KnowledgeBoat Logo
OPEN IN APP

Chapter 9

Excretory System in Humans

Class 7 - Living Science Biology Ratna Sagar


Check your progress

Question 1

The organs that help our body to get rid of waste are called respiratory organs.

Answer

False

Corrected Statement — The organs that help our body to get rid of waste are called excretory organs.

Question 2

Liver produces bile pigment from the haemoglobin of dead RBCs.

Answer

True

Question 3

Each kidney contains millions of microscopic filtering units called ureters.

Answer

False

Corrected Statement — Each kidney contains millions of microscopic filtering units called nephrons.

Question 4

The Bowman's capsule and glomerulus together form the Malpighian body.

Answer

True

Question 5

Water is reabsorbed by the renal blood capillaries during filtration.

Answer

True

Tick the most appropriate answer

Question 1

Nitrogenous waste products are removed through

  1. lungs
  2. kidneys
  3. sweat glands
  4. liver

Answer

kidneys

Reason — Nitrogenous waste products like urea, ammonia and uric acid are removed through kidneys.

Question 2

The opening at the bottom of the urinary bladder is called

  1. nephron
  2. uriniferous tubule
  3. urethra
  4. nephridia

Answer

urethra

Reason — A tube-like opening at the bottom of the urinary bladder through which urine is passed out is called urethra.

Question 3

The functional unit of a kidney is called

  1. nephron
  2. glomerulus
  3. uriniferous tubule
  4. ureter

Answer

nephron

Reason — Each kidney contains millions of filtration units called nephrons.

Question 4

The Bowman’s capsule and glomerulus together form the

  1. urinary body
  2. renal tubule
  3. Malpighian body
  4. urinary tubule

Answer

Malpighian body

Reason — The Bowman’s capsule is a cup shaped structure at one end of nephron inside which there is a network of blood capillaries called glomerulus. These form Malpighian body.

Question 5

Blood containing waste material enters the kidneys through the

  1. renal artery
  2. renal vein
  3. portal artery
  4. portal vein

Answer

renal artery

Reason — Blood containing waste material enters the kidneys through the renal artery.

Question 6

Urinary tract infections occur due to

  1. E. coli
  2. Azotobacter
  3. Lactobacillus
  4. Nitrosomonas.

Answer

E. coli

Reasons — E. coli causes Urinary tract infections when it enter the urinary tract through urethra.

Fill in the blanks

Question 1

............... produces bile pigments from the haemoglobin of broken RBCs.

Answer

Liver produces bile pigments from the haemoglobin of broken RBCs.

Question 2

............... are a pair of reddish-brown, bean-shaped structures that lie on the either side of the backbone.

Answer

Kidneys are a pair of reddish-brown, bean-shaped structures that lie on the either side of the backbone.

Question 3

Urine contains ..............., ............... and ............... as nitrogenous waste.

Answer

Urine contains ammonia, uric acid and Urea as nitrogenous waste.

Question 4

............... carries urine from the kidney to the urinary bladder.

Answer

Ureter carries urine from the kidney to the urinary bladder.

Question 5

The network of blood capillaries inside the Bowman's capsule is called ............... .

Answer

The network of blood capillaries inside the Bowman's capsule is called Glomerulus.

Differentiate between

Question 1

kidneys and urinary bladder

Answer

Sl.
No.
KidneysUrinary Bladder
1.Kidneys are a pair of reddish-brown bean-shaped structures.Urinary Bladder is a pouch-like muscular structure located in the lower abdomen.
2.Kidneys filter the impure blood and produce urine.Urinary Bladder temporarily stores urine.

Question 2

ureter and urethra

Answer

Sl.
No.
UreterUrethra
1.Ureters are the narrow tubes that lead out from each kidney.Urethra is a tube-like opening at the bottom of the urinary bladder.
2.Ureter carry the urine from the kidneys to the urinary bladder.Urine is passed out through Urethra.

Question 3

Bowman’s capsule and glomerulus

Answer

Sl.
No.
Bowman's CapsuleGlomerulus
1.The cup-shaped structure present at one end of Nephron is called Bowman's capsule.The network of Blood Capillaries inside the Bowman's capsule is called Glomerulus.
2.It absorbs small solutes and water from blood.The impure blood flows through it.

Question 4

filtration and reabsorption.

Answer

Sl.
No.
FiltrationReabsorption
1.Filtration is the first step of process of urine formation.Reabsorption is the second step of process of urine formation.
2.It involves filtration of water and small solutes in the Bowman's capsule.In reabsorption, water and useful solutes are reabsorbed by renal blood capillaries from the filtrate of the filtration process.

Question 5

secretion and excretion.

Answer

Sl.
No.
SecretionExcretion
1.This is the third step of urine formation.This is the final step of urine formation.
2.After reabsorption, some ions are added to the filtrate to form urine. This is called secretion.In excretion, urine formed in the kidneys is collected in the urinary bladder and once it is full, urine is passed out through the Urethra.

Find the odd one out. Give reasons for your choice

Question 1

ureter, kidney, urinary bladder, lung, urethra

Answer

Lung

Reason — Lung is a part of respiratory system while others are parts of excretory system.

Question 2

skin, heart, lung, liver, kidney

Answer

Heart

Reason — Heart is part of circulatory system while others organs are part of the excretory system.

Question 3

urea, salts, blood, carbon dioxide, bile

Answer

Blood

Reason — Except blood, all are waste materials.

Question 4

filtration, respiration, secretion, excretion, reabsorption

Answer

respiration

Reason — Except respiration, all are steps of urine formation.

Answer the following in short

Question 1

Why do we need to remove waste products from our body from time to time?

Answer

We need to remove waste products from our body from time to time because they may become toxic or poisonous if allowed to accumulate inside the body.

Question 2

List the types of excretory products in humans.

Answer

The types of excretory products in humans are:

  1. Nitrogenous waste products
  2. Extra salts
  3. Bile pigments
  4. Excess Vitamins
  5. Carbon dioxide and water

Question 3

What are the two distinct regions shown in the longitudinal section of a kidney?

Answer

The two distinct regions shown in the longitudinal section of a kidney are:

  1. Outer dark region called Cortex.
  2. Inner lighter region called Medulla.

Question 4

What is a urinary tract infection?

Answer

Urinary tract infection (UTI) is an infection that occurs in the urinary system due to bacteria such as E. coli. The infection starts at the opening of urethra but can spread to urinary bladder and kidney.

Question 5

What causes kidney stones?

Answer

When the urine becomes concentrated and contains more Calcium Oxalate and Uric acid, the dissolved material stick together forming a mass known as kidney stones. These are formed due to less consumption of water.

Answer the following in detail

Question 1

Draw a labelled diagram of the urinary system in humans and describe each part.

Answer

The labelled diagram of the urinary system in humans is shown below:

Draw a labelled diagram of the urinary system in humans and describe each part. Excretory System in Humans, Living Science Biology Ratna Sagar Solutions ICSE Class 7.

The human urinary system consists of following parts:

  1. Kidneys — These are a pair of reddish-brown, bean-shaped structures that are located just above the waist on either side of the backbone. They filter the impure blood and produce urine.
  2. Ureters — These are narrow tubes that lead out from each kidney. These tubes carry urine from the kidneys to the urinary bladder.
  3. Urinary bladder — It is a pouch-like muscular structure in which urine is stored temporarily. In an adult male, the average capacity of the urinary bladder varies from 150 to 300 mL.
  4. Urethra — It is a tube-like opening at the bottom of the urinary bladder through which urine is passed out.

Question 2

Explain the structure of a nephron with the help of a diagram.

Answer

A nephron is the functional unit of a kidney. Each nephron consists of a cup-shaped structure at one end called the Bowman's capsule. It extends into a long urinary tubule that is surrounded by a network of renal capillaries. The urinary tubules of nephrons in each kidney join to form a common tube called the ureter. Inside the Bowman’s capsule, is a network of blood capillaries called glomerulus. The Bowman’s capsule and glomerulus together form the Malpighian body.

Below diagram shows the structure of a nephron:

Explain the structure of a nephron with the help of a diagram. Excretory System in Humans, Living Science Biology Ratna Sagar Solutions ICSE Class 7.

Question 3

Describe the process of urine formation.

Answer

The process of blood filtration by kidneys and urine formation can be explained in the following steps:

  1. Filtration — The renal artery brings the blood containing waste material to the kidneys. It then enters the glomerulus under high pressure. Water and small solutes are filtered in the Bowman’s capsule.
  2. Reabsorption — The filtrate passes through the thin walls of the Bowman’s capsule into the urinary or renal tubule. As it passes through the tubule, water and many useful substances are reabsorbed by the renal blood capillaries.
  3. Secretion — The remaining liquid, along with waste such as urea, uric acid and so on, is called urine and is collected in the urinary bladder.
  4. Excretion — Urine leaves the kidneys and passes into the urinary bladder through the ureters. When the urinary bladder is full, urine is passed out through the urethra.

Below diagram shows the process of urine formation:

Describe the process of urine formation. Excretory System in Humans, Living Science Biology Ratna Sagar Solutions ICSE Class 7.

Question 4

Write a short note on artificial kidneys.

Answer

Kidneys play an important role not only by filtering the blood and getting rid of waste products, but also by balancing the salt levels in the body, controlling blood pressure and stimulating the production of red blood cells. A person can lead a normal life with one kidney but when both of them stop functioning, it can prove fatal if no treatment is provided. An artificial kidney or a dialyser is a machine used to filter the blood of a patient whose kidneys are damaged. This process is called dialysis. In this process the blood is directed from veins into the dialyser through a tube connected to veins. The dialyser filters the blood and filtered blood is again directed inside the body.

Write a short note on artificial kidneys. Excretory System in Humans, Living Science Biology Ratna Sagar Solutions ICSE Class 7.

Questions 5

Give the causes and symptoms of

  1. urinary tract infection.
  2. kidney stones.

Answer

  1. Urinary tract infection
    Causes — Urinary tract infection (UTI) usually occurs when bacteria such as E. coli enters the urinary tract.
    Symptoms — Following are the symptoms of UTI:
    • a burning sensation while passing urine.
    • a frequent urge to urinate.
    • pain in the back or lower abdomen.
    • cloudy and strange-smelling urine.
    • fever-like feeling if the infection has reached the kidneys.
  2. Kidney Stones
    Causes — When urine becomes concentrated with calcium oxalate and uric acid, an accumulation of these dissolved minerals sticks together forming kidney stones. The main cause of kidney stones is lack of water in the body.
    Symptoms — Following are the symptoms of kidney stones:
    • severe pain in the sides of the abdomen
    • blood in the urine
    • nausea and vomiting
    • reduced amount of urine excreted
    • burning sensation during urination
    • persistent urge to urinate

Correct the sequence

Questions 1

Correct the sequence of the following steps to explain the process of urine formation:

  1. Blood enters the glomerulus under high pressure.
  2. The filtrate passes through the thin walls of the Bowman's capsule into the renal tubule.
  3. As the filtrate passes through the tubule, water and many useful substances are reabsorbed by the walls of the blood capillaries.
  4. Water and small solutes are filtered in the Bowman's capsule.
  5. The remaining liquid, along with waste is called urine and is collected in the urinary bladder.
  6. Blood containing waste material enters the kidneys through the renal artery.

Answer

  1. (6) Blood containing waste material enters the kidneys through the renal artery.
  2. (1) Blood enters the glomerulus under high pressure.
  3. (4) Water and small solutes are filtered in the Bowman’s capsule.
  4. (2) The filtrate passes through the thin walls of the Bowman’s capsule into the renal tubule.
  5. (3) As the filtrate passes through the tubule, water and many useful substances are reabsorbed by the walls of the blood capillaries.
  6. (5) The remaining liquid, along with waste is called urine and is collected in the urinary bladder.

Identify the organ

Question 1

Identify the organ in the picture and answer the questions that follow.

Identify the organ in the picture. Label the diagram. Excretory System in Humans, Living Science Biology Ratna Sagar Solutions ICSE Class 7.
  1. Label the diagram
  2. What kind of treatment should be given to a person in case of failure of this organ?

Answer

  1. The organ in the picture is Kidney. The labelled diagram is shown below:
Kidney labelled diagram. Excretory System in Humans, Living Science Biology Ratna Sagar Solutions ICSE Class 7.
  1. A person with failed kidneys has to undergo dialysis frequently to filter their blood.

Think and answer

Question 1

One of Maya's organs is not functioning properly. There is extra fluid build up in her body causing swelling in her ankles and feet. Read the question and circle the correct answer.

  1. Which of Maya's organs is not working properly? (brain/heart/kidneys)
  2. She should see a (nephrologist/cardiologist/neurologist).
  3. Maya most probably needs a (pacemaker/dialysis/skin graft).

Answer

  1. Kidneys
  2. Nephrologist
  3. Dialysis
PrevNext