1. Introduction to Diversity The world is home to a large variety of living organisms, visible (e.g., plants, animals, birds) and microscopic. Biodiversity: Refers to the number and variety of organisms on Earth. Known and described species: 1.7–1.8 million. New species continue to be discovered with exploration. 2. Need...
1. Introduction to Taxonomic Categories Classification Process: Involves multiple hierarchical steps. Each step represents a rank or category. Taxonomic Hierarchy: Combination of all taxonomic categories. Categories are units of classification (referred to as taxa). Example: Insects: Share common features like three pairs of jointed legs. Classified into a rank/category...
Characteristics of Living Things: Exclusive Characteristic: The ability to perceive events in the environment and retain their memory is a unique characteristic of living things. Distinguishing Feature: The ability to interact with the environment and undergo progressive evolution is a key feature that separates living organisms from non-living things. Biological Organization: The...
Biology: The study of life forms and living processes. Diversity: The living world is incredibly diverse with a vast array of organisms. Early Perceptions: Early humans differentiated between living and non-living things. They often attributed divine qualities to both inanimate objects (wind, fire) and living organisms (plants, animals). These...
Ernst Mayr: The Darwin of the 20th Century Early Life and Passion: Born in Germany in 1904. Early fascination with birds sparked his interest in biology. Defining a Species: Revolutionized the concept of a species. Defined a species as a group of interbreeding populations reproductively isolated from others. This...
Meiosis is essential for maintaining the chromosome number in sexually reproducing organisms across generations. Although it reduces the chromosome number by half, fertilization restores it, ensuring genetic stability. Additionally, meiosis introduces genetic variability through crossing over and independent assortment, leading to unique genetic combinations. These variations are crucial for evolution, as they enhance adaptability and...
Cytokinesis I is the final step of Meiosis I, where the cytoplasm divides, forming two haploid daughter cells. In animal cells, a cleavage furrow develops, which deepens and splits the cell into two. In plant cells, a cell plate forms at the center and extends outward to separate the two new cells. This process ensures that each daughter...
Overview Meiosis II is initiated immediately after cytokinesis of Meiosis I. It resembles mitosis in its process. Results in the formation of four haploid daughter cells. Phases of Meiosis II 1. Prophase II: Begins immediately after cytokinesis, often before chromosomes fully elongate. Chromosomes become compact again. Nuclear membrane disappears...
Prophase I: Longer and more complex than prophase of mitosis. Subdivided into five phases based on chromosomal behavior: Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis. 1. Leptotene: Chromosomes gradually become visible under a light microscope. Compaction of chromosomes continues throughout this stage. 2. Zygotene: Chromosomes start pairing together, a process...
Definition: Meiosis is a specialized cell division that reduces chromosome number by half, resulting in the production of haploid daughter cells from diploid cells. It ensures the production of a haploid phase in sexually reproducing organisms, while fertilization restores the diploid phase. Occurs during gametogenesis in plants and animals,...