WBBSE Class 9 Life Science Solutions Chapter 3.5 Excretion

Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.5 Excretion offer valuable context and analysis.

WBBSE Class 9 Science Chapter 3.5 Question Answer – Excretion

Very Short Questions and Answers : (1 mark for each question)

Question 1.
Name a tree, which removes excretory materials by exfoliation of bark.
Answer:
Guava tree removes excretory materials by exfoliation of bark.

Question 2.
Name a plant, which stores most of its excretory matters in leaves.
Answer:
Tea plant stores most of its excretory matters (tannin, theine) in leaves.

Question 3.
Which type of plant excretory substance is disposed through skin of orange?
Answer:
Volatile oil or essential oil is disposed through skin of orange.

Question 4.
What is clove oil?
Answer:
Clove oil is an essential oil excreted by cloves.

Question 5.
Name a medicinally important plant, which disposes its excretory matters through bark.
Answer:
Arjun (Terminalia arjuna) tree disposes its excretory matters through bark.

Question 6.
Which economically important material is excreted from Hevea brasiliensis?
Answer:
Latex of Hevea brasiliensis is the economically important excretory material used to prepare commercial rubber.

Question 7.
Name the plant, whose latex is taken as a supplement of milk.
Answer:
Latex of Brosimum galactodendron is taken as a supplement of milk by the people of Venezuela.

Question 8.
Name a water-soluble non-nitrogenous excretory material of plant.
Answer:
Gum is a water-soluble non-nitrogenous excretory material of plant.

Question 9.
Which part of Rauvolfia plant is the source of reserpine?
Answer:
Root of Rauvolfia plant is the source of reserpine.

Question 10.
From which part of cinchona plant is quinine extracted?
Answer:
Quinine is extracted from the bark of cinchona plant.

Question 11.
What is the source of atropine?
Answer:
Leaves and roots of Atropa belladonna are the sources of atropine.

Question 12.
Which type of plant excretory matters are insoluble in water but most have great medicinal importance?
Answer:
Alkaloids are insoluble in water but most have great medicinal importance.

Question 13.
Name the plant whose excretory material is used for preparing varnish.
Answer:
Excretory material of pine tree is used for preparing varnish.

Question 14.
Name an edible plant excretory matter.
Answer:
Camphor is an edible plant excretory matter.

Question 15.
Name a plant excretory matter used as a common nerve stimulant.
Answer:
Caffeine is used as a common nerve stimulant.

Question 16.
Which alkaloid is used to control hypertension?
Answer:
Reserpine is used to control hypertension.

Question 17.
Name the excretory organ of Amoeba.
Answer:
Contractile vacuole is the excretory organ of Amoeba.

Question 18.
Which is the excretory organ of annelids?
Answer:
Nephridia is the excretory organ of annelids.

Question 19.
From where do malpighian tubules collect excretory materials?
Answer:
Malpighian tubules collect excretory materials from haemolymph.

Question 20.
What is the excretory organ of prawn called?
Answer:
The excretory organ of prawn is called green gland or antennary gland.

Question 21.
What is the structural and functional unit of kidney called?
Answer:
The structural and functional unit of kidney is called nephron.

Question 22.
Which is the site of ultrafiltration in a nephron?
Answer:
Malpighian corpuscle is the site of ultrafiltration in a nephron.

Question 23.
Which portion of human excretory system stores urine for sometime inside the body?
Answer:
Urinary bladder stores urine for sometime inside the body.

Question 24.
In which organ of vertebrate animals is urine prepared?
Answer:
Urine is prepared in the kidneys of vertebrates.

Question 25.
Which branch of artery forms the glomerulus?
Answer:
Afferent renal arteriole forms the glomerulus.

Question 26.
Which arteriole comes out from the glomerulus of nephron?
Answer:
Efferent renal arteriole comes out from the glomerulus of nephron.

Question 27.
Which region of kidney possesses more number of nephrons?
Answer:
Cortical region of kidney possesses more number of nephrons.

Question 28.
Name two materials which are reabsorbed in blood from renal tubule.
Answer:
Amino acids and glucose are two materials reabsorbed in blood from renal tubule.

Question 29.
Name a vitamin which is reabsorbed from glomerular filtrate to blood.
Answer:
Vitamin C is reabsorbed from glomerular filtrate to blood.

Question 30.
Name a hormone, which controls the reabsorption of water from renal tubule.
Answer:
Antidiuretic hormone or ADH controls the reabsorption of water from renal tubule.

Question 31.
Name an excretory material, which is disposed through faeces.
Answer:
Bilirubin is excreted through faeces.

Question 32.
Which main excretory material is eliminated through lungs?
Answer:
Carbon dioxide is the main excretory material, eliminated through lungs.

Question 33.
Through which glands are the fatty excretory materials eliminated from human body?
Answer:
The fatty excretory materials of human body are eliminated through sebaceous glands of the skin.

Question 34.
How much glomerular filtrate is produced in the two kidneys of a healthy adult individual in 24 hours?
Answer:
In 24 hours, about 170 L of glomerular filtrate is produced in the two kidneys of a healthy adult individual.

Question 35.
How much urine is excreted by a healthy adult individual in 2 4 hours?
Answer:
In 24 hours, a healthy adult individual excretes about 1.5 L of urine.

Short Questions and Answers : (2 marks for each question)

Question 1.
What is meant by excretion?
Answer:
Excretion is the process by which harmful metabolic waste products are eliminated from the body of an organism in order to keep it fit and healthy.

Question 2.
Why is excretion treated as a catabolic reaction?
Answer:
By the process of excretion, different metabolic waste matters are eliminated from the body of an organism. This process reduces the dry weight of the organism. Therefore, excretion is treated as a catabolic process.

Question 3.
What is gum?
Answer:
The highly viscous, non-nitrogenous, watersoluble, carbohydrate-rich plant excretory material, produced within the plant body by conversion of cellulose, is called gum.

Question 4.
What are resins?
Answer:
Resins are solid, amorphous or semi-solid, inflammable plant excretory material, which are usually transparent or translucent and yellowish to brown in colour and are soluble in organic solvents (as ether) but not in water. Resins are secreted from injured parts of plants like pine, sal etc.

Question 5.
What are volatile oils or essential oils?
Answer:
Volatile oils or essential oils are quickly evaporating plant excretory materials having a typical odour. Volatile oils are stored in the leaves of lemon, eucalyptus, citronella, etc. and fruits of lemon, orange, etc.

Question 6.
What are alkaloids?
Answer:
Alkaloids are generally colourless, complex nitrogenous organic bases with bitter taste, occuring especially in flowering plants. Example-Morphine, quinine, reserpine etc.

Question 7.
What is latex?
Answer:
A thick, milky white fluid, excreted by many flowering plants (angiosperms), composed of a complex emulsion of proteins, alkaloids, starches, sugars, oils, tannins, resins and gums which coagulate on exposure to air, is called latex. Example-Para-rubber (Hevea brasiliensis), rubber (Ficus elastica), banyan (Ficus benghalensis), different cacti etc.

Question 8.
Mention the sourse and medicinal importance of reserpine.
Answer:
Source: Root extract of Rauvolfia serpentina or ‘sarpagandha’ plant.
Medicinal importance:

1. It is used to control hypertension.
2. Reserpine is a good nerve soother.
3. It is a good medicine for insomnia.

Question 9.
Mention the source and medicinal importance of morphine.
Answer:
Source: Fruit coat of Papaver somniferum or poppy plant.
Medicinal importance:
1. Morphine is used to treat severe pain.
2. It is a strong sedative.

Question 10.
Mention the source and medicinal importance of quinine.
Answer:
Source: Bark of cinchona plant.
Medicinal importance:
1. it is used to treat malaria.
2. It is a good medicine for intestinal disorder.

Question 11.
Mention the source and medicinal importance of caffeine.
Answer:
Source: Seeds of Coffea arabica or coffee plant.
Medicinal importance:
1. It is a good nerve stimulant.
2. It is a moderate pain killer.

Question 12.
Mention the source and medicinal impertance of daturine.
Answer:
Source: Seeds of Datura stramonium or ‘dhutura’ plant.
Medicinal importance:
1. It is used as a medicine for asthma.
2. It is used to prepare narcotic drug.

Question 13.
Mention the source and medicinal importance of atropine.
Answer:
Source: Leaves and roots of Atropa belladonna.
Medicinal importance:
1. It is used to dilate the pupil before ophthalmological investigation.
2. It also used to treat certain inflammatory conditions of the eye.

Question 14.
Mention the source and medicinal importance of theine.
Answer:
Source: Leaves of tea plant.
Medicinal importance: It is consumed as a mild nerve stimulant.

Question 15.
What is tannin? What are its sources?
Answer:
Tannin: Tannin is a bitter tasting carbon-rich material excreted by plants.
Sources of tannin: Tea leaves, haritaki and bohera fruits, stems of Acacia catechu etc.

Question 16.
Mention the source and medicinal importance of azadirachtin.
Answer:
Source: Leaves, stems and fruits of Azadirachta indica or neem plant.
Medicinal importance:
1. It is used as a good medicine to treat various skin problems.
2. It is also used as an effective pesticide.

Question 17.
Mention the source and medicinal importance of strychnine.
Answer:
Source: Seeds of Strychnos nux-vomica.
Medicinal importance: It is used as homeopathic medicine to treat digestive enzyme.

Question 18.
Mention the economic importance of gum.
Answer:
The economic importances of gum are as follows-

1. Gum is used as glue in book-binding industry.
2. It is used as a fixative of lime-based paints, inks and water-based paints.
3. Gums of some plants are used to prepare chocolates.

Question 19
Mention the economic importance of latex.
Answer:
The economic importances of latex are as follows-

1. Latex of rubber plants is the raw material used in industrial rubber, which is used to prepare all rubber material starting from vehicle tyres to pencil erasers.
2. Latex of papaya plant is a source of the protein-digesting enzymepapaine.
3. Latex of Brosimum galactodendron is consumed as a supplement of milk.

Question 20.
Mention the economic importance of resin.
Answer:
The economic importances of resin are as follows-

1. Hard resin is used as a sealing material.
2. Liquid resin is used to prepare turpentine oil.
3. Asafoetida is used as an essence for cuisines.
4. Resin of sal is used to as ‘dhuna’.

Question 21.
Mention the economic importance of tannin.
Answer:
The economic importances of tannin are as follows-

1. It is used in tannery to tan leather.
2. Tannin is used to prepare certain type of ink.
3. It is used as ‘kattha’ or ‘khair’ in betel leaf.

Question 22.
How do unicellular organisms perform excretion?
Answer:
Unicellular organisms like Amoeba, Paramoecium, Euglena etc. carry out excretion with the help of contractile vacuoles. In this process, excess water from cytoplasm enters into a small vacuole. Gradually, it swells and moves towards the periphery. Finally, it bursts and expels water and dissolved waste materials outside the body.

Question 23.
Mention the economic importance of essential oil or volatile oil.
Answer:
The economic importances of essential oil are as follows-

1. It is used to prepare essence for soap, body or hair oil and several other cosmetic items.
2. Essential oil is used to add flavour to different preparations of sweets.
3. Essential oil obtained from eucalyptus is used in pain balms.

Question 24.
How does excretion help in maintaining water balance in a living body?
Answer:
Due to the deposition of waste matters, osmotic pressure in cells changes. As a result, more water enters into the cells, that hampers their normal biological processes. By excretion, waste matters are eliminated from the cells along with water. Thus, excretion helps to maintain water balance and osmotic pressure within cells and tissues of a living body.

Question 25.
How are the metabolic wastes of plants eliminated?
Answer:
In plants, some metabolic wastes are stored in specialised cells or tissues, that are eliminated during any physical injury. Some other excretory matters are deposited in organs like leaves, fruits, barks, which plants shed naturally.

Question 26.
How do animals dispose excretory matter?
Answer:
In animals, toxic excretory products are transported from tissues to specific excretory organs by circulatory system. From these organs, metabolic wastes are eliminated from the body.

Question 27.
How do flame cells work as excretory organ?
Answer:
In animals like tapeworm, liver fluke, etc, the main excretory tube spreads fine branches inside the body, called excretory tubule. Free end of each excretory tubule bears a flame cell, with a tuft of long cilia. These cells collect metabolic wastes and release those matters in the excretory tubule. The entire excretory matters, from all those tubules, reach the main excretory duct and are disposed finally through excretory pore.

Question 28.
Mention the role of nephridium in excretion.
Answer:
Nephridium is the excretory organ of annelids, such as earthworm, leech, etc. Each nephridium (piural nephridia) has three portionsnephritides, tubule and nephridiopore. Nephrostome is a ciliated funnel-shaped end of nephridium, which collects metabolic wastes from coelomic fluid. The coiled tubule collects excretory substances from surrounding blood capillaries.
All these materials are then released outside through nephridiopore, present on the skin.

Question 29.
How do malpighian tubules work as an excretory organ of insects?
Answer:
Malpighian tubules are present as a tuft of very fine tubules, at the junction of mid-gut and hind-gut of insects. These tubules absorb nitrogenous waste matters from haemolymph (insect blood) and dispose it inside the alimentary canal. Finally, the excretory products are eliminated along with faeces of insects.

Question 30.
Distinguish between latex and alkaloid.
Answer:

Features	Latex	Alkatoid
1. General nature	Milky white fluid	Colourless, faintly yellow to dark brown, non-secretory matter
2. Chemical nature	Non-nitrogenous	Nitrogenous
3. Medicinal importance	Insignificant	High medicinal value

Question 31.
Distinguish between maipighian corpuscle and malpighian tubule.
Answer:

Features	Malpighian copuscle	Malpighian tubule
1. Occurence	At the free end of nephron of all vertebrates	At the junction of mid-gut and hind-gut of insects
2. Structure	Knob-like corpuscular structure	Fine tubular structures
3. Components	Glomerulus and Bowman’s capsule	Only a close-ended tubular structure
4. Function	Ultrafiltration of blood	Absorption of excretory matters from haemolymph

Long Questions and Answers : (5 marks for each question)

Question 1.
What is the significance of excretion?
Answer:
Significance of excretion
Excretion is an important physiological process which helps to lead a healthy life. Its significance is discussed below.
1. Maintenance of fit and healthy life: Excretion removes all toxic and harmful matters produced in the cells by various metabolic activities.
2. Maintenance of water balance: Excretion removes excess water from the cells to maintain water balance in the body.
3. Recycling of matters: By excretion, many elements, present in the waste materials, are disposed in nature. These are made available for reuse by action of decomposers.
4. Economic importance: Many plant excretory products, especially alkaloids, have certain medicinal importance. Gums, resins, tannins, latex etc. are used for industrial purposes. Some nitrogen-rich animal excretory products are used as fertilisers.

Question 2.
How do plants dispose excretory materials?
Answer:
Excretion in plants
Plants eliminate excretory products by the following processes.
1. Shedding of leaves: Trees, such as hog palm, Albizia, silk cotton etc. store excretory substances in leaves. These trees shed leaves once a year to dispose those excretory substances.

2. Exfoliation of barks: Some trees, such as guava, arjun etc. deposit waste matters in their bark. These plants naturally peel off their bark to eliminate those waste matters from time to time.

3. Shedding of fruits: Plants like lemon, apple, tamarind etc. store excretory matters, like different organic acids (eg, citric acid, tartaric acid, malic acid, etc.) or essential oils in their fruits. These matters are removed from these plants by shedding of fruits.

4. Shedding of flowers: In some plants, excretory products are stored in their flowers. These products are excreted when different parts of the flowers are shedded off. Example-Clove flower.

5. Aikaloids: Sometimes alkaloids are stored in the stems and leaves of some plants like banyan, Calotropis etc. In alkaloids different types of excretory products remain solubilised. In case of injury, these alkaloids are released outside and in this way other soluble excretory products are also relaeased.

6. Resin secretion: In the resin ducts of stem and leaves of some plants, like pine, a complex insoluble excretory product called resin is present.

7. Gum excretion: In some plants such as babul, soluble wastes are excreted in the form of gum.

8. Excretion of water: Potato, tomato etc. solubilise different excretory products in water and then excrete them with the help of hydathodes.

Question 3.
Name the non-nitrogenous excretory products of plants. Compare them. Non-nitrogenous excretory products of plants
Answer:
The non-nitrogenous excretory products of plants are gum, latex and resin.
Comparison among gum, latex and resin

Question 4.
Distinguish between excretion in plants and animals.
Answer:
Differences between excretion in plants and animals

Features	Plants	Animals
1. Definite excretory organ and excretory system	Absent	Present
2. Amount of excretory products formed	Less	More
3. Nature of excretory products	Simpler and less harmful	More complex and more harmful
4. Fate of excretory products	Mostly stored	Generally excreted from the body and partially stored in some cases
5. Reutilisation of the excretory products	Some excretory products are used in metabolism	Generally not used
6. Nitrogenous excretory product	Less	More
7. Toxicity	Less	More

Question 5.
Briefly describe the structure of human excretory system.
Answer:
Structure of human excretory system
Human excretory system consists of a pair of kidneys, two ureters, a urinary bladder and a urethra.
1. Kidneys: The kidneys are brown coloured, bean-shaped structures, positioned at either side of vertebral column, just below the ribs. The concave face of the kidney is called the pelvis. The section of kidney shows two distinct regions-outer cortex and inner medulla. A renal artery enters and a renal vein leaves each kidney through the pelvis. Numerous fine tubular structures, called nephrons, are present in kidneys, which filters blood from the specially designed renal capillaries.

2. Ureter: Ureters are two in number. Each ureter is a 35 cm long, slightly curved tube, emerging from the renal pelvis. Ureters are usually 2-4 mm in diameter. The ureters connect kidneys to the urinary bladder, present at the lower portion of the abdominal cavity.

3. Urinary bladder and urethra: Urinary bladder is a muscular sac, located at the front lower portion of the abdominal cavity. Urethra is a muscular tube that descends from the floor of the bladder. The base of urethra is equipped with sphincter muscles, which help to hold the urine inside urinary bladder.
Urine enters the urinary bladder via the ureters and leaves via urethra. The capacity of a typical human bladder is 300-500 ml.

Question 6.
Briefly describe the structure of nephron.
Answer:
Structure of nephron
A nephron has two parts-malpighian corpuscles and renal tubule.
1. Malpighian corpuscles: It is situated at the free and blind end of a nephron. This portion is composed of Bowman’s capsule and glomerulus. The free and blind end of nephron forms a cup-shaped double-walled structure, called the Bowman’s capsule. A fine branch of renal artery enters into the Bowman’s capsule as afferent arteriole. It ramifies to form a capillary network inside the capsule, where these capillaries reunite and return as efferent arteriole. It is comparatively narrower than the afferent arteriole. This capillary network is called glomerulus.

2. Renal tubule: It is a convoluted tubule, extending from the base of the Bowman’s capsule and ending in the collecting tubule. Renal tubule has three parts-proximal convoluted tubule, which starts from the base of the Bowman’s capsule; loop of Henle, which is a ‘U’-shaped loop-like structure, and distal convoluted tubule, which ultimately meets a comparatively wider collecting tubule. Several collecting ducts finally unite to form thicker ducts, called the duct of Bellini.

Question 7.
Describe the steps of urine formation in human kioney.
Answer:
Steps of urine formation in human kidney
The mechanism of urine formation in nephron involves four different phases, which are mentioned below.
1. Glomerular ultrafiltration: Due to increased blood pressure in the glomerular capillaries, water from blood plasma enters into Bowman’s capsule. This water carries different excretory materials like urea, uric acid, etc. and many essential substances like glucose, amino acids, smaller protein molecules, salts, ions, vitamins, etc. This process is known as glomerular ultrafiltration and the dilute fluid, collected in the Bowman’s capsule, is called glomerular filtrate.

2. Reabsorption: Glucose and different ions (K⁺, Na⁺. etc.) are reabsorbed in cells of renal tubule from the glomerular filtrate by active transport. Cells of proximal convoluted tubules reabsorb the small protein molecules by phagocytosis. Ions like phosphates, bicarbonates, chlorine, etc., vitamin C, amino acids and many other substances are reabsorbed by renal tubule. All these reabsorbed essential materials then return to the blood.

3. Secretion: Creatine, creatinine, hippuric acid, etc. are some excretory materials, which are secreted from the renal tubule.

4. Passive absorption of water: Excess water from the glomerular filtrate is reabsorbed by passive transport in the loop of Henle and distal convoluted tubule. Reabsorption of water is controlled by a posterior pituitary hormone, named Antidiuretic Hormone (ADH).
After these four steps, normal concentrated urine is formed in nephron, which is received by the collecting tubule and finally reach the duct of Bellini.

Question 8.
Write about the roles of the accessory excretory organs other than the kidney.
Answer:
Roles of excretory organs other than kidney