Life Processes Class 10 Science (Biology) Complete Chapter Revision Under 45 Mins | Board Exams 2023

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A dedicated 45-minute session is set aside to review key board examination concepts with full attention. Learners are instructed to capture any uncertainties in writing for later clarification rather than interrupting the flow of the lesson. Preparedness with textbooks and notebooks is essential to record important points throughout the session. This methodical approach reinforces continuous revision and deepens understanding of the material.

Life processes are defined as the essential biological activities required to maintain body function and ensure survival. These functions operate continuously, regardless of whether one is resting or actively moving. They represent the basic operations that keep the body alive and functioning. The focus is on outlining four specific processes that are crucial to sustaining life.

Autotrophic Nutrition: Mastery of Photosynthesis Food fuels every bodily activity, and some organisms generate their own food through photosynthesis. In this process, chlorophyll absorbs sunlight while plants take in carbon dioxide through stomata and water via their roots. Light energy is converted into chemical energy by splitting water molecules and reducing carbon dioxide into glucose, with excess glucose transforming into stored starch.

Heterotrophic Nutrition: Diverse Food Acquisition Strategies Many organisms rely on external sources for food, adopting methods such as saprophytic, parasitic, or holozoic nutrition. Saprophytic organisms decompose dead material by releasing enzymes outside their bodies, whereas parasitic organisms extract nutrients from a host. Holozoic nutrition involves the ingestion of food, followed by internal breakdown to release nutrients and energy.

Holozoic Nutrition: The Five-Step Path from Ingestion to Ejection Food enters organisms and undergoes a systematic sequence: ingestion, digestion, absorption, assimilation, and ejection. Digestion converts complex substances into simpler, soluble forms that the body can use. Even simple organisms like amoeba rely on pseudopodia and food vacuoles to capture and process nourishment.

Human Digestive System: A Coordinated Process of Mechanical and Chemical Breakdown In humans, the journey begins in the buccal cavity where teeth, tongue, and saliva initiate mechanical breakdown and enzymatic action on starch. Peristalsis drives the bolus through the esophagus to the stomach where gastric juices, including hydrochloric acid and pepsin, further break down proteins. In the small intestine, bile from the liver and enzymes from the pancreas complete digestion, while villi absorb nutrients and the large intestine reclaims water and eliminates waste.

Cellular Respiration: Unlocking Energy from Glucose Glucose breakdown releases energy essential for both physical and chemical processes within the body. This energy liberation occurs through cellular respiration, a critical biochemical pathway inside cells. The process ensures continuous energy production necessary for sustaining life and bodily functions.

Glucose Conversion Fuels Cellular Energy A six-carbon glucose molecule undergoes a sequence of steps, starting with its conversion to pyruvate in the cytoplasm. The pyruvate then enters the mitochondria where, in the presence of oxygen, it is fully broken down to generate adenosine triphosphate (ATP). In oxygen-deficient conditions, the conversion diverts pyruvate to form lactic acid or ethanol via fermentation, resulting in lower energy output.

Air's Journey from Inhalation to Cellular Oxygenation Oxygen essential for aerobic respiration is drawn from the environment through the respiratory system. Air enters via the nostrils and is refined in the nasal cavity, where hairs and mucus trap impurities. It then courses through the pharynx, larynx, and trachea, ultimately reaching the bronchi and alveoli in the lungs where oxygen is absorbed into the bloodstream.

Alveoli, balloon-like structures surrounded by blood vessels, are where oxygen-rich air meets carbon dioxide-rich blood. Oxygen diffuses from the alveoli into the blood while carbon dioxide moves from the blood into the alveoli due to concentration differences. Red blood cells, carrying hemoglobin with high affinity for oxygen, facilitate oxygen transport, while carbon dioxide dissolves easily in blood and is expelled from the body.

The diaphragm contracts downward during inhalation while the ribcage expands, drawing air into the chest cavity, and reverses its motion during exhalation to expel air. This dome-shaped muscle separates the thoracic and abdominal cavities, ensuring effective respiratory dynamics. Aquatic organisms breathe more rapidly with their gills to compensate for the lower oxygen content in water compared to land. Nutrients and oxygen produced from digestion and respiration are then efficiently transported to cells to sustain energy production.

Plant Vascular Transport Through Xylem and Phloem Plants draw water from the roots and channel it upward in a unidirectional flow through xylem, where structures like tracheids and vessels rely on a transpirational pull created by water loss from leaves. This suction mechanism not only supports the movement of water and minerals but also ensures that the essential elements reach the photosynthetic sites. Nutrients produced in the leaves are then distributed to various plant parts through phloem, a process called translocation that consumes ATP and uses osmotic pressure to overcome concentration differences.

Circulatory System: Blood Composition and Function The human circulatory system transports vital elements using blood, blood vessels, and the heart as its core components. Blood, a fluid connective tissue, consists of plasma along with red blood cells that deliver oxygen, white blood cells that offer defense, and platelets that trigger clotting during injuries. This well-organized network ensures efficient distribution of oxygen and nutrients while rapidly responding to bodily injuries through clot formation.

The circulatory system relies on specialized blood vessels to transport oxygen and carbon dioxide throughout the body. Arteries carry oxygen-rich blood from the heart under high pressure without valves, whereas veins return deoxygenated blood at lower pressure using valves to prevent backflow. Capillaries, being one cell thick, enable the crucial gas exchange between blood and tissues.

The human heart consists of four distinct chambers: two upper receiving chambers called atria and two lower pumping chambers known as ventricles. The right side of the heart is designed to receive deoxygenated blood, while the left side welcomes oxygenated blood. Essential valves, like the tricuspid valve between the right atrium and ventricle, ensure a one-way flow of blood, maintaining efficient circulation.

Double circulation maintains efficient blood flow through two distinct circuits. The right side of the heart collects deoxygenated blood from the body via the superior and inferior vena cavae, sending it to the lungs through the pulmonary artery. Oxygenated blood returns via the pulmonary vein to the left side of the heart, where the left ventricle pumps it through the aorta to supply the systemic circuit. A bicuspid valve prevents backflow, ensuring that both pulmonary and systemic paths operate smoothly.

Excretion is the process of eliminating nitrogenous metabolic waste, critical for preventing toxic buildup in living organisms. It ensures that harmful substances are regularly removed, safeguarding the body's internal environment. In plants, waste management occurs through mechanisms like transpiration, diffusion, and the secretion of resins and gums, which help dispel excess water, salts, and even byproducts from photosynthesis.

The human body relies on a pair of kidneys located in the abdomen to filter out nitrogenous metabolic waste. Filtered toxins travel through long ureters to the urinary bladder before exiting via the urethra. This structured pathway ensures efficient removal of waste and maintains internal balance.

Nephrons, the structural and functional units of the kidneys, generate urine by filtering blood at high pressure within the glomerulus housed in Bowman’s capsule. Toxic metabolic wastes like urea are separated while essential nutrients, water, and amino acids are reabsorbed in the tubules. The remaining filtrate flows through collecting ducts into the ureter, is stored temporarily in the bladder, and is eventually expelled through the urethra.

Balancing Leaks with Lymph Flow Capillaries sometimes develop tiny leaks that let plasma, cells, and proteins seep into surrounding tissues, forming extracellular fluid. The imbalance created by this leakage is remedied when the remaining molecules are redirected into separate vessels. These vessels, known as lymph vessels, collect the redirected fluid, which then becomes lymph that helps maintain the body's equilibrium.

Fluid Movement and Nutrient Transformation Transpiration in plants generates a suction force that lifts water upward to sustain fluid movement. The pancreas operates with dual functionality, secreting both digestive enzymes and hormones to break down starch into simpler sugars. Food substances are moved through the phloem by translocation, while in the kidneys, a network of capillaries known as the glomerulus uses high pressure to filter waste and essential molecules.

Four-Chambered Heart: Efficient Circulation and Separation The heart functions as a four-chambered pump with atria that receive blood and ventricles that propel it, ensuring proper circulation. A distinct division between the right and left sides prevents the mixing of deoxygenated and oxygenated blood. Valves guide the directional flow during contraction and relaxation, with systolic pressure generated during pumping and diastolic pressure during resting phases. This coordinated action maintains an efficient double circulation system.