Question 1
Describe the structure and functioning of nephrons.
Nephron is the basic filtration unit in the kidney. It consists of a tubule which is connected with a collecting duct at one end and a cup shaped structure at the other end, called Bowman's capsule. Every Bowman's capsule contains a cluster of capillaries called glomerulus within the cup-shaped structure. The blood enters into glomerulus through afferent arteriole of renal artery and leaves it through efferent arteriole. This causes filtration of the blood. Then the filtrate passes into the tubular part of the nephron. Here, useful substances such as glucose, amino acids, salts and some water are re-absorbed into the blood by the capillaries surrounding the nephron tubule. The filtrate which remains after the re-absorption is called the urine, which is collected from nephron by the collecting duct to carry it to the urinary bladder and then to the urethra.
Chapter 5: Life Processes — Quick Revision Guide
Introduction
Life processes are the basic functions performed by all living organisms to sustain life. This chapter covers nutrition (autotrophic and heterotrophic), respiration, transportation, and excretion in plants and animals.
Key Points at a Glance
- Photosynthesis: 6CO2 + 6H2O → C6H12O6 + 6O2 (in chloroplasts using chlorophyll and sunlight)
- Stomata: tiny pores for gas exchange and transpiration; guard cells control opening/closing
- Human digestive system: mouth (salivary amylase) → stomach (HCl, pepsin) → small intestine (bile, trypsin, lipase; absorption by villi) → large intestine → anus
- Aerobic respiration (mitochondria): glucose + O2 → CO2 + H2O + 38 ATP
- Anaerobic: in yeast → ethanol + CO2; in muscles → lactic acid; both yield 2 ATP
- Xylem: transports water upward (dead cells, transpiration pull); Phloem: transports food bidirectionally (living cells, uses ATP)
- Heart: 4 chambers, double circulation (pulmonary + systemic); septum prevents mixing
- Blood: plasma + RBCs (O2 via haemoglobin) + WBCs (immunity) + platelets (clotting)
- Nephron: Bowman's capsule + glomerulus → filtration → reabsorption → urine; dialysis for kidney failure
- Plant excretion: transpiration, leaf fall, stored in vacuoles, resins/gums
Real-World Connections
Photosynthesis is the basis of all food chains; fermentation used in bread and alcohol production; blood donation saves lives; dialysis machines sustain patients with kidney failure.
Quick Self-Test (5 Questions)
- What is the most important concept you learned from this chapter?
- Can you write three key equations/formulae from this chapter from memory?
- Draw a labelled diagram relevant to this chapter without looking at your notes.
- Explain one real-world application of a concept from this chapter.
- What is one common mistake students make in this chapter, and how can you avoid it?
Further Study
- NCERT Textbook Chapter 5
- NCERT Exemplar Problems
- Bright Tutorials Detailed Notes: ch05-life-processes.html
- Bright Tutorials Practice Questions: ch05-life-processes.html
- Previous Year CBSE Board Papers