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Chapter life process, Study notes of Environmental science

Environmental science

Science class 10th biology 2026

Typology: Study notes

2011/2012

Available from 05/08/2026

dibyajyoti-sena
dibyajyoti-sena 🇮🇳

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EXCRETION
Excretion:- The process of removal of harmful metabolic wastes from the body is called
excretion.
Types of wastes:-
i) Solid wastes- faeces
ii) Liquid wastes – urine, sweat
iii) Gaseous wastes- CO2
►Organisms are classified on the basis of excretion of nitrogenous waste products:-
i) Ammonotelic animals:- excrete out ammonia.
Ex- many fishes, protozoa, sponge, etc.
ii) Ureotelic animals:- excrete out urea.
Ex- Human beings, mammals
iii) Uricotelic animals:- excrete out uric acid.
Ex- birds, insects, many reptiles.
EXCRETION IN HUMAN BEINGS (Working)
i) The Excretory system of humans includes a pair of kidneys, a pair of ureters, a
urinary bladder and a urethra.
ii) The blood in our body is constant passing through kidneys. The oxygenated blood
with waste products (dirty blood) enters into kidney through aorta and renal artery.
iii) The kidneys clean the blood by filtering it to remove waste products like urea, salts
and excess water and excrete them in the form of urine.
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EXCRETION

Excretion:- The process of removal of harmful metabolic wastes from the body is called excretion. Types of wastes:- i) Solid wastes- faeces ii) Liquid wastes – urine, sweat iii) Gaseous wastes- CO ► Organisms are classified on the basis of excretion of nitrogenous waste products:- i) Ammonotelic animals:- excrete out ammonia. Ex- many fishes, protozoa, sponge, etc. ii) Ureotelic animals: - excrete out urea. Ex- Human beings, mammals iii) Uricotelic animals:- excrete out uric acid. Ex- birds, insects, many reptiles. EXCRETION IN HUMAN BEINGS (Working) i) The Excretory system of humans includes a pair of kidneys, a pair of ureters, a urinary bladder and a urethra. ii) The blood in our body is constant passing through kidneys. The oxygenated blood with waste products (dirty blood) enters into kidney through aorta and renal artery. iii) The kidneys clean the blood by filtering it to remove waste products like urea, salts and excess water and excrete them in the form of urine.

iv) The urine produced in the kidneys passes through the ureters into urinary bladder where it is stored until it is released through urethra. v) When expanded urinary bladder leads to the urge to pass, then it out through the urethra. Q- Describe the structure, function (working) of nephron. Draw diagram also. Ans- Structure: - i) Nephron is the structural and functional unit of kidney. ii) Each Nephron has 2 main parts : - a) Glomerulus b) Renal tubule iii) Glomerulus- Glomerulus is formed by a cluster/bundle of blood capillaries. It is protected by Bowman’s capsule. iv) Renal tubule is composed of following parts: - a) Bowman’s Capsule – It is a Cup-like structure, which encloses glomerulus and protects it. It also collects the filtrates. b) PCT- Proximal Convoluted Tubule

vii) Collecting Duct- All these wastes are collected in the collecting duct, that is urine. viii) Urine thus produced is passed to the urinary bladder through ureters. ix) Urinary bladder is a muscular bag where urine is stored and passed out (discharged) through urethra. V.IMP Process involved in Urine Formation:-

  1. Glomerular filtration (ultra filtration)
  2. Selective Reabsorption
  3. Tubular Secretion Definition:-
  4. Filtration of blood occurring in the Glomerulus is called Glomerular filtration.
  5. The absorption of useful substances are selectively reabsorption into the blood.
  6. The phenomena of active secretion of metabolic wastes from capillaries and interstitial fluid into tubule is called tubular secretion.

V. IMP Q- Maximum reabsorption of useful substances back into the blood from the filtrate in a nephron occurs in:- PCT (Proximal Convoluted Tubule) Reason- This is due to the presence of simple brush- border cuboidal epithelial tissues, which increases the surface area for absorption. THE DIAGRAM GIVEN BELOW IS FOR UNDERSTANDING REABSORPTION AND SECRETION OF SUBSTANCES AT DIFFERENT PARTS BY INDICATING WITH ARROW NO NEED TO DRAW/CAN BE PASTED Hemodialysis/ Dialysis- An artificial kidney is a device to remove nitrogenous waste products from the blood through dialysis. ►Normal filtration in a healthy adult- 180L daily ( Means 125 ml per minute ) ► Blood is formed in - Bone marrow

Mechanism:- It works on the Principle of Diffusion. CBQ on Artificial Kidney Durning haemodialysis, the patient's blood is cleaned by filtration of semi- permeable membranes before being returned to the body. (+ Extra story will be there) i) The Haemodialyzer has semi permeable lining of tubes which help to- a) To maintain osmotic pressure of blood b) To filter nitrogenous wastes from the dialyzing solution. c) In passing the waste products in the dialyzing solution. (ANS) d) To pump purified blood back into the blood of the patient. (ii) Which one of the following is not a function of artificial kidney? a) To remove nitrogenous wastes from the blood- b) To remove excess fluids from the blood. c) To reabsorb essential nutrients from the blood. d) To filter and purify the blood. (iii) The 'used dialysing' solution’ is rich in- (a) urea and excess salts (b) blood cells (c) lymph (d) proteins. (iv) Which part of the nephron in human kidney, serves the function of reabsorption of certain substances? (a) Glomerulus (b) Bowman's Capsule (c) Tubules (NOTE- Mainly in PCT) (d) Collecting duct

Excretion in Plants:- ►Carbon dioxide, excess water and nitrogenous compounds are the major excretory products in plants. ►Excretion of gaseous waste in plants takes place through stomata on leaves. ► Oxygen released during photosynthesis and carbon dioxide released during respiration. ► Excess water is excreted by transpiration. ► Waste products may be stored in leaves that fall off. ► Other waste products are stored as resins and gums, especially in old xylem. ► Plants also excrete some waste substances into the soil around them. ==================================================