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➻Endothermic and exothermic reactions are two types of chemical reactions that differ primarily in the flow of energy, particularly heat. 👉 Endothermic Reactions - Definition: An endothermic reaction is a chemical reaction that absorbs heat from its surroundings. This results in a decrease in temperature in the surrounding environment. - Characteristics:   - Requires energy input (often in the form of heat) to proceed.   - The enthalpy change (ΔH) is positive. - Examples:   - Photosynthesis: Plants absorb sunlight to convert carbon dioxide and water into glucose and oxygen.   - Dissolving ammonium nitrate in water: This process absorbs heat and feels cold to the touch. 👉 Exothermic Reactions - Definition: An exothermic reaction is a chemical reaction that releases heat to its surroundings, leading to an increase in temperature in the surrounding environment. - Characteristics:   - Releases energy (usually in the form of heat) during the reaction.   - The enthalpy change (ΔH) is negative. - Examples:   - Combustion of fuels: Burning wood or gasoline releases heat and light.   - Cellular respiration: The process by which cells convert glucose and oxygen into carbon dioxide, water, and energy. #grade10 @knowledgebach9

Biochemical molecules 👉Biochemical molecules are essential components of living organisms and play crucial roles in biological processes. They can be categorized into four main types: carbohydrates, lipids, proteins, and nucleic acids. Here's a brief overview of each: 👉 1. Carbohydrates - Structure: Composed of carbon (C), hydrogen (H), and oxygen (O) in a ratio of approximately 1:2:1. - Function: Serve as energy sources, structural components, and cell recognition molecules. - Types:   - Monosaccharides: Simple sugars like glucose and fructose.   - Disaccharides: Two monosaccharides linked together, such as sucrose (table sugar).   - Polysaccharides: Long chains of monosaccharides, such as starch, glycogen, and cellulose. 👉 2. Lipids - Structure: Diverse group of hydrophobic molecules primarily composed of carbon and hydrogen. - Function: Store energy, form cell membranes, and serve as signaling molecules. - Types:   - Fats and Oils: Triglycerides made from glycerol and fatty acids.   - Phospholipids: Major components of cell membranes, consisting of two fatty acids and a phosphate group attached to a glycerol backbone.   - Steroids: Hormones like cholesterol and testosterone. 👉3. Proteins - Structure: Composed of amino acids linked by peptide bonds. There are 20 different amino acids that can combine in various sequences. - Function: Perform a wide range of functions including catalyzing reactions (enzymes), transporting molecules, providing structural support, and facilitating communication within and between cells. - Levels of Structure:   - Primary: Sequence of amino acids.   - Secondary: Local folding into structures like alpha-helices and beta-sheets.   - Tertiary: Overall three-dimensional shape.   - Quaternary: Complexes formed by multiple polypeptide chains. 👉 4. Nucleic Acids - Structure: Composed of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base. - Function: Store and transmit genetic information. - Types:   - DNA (Deoxyribonucleic Acid): Double-stranded molecule that carries genetic instructions for development and functioning.   - RNA (Ribonucleic Acid): Single-stranded molecule involved in protein synthesis and regulation of gene expression. 👉 Importance of Biochemical Molecules Biochemical molecules are vital for life as they participate in virtually every cellular process. They are involved in metabolism, cell signaling, immune responses, and the replication of genetic material. Understanding these molecules is fundamental to fields such as biochemistry, molecular biology, and medicine. #grade10 @knowledgebach9

ካርል ማርከስ ከመሞቱ ትንሽ ቀናት በፊት ታሞ የአልጋ ቁራኛ በነበረበት ጊዜ አንዷ የቤት ሰራተኛው ወደአልጋው ጠጋ በማለት "ለትውልድ የመጨረሻ ቃል ማስቀመጥ ትፈልጋለህ?" ብላ ጠየቀችው። ማርክስ እንዲህ ሲል መለሰ `` ከዚህ ለቀሽ ውጪ! በህይወታቸው ፈሪነታቸው ያደደባቸው ብቻ ናቸው የመጨረሻ ቃል የሚናገሩት `` ካርል ማርከስ ፈላስፋ፣ የፖለቲካ ኢኮኖሚ ተቺ፣ የታሪክ ተመራማሪ፣ Social researcher፣ Political activist፣ ጋዜጠኛ እና የጀርመን ሶሻሊስት አብዮተኛ ሰው ነበር..። `` የሰው ልጅ ታሪክ የምግብ ፍለጋ ታሪክ ነው..`` -Karl marx @knowledgebach9