Excretion in Humans Class 7 Biology

ICSE Living Science Biology for Class 7 Solutions Chapter 7 Excretion in animals and plants

State if the following statements are true or false. Correct the statemenet if it is false.

Question 1.
The organs that help our body to get rid of waste are called respiratory organs.
Answer:
False. The organs that help our body to get rid of waste are called excretory organs.

Question 2.

Each kidney contains millions of microscopic filtering units called ureters.
Answer:
False. Each kidney contains millions of microscopic filtering units called nephrons.

Question 3.
The Bowman’s capsule and glomerulus together form the Malpighian body.
Answer:
True

Question 4.
Liver produces bile pigments from the haemoglobin of broken RBCs.
Answer:
True

A. Tick the most appropriate answer.

Question 1.
The process of removing waste from the body is callec –
a. respiration
b. excretion
c. inspiration
d. expiration
Answer:
b. excretion

Question 2.
The opening of the urinary bladder is called –
a. nephron
b. uriniferous tubule
c. urethra
d. nephridia
Answer:
c. urethra

Question 3.

A network of capillaries present in the Bowman’s capsule is called –
a. Malphigian body
b. glomerulus
c. Uriniferous tubule
d. ureter
Answer:
b. glomerulus

Question 4.

The blood vessel that supplies impure blood to a kidney is the –
a. renal artery
b. renal vein
c. portal artery
d. portal vein
Answer:
a. renal artery ‘

Question 5.
The Bowman’s capsule and glomerulus together form the –
a. urinary body
b. Malpighian tubule
c. Malpighian body
d. urinary tubule
Answer:
c. Malpighian body

Question 6.

Quinine is used in the treatment of –
a. filaria
b. dengue
c. malaria
d. paralysis
Answer:
c. malaria

Question 7.
Plants maintain the concentration of sap inside their body with –
a. respiration
b. transpiration
c. osmosis
d. absorption
Answer:
b. transpiration

Question 8.

Transpiration is affected by –
a. light and temperature
b. humidity and wind
c. wind and temperature
d. all of these
Answer:
d. all of these

B. Fill in the blanks.

Question 1
…………. 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 2.
Urine contains …………… and …………. as nitrogenous waste.
Answer:
Urine contains urea, ammonia and uric acid as nitrogenous waste.

Question 3.
carries urine from the kidney to the urinary …………. bladder.
Answer:
Ureter carries urine from the kidney to the urinary bladder.

Question 4.
Malpighian body consists of Bowman’s capsule and ………….
Answer:
Malpighian body consists of Bowman’s capsule and glomerulus.

Question 5.
…………. produces bile pigments from the haemoglobin of broken RBCs.
Answer:
Liver produces bile pigments from the haemoglobin of broken RBCs.

Question 6
………….. are present in the stem of pine tree that make the pinewood strong and durable.
Answer:
Resins are present in the stem of pine tree that make the pinewood strong and durable.

Question 7.
……………. is found in the seeds of poppy plants.
Answer:
Morphine is found in die seeds of poppy plants.

Question 8.
When air is humid, the rate of transpiration is …………..
Answer:
When air is humid, the rate of transpiration is low.

C. Differentiate between

Question 1.
ureter and urethra.
Answer:
Ureter :

• It is a tube that leads out from each kidney.
• These tubes carry urine from the kidneys of the urinary bladder.
• There are two ureters.

urethra :

• It is a canal like opening at the bottom of the urinary bladder.
• This opening excretes urine out of the body.
• There is only one urethra.

Question 2.
bowman’s capsule and glomerulus.
Answer:
Bowman’s capsule :
Each nephron of kidney consists of a cup-shaped structure at one end called tire Bowman’s capsule.

Glomerulus :
Glomerulus is a network of blood capillaries present inside the Bowman’s capsule.

Question 3.
tannins and resins.
Answer:
Tannins

• These are group of complex compounds found in the bark and leaves.
• Its presence in tea leaves makes tea taste bitter.

Resins :

• These are the secretions of many plants like coniferous trees.
• It is used in the production of varnishes and adhesives and perfumes and incense.

Question 4.
excretion and transpiration Ans.
Excretion

• It is the process of removing or getting rid of waste matter from the body.
• Excretion rate is independent of time of the day.
• All living beings have special organs called excretory organs to get red of their harmful wastes.
• It occurs both in plants and animals.

Transpiration :

• It is the process of losing excess water from aerial plant parts in the form of water vapour.
• Rate of transpiration is more during the day.
• Plants lose water through stomata and lenticels.
• It occurs only in plants.

D. Find the odd one out. Give reasons for your choice.

Question 1.
ureter, kidney, urinary bladder, lung, urethra
Answer:
lung, because all others are organs of excretory system . and it is a respiratory organ.

Question 2.
skin, heart, lung, liver, kidney
Answer:
Heart because it helps to pump blood in our body and the, rests help in excretion.

Question 3.
tannin, urine, latex, resin
Answer:
urine, because it is excretory product of animals and rests \ are excretory products of plants.

E. Answer the following in short

Question 1.
What is excretion ?
Answer:
The process of removing waste, formed as a result of chemical reactions in the body is called excretion.

Question 2.
What are the main organs involved in the human excretory system ?
Answer:
The main organs involved in the human excretory system are a pair of bean shaped kidneys, ureters from each kidney, urinary bladder, urethra.

Question 3.
What is urethra ?
Answer:
Urethra is a canal like opening at the bottom of the urinary bladder through which urine is passed out from the body.

Question 4.
List five waste products of plants.
Answer:
Tannins, resins, latex, gums, essential oils, caffeine, qiunine, morphine, etc.

Question 5.
Define transpiration in plants.
Answer:
The process of losing excess water in the form of water vapour from a living plant is known as transpiration.

F. Answer the following in detail.

Question 1.
Draw a labelled diagram of the urinary system in human beings and describe each part.
Answer:
Human beings have urinary system to eliminate nitrogenous waste products. It consists of –

• Kidneys – These are a pair of reddish-brown, bean-shaped structures that lie on either side of the backbone. They filter the impure blood and produce urine.
• Ureters – A pair of ureters are tubes that lead out from each kidney. These tubes carry urine from the kidneys to the urinary bladder.
• Urinaiy bladder – It is a pouch-like muscular structure in which urine is stored temporarily.
• Urethra – It is a canal like opening at the bottom of the urinary bladder through which urine is passed out.
  urinary bladder
  

Question 2.
Explain the structure of a nephron with the help of a diagram.
Answer:
The microscopic filtering unit of kidney is called nephron or uriniferous tubule. Each nephron consists of a cup-shaped structure at one end called Bowman’s capsule. Inside the cup is a network of blood capillaries called glomerulus. The Bowman’s capsule and the glomerulus together form the Malpighian body. The Bowman’s capsule extends into a long tubule. These tubules are surrounded by a network of renal capillaries. The urinary tubules of the nephrons in each kidney joins to form a common tube called ureter.

Question 3.
Describe the process of urine formation.
Answer:
The process of urine formation takes place in the following steps :

• Glomerular Alteration – Blood containing waste material enters the kidneys through the renal artery. It then enters the glomerulus under high pressure. Water and small solutes are filtered in the Bowman’s capsule.
• Tubular reabsorption – Filterate 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.
• Tubular secretion – The remaining liquid, along with wastes such as urea, uric acid, etc is called urine and is collected in the urinaiy bladder.
• 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.
  

Question 4.
How do skin and lungs help in excretion ?
Answer:
Skin – excretes excess water, urea, salts and other metabolic wastes in the form of sweat. These waste products are carried by the blood from all body parts to sweat glands in the skin.
Lungs – Eliminate carbon dioxide produced as a result of respiration through the nose.

Question 5.
Explain the process of transpiration. Describe some factors that effect it.
Answer:
Large quantities of water are absorbed by plants for photosynthesis and other processes. Excess of water is lost in the form of water vapour through the stomata and lenticels from the aerial parts of the plant by transpiration. It helps plants to maintain the concentration of sap inside the . plant body. If plants do not remove excess water through transpiration, the dilute sap will prevent further absorption of water and minerals from the soil.

Factors affecting rate of transpiration are :

• Sunlight – Rate of transpiration is more during the day as
  stomata are open. Stomata remain closed at night and thus no transpiration takes at night.
• Temperature – Transpiration is more on hot days than on
  cold days.
• Wind – Blowing wind removes water vapour faster from the leaves and hence transpiration rate increases.
• Humidity – If the air is humid, rate of transpiration is low. In the rainy season, transpiration is less since humidity is more.

Question 6.
Write a short note on artificial kidneys. ‘
Answer:
Artificial kidneys : Kidneys play an important role not only by filtering the blood and getting rid of waste products, but also by balancing 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 could 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.

G. Correct the sequence of the following steps to explain the process of urine formation.

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

Answer:

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

H. One of Harry’s organs is not functioning’properly. There is extra fluid build up in his body causing swelling in his ankles and feet. What should Harry do?

Tick the correct answer.

Question 1.
Which of Harry’s organs is not working properly ? (brain/heart/kidneys)
Answer:
Kidneys

Question 2.
He should see a (nephrologist/cardiologist/neurologist)
Answer:
nephrologist

Question 3.
Harry most probably needs a (placemaker/dialysis/skin graft)
Answer:
dialysis

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

Question 1.
Label the marked parts
Answer:

a → Cortex
b → Medulla
c → Renal artery (blood with waste products)
d → Renal vein (clean blood)
e → Ureter

Question 2.
What kind of treatment should be given to a person with a failure of this organ ?
Answer:
Dialysis