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Linux fundamentals Operating System It is a middle man between user and hardware to communicate with device.      2. kernal Core of OS It manages memory, give tasks to CPU, controls hardware.      3.Shell Interface(Bridge between user and kernal) Types:-  CLI(Command Line Interface):- Terminal GUI(Graphical User Interface):- Normal Windows Note:- User -> Shell -> Kernal -> hardware

This is a python code to scan the system and print the username working directory, ip  address of user's device. Code import subprocess user = subprocess . run ([ "whoami" ], capture_output = True , text = True ) dire = subprocess . run ([ "pwd" ], capture_output = True , text = True ) username = subprocess . run ([ "uname" , "-r" ], capture_output = True , text = True ) ipad = subprocess . run ([ "ip" , "a" ], capture_output = True , text = True ) o1 = user . stdout o2 = dire . stdout o3 = username . stdout print ( f "Username: { o1 } " ) print ( f "Directory: { o2 } " ) print ( f "Kernel Version: { o3 } " ) o4 = ipad . stdout lines = o4 . splitlines () for line in lines :     if "inet" in line and "scope global" in line :         ip_address = line . strip (). split ()[ 1 ]. split ( "/" )[ 0 ]         print ( f "IP Address: { ip_address } " )...

 DNA What is DNA? DNA ( Deoxyribonucleic Acid ) is the genetic material that carries hereditary information in almost all organisms. The concept of DNA as genetic material was proven by experiments like that of Oswald Avery and Hershey and Chase . Structure of DNA Proposed by James Watson and Francis Crick (1953): DNA has a double helix structure Made of two polynucleotide chains Backbone: sugar (deoxyribose) + phosphate Nitrogen bases: Purines: Adenine (A), Guanine (G) Pyrimidines: Thymine (T), Cytosine (C) Base pairing (Chargaff’s rule) : A = T (2 hydrogen bonds) G ≡ C (3 hydrogen bonds) Strands are antiparallel (5’ → 3’ and 3’ → 5’) Components of DNA Each nucleotide consists of: Nitrogenous base Pentose sugar Phosphate group Functions of DNA Stores genetic information Controls protein synthesis Transfers hereditary traits Regulates cell activities DNA Replication Occurs in S-phase of cell cycle Semi-conservative ...

Code # Writing a program to print the sum of the series 1+(1+2)+(1+2+3)....(1+2+3+n). import math n = int ( input ( "Enter value of n you want to find the sum of the series:- " )) b = 0 for i in range ( 1 , n + 1 ):     for j in range ( 1 , i + 1 ):                 b = b + j print ( b )

Hybridisation 1.What is Hybridisation? Hybridisation is the mixing of atomic orbitals of similar energy (like s, p, d) to form new equivalent orbitals called hybrid orbitals . This concept was introduced by Linus Pauling to explain molecular shapes 2.Why is Hybridisation Needed? Without hybridisation: Orbitals have different shapes and energies Bond angles and molecular geometry cannot be explained properly   Hybridisation helps explain: Shape of molecules Bond angles Bond formation  Types of Hybridisation 1. sp Hybridisation Mixing: 1 s + 1 p Number of hybrid orbitals: 2 Geometry: Linear Bond angle: 180°   Example : BeCl₂ CO₂ 2. sp² Hybridisation Mixing: 1 s + 2 p Number of hybrid orbitals: 3 Geometry: Trigonal planar Bond angle: 120° Example : BF₃ Ethene (C₂H₄) 3. sp³ Hybridisation Mixing: 1 s + 3 p Number of hybrid orbitals: 4 Geometry: Tetrahedral Bond angle: 109.5° Example : CH...

BREATHING AND EXCHANGE OF GASES 1. The Human Respiratory System The pathway starts at the External Nostrils and ends at the Alveoli , which are the primary sites of gas exchange. Conducting Part: From nostrils to terminal bronchioles. It humidifies the air, brings it to body temperature, and filters out foreign particles. Respiratory Part: The Alveoli and their ducts. This is where the actual exchange of gases occurs between the air and the blood. 2. Mechanism of Breathing Breathing involves two stages: Inspiration (active) and Expiration (passive during normal breathing). This relies on a pressure gradient between the lungs and the atmosphere. Inspiration: The Diaphragm contracts (moves down) and External Intercostal Muscles lift the ribs. This increases the thoracic volume, lowers the intra-pulmonary pressure, and air rushes in. Expiration: Muscles relax, the diaphragm moves up, thoracic volume decreases, pressure increases, and air is pushed out. 3. Respiratory Volumes (The...

PHOTOSYNTHESIS IN HIGHER  PLANTS The Basics: Where and How? Site: Mesophyll cells in leaves contain Chloroplasts . Pigments: Chlorophyll a (the main pigment), Chlorophyll b , Xanthophylls, and Carotenoids. Equation: $$6CO_2 + 12H_2O \xrightarrow{\text{Light}} C_6H_{12}O_6 + 6H_2O + 6O_2$$ 1. The Light-Dependent Reaction (Photochemical Phase) This happens in the Thylakoids (Grana) . It requires direct sunlight to produce high-energy intermediates: ATP and NADPH . Key Steps: Light Absorption: Chlorophyll absorbs light at specific wavelengths (Absorption Spectrum). Water Splitting (Photolysis): Water is broken down into protons, electrons, and oxygen. This is the source of the oxygen we breathe! Photophosphorylation: The process of creating ATP using light. Non-Cyclic (Z-Scheme): Involves both PS II and PS I. It produces both ATP and NADPH. Cyclic: Involves only PS I. It produces only ATP. 2. The Light-Independent Reaction (Biosynthetic Phase) Commonly called the Dark Reactio...

THE CELL CYCLE  An Overview The cell cycle is the sequence of events where a cell duplicates its genome, synthesizes other constituents, and eventually divides into two daughter cells. 1. Interphase (The Preparation Phase) This is the "quiet" phase where the cell grows. It actually accounts for 95% of the total duration of the cell cycle. G1 Phase (Gap 1): The cell is metabolically active and grows continuously but does not replicate its DNA. S Phase (Synthesis): DNA replication occurs. The amount of DNA per cell doubles (from $2C$ to $4C$ ), but the chromosome number remains the same. G2 Phase (Gap 2): Proteins are synthesized in preparation for mitosis while cell growth continues. G0 Phase (Quiescent Stage): Cells that do not divide further exit G1 and enter an inactive stage (e.g., heart cells or nerve cells). 2. M Phase (Mitosis) This is the most dramatic period, involving a complete reorganization of virtually all components of the cell. It is divided into four sta...