1. What Defines Living Beings?
- Living beings exhibit activities like movement, growth, and breathing.
- Visible movement is common evidence of life but not a defining feature (e.g., dormant plants and sleeping animals).
- Invisible molecular movements within organisms are crucial for life.
- Viruses lack molecular movement unless inside a host, leading to debate about whether they are alive.
2. Why Molecular Movement is Essential for Life
- Living organisms are highly organized, with tissues, cells, and molecular structures.
- Environmental factors can cause these structures to break down.
- Molecular movement helps repair and maintain order in living systems.
3. What Are Life Processes?
- Life processes are essential activities that maintain the structure and function of living organisms.
- These processes include obtaining energy (nutrition), energy conversion (respiration), material transport, and waste removal (excretion).
4. Energy and Nutrition
- Energy is needed for all maintenance processes.
- Food serves as the source of energy and raw materials.
- Life on Earth is carbon-based; organisms rely on carbon-based food sources.
- Autotrophs (e.g., plants) create food using sunlight, carbon dioxide, and water.
- Heterotrophs (e.g., animals, fungi) consume autotrophs or other organisms for energy.
5. Photosynthesis: Energy Creation in Autotrophs
- Photosynthesis is the process where plants convert sunlight into chemical energy (carbohydrates).
- Key Steps:
- Absorption of light by chlorophyll.
- Conversion of light energy to chemical energy and water splitting into oxygen and hydrogen.
- Reduction of carbon dioxide into carbohydrates.
- Excess carbohydrates are stored as starch.
6. Leaf Structure and Gas Exchange
- Photosynthesis occurs in chloroplasts found in leaf cells.
- Stomata are tiny pores in leaves that allow gas exchange (CO₂ in, O₂ out).
- Guard cells regulate stomata opening and closing to minimize water loss.
7. Other Raw Materials for Plant Growth
- Water: Absorbed by roots and used in photosynthesis.
- Minerals: Nitrogen, phosphorus, magnesium, and iron are absorbed from soil for protein and compound synthesis.
- Nitrogen: Taken in as nitrates/nitrites or fixed from atmospheric nitrogen by bacteria.
8. Energy Utilization
- Energy from food is used to:
- Maintain body order.
- Enable growth and synthesis of proteins.
- Oxidation-reduction reactions in cells convert food into usable energy.
9. Transportation and Waste Management in Multicellular Organisms
- Larger, complex organisms need transport systems for distributing nutrients and oxygen.
- Waste products from metabolic reactions must be removed (excretion).
- Specialized tissues perform these functions (e.g., circulatory and excretory systems).
Additional Insights for Competitive Exams
- Characteristics of Life: Understand molecular movements, organization, and maintenance as core indicators of life.
- Autotrophs vs. Heterotrophs:
- Autotrophs: Use inorganic substances to create food.
- Heterotrophs: Depend on autotrophs for energy.
- Photosynthesis Key Formula:
- 6CO2+6H2O → C6H12O6+6O2
- Role of Minerals: Essential for metabolic functions and structural integrity of cells.
- Adaptations in Desert Plants: Carbon fixation happens at night to conserve water.
Heterotrophic Nutrition
- Organisms depend on others for food.
- Nutrition depends on food type, availability, and how it is obtained.
- Different strategies:
- External Digestion: Breakdown of food outside the body, e.g., fungi like bread moulds, yeast, and mushrooms.
- Internal Digestion: Food is ingested whole and broken down inside the body.
- Parasitic Nutrition: Nutrients are obtained from living hosts without killing them (e.g., cuscuta, ticks, lice, leeches).
How Organisms Obtain Nutrition
- In single-celled organisms:
- Amoeba: Uses extensions called pseudopodia to engulf food into a food vacuole. Digestion occurs inside the vacuole.
- Paramoecium: Food enters a specific spot via cilia movement.
Human Nutrition
- Food passes through the alimentary canal, a long tube with specialized regions.
- Process:
- Mouth:
- Food is crushed by teeth and mixed with saliva containing the enzyme salivary amylase to break starch into sugar.
- Muscular tongue moves food.
- Esophagus: Moves food to the stomach via rhythmic contractions (peristalsis).
- Stomach:
- Mixes food with gastric juice (contains HCl, pepsin, and mucus).
- HCl provides acidity for pepsin activity and kills germs.
- Small Intestine:
- Main site for digestion of carbohydrates, proteins, and fats.
- Liver produces bile to emulsify fats, and pancreas secretes enzymes like trypsin (for proteins) and lipase (for fats).
- Nutrients are absorbed through villi (finger-like projections) into the blood.
- Large Intestine:
- Absorbs water and forms feces, which exit via the anus.
- Mouth:
Key Concepts for Competitive Exams
- Enzymes: Biological catalysts (e.g., amylase, lipase). Know their functions.
- Digestion Time in Herbivores vs. Carnivores: Herbivores have longer intestines to digest cellulose.
- Role of Bile: Emulsifies fats, making enzyme action easier.
- Peristalsis: Essential for moving food through the digestive tract.
Respiration
- Types:
- Aerobic Respiration: Uses oxygen to break down glucose into CO₂ and H₂O, releasing high energy.
- Anaerobic Respiration: Without oxygen; produces less energy (e.g., lactic acid in muscles).
- ATP (Adenosine Triphosphate):
- The “energy currency” of the cell.
- Formed during respiration and used for cellular activities.
- Respiratory Organs:
- Plants: Use stomata for gas exchange.
- Humans: Use lungs with alveoli to maximize surface area for gas exchange.
- Aquatic Animals: Extract dissolved oxygen via gills.
Transportation in Humans
- Blood:
- Plasma: Carries nutrients and wastes.
- RBCs (Red Blood Cells): Carry oxygen via hemoglobin.
- WBCs: Fight infections.
- Heart: Pumps blood throughout the body.
- Double circulation system: Separates oxygen-rich and oxygen-poor blood.
Blood Pressure
- Definition: The force blood exerts on vessel walls.
- Types of Pressure:
- Systolic Pressure: During heart contraction (normal: 120 mm Hg).
- Diastolic Pressure: During heart relaxation (normal: 80 mm Hg).
- Comparison:
- Higher in arteries (close to heart, high pressure).
- Lower in veins (far from heart, low pressure).
Blood Vessels
- Arteries:
- Carry blood away from the heart.
- Thick, elastic walls to handle high pressure.
- Veins:
- Bring blood back to the heart.
- Thin walls, valves to prevent backflow.
- Capillaries:
- Smallest vessels, one-cell-thick walls.
- Enable material exchange between blood and tissues.
Platelets and Clotting
- Role of Platelets:
- Help stop blood loss when vessels are injured.
- Plug leaks by forming blood clots.
- Importance:
- Prevents blood loss and maintains pressure for efficient circulation.
Lymph
- Definition: A clear fluid derived from blood plasma.
- Formation:
- Plasma, proteins, and cells escape capillaries into tissues.
- Functions:
- Carries fats from the intestine.
- Drains excess fluid back into blood.
- Structure:
- Lymphatic capillaries → Large lymph vessels → Veins.
Transport in Plants
- Raw Materials for Plants:
- Water, minerals (from soil).
- CO₂, light (for photosynthesis).
- Two Transport Systems:
- Xylem: Moves water and minerals from roots upward.
- Phloem: Distributes food (sugar) and other products both upward and downward.
Water Transport in Plants
- Root Pressure:
- Roots absorb water by creating ion concentration differences.
- Pushes water upward at night.
- Transpiration Pull:
- Evaporation of water from leaves creates suction.
- Main daytime force driving water upward.
Food Transport (Translocation)
- Phloem Function:
- Transports sugars, amino acids, and other products.
- Requires energy (ATP).
- Mechanism:
- Increases osmotic pressure in phloem.
- Moves substances to where they’re needed (e.g., growing buds, storage).
Excretion
- In Humans:
- Organs: Kidneys, ureters, bladder, urethra.
- Function: Filters nitrogenous waste (urea) and excess water from blood.
- Unit: Nephron (basic filtering unit in kidneys).
- Process:
- Filtration in Bowman’s capsule.
- Reabsorption of useful substances (e.g., glucose, water).
- Waste forms urine.
- Artificial Kidney:
- Used in kidney failure.
- Removes wastes through dialysis without reabsorption.
- In Plants:
- Oxygen (photosynthesis byproduct) diffuses out.
- Excess water released by transpiration.
- Wastes stored in vacuoles, old xylem, or shed with leaves.
Key Concepts for Competitive Exams
- Blood Pressure:
- Know systolic/diastolic pressures and their significance.
- Understand why arteries have thick walls and veins have valves.
- Plant Transport:
- Difference between xylem (passive, water) and phloem (active, food).
- Role of root pressure and transpiration pull.
- Excretion:
- Structure of nephron and how filtration/reabsorption occurs.
- Role of kidney dialysis.
- Extra Knowledge:
- Transpiration helps regulate temperature in plants.
- Lymphatic system plays a secondary role in immune defense and nutrient transport.
THESE ALL ARE THE NOTES OF CHAPTER 5. AND AFTER SOME TIME YOU GET IMPORTANT QUESTIONS HERE. *#THANKS FOR VISITING, VISIT AGAIN#* 😊