Biology Notes PDF

**Kingdom Protista** comprises diverse eukaryotic organisms with three main subgroups: 1. 2. 3. **Prokaryotic Cells**: - - - - **Eukaryotic Cells**: - - - - - 1. 2. 3. 4. 5. 6. ### **Mitosis** **Why It Occurs:\ **Mitosis is essential for growth, tissue repair,...

**Kingdom Protista** comprises diverse eukaryotic organisms with three main subgroups: 1. 2. 3. **Prokaryotic Cells**: - - - - **Eukaryotic Cells**: - - - - - 1. 2. 3. 4. 5. 6. ### **Mitosis** **Why It Occurs:\ **Mitosis is essential for growth, tissue repair, and asexual reproduction in eukaryotic cells. It ensures that two daughter cells receive identical copies of the parent cell\'s DNA. **Phases of Mitosis:** 1. 2. 3. 4. 5. a. b. c. d. 6. e. **Gametogenesis:** - - - - - - - - **Arteries**: - - **Veins**: - - **Capillaries**: - - **Heat Loss**: - - **Heat Retention**: - - **Mouth**: Chews food and begins digestion with saliva. **Esophagus**: Transports food to the stomach via peristalsis. **Stomach**: Produces acid and enzymes to digest proteins. **Small Intestine**: Absorbs nutrients into the bloodstream. **Large Intestine**: Absorbs water and forms solid waste. **Liver**: Produces bile to emulsify fats. **Pancreas**: Secretes enzymes for digestion. **Rectum/Anus**: Stores and expels waste. ### **Accessory Organs of Digestion:** 1. 2. 3. ### **pH Changes and Why:** - - ### **Leaf Structures & Functions:** 1. 2. 3. 4. 5. 6. **Parenchyma**: General metabolic functions; often stores food or water. **Collenchyma**: Provides flexible support, particularly in growing tissues. **Sclerenchyma**: Provides rigid support, with thick walls containing lignin. **Guard Cells**: Regulate the opening and closing of stomata for gas exchange. **Xylem**: Transports water and minerals from the roots to the rest of the plant. It has thick, lignified walls for structural support. **Phloem**: Transports nutrients, primarily sugars, from the leaves (where they\'re produced) to other parts of the plant. It consists of sieve tubes and companion cells. **Apical Meristem**: Found at the tips of roots and shoots. Responsible for primary growth (increasing length). **Lateral Meristem**: Located in the cambium layers (vascular and cork cambium). Responsible for secondary growth (thickness). Variation refers to differences in traits within a population. These can be genetic (due to mutations, inheritance) or environmental (due to factors like climate or diet). Variation is crucial for evolution, providing the diversity needed for natural selection to act upon. Selective pressure refers to environmental factors that influence which individuals survive and reproduce. These factors, like predators or climate, favor individuals with traits better suited to the environment, driving natural selection. Lamarck\'s theory proposed that organisms evolve through acquired traits, passing on changes made during their lifetimes. Darwin\'s theory of natural selection, in contrast, suggests that individuals with favorable traits are more likely to survive and reproduce, passing those traits on to offspring. Darwin\'s theory is widely accepted today, while Lamarck\'s is largely dismissed. **Artificial Selection**: Humans intentionally breed organisms with desirable traits. **Natural Selection**: Organisms with advantageous traits are more likely to survive and reproduce, passing on those traits. **Acquired Characteristics/Traits**: Traits gained during an organism\'s life, not genetically passed down (Lamarck\'s theory). **Allopatric Speciation**: New species form when populations are geographically isolated. **Sympatric Speciation**: New species form without geographic isolation, often due to behavioral or ecological differences.