGY Q1

1. Introduction to Biology

• Biology: Study of living things and their vital processes.

1.1 Branches of Biology

• Botany: Study of plants.

• Zoology: Study of animals.

• Anatomy & Physiology: Study of body structures & functions.

• Genetics: Study of genes & heredity.

• Ecology: Study of relationships between organisms and their environment.

• Microbiology: Study of microscopic organisms.

• Cytology: Study of individual cells.

• Histology: Study of tissues.

1.2 Characteristics of Life

• Organized in a hierarchical pattern.

• Ability to reproduce, grow, and develop.

• Requires and processes energy (metabolism).

  • Autotrophs: Produce their own food (e.g., photosynthesis).

  • Heterotrophs: Consume other organisms for energy.

• Regulates internal processes (homeostasis).

• Responds to stimuli.

• Adapts and evolves over generations (natural selection).

2. The Cell Theory

• Cells: Basic unit of life.

• Key Contributors:

  • Robert Hooke: Coined the term “cell”.

  • Anton van Leeuwenhoek: First to observe live cells.

  • Rudolf Virchow: “Omnis cellula e cellula” (all cells come from pre-existing cells).

  • Matthias Schleiden: Focused on plant cells.

  • Theodore Schwann: Focused on animal cells.

2.2 Modern Cell Theory

• All living things are made up of cells.

• Cells are the basic unit of life.

• Cells come from pre-existing cells.

3.0 Cell Structure

• Prokaryotic Cells: No nuclear membrane, simpler structure.

• Eukaryotic Cells: With nuclear membrane, more complex.

3.1 Parts of a Eukaryotic Cell

• Organelles: Internal parts of a cell.

  • Cell Membrane: Controls passage of materials.

  • Cytoplasm: Surrounds organelles.

  • Mitochondria: Powerhouse of the cell.

  • Vacuole: Stores food & water.

  • Nucleus: Control center containing DNA.

  • Ribosomes: Site of protein synthesis.

  • Endoplasmic Reticulum: Protein and lipid production.

  • Golgi Apparatus: Modifies and packages proteins and lipids.

  • Flagella/Cilia: Involved in locomotion.

3.2 Animal vs. Plant Cells

• Animal Cells: Have centrioles and lysosomes.

• Plant Cells: Have cell walls and plastids (e.g., chloroplasts).

3.3 Cell Differentiation

• Process by which cells change their function or type.

4. The Cell Membrane

• Structure: Phospholipid bilayer with proteins and carbohydrates.

• Models: Fluid mosaic model.

4.1 Cell Transport Mechanisms

• Passive Transport: No energy required (e.g., diffusion, osmosis).

• Active Transport: Requires energy (e.g., ATP).

5. Cell Cycle: Mitosis

• Phases: Prophase, Metaphase, Anaphase, Telophase.

• Control: Regulated by internal and external factors.

6. Cell Cycle: Meiosis

• Meiosis I & II: Produces four haploid daughter cells.

• Significance: Genetic variation and gamete production.

6.1 Genetic Disorders & Chromosomal Errors

• Karyotyping: Analyzing chromosome structure.

• Non-disjunction: Failure of chromosomes to separate properly.