Life Processes
Understanding how living organisms maintain themselves through nutrition, respiration, transportation, and excretion
Introduction to Life Processes
How do we distinguish between living and non-living things? While movement is often a visible indicator, life processes involve much more than what meets the eye. At the molecular level, continuous movement and maintenance processes are essential for survival.
Key Characteristics of Living Organisms
- Maintenance of organized structure
- Continuous repair of cellular components
- Molecular movement at microscopic levels
- Energy requirement for maintenance processes
All living organisms must perform certain basic functions to remain alive. These maintenance processes, called life processes, include nutrition, respiration, transportation, and excretion.
Learning Outcomes
After studying this chapter, students will be able to:
- Explain the criteria used to determine if something is alive
- Differentiate between autotrophic and heterotrophic nutrition
- Describe the process of photosynthesis and its importance
- Explain the human digestive system and process of digestion
- Compare aerobic and anaerobic respiration
- Describe the human respiratory system
- Explain the transportation systems in humans and plants
- Describe excretion processes in humans and plants
Period-Wise Teaching Plan
This chapter is designed to be covered over 8 periods, each lasting 45 minutes. Below is the detailed period-wise plan:
Topics: What are life processes, criteria for something to be considered alive, molecular movement, maintenance processes.
Activities: Discussion on living vs non-living, video presentation on cellular processes.
Topics: Autotrophic nutrition, photosynthesis process, raw materials for photosynthesis.
Activities: Activity 5.1 - Testing for starch in leaves, diagram drawing of photosynthesis.
Topics: Heterotrophic nutrition, types of heterotrophic nutrition, human digestive system.
Activities: Activity 5.3 - Effect of saliva on starch, model of digestive system.
Topics: What is respiration, aerobic respiration, anaerobic respiration, energy production.
Activities: Activity 5.4 - Testing for CO₂ in exhaled air, comparison of aerobic and anaerobic respiration.
Topics: Human respiratory system, mechanism of breathing, gas exchange in alveoli.
Activities: Activity 5.5 - Anaerobic respiration in yeast, model of respiratory system.
Topics: Transportation in humans, blood components, circulatory system, transportation in plants.
Activities: Activity 5.6 - Observing transpiration, blood cell microscopy (if available).
Topics: Excretion in humans, urinary system, nephron structure and function, excretion in plants.
Activities: Activity 5.7 - Examining kidney structure, discussion on plant excretion methods.
Topics: Revision of all concepts, important questions, doubt clearing.
Activities: Chapter quiz, group discussion, Q&A session.
Teaching Methodology
The teaching approach for this chapter should be a blend of:
- Interactive lectures with multimedia presentations
- Hands-on activities and experiments
- Group discussions and collaborative learning
- Visual aids like charts, models, and diagrams
- Regular assessment through quizzes and assignments
Nutrition
Nutrition is the process of obtaining energy and materials from outside the body to support growth, development, and maintenance.
Autotrophic Nutrition
Autotrophs like green plants and some bacteria synthesize their own food using simple inorganic substances (CO₂ and H₂O) with the help of sunlight through photosynthesis.
6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂
Three main events occur during photosynthesis:
- Absorption of light energy by chlorophyll
- Conversion of light energy to chemical energy and splitting of water molecules
- Reduction of carbon dioxide to carbohydrates
Heterotrophic Nutrition
Heterotrophs obtain nutrition from complex organic substances. This includes:
- Holozoic nutrition: Ingestion of complex organic material (animals)
- Saprophytic nutrition: Feeding on dead organic matter (fungi)
- Parasitic nutrition: Deriving nutrition from host organisms (ticks, lice, tapeworms)
Nutrition in Human Beings
The human digestive system consists of the alimentary canal and digestive glands. The process involves:
- Ingestion through mouth
- Digestion by mechanical and chemical processes
- Absorption in the small intestine
- Assimilation by cells
- Egestion of undigested material
Did You Know?
The small intestine has finger-like projections called villi that increase the surface area for absorption. If spread out, the absorptive surface would cover about 250-300 m² - approximately the size of a tennis court!
Activities & Experiments
Test variegated leaves to demonstrate that chlorophyll is essential for photosynthesis and starch production.
Use potassium hydroxide to absorb CO₂ and show that carbon dioxide is necessary for photosynthesis.
Demonstrate the digestive action of salivary amylase on starch.
Respiration
Respiration is the process of releasing energy from food for use by cells. It involves the breakdown of glucose to produce ATP, the energy currency of cells.
Aerobic Respiration
Occurs in the presence of oxygen, producing more energy (36-38 ATP molecules per glucose molecule):
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP)
Anaerobic Respiration
Occurs in the absence of oxygen, producing less energy (2 ATP molecules per glucose molecule):
In yeast: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + Energy
In muscles: C₆H₁₂O₆ → 2C₃H₆O₃ + Energy
Respiratory System in Humans
The human respiratory system includes nostrils, nasal passage, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli. Gas exchange occurs in the alveoli where oxygen diffuses into blood and carbon dioxide diffuses out.
Activities & Experiments
Use lime water to test for carbon dioxide in exhaled air.
Demonstrate fermentation in yeast and production of CO₂.
Transportation
Transportation systems move materials within organisms to where they are needed.
Transportation in Human Beings
The human circulatory system consists of the heart, blood vessels, and blood. It transports oxygen, nutrients, hormones, and waste products.
Components of Blood
- Plasma: Liquid matrix containing nutrients, hormones, waste products
- Red Blood Cells: Contain hemoglobin for oxygen transport
- White Blood Cells: Fight infections
- Platelets: Help in blood clotting
Double Circulation: Blood passes through the heart twice in one complete cycle of the body - once through pulmonary circulation (to lungs) and once through systemic circulation (to body parts).
Transportation in Plants
Plants have two specialized tissues for transportation:
- Xylem: Transports water and minerals from roots to other parts
- Phloem: Transports food from leaves to storage organs and growing parts
Transpiration
The process of water loss from plant surfaces, mainly through stomata. It creates a suction pull that helps in upward movement of water and minerals from roots.
Observe the process of transpiration in plants by covering a potted plant with a plastic bag and observing water droplets.
Excretion
Excretion is the process of removing metabolic wastes from the body.
Excretion in Human Beings
The human excretory system consists of kidneys, ureters, urinary bladder, and urethra. The functional unit of the kidney is the nephron, which filters blood and forms urine.
- Glomerular Filtration: Blood is filtered in glomerulus
- Reabsorption: Useful substances are reabsorbed
- Secretion: Additional wastes are secreted into urine
Excretion in Plants
Plants use different strategies for excretion:
- Oxygen released during photosynthesis
- Excess water removed through transpiration
- Waste products stored in leaves that fall off
- Wastes stored as resins and gums in old xylem
- Some wastes excreted into soil
Examine a model or diagram of the kidney and identify its main parts and their functions.
Teaching Resources
Key Terms
- Autotrophs: Organisms that make their own food
- Heterotrophs: Organisms that depend on others for food
- Photosynthesis: Process of making food by plants
- Alveoli: Air sacs in lungs for gas exchange
- Haemoglobin: Oxygen-carrying pigment in blood
- Nephron: Functional unit of kidney
- Xylem: Plant tissue for water transport
- Phloem: Plant tissue for food transport
- ATP: Energy currency of cells
Assessment Questions
Chapter Review Questions
- Why is diffusion insufficient to meet the oxygen requirements of multi-cellular organisms like humans?
- What criteria do we use to decide whether something is alive?
- What are the differences between autotrophic and heterotrophic nutrition?
- Describe the process of photosynthesis and write its chemical equation.
- Explain the human digestive system with a labeled diagram.
- Differentiate between aerobic and anaerobic respiration.
- Describe the mechanism of breathing in human beings.
- Explain the transportation system in human beings.
- Describe the process of urine formation in kidneys.
- How do plants excrete their waste products?
Additional Resources
- Interactive 3D model of human digestive system
- Video demonstration of photosynthesis experiment
- Virtual lab on respiration in yeast
- Quiz on life processes
- Printable diagrams for labeling practice
