10th Class Biology 4th Lesson Excretion - The Wastage Disposing System Textbook Questions and Answers

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Question 1.What is meant by excretion? Explain the process of formation of urine?
(OR) What are the different stages in urine formation? Explain what happens in those stages. (OR) Explain various steps in the mechanism of urine formation.

Answer: Excretion: Excretion is a biological process involved in separation and removal of toxic wastes from the body

Formation of urine involves four stages:
  • Glomerular filtration
  • Tubular reabsorption
  • Tubular secretion and
  • Concentration of urine
  • Glomerular filtration
  • Blood flows from renal artery to glomerulus through afferent arteriole
  • Filtration of blood occurs in the glomerulus
  • Glomerular filtrate is also known as primary urine which almost equal to blood in chemical composition except the presence of blood cells
  • Tubular reabsorption
  • The primary urine passes into proximal convoluted tubule
  • Useful substances like glucose, amino acids, sodium chloride, potassium ion, bicarbonate ion, water are reabsorbed into peritubular network
  • Tubular secretion
  • After reabsorption in proximal convoluted tubule (PCT) the urine travels through the loop of Henle into distal convoluted tubule
  • Here some other wastes like extra salts ions of K+, Na+, Cl- and H+ secrete from peritubular capillaries into distal convoluted tubule which are surrounded by peritubular network
  • Concentration of urine
  • 75% of water content of the nephric filtrate is reabsorbed in the region of proximal convoluted tubule and 10% of water passes out of filtrate through osmosis in the area of loop of Henle
  • The concentration of urine takes place in the area of collecting tubes in the presence of hormone called vasopressin. The hormone is secreted only when concentrated urine is to be passed out
Question 2.How are waste products excreted in Amoeba?
(OR) Write the process of excretion in amoeba.


  • Specific excretory organs are absent in unicellular organisms like amoeba
  • Amoeba possess osmoregulatory organell called contractile vacuole
  • It collects water and wastes from the body, swells up, reaches the surface and bursts to release its content to outside
  • The main excretion takes place through body surface by simple diffusion
  • The waste material carbon dioxide is removed by diffusion through the cell membrane
Question 3.Name different excretory organs in human body and excretory material generated by them?

Answer: Different excretory organs in human body and excretory material generated by them are as follows

Excretory organ Excretory material generated
Kidney Filters blood and eliminates nitrogenous wastes and other harmful things. Filters urea from the blood
Lungs They remove carbon dioxide and water in respiration
Skin Sweat and metabolic wastes. Sebaceous glands in skin eliminates sebum which contains waxes, sterols, hydrocarbons and fatty acids
Liver Bile pigments bilirubin, biliverdin are metabolic wastes of haemoglobin of dead red blood cells. Urochrome is eliminated through urine. Liver also eliminates cholesterol and derivatives of steroid hormones, extra drug, vitamins and alkaline salts. Urea is also formed in liver
Intestine Excess salts of calcium, magnesium and iron are excreted by epithelial cells of colon for elimination along with faeces
Eccrine glands These allow excess water to leave the body. They are present mainly on the forehead, the bottoms of the feet and the palms
Salivary glands and Lacrimal glands Small amount of nitrogenous wastes are also eliminated through saliva & tears
Question 4.Deepak said that Nephrons are functional and structural units of kidneys. How will you support him?
(OR) How can you say that kidney is suitable for the filtration of biological waste from blood in man?

Answer: I support Deepaks statement that nephrons are functional units of kidneys because

  • Nephrons chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine
  • Nephron eliminates wastes from the body, regulates blood volume and blood pressure, controls levels of electrolytes and metabolites and regulates blood pH
  • Its functions are vital to life and are regulated by the endocrine system
  • Hence, nephrons are the functional units of kidneys
Question 5.How do plants manage the waste materials?


  • Plants can get rid of excess water by a process like transpiration and guttation
  • Waste products may be stored in leaves, bark and fruits
  • When these dead leaves, bark, and ripe fruits fall off from the tree, the waste products in them are got rid of
  • Some of the plant waste gets stored in the fruits in the form of solid bodies called Raphides. e.g: Yam
  • Several plants prepare chemicals and store them in roots, leaves, seeds to protect against herbivores
  • The plants excrete carbon dioxide produced as a waste during respiration only at night time
  • The plants excrete oxygen as a waste only during the daytime
  • The plants get rid of wastes by secreting them in the form of gums and resins
  • Plants also excrete some waste substances into the soil around them
Question 6.Why do some people need to use a dialysis machine? Explain the principle involved in it


  • Kidneys are vital organs for filtration of nitrogenous waste material from blood and for survival of a person
  • Factors like infections, injury, very high blood pressure, very high blood sugar restrict blood flow to kidneys
  • This leads to accumulation of poisonous wastes in the body and leads to death
  • When both kidneys are damaged DIALYSIS machine is used to filter the blood of a person
  • This process is called HAEMODIALYSIS
  • In this process blood is taken out from the main artery, mixed with an anticoagulant such as HEPARIN and then pumped into the apparatus called DIALYZER
  • In this apparatus, blood flow through channels or tubes and are embedded in the dialyzing fluid
  • The membrane separates the blood flowing inside the tube and dialyzing fluid by osmosis
  • The dialyzing fluid has the same composition as that of plasma, except nitrogenous wastes
  • Therefore, nitrogenous waste materials move out from the blood freely, there by cleaning the blood of its wastes
  • This process is called DIALYSIS. Cleaned blood is pumped back to the body through a vein after adding HEPARIN
Question 7.What is meant by osmoregulation? How is it maintained in human body?


  • The process of constant maintaining of the water and salt contents in the body is called osmoregulation
  • The kidneys are the main osmoregulatory organs in human body.
  • The function of kidney is to filter blood and maintain the dissolved ion concentrations of body fluids
  • The nephron is the functional unit of the kidney, which actively filters blood and generates urine
  • The hormone VASOPRESSIN maintains osmotic concentration of body fluids
  • 75% of water content of nephric filtrate is reabsorbed in the PCT (proximal convoluted tubule) and only 10% of water passes out of filtrate through osmosis in the area of loop of Henle
  • Thus osmoregulation is maintained in human body
Question 8.Do you find any relationship between circulatory system and excretory system? What are they?


  • Circulatory system delivers oxygen, nutrients, water, hormones and other essential to each cell of the body
  • And it also transports all the carbon dioxide and other waste products of the cells to the lungs to be expired (exhaled) or to the kidneys to be excreted
  • The excretory system is closely related to the circulatory system by virtue of the process of cleansing the blood of waste, removing excess fluids and generally keeping other fluids in balance
  • Excretory system releases hormones to elevate blood pressure and accelerate red blood cell production
  • Kidney stimulates the red blood cell production by erythropoetin and regulates blood pressure with the secretion of renin
Question 9.Give reasons.
A) Always vasopressin is not secreted?


  • Vasopressin is secreted only when concentrated urine is to be passed out
  • If vasopressin is not produced in sufficient quantities, very large amount of urine (more than 15 litres per day, normal persons excrete about one litre in a day) is excreted by the person which produces dilute urine
  • Deficiency of vasopressin causes DIABETES INSIPIDUS
  • Therefore vasopressin is always not secreted but only to concentrate urine
B) When urine is discharged, in beginning it is acidic in nature later it becomes alkaline?


  • Urine contains 96% of water, 2.5% of organic substances and 1.5% of inorganic solutes
  • Urine is acidic in the beginning of its formation
  • Gradually it becomes alkaline due to the decomposition of urea to form AMMONIA
C) Diameter of afferent arteriole is bigger than efferent arteriole?


  • Glomerulus develops from an afferent arteriole. It gives rise to an efferent arteriole
  • The diameter of afferent arteriole is bigger than the efferent arteriole
  • The narrower out let of efferent arteriole exerts pressure in the glomerulus and enables the blood to remain more time, thus helps in proper filtration of blood by ultrafiltration
D) Urine is slightly thicker in summer than in winter?


  • In summer, a large quantity of water is lost in the form of sweat
  • To save the body from suns heat and to maintain water balance sweat glands secrete more sweat
  • The remaining waste materials get concentrated
  • Due to the high concentration of the remaining waste materials urine is slightly thicker in summer than in winter
Question 10.Write differences between
  • Functions of PCT and DCT
  • Kidney and Artificial kidney
  • Excretion and Secretion
  • Primary metabolites and Secondary metabolites


  • Functions of PCT and DCT: Functions of PCT
  • Reabsorbs glucose, amino acids, phosphate, potassium, urea and other organic solutes from the filtrate into the peritubular network
  • The PCT regulates pH of the filtrates by exchanging hydrogen ions in the interstitium for bicarbonate ions in the filtrate
  • It is also responsible to secreting organic acids such as creatinine and other bases into the filtrate
  • Proximal convoluted tubule regulates the pH of the filtrate in the kidneys
  • Functions of DCT:
  • It maintains a proper concentration and pH of the urine
  • Extra salts, ions of K+, Na+, Cl- and H+ secrete from peritubular capillaries into DCT
  • It secretes ammonium ions and hydrogen ions
  • It is relatively impermeable to water but in the pressure of Antidiuretic hormone
  • Kidney and Artificial kidney
Kidney Artificial kidney
1. It is a natural excretory organ in human beings to filter blood and forms urine 1. It is a device to remove nitrogenous waste products from the blood through dialysis
2. Kidney is used to filter blood in healthy persons 2. It is used in persons when both kidneys are damaged
3. Blood that passes through kidney contains nitrogenous wastes 3. Dialysing fluid used in dialysis machine do not contain nitrogenous wastes
4. Persons blood passes through Malphigian body and renal tubule during filtration 4. Patients blood is passed through number of tubes with semipermeable lining suspended in a tank filled with dialysing fluid
6. The filtration in the glomerulus is called pressure filtration or ultra filtration 6. The filtration in artificial kidney is known as haemodialysis
7. Anticoagulant heparin is present in the blood vessels 7. Heparin is added to the blood before pumping into the apparatus
(ADH) its permeability to water increases making urine concentrated.
C) Excretion and Secretion?
Excretion Secretion
1. It is the removal of materials from a living being 1. It is movement of material from one point to other point
2. Excretion is passive in nature 2. Secretion is active in nature
3. Humans excrete materials such as tears, urine, carbon dioxide and sweat 3. Humans secretions includes enzymes, hormones and saliva
4. Excretion is mostly body waste 4. Secretion is important materials that can be metabolized and used by our bodies
5. Plants excrete through roots into its surroundings and falling off leaves and bark 5. Secretions occur in the plant body in the form of latex, resins, gums etc
D) Primary metabolites and Secondary metabolites?
(OR) What are primary and secondary metabolites in plants? Give examples.


Primary metabolites Secondary metabolites
1. These are involved in normal growth, development and reproduction 1. These are not directly involved in the normal growth, development and reproduction
2. Examples for primary metabolites are carbohydrates, fats and proteins 2. Examples for secondary metabolites are alkaloids, tannins, resins, gums and latex etc
Question 11.There is a pair of bean-shaped organs P in the human body towards the back, just above the waist. A waste product Q formed by the decomposition of unused proteins in liver is brought into organ P through blood by an artery R. The numerous tiny filters S present in organ P clean the dirty blood goes into circulation through a vein T. The waste substance Q other waste salts and excess water form a yellowish liquid U which goes from organ P into a bag like structure V through two tubes W. This liquid is then thrown out of the body through a tube X?
(a) What is (i) organ P and (ii) waste substance Q?
  • Organ P is kidney and
  • Waste substance Q is urea
(b) Name (i) artery R and (ii) vein T?


  • Artery R is Renal artery and
  • Vein T is Renal vein
(c) What are tiny filters S known as?

Answer: The tiny filters S are Nephrons

(d) Name (i) Liquid (ii) Structure V (iii) Tubes W (iv) Tube X?


  • Liquid U is urine
  • Structure V is urinary bladder
  • Tube W is ureters
  • Tube X is urethra
Question 12.The organ A of a person has been damaged completely due to a poisonous waste material B has started accumulation in his blood, making it dirty. In order to save this persons life, the blood from an artery in the persons arm is made to flow into long tubes made of substance E which are kept in coiled form in a tank containing solution FvThis solution contains three materials G, H and I and similar proportions to those in normal blood. As the persons blood passes through long tubes of substance E, most of the wastes present in it go into solution F The clean blood is then put back into a vein in the person for circulation.
(a) What is organ A?

Answer: Kidney

(b) Name the waste substance B?

Answer: Urea

(c) What are (i) E and (ii) F?


  • Long tubes E are made of cellulose
  • Solution F is dialysing fluid contains three materials like: water, glucose and salts
(d) What are G, H and I?

Answer: Waste molecules, nutrient molecules and water

(e) What is the process described above known as?

Answer: Dialysis

Question 13.Imagine what happens if waste materials are not sent out of the body from time to time?
(OR) What happens when the waste products are not sent out from the body?


  • If waste materials are not sent out of the body from time to time, our body is filled with extra water and waste products
  • ThIs condition ¡s called UREMIA. 1f kidneys stop working completely it leads to UREMIA
  • Our hands and feet may swell
  • We feel tired and weak because our body needs clean blood to function properly
  • These waste materials turn into toxic and it leads to death
Question 14.To keep your kidneys healthy for long period what questions will you ask a nephrologist/urologist?


  • How can I prevent the formation of stones in kidney
  • Does renal failure hereditary
  • What are the dietary measures to be taken for normal functioning of kidney
  • How diabetes harm kidneys
  • What shall I do to keep my kidneys healthy for a long time
  • What are the factors responsible for kidney failure
  • How can we know that there is a problem In the kidneys
  • Is there any relationship between blood pressure and kidney function
  • What are the signs of kidney failure
  • Why is smoking bad for kidneys
Question 15.What are the gum yielding trees in your surroundings? What procedure you should follow to collect gum from trees?

Answer: In our surroundings neem, acacia, eucalyptus, sapota are some of the gum yielding plants

Process of collecting gum from trees:
  • Gum will flow naturally from cracks in the bark of acacia and neem trees
  • Gum is collected about four weeks after stripping and can be repeated every few weeks thereafter for several months
  • Mature plants are selected for taking gum
  • Suitable stem parts are selected
  • Grooves are made by break the bark away about three foot from the ground and 10 inches wide with a sharp sickle or knife
  • We can fit a container at the lower end tightly, so that when gum begins to seep out, it will drip into it
  • The plants are to be kept undisturbed for at least two or three weeks
  • When the container is seen filled with gum they are removed
  • It is collected and stored for supply and used as adhesives, binding agents, in the preparation of medicines etc
  • Break some shallow notches in a V shape, with the point of the V diectly above the centre of the bucket
  • Leave the bucket attached to the tree until the gun begins to seep out and drains into it
  • Remove any nails or other metal things from the tree and after taking down the gum collection bucket
Question 16.Collect the information about uses of different kinds of alkaloids, take help of Library or Internet?

Answer: Common alkaloids in plants and their uses are

Alkaloid Plant Part Uses
Quinine Cinchona officinalis (Cinchona) Bark Antimalarial drug
Nicotine Nicotiana tobacum (Tobacco) Leaves Insecticide
Morphine, Cocaine Papaver somniferum (Opium) Fruit Pain killer
Reserpine Rauwolfia serpentiana (Snake root) Root Rauwolfia serpentiana (Snake root)
Caffeine Coffea Arabica (Coffee plant) Seed Central nervous system stimulant
Nimbine Azadirachta indica (neem) Azadirachta indica (neem) Antiseptic
Scopolamine Datura stramonium Fruit, Flower Sedative
Pyrethroids Tridax Flower Insecticides
Ephedrine Ephedra species Leaves, Stems Relieves the discomfort of common cold, sinusitis, hay fever, bronchial asthma
Caffeine Erythroxylon coca Leaves Anesthetic
Tubocuranine Chondrodendron tomentosum Bark Muscle relaxent in surgery
Vincristine and Vinblastine Vinca rosea Leaves, flowers Chemotherapy agent in treatment of many types of cancer
Mescaline Anhalonium species Dried parts of the plant Hallucinogenic
Psilocybine Psilocybe Mexicana Dried pulve -rised fruit bodies Hallucinogenic (usually arising from a disorder of the nervous system)
Coniine Conium maculatum All plant parts Active ingredient in poison hemlock
Strychnine Strychnos species Dried ripe seeds Powerful poison
Question 17.Draw a neat labelled diagram of L.S of kidney
(OR) Draw a neat labelled diagram of internal structure of Kidney. Write the function of Renal artery and Renal vein.


  • Renal artery supplies oxygenated blood with nitrogenous waste - products to kidneys
  • Renal vein collects nitrogenous waste free and deoxygenated blood from kidneys
Question 18.Draw a diagram of a Nephron, and explain its structure?
Describe the structure of nephron with the help of diagram. (OR)

Answer: Structure of the Nephron

Each Nephron has basically two parts:
  • Malpighian body
  • Renal tubule
  • Malpighian Body
  • It consists of Bowmans capsule and bunch of fine blood capillaries called the glomerulus
  • Glomerulus develops from afferent arteriole. It gives rise to an efferent arteriole
  • Renal Tubule
  • It has three parts
  • Proximal Convoluted Tubule (PCT)
  • Loop of Henle
  • U shaped second or Distal Convoluted Tubule (DCT)
  • Distal convoluted tubule open into a COLLECTING TUBE. Collecting tubes form PYRAMIDS and CALYCES which open into PELVIS
  • Pelvis leads into the URETER
  • All the parts of the renal tubule are covered by a network of PERITUBULAR CAPILLARIES fromed from EFFERENT ARTERIOLE
  • The peritubular capillaries join to form RENAL VENULE, which joins the other venules to form RENAL VEIN
  • Question 19.Draw a block diagram showing the path way of excretory system in human being?

    Answer: Block diagram showing the path way of excretory system in human beings.

    Question 20.If you want to explain the process of filtration in kidney, what diagram you need to draw ?


    Question 21.List out the things that makes you amazing in excretory system of human being?
    (OR) How do you appreciate the functioning of excretory system of human being?


    • In human beings during metabolic activities many waste products like water, nitrogenous compounds like ammonia, urea, uric acid, bile pigments, excess salts, etc. the toxic wastes are produced
    • To excrete all these waste materials in human beings there is an excretory system consisting of a pair of kidneys, a pair of ureters, urinary bladder and urethra
    • Each kidney is made up of more than one million nephron. These are the structural and functional units of excretory system
    • Per day 170 litres of water is filtered by kidneys. Out of this 168.2 litres is reabsorbed. This is a wonderful mechanism
    • Total amount of urine excreted per day is about 1.6 to 1.8 litres
    • The kidneys have a great reserve power. If one kidney is removed due to disease or damage, the other kidney can take up the function of both the kidneys
    • It is so amazing that the 10 cm in length, 5-6 cm in breadth and 4 cm thickness size of the kidney can do filtration of blood and can remove all the poisonous substances from the human body and keeping the organism healthy
    • Skin is also an excretory organ responsible for elimination of wastes in the form of sweat along with various toxins
    • Question 22.You read about Brain dead in this chapter. What discussions would you like to have? Why do you think so?


      • When some one is brain dead, there is no blood flow or oxygen to their brain
      • The brain stops functioning in any capacity
      • Because the ventilator is breathing for the person organs such as the heart and liver continue to receive oxygen and one able to function for a few days after the brain has dead
      • Unless damaged by injury we can transplant organs like kidney liver, heart, lungs, pancreas, skin, bone, intestine and eyes (Retina) from brain dead patients
      • The process of transplantation of organs from brain dead patients to another is called cadaver transplantation
      • There is very less awareness among people about organ donation
      • Society needs much awareness in organ donation so that we can save many lives who are in need of different organs for their survival
      • Those who are willing to donate their organs have to sign in an application form at the transplantation facility hospital
      • Some voluntary organisations like working on this aspect
      Question 23.We the people have very less awareness about organ donation, to motivate people to write slogans about organ donation

      Answer: Slogans about organ donation

      • Organ donation saves lives
      • Give a life, gift of life
      • Donate organs today for better tomorrow
      • The measure of a life, after all is not its duration but its donation
      • Change your thoughts and you change your world
      • Organ donation is icky (disagreeable) but recycle yourself is sticky
      • What you have seen?
      • Have a heart, save a life
      • The gift of life pass it on
      • Organ donation is a gift for life
      Question 24.After learning this chapter what habits you would like to change or follow for proper functioning of kidneys?
      (OR) What habits you would like to follow for the proper functioning of kidneys?


      • I always eat the home cooked meals
      • I should adapt to take low salt diet
      • I eat the food that are lower in protein which can help to decrease the levels of protein, avoid eating cakes, pies, cookies, candies and pastries (junk foods), take fruits containing simple carbohydrates
      • I would like to drink sufficient water nearly 5-6 litres per day.
      • I never forget drinking more water after meals
      • I avoid taking high phosphorus foods like cheese, cola, soft drinks, butter but I replace them with butter milk, sharbat etc
      • I eat low potassium levels fruits like apples, watermelon, cucumber, grapes, cherries, carrots, etc. because high potassium levels cause irregular heart beats
      • I avoid high sodium contents like potato chips, bacon (cured meat from pig) cheese, meat, canned vegetables, caned soups frozen dinners and table salt, which damage kidneys
      Fill in the blanks.
    • Earthworm excretes its waste material through ----
    • The dark coloured outer zone of kidney is called ----
    • The process of control of water balance and ion concentration within organism is called ----
    • Reabsorption of useful product takes place in ---- part of nephron
    • Gums and resins are the ---- products of the plants
    • Bowmans capsule and tubule taken together make a ----
    • The alkaloid used for malaria treatment is ----
    • The principle involved in dialysis is ----
    • Rubber is produced from ---- of Heavea braziliensis
    • ---- performed first Kidney Transplantation


    • nephridia
    • cortex
    • osmoregulation
    • tubular
    • secondary metabolic
    • malphigian tubule
    • quinine
    • Osmosis and filtration
    • latex
    • Dr. Charles Hufnagel
      • Choose the correct answer. 1.
        The structural and functional unit of human kidney is called [ ]
        • Neuron
        • Nephron
        • Nephridia
        • Flame cell

        Answer: B

        The excretory organ in cockroach [ ]
        • Malpighian tubules
        • Raphids
        • Ureters
        • Nephridia

        Answer: A

        Which of the following is the correct path taken by urine in our body? [ ]
        • Kidney, urethra, ureters, bladder
        • Kidney, ureters, bladder, urethra
        • Kidney, bladder, ureters, urethra
        • Kidney, urethra, bladder, ureters

        Answer: C

        Malpighian tubes are excretory organs in [ ]
        • Earthworm
        • Housefly
        • Flatworm
        • Hen

        Answer: B

        Major component of urine is [ ]
        • Urea
        • Sodium
        • Water
        • Creatine


        Special excretory organs are absent in [ ]
        • Birds
        • Amoeba
        • Sponges
        • A and B

        Answer: B

        Which of the following hormones has direct impact on urination? [ ]
        • Adrenal
        • Vasopressin
        • Testosterone
        • Estrogen

        Answer: B

        Amber colour to urine due to [ ]
        • Urochrome
        • Bilirubin
        • Biliverdin
        • Chlorides

        Answer: A

        Sequence of urine formation in the nephron is [ ]
        • Glomerular filtration ? Tubular reabsorption ? Tubular secretion
        • Tubular reabsorption ? Tubular secretion ? Glomerular filtration
        • Tubular secretion ? Glomerular filtration ? Tubular reabsorption
        • Tubular reabsorption ? Concentration of urine ? Tubular secretion

        Answer: A

        Part of the nephron that exists in outer zone of kidney [ ]?
        • Loop of the Henle
        • PCT
        • DCT
        • Bowmans capsule

        Answer: D

        After having lunch or dinner one can feel to pass urine, because of [ ]
        • Stomach pressures on bladder
        • Solids become liquids
        • Water content in food material
        • Sphincter relaxation

        Answer: D

        10th Class Biology 4th Lesson Excretion - The Wastage Disposing System InText Questions and Answers

        10th Class Biology Textbook Page No. 75
        Question 1.What products would the organism be able to take up for other activities?

        Answer: Oxygen produced in the photosynthesis process is used by all the living organisms on the earth for breathing. Without oxygen life would not be possible on the earth. No organism can survive. Carbon dioxide produced in respiration will be taken up by plants to prepare food materials, in the process of photosynthesis. Plants are called autotrophs because they produce food for ail the animals and human beings directly or indirectly

        Question 2.What are the products would cause harm to the body, if they are not removed?

        Answer: Nitrogenous compounds like ammonia, urea, uric acid, bile pigments, excess salts are toxic to the body. So they should be removed

        Question 3.What happens if harmful products are not removed from our body every day?

        Answer: If harmful products are not removed from our body they get accumulated in the body and becomes toxic. This leads to the death of the person

        Question 4.What are the substances present in blood?

        Answer: The substances present in blood are Glucose, Sodium, Potassium, Chlorides, Urea, Creatinine, Uric acid, Cholesterol, Triglycerides, Calcium Phosphorous, Bilirubin, Proteins, Albumin

        Question 5.What are the substances present in urine?

        Answer: Protein, Creatinine, Calcium, Phosphorous, Uric acid, Sodium, Potassium are the sub-stances present in urine

        Question 6.What are the substances present both in blood and urine?

        Answer: Sodium, Potassium, Chlorides, Urea, Uric acid, Calcium, Phosphorous are the sub¬stances present in blood and urine in common

        Question 7.Which substances are present above the normal limits both in the blood and urine?

        Answer: Urea, Uric acid, Cholesterol, Calcium, Creatinine are present above the normal limits both in the blood and urine

        Question 8.What do you think reading above normal limits indicates?

        Answer: If any material is above the normal limits, it causes health problem which leads to a disease and damage of the organs

        10th Class Biology Textbook Page No. 77
        Question 9.What are the materials needed to be removed from our body?

        Answer: Carbon dioxide, water and nitrogenous compounds such as ammonia, urea and uric acid are the waste materials needed to be removed from our body

        Question 10.From where are these materials removed?

        Answer: Carbon dioxide is eliminated through lungs while small amounts of water is eliminated through body surface (sweating) and through lungs during respiration. An excretory organ system is present for excreting the nitrogenous wastes along with salts, excess water

        Question 11.What are the organs that separate excretory materials?

        Answer: Flame cells in flat worms, Nephridia in Annelids, Malphigian tubules in Arthropods, kidneys in all vertebrates are the excretory organs that separate excretory materials and eliminate them

        Question 12.Why do you think the body must remove waste substances?

        Answer: For the smooth functioning of the body the body should be healthy. Waste materials are the toxic substances, which are harmful to the body. So they should be eliminated. If they remain in the body, it leads to the unhealthy conditions to the organisms

        10th Class Biology Textbook Page No. 79
        Question 13.Think why the diameter of the efferent arteriole is less than that of afferent arteriole?

        Answer: The diameter of the efferent arteriole is less than afferent arteriole so as to create pressure in the glomerulus to filter the waste materials. Due to this, blood remains in glomerulus more time

        Question 14.Why the nephron is considered to be the structural and functional unit of the kidney?


        • The kidney is made up of more than one million nephrons
        • Hence it is called as the structural unit of the kidney
        • Filtration of blood to remove nitrogenous substances occur in nephron
        • So it is called as functional unit of the kidney
        10th Class Biology Textbook Page No. 80
        Question 15.Which arteriole has more diameter, afferent or efferent?

        Answer: Afferent arteriole has more diameter than efferent arteriole

        Question 16.What are the substances that are filtered into the glomerular capsule?

        Answer: The substances that are filtered into the glomerular capsule are waste molecules, nutrient molecules and water

        Question 17.If you drink more water, will you pass more urine?

        Answer: Yes. If we drink more water, we will pass more urine

        Question 18.What are the substances reabsorbed into peritubular network from Proximal Convoluted Tubule (PCT)?

        Answer: Glucose, Amino acids, Vitamin - C, Potassium, Calcium, Sodium chlorides and 75% of water are the substances reabsorbed into peritubular network from proximal convoluted tubule

        Question 19.What are the substances that secretes into Distal Convoluted Tubule (DCT)?

        Answer: The substances that secretes into Distal Convoluted Tubule are extra salts, ions of K Na+, C/" and H+ ions

        10th Class Biology Textbook Page No. 81
        Question 20.Why more urine is produced in winter?


        • Due to the cold condition, our body does not lose the water in the form of sweat
        • In the same condition, blood flow to our internal organs is increased, to keep our organs warm
        • The increase in the blood flow to the kidneys causes more blood to be filtered
        • These two causes more urine is produced in winter
        Question 21.What happens if reabsorption of water does not take place?

        Answer: If reabsorption of water does not take place

        • water levels decreases in the body and leads to malfunctioning of metabolism
        • osmoregulation of body fluids will be disturbed
        • circulation of blood does not take place due to increase in its concentration
        • the useful substances like nutrients, salts, hormones, vitamins are not absorbed they excrete out
        10th Class Biology Textbook Page No. 83
        Question 22.What happens if both kidneys fail completely?


        • Complete and irreversible kidney failure is called End Stage Renal Disease (ESRD)
        • If kidneys stops working completely, our body is filled with extra water and waste products
        • This condition is called UREMIA
        • Our hands or feet may swell. We may feel tired and weak because our body needs clean blood to function properly
        • The solution to this problem is either dialysis or kidney transplantation
        10th Class Biology Textbook Page No. 84
        Question 23.Is there any long term solution for kidney failure patients?

        Answer: The best long term solution for kidney failure is kidney transplantation. A functioning kidney which is a good match to the body is used in transplantation from a donor preferably a closed relative

        Question 24.Where is the transplanted kidney fixed in the body of a kidney failure patient?

        Answer: Kidney transplantation involves placing a healthy kidney into the body where it can perform all of the functions that a failing kidney cannot. The new kidney is placed on the lower right or left side of the abdomen where it is surgically connected to nearby blood vessels. Placing the kidney in this position allows it to be easily connected to blood vessels and the bladder. The vein and the artery of the new kidney are attached to the bodys vein and artery. The new kidneys ureter is attached to the bodys bladder to allow urine to pass out of the body.

        Question 25.What about the failed kidneys?


        • In most cases the old kidneys will not be removed
        • This is because even failed kidneys release chemicals that help the body work
        • However if those kidneys have a disease that cause on going problems such as persistent kidney infections or intestinal blockage, then the transplantion would be considered removing the old kidney
        • The two most common medical conditions requiring "native nephrectomy" or "congenital reflux" disease and polycystic disease
        Question 26.Can donor survive his / her life with single kidney without any complications?


        • There are some risks
        • There is a chance of affecting his/her life spn or life style is extremely low with surgery and anaesthesia
        • The risk of minor complications like wound infection because the kidney donar operation is a major surgical procedure
        • Donar feels less energy and need about 4 to 6 weeks to return to their activities
        Question 27.hat are the other excretory organs of human body?

        Answer: Lungs, Skin, Liver are the other excretory organs of human body. 10th Class Biology Textbook Page No. 85

        Question 28.Collect information on sebum and prepare a news bulletin, display it on bulletin


        • Sebum is a complex mixture of naturally produced fats, oils, waxes, cholesterol etc
        • It is secreted by SEBACEOUS glands present in the DERMIS of skin
        • The fat and OMS present in the sebum do not originate directly from the fats and oils consumed in the diet
        • SEBUM is manufactured and stored by the sebaceous glands under the direction of biological process
        • Sebaceous glands are found in great number on the face, scalp and on all parts of the skin
        • The function of sebum : it prevent the skin from becoming dry
        Question 29.People in cold countries get very less/no sweat. What changes occur in their skin and in other excretory organs?


        • Regulation of body temperature is one of the functions of skin
        • To maintain the body temperature, skin produces sweat
        • In cold countries environment is very cool. So there is no production of sweat
        • In these conditions there will be more pressure on other excretory organs
        10th Class Biology Textbook Page No. 86
        Question 30.Do plants excrete like animals?


        • Plants do not have specific organs to excrete the waste materials which are formed during metabolism
        • As in animals carbon dioxide, water, ammonia and other nitrogenous wastes are also formed in plants
        • In plants, carbon dioxide released during respiration is sent out through stomata of leaves
        • Plants discharge the excess water in the form of water vapour during transpiration by leaves. Due to this, the heat in the plants is reduced
        • In germinating seeds carbon dioxide formed during respiration is released into atmosphere
        • Plants have the capacity to utilise the by- products of one metabolic activity as the raw materials for another metabolic activity
        • For example, oxygen released during photosynthesis is utilised for respiration; carbon dioxide released during respiration is utilised for photosynthesis. Plants convert nitrogen and ammonia into nitrates
        Question 31.How do plants manage or send out waste products from its body?


        • Plants can get rid of excess water by a process like transpiration and guttation. Waste products may be stored in leaves, bark and fruits
        • When these dead leaves, bark, and ripen fruits fall off from the trees, then waste products in them are got rid off
        • In some plants, waste gets stored in the fruits in the form of solid bodies called Raphides. Example : Yam (pendalam)
        • Several compounds are synthesized by the plants for their own use specially for defense
        • Several plants prepare chemicals and store them in shoots, leaves, seeds for protection against herbivores
        • Most of the chemicals are unpleasant to taste and hence herbivores do not prefer to eat such plants. Some of the chemicals are toxic and may even kill the animal that eats them
        • Some of the plants release attractants for other organisms which will help the plants for pollination. For example, plants having root nodules secrete chemicals to attract rhizobia into the surroundings of the roots and form a symbiotic relationship with the rhizobium
        10th Class Biology Textbook Page No. 87
        Question 32.Why do plants shed their leaves and bark periodically?


        • In summer season, transpiration rate is very high in plants
        • To reduce the transpiration rate plants shed their leaves
        • And some waste materials are also stored in leaves and removed by shedding of leaves
        • Bark is the outer zone of plants, which contain phloem to transport food materials
        • In the growing period cambium produces bark tissue. When new bark tissue is produced, the old bark is removed
        • In this process the old and dead cells filled with waste materials are also removed
        Question 33.Name the alkaloids which are harmful to us

        Answer: The harmful alkaloids are :

        • Nicotine is harmful. It causes cancer to lung, throat, tongue and affects the nervous system
        • Morphine which is used as a pain killer, may effect kidneys if they are used more
        • Cocaine, scopolamine (Datura) etc are the alkaloids which are harmful to us
        • Nitrogenous substances are also found in the walls of pollen grain, if they enter our body. Ex : they cause allergy
        10th Class Biology Textbook Page No. 89
        Question 34.Do roots secrete?

        Answer: Yes, roots also can secrete a portion of their peculiar secretions back into the soil

        Question 35.Do you think is there any relation between reduction in yielding and root secretions?


        • Yes, there is a relation between reduction in yielding and root secretions
        • For example plants like apple where a single apple crop is yielded for 4 or 5 years continuously in the same soil, it fails to produce fruits
        • It will not give proper yield even if you use lot of fertilizers
        Question 36.Why do we get peculiar smell when you shift the potted plants?


        • Some peculiar secretions are secreted and sent out from roots into soil
        • When we shift the potted plant we get peculiar smell due to the chemical reaction of the secretion in the soil to make it fertile
        Think and Discuss 10th Class Biology Textbook Page No. 82
        Question 1.Do cells need excretion?

        Answer: Yes, the cells need excretion to keep all the body organs healthy

        Question 2.Why are we advised to take sufficient water ?

        Answer: We are advised to take sufficient water because filtration of waste products becomes easy and there is a free flow of urine including salts, And also body temperature will be maintained

        Question 3.Why do some children pass urine during sleep at night until 15 or 16 years of age?

        Answer: Children pass urine during sleep at night because one or more of the following reasons

        • The childs urinary bladder is maturing more slowly than usual. The capacity of the bladder may be reduced
        • The risk of child passing urine in night time is due to the hereditory factor that one or both parents wet the bed as children
        • Some children wet the bed because they do not make enough levels of vasopressin which reduces the urine production
        • Physical or emotional problems may cause bed wetting
        • A stressful situation can trigger bed wetting include moving to a new house, changing schools, the death of a loved one or being sexually given bad effect
        10th Class Biology Textbook Page No. 84
        Question 4.Why are weeds and wild plants not affected by insects and pests? (OR) Ravi went to his cotton field. There he observed some of the cotton leaves were affected by insects. He also observed that weeds in between are not affected. Give reasons?

        Answer: Some plants like weeds and wild plants prepare chemicals which are unpleasant to taste and some chemicals are toxic and may even kill. So insects and pests do not touch them

        10th Class Biology 4th Lesson Excretion - The Wastage Disposing System Activities

        Activity - 1
        How do you study the external and internal features of kidney ? (OR) Explain the procedure and observations of the experiment conducted to observe internal structure of the kidney

        Answer: Aim: Studying the external and internal features of a kidney. Materials required: Freshly collected specimen of sheep/goats kidney from the butcher or 3D model of a kidney sharp blade/ scalpel, tray and a jug of water

        Procedure for observation:
        • Wash the kidney so that blood is completely drained from it.
        • Put the kidney in the tray and observe it carefully
        • Note down the observation in the notebook
        • With the help of sharp blade take the longitudinal section of the kidney and observe internal structure
        • Draw what you have observed and compare it with the figure given
        • After observing the L.S. of kidney answer the following questions given under
        What is the shape of kidneys?

        Answer: The shape of kidneys is bean shape

        What is the colour of kidney ?

        Answer: Colour of kidney is reddish brown

        Do you find any attachments on upper portion of kidney?

        Answer: Yes. Adrenal glands are attached to kidneys on upper portion

        Is the internal structures similar to fig - 2?

        Answer: Yes. It is similar to internal structure of fig - 2

        What is the colour of the outer part in L.S. of kidney?

        Answer: The colour of the outer part of the kidney is Dark

        In L.S. of kidney where do you find dark brown colour portion?

        Answer: Dark colour portion is found on the outer zone of kidney

        How many tubes are coming out from kidney fissure ?

        Answer: Two tubes are coming from kidney

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