Questions
6 questions in typical board papers
Difficulty
Medium
Importance
Core - never skip
Overview
Life Processes covers the essential functions—nutrition, respiration, transportation, and excretion—that sustain living organisms. This topic is a cornerstone of the CBSE biology syllabus, frequently tested through conceptual questions and diagram-based analysis. Aspirants must master the pathways of energy conversion and the systematic flow of materials in the human body.
Nutrition
Nutrition involves the intake and utilization of nutrients to maintain metabolic processes. It is divided into autotrophic mode, seen in plants via photosynthesis, and heterotrophic mode, characteristic of animals.
- Photosynthesis equation: 6CO2 + 12H2O -> C6H12O6 + 6O2 + 6H2O
- Role of chlorophyll: Capture of light energy
- Stomata: Small pores for gas exchange
- Peristaltic movement in the alimentary canal
- Emulsification of fats by bile salts
Respiration
Respiration is the cellular process where glucose is broken down to release ATP. Students must differentiate between aerobic respiration (oxygen-dependent) and anaerobic respiration (oxygen-absent).
- Aerobic: Complete oxidation into CO2 and H2O
- Anaerobic in yeast: Ethanol + CO2 + Energy
- Anaerobic in muscle cells: Lactic acid production
- ATP is the energy currency of the cell
- Alveoli provide surface area for gas exchange
Transportation
Transportation entails the movement of substances within organisms using complex circulatory systems. In humans, this involves the double circulation of blood through a four-chambered heart.
- Xylem: Water and mineral transport
- Phloem: Translocation of food/sucrose
- Double circulation: Pulmonary and systemic
- Platelets: Role in blood clotting
- Blood pressure: 120/80 mmHg (systolic/diastolic)
Excretion
Excretion is the removal of nitrogenous waste products from the body to maintain homeostasis. The nephron serves as the primary functional unit for filtration in the human kidney.
- Glomerulus: Site of ultrafiltration
- Tubular reabsorption: Selective water/salt recovery
- Ureter: Transport of urine to bladder
- Plants excrete waste via transpiration and leaf shedding
- Osmoregulation: Water balance maintenance
Formula Sheet
Photosynthesis: 6CO2 + 12H2O -> C6H12O6 + 6O2 + 6H2O
Cellular Respiration: C6H12O6 + 6O2 -> 6CO2 + 6H2O + 38ATP
Exam Tip
Always balance chemical equations provided in your answers and use labeled flowcharts for complex physiological processes to maximize score efficiency.
Common Mistakes
- Confusing the role of xylem and phloem, especially regarding the direction of transport.
- Failing to include the specific conditions (presence or absence of oxygen) in respiration pathway diagrams.
- Neglecting to label essential anatomical diagrams, which are mandatory for full marks.
More Revision Notes
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