Grade 12 Biology Notes PDF

Here's the clean and combined version of your Grade 12 Biology notes from \*\*Chapter 1 to Chapter 5\*\*, including the full explanation of \*\*Meiosis\*\*: \-\-- \#\#\# \*\*Chapter 1: Biology: It\'s All About You\*\* \- \*\*Global Warming and Deadly Viruses\*\*: The study of biology can help in...

Here's the clean and combined version of your Grade 12 Biology notes from \*\*Chapter 1 to Chapter 5\*\*, including the full explanation of \*\*Meiosis\*\*: \-\-- \#\#\# \*\*Chapter 1: Biology: It\'s All About You\*\* \- \*\*Global Warming and Deadly Viruses\*\*: The study of biology can help in understanding the impact of climate change on viruses and disease. \- \*\*Lesson 1.1: The Study of Life\*\* \- Biology is the study of living organisms and their interactions with the environment. \- \*\*Lesson 1.2: Importance of Studying Biology\*\* \- Understanding biology helps in solving medical, environmental, and technological problems. \- \*\*Lesson 1.3: Biology as a Science\*\* \- Biology follows scientific methods to understand living things. \- \*\*Lesson 1.4: Life and Its Beginnings\*\* \- Life started from basic molecular interactions leading to complex organisms. \- \*\*Lesson 1.5: Unifying Themes About Life\*\* \- \*\*Cell Theory\*\*: All living things are made of cells. \- \*\*Evolution\*\*: Living organisms evolve through natural selection. \- \*\*Energy\*\*: Life depends on the transfer of energy. \- \*\*Lesson 1.6: Biology Careers in the 21st Century\*\* \- Careers include biotechnology, environmental science, and medicine. \- \*\*Lesson 1.7: Twenty-First Century Biology\*\* \- Biology continues to advance in fields like genetics, genomics, and biotechnology. \-\-- \#\#\# \*\*Chapter 2: Life in a Cell\*\* \- \*\*The Cell from Hell\*\*: Some cells, such as harmful viruses or bacteria, can cause devastating effects. \- \*\*Lesson 2.1: The Cell and Its Beginning\*\* \- Life starts with cells; the building blocks of all organisms. \- \*\*Lesson 2.2: The Invisible World Through the Lens of a Microscope\*\* \- Microscopes allow us to see the tiny structures of cells. \- \*\*Lesson 2.3: Basic Cell Types\*\* \- \*\*Prokaryotic Cells\*\*: Simple, no nucleus (e.g., bacteria). \- \*\*Eukaryotic Cells\*\*: Complex, with a nucleus (e.g., plant and animal cells). \- \*\*Lesson 2.4: The Cell's Intricate Machinery\*\* \- Cells have organelles like the \*\*nucleus\*\* (control center), \*\*mitochondria\*\* (powerhouse), and \*\*ribosomes\*\* (protein synthesis). \- \*\*Lesson 2.5: Varieties of Cells in the Body\*\* \- Different cells perform specialized functions (e.g., muscle cells, nerve cells). \-\-- \#\#\# \*\*Chapter 3: Divide and Multiply (Cell Division)\*\* \- \*\*Lesson 3.1: The Cells\' Need to Divide\*\* \- \*\*Cell Division\*\* is essential for growth and repair. \- \*\*Types\*\*: \- \*\*Mitosis\*\*: Division of body cells. \- \*\*Meiosis\*\*: Division of sex cells (gametes). \- \*\*Lesson 3.2: Chromosomes\*\* \- Chromosomes are structures within the nucleus that carry DNA. \- \*\*Lesson 3.3: The Cell Cycle\*\* \- The \*\*cell cycle\*\* consists of \*\*Interphase\*\* (growth and DNA replication), \*\*Mitosis\*\*, and \*\*Cytokinesis\*\* (cytoplasmic division). \- \*\*Lesson 3.4: The Mechanism of Cell Division\*\* \- Mitosis includes \*\*Prophase, Metaphase, Anaphase, and Telophase\*\*, followed by \*\*Cytokinesis\*\*. \- \*\*Lesson 3.5: Regulation of the Cell Cycle\*\* \- Checkpoints regulate the cycle, ensuring proper division. \- \*\*Lesson 3.6: Cancer: Growing Out of Control\*\* \- \*\*Cancer\*\* occurs when cells divide uncontrollably due to mutations in genes regulating the cell cycle. \-\-- \#\#\# \*\*Chapter 4: Preparation for Next Generations (Meiosis and Reproduction)\*\* \- \*\*Lesson 4.1: The Human Life Cycle and Sexual Reproduction\*\* \- Sexual reproduction involves the fusion of \*\*gametes\*\* (sperm and egg). \- \*\*Lesson 4.2: Chromosomes and Sex Cells\*\* \- \*\*Diploid Cells\*\*: 46 chromosomes (23 pairs in humans). \- \*\*Haploid Cells\*\*: Gametes with 23 chromosomes (half the number). \- \*\*Lesson 4.3: Meiosis\*\* \- Meiosis is the process by which \*\*gametes\*\* are produced, creating genetic diversity. \#\#\#\# \*\*Phases of Meiosis\*\* \*\*Meiosis I\*\*: \- \*\*Prophase I\*\*: Chromosomes pair up (synapsis), crossing over occurs. \- \*\*Metaphase I\*\*: Homologous chromosomes align in the center. \- \*\*Anaphase I\*\*: Homologous chromosomes separate. \- \*\*Telophase I\*\*: Cells divide into two haploid cells. \*\*Meiosis II\*\* (similar to mitosis but in haploid cells): \- \*\*Prophase II\*\*: Chromosomes condense. \- \*\*Metaphase II\*\*: Chromosomes line up at the center. \- \*\*Anaphase II\*\*: Sister chromatids separate. \- \*\*Telophase II\*\*: Cells divide again, resulting in four unique haploid cells (gametes). \- \*\*Lesson 4.4: Gametogenesis\*\* \- \*\*Spermatogenesis\*\*: Production of sperm. \- \*\*Oogenesis\*\*: Production of eggs. \- \*\*Lesson 4.5: Importance of Meiosis\*\* \- Meiosis increases \*\*genetic diversity\*\* through crossing over and independent assortment. \- \*\*Lesson 4.6: Genetic Disorders Associated with Meiosis\*\* \- \*\*Non-disjunction\*\* leads to disorders like \*\*Down syndrome\*\*. \-\-- \#\#\# \*\*Chapter 5: Cells in Action (Cell Membrane and Transport)\*\* \- \*\*Lesson 5.1: The Cell and Its Environment\*\* \- The \*\*cell membrane\*\* controls the movement of substances in and out of the cell. \- \*\*Lesson 5.2: The Cell Membrane\*\* \- The \*\*fluid mosaic model\*\* describes the structure of the membrane, consisting of a phospholipid bilayer with embedded proteins. \- \*\*Lesson 5.3: Transport of Molecules Across Cell Membranes\*\* \- \*\*Passive Transport\*\*: Movement without energy. \- \*\*Diffusion\*\*: Molecules move from high to low concentration. \- \*\*Facilitated Diffusion\*\*: Transport via protein channels. \- \*\*Osmosis\*\*: Movement of water across the membrane. \- \*\*Lesson 5.4: Diffusion\*\* \- \*\*Simple Diffusion\*\*: Movement of molecules like oxygen across the membrane. \- Driven by the \*\*concentration gradient\*\*. \- \*\*Lesson 5.5: Osmosis\*\* \- Water moves through the membrane from areas of low solute concentration to high solute concentration. \- \*\*Hypertonic\*\*: Water moves out, causing the cell to shrink. \- \*\*Hypotonic\*\*: Water moves in, causing the cell to swell. \- \*\*Isotonic\*\*: Balanced movement of water. \- \*\*Lesson 5.6: Facilitated Diffusion\*\* \- Molecules move with the help of \*\*carrier proteins\*\*. \- \*\*Aquaporins\*\* help transport water across the membrane. \-\--