9th class notes of Biology comprising of all chapters are as follows;
Biology 9th Chapter No.1 Introduction to Biology
On the 9th grade introduction to biology, students embark on an exciting journey to explore the fascinating world of life sciences. This foundational course serves as a gateway to understanding the fundamental principles that govern all living organisms. The levels of organization in biology refer to the hierarchical arrangement of living things, from the smallest building blocks to the most complex systems. At the subatomic and atomic level, matter consists of elements, and bioelements play a crucial role in forming living organisms. Introduction to Biology Full Notes
Biology 9th Chapter No.2 Solving a Biological Problem
The scientific method is a systemized approach to acquiring knowledge through observations and experiments. In biology, the method is termed the “biological method,” and it involves several key steps. The process begins with recognizing a biological problem, followed by making observations, both qualitative and quantitative. Based on these observations, a biologist formulates a hypothesis, a tentative explanation that might be true and is testable. Deductions are drawn from the hypothesis to predict expected results. Solving a Biological Problem Full Notes
Biology 9th Chapter No.3 Biodiversity
Biodiversity, the variety of organisms present in different ecosystems, is a key aspect of life on Earth. There are over 10 million kinds of organisms, but only a fraction of them have been studied and cataloged by biologists. Despite the diverse forms of life, there is a fundamental unity shared by all living organisms. Biodiversity plays a crucial role in providing food, drugs, and materials for human use, as well as regulating ecosystems and maintaining atmospheric and water chemistry. Biodiversity Full Notes
Biology 9th Chapter No.4 Cells and Tissues
Cells are the basic building blocks of life, and they are found in all living organisms. The wing of a butterfly, the shiny layer of our eyes, the meat we eat, and even everyday objects like eyelashes, fingernails, and wood are all composed of cells. In this chapter, we will explore the internal structure of cells and how they group together to form tissues. Cells and tissues Full Notes
Biology 9th Chapter No.5 Cell Cycle
The fundamental characteristic of life is reproduction, which occurs at various levels of organization. Rudolf Virchow proposed the principle that all cells come from pre-existing cells. The cell cycle consists of interphase and the mitotic phase (M phase). Interphase, comprising G1, S, and G2 phases, is a period of high metabolic activity during which the cell grows, duplicates chromosomes, and prepares for mitosis. After G2 phase, the cell enters the division phase (M phase), wherein mitosis occurs, leading to the formation of two daughter cells. Some cells may enter a quiescent state called G0 phase, halting their division temporarily or permanently. Interphase typically constitutes around 90% of the total cell cycle duration. Cell Cycle Full Notes
Biology 9th Chapter No.6 Enzymes
Metabolism is the set of biochemical reactions that sustain life in living organisms, enabling growth, reproduction, and response to the environment. It involves anabolism, where larger molecules are synthesized, and catabolism, where larger molecules are broken down, with energy released in catabolism and utilized in anabolism. Enzymes, acting as biocatalysts, play a crucial role in metabolism by speeding up and regulating the reactions. Activation energy is required for all reactions, but enzymes lower this barrier, facilitating faster reaction rates by altering substrate shape and orientation. The concept of metabolism was first introduced by Ibn-e-Nafees, recognizing the continuous changes occurring in the body and its parts. Enzymes Full Notes
Biology 9th Chapter No.7 Bioenergetics
Bioenergetics focuses on the study of energy relationships and transformations in living organisms. Organisms obtain energy by metabolizing the food they consume, where potential energy is stored in the bonds of the food. Breaking down these bonds releases kinetic energy, some of which is stored as potential energy in ATP molecules, while the rest is dissipated as heat. ATP (adenosine triphosphate) is the primary energy currency in cells and serves as the main source of energy for various cellular functions like macromolecule synthesis, movement, nerve impulses, active transport, and more. ATP’s ability to store and release energy is attributed to its molecular structure, which includes adenine, a double-ringed nitrogenous base, ribose, a five-carbon sugar, and three phosphate groups arranged linearly. Bioenergetics Full Notes
Biology 9th Chapter No.8 Nutrition
Nutrition is the process through which living organisms obtain and utilize nutrients for growth and energy. Autotrophic organisms prepare their own food using water, carbon dioxide, and minerals, while heterotrophic organisms obtain their food from other sources. In plants, mineral nutrition is essential for various activities and structures. Macronutrients, required in larger quantities, include carbon, hydrogen, oxygen, nitrogen, magnesium, and potassium, while micronutrients, needed in smaller quantities, include iron, molybdenum, boron, zinc, and others. Nutrition Full Notes
Biology 9th Chapter No.9 Transport
The xylem tissue in plants transports water and dissolved substances from roots to aerial parts, consisting of vessel elements and tracheids. Phloem tissue, on the other hand, conducts dissolved organic matter (food) between different parts of the plant, composed of sieve tube cells and companion cells. Water moves from areas of higher water potential to lower water potential, with the relationship between solute concentration and water potential being inverse. In humans, transport is carried out by the blood circulatory system and the lymphatic system. The blood circulatory system is a closed network of arteries, veins, and capillaries, containing blood plasma and blood cells. Blood plasma constitutes about 55% of blood volume, while cells make up approximately 45%. Transport Full Notes