NCERT Exemplar Class 7 Science Chapter – 11-Transportation in Animals and Plants- (Solved with detailed explanation)
MULTIPLE CHOICE QUESTIONS
Question 1- The muscular tube through which stored urine is passed out of the body is called –
(a) kidney
(b) ureter
(c) urethra
(d) urinary bladder
Correct Answer- (c) urethra
Explanation- The urethra is the muscular tube that conveys urine from the urinary bladder to the outside of the body. The kidney filters the blood to produce urine, which is then passed to the urinary bladder via the ureters. The bladder stores urine until it is expelled from the body through the urethra.
Question 2- They are pipe-like, consisting of a group of specialised cells. They transport substances and form a two-way traffic in plants. Which of the following terms qualify for the features mentioned above?
(a) Xylem tissue
(b) Vascular tissue
(c) Root hairs
(d) Phloem tissue
Correct Answer- (d) Phloem tissue
Explanation- Phloem tissue is responsible for the transport of nutrients, particularly sugars made by photosynthesis, to all parts of the plant. This process is known as translocation and is a two-way system that distributes food from leaves to other parts of the plant. Xylem, on the other hand, mainly carries water and minerals from the roots to the rest of the plant and usually operates in one direction – upwards.
Question 3- The absorption of nutrients and exchange of respiratory gases between blood and tissues takes place in –
(a) veins
(b) arteries
(c) heart
(d) capillaries
Correct Answer- (d) capillaries
Explanation- Capillaries are the smallest blood vessels in the body’s circulatory system, and they connect arteries and veins. Their thin walls allow the exchange of nutrients, waste products, and respiratory gases (oxygen and carbon dioxide) between blood and the tissues.
Question 4- In which of the following parts of the human body are sweat glands absent?
(a) Scalp
(b) Armpits
(c) Lips
(d) Palms
Correct Answer- (c) Lips
Explanation- Sweat glands are present in the skin throughout the body except for the margins of the lips, nail beds, and the eardrums, among a few other areas. Therefore, lips do not have sweat glands.
Question 5- In a tall tree, which force is responsible for pulling water and minerals from the soil?
(a) Gravitational force
(b) Transportation force
(c) Suction force
(d) Conduction force
Correct Answer- (c) Suction force
Explanation- The suction force, generated by transpiration, pulls water and minerals from the soil. This force is due to the evaporation of water from the surfaces of leaves, creating a negative pressure that draws water upward through the xylem vessels from the roots to the top of the plants, even against gravity.
Question 6- Aquatic animals like fish excrete their wastes in gaseous form as
(a) Oxygen
(b) Hydrogen
(c) Ammonia
(d) Nitrogen
Correct Answer- (c) Ammonia
Explanation- Aquatic animals like fish typically excrete ammonia, which is highly soluble in water. This form of nitrogenous waste is less energy-intensive to produce than urea or uric acid, making it an efficient means of excretion for organisms in aqueous environments.
VERY SHORT ANSWER QUESTIONS
Question 7- Veins have valves which allow blood to flow only in one direction. Arteries do not have valves. Yet the blood flows in one direction only. Can you explain why?
Answer- The blood in arteries flows in one direction due to the pressure created by the pumping action of the heart. When the heart contracts, it pushes blood into the arteries with significant force, which maintains the unidirectional flow of blood. Additionally, the elasticity of the arterial walls helps maintain pressure on the blood between heartbeats, ensuring continuous forward movement.
Question 8- What is the special feature present in a human heart which does not allow mixing of blood when oxygen-rich and carbon dioxide-rich blood reach the heart?
Answer- The special feature that prevents the mixing of oxygen-rich and carbon dioxide-rich blood in the human heart is the presence of septa (singular- septum). The heart has a muscular wall called the septum that divides it into the right and left halves, ensuring that oxygenated and deoxygenated blood are kept separate.
Question 9- Name the organ which is located in the chest cavity with its lower tip slightly tilted towards the left.
Answer- The organ located in the chest cavity with its lower tip slightly tilted towards the left is the heart.
Question 11- Arrange the following statements in the correct order in which they occur during the formation and removal of urine in human beings.
(a) Ureters carry urine to the urinary bladder.
(b) Wastes dissolved in water are filtered out as urine in the kidneys.
(c) Urine stored in the urinary bladder is passed out through the urinary opening at the end of the urethra.
(d) Blood containing useful and harmful substances reaches the kidneys for filtration.
(e) Useful substances are absorbed back into the blood.
Answer- The correct sequence of events in the formation and removal of urine in human beings is as follows-
- (d) Blood containing useful and harmful substances reaches the kidneys for filtration.
- (b) Wastes dissolved in water are filtered out as urine in the kidneys.
- (e) Useful substances are absorbed back into the blood.
- (a) Ureters carry urine to the urinary bladder.
- (c) Urine stored in the urinary bladder is passed out through the urinary opening at the end of the urethra.
Explanation- First, blood containing both useful and harmful substances is delivered to the kidneys, where filtration occurs. The kidneys filter out waste dissolved in water to create urine while reabsorbing useful substances back into the blood. The formed urine is then transported by the ureters to the urinary bladder, where it is stored until urination occurs. During urination, urine is expelled from the bladder through the urethra.
Question 12- Paheli uprooted a rose plant from the soil. Most of the root tips, with root hairs got left behind in the soil. She planted it in a pot with new soil and watered it regularly. Will the plant grow or die? Give reason for your answer.
Answer- The rose plant may struggle to grow if most of the root tips with root hairs are left behind because root hairs are critical for water and nutrient absorption. However, if the remaining part of the root system is still healthy and capable of regenerating new root hairs, and if Paheli provides good care such as proper watering and soil with sufficient nutrients, the plant has a chance to recover and grow.
Explanation- Root hairs are important structures for a plant because they increase the surface area for absorption of water and nutrients, which are vital for the plant’s survival. If a plant loses a significant number of root hairs, it may experience stress due to reduced absorption capacity. Nonetheless, plants have the ability to regenerate lost tissues. With proper care and under suitable conditions, new root hairs can form, and the plant can resume normal growth. Regular watering and nutrient-rich soil would support this recovery process.
Question 13- (a) Name the only artery that carries carbon dioxide-rich blood. (b) Why is it called an artery if it does not carry oxygen-rich blood?
Answer- (a) The only artery that carries carbon dioxide-rich blood is the pulmonary artery.
(b) It is called an artery because arteries are defined by the direction of blood flow from the heart and not by the oxygen content of the blood they carry. The pulmonary artery carries blood away from the heart to the lungs, hence it is termed an artery despite carrying oxygen-poor blood.
Explanation- Typically, arteries carry oxygenated blood from the heart to the rest of the body, and veins carry deoxygenated blood back to the heart. However, the pulmonary artery is an exception to this rule. It carries deoxygenated, carbon dioxide-rich blood from the right ventricle of the heart to the lungs for oxygenation. The term “artery” reflects the vessel’s function of transporting blood away from the heart rather than the type of blood it carries.
Question 14- Boojho’s uncle was hospitalised and put on dialysis after a severe infection in both of his kidneys.
- (a) What is dialysis?
- (b) When does it become necessary to take such a treatment?
Answer- (a) Dialysis is a medical procedure that artificially removes waste products and excess fluid from the blood when the kidneys are no longer able to perform this function naturally.
(b) It becomes necessary to take such a treatment when an individual has kidney failure or severe kidney dysfunction, which impedes the kidneys’ ability to filter and clean the blood effectively.
Explanation- Dialysis acts as a substitute for many of the normal duties of the kidneys. It is often required when one suffers from end-stage kidney disease or temporary kidney failure, where the kidneys cannot adequately filter the blood. During dialysis, blood is circulated outside of the body through a machine that removes unwanted waste products and excess fluids, a function that healthy kidneys would typically perform. The clean blood is then returned to the body. This treatment can be life-saving and is critical for patients awaiting a kidney transplant or for those who are not transplant candidates.
Question 15- Name the process and the organ which helps in removing the following wastes from the body.
- (a) Carbon dioxide
- (b) Undigested food
- (c) Urine
- (d) Sweat
Answer-
- (a) The process of removing carbon dioxide from the body is called respiration, and the organs involved are the lungs.
- (b) The removal of undigested food is a part of the process called egestion, and the organ responsible for this is the large intestine, ending at the anus where the waste is expelled.
- (c) The process of removing urine from the body is known as excretion, and the organ which stores urine before it is expelled is the urinary bladder.
- (d) The removal of sweat is a part of thermoregulation and excretion, and the organs responsible for sweat production are the sweat glands in the skin.
Explanation- Each process and organ is specialised for handling different types of waste in the body-
- Respiration in the lungs allows for gas exchange, where oxygen is taken in, and carbon dioxide, a waste product of metabolism, is expelled.
- Egestion is the process by which the body disposes of undigested food through defecation.
- Excretion of urine is conducted by the kidneys, which filter waste from the blood, creating urine that is then stored in the urinary bladder until it can be expelled.
- Sweat glands produce sweat, which not only helps to cool the body but also removes small amounts of waste products like urea and salts.
Question 17- Paheli noticed water being pulled up by a motor-pump to an overhead tank of a five-storeyed building. She wondered how water moves up to great heights in the tall trees standing next to the building. Can you tell why?
Answer- Water moves up to great heights in the tall trees through a process called transpiration pull.
Explanation- In trees, water is absorbed by the roots from the soil and travels upwards through specialised vascular tissues known as xylem. The process driving this upward movement is largely due to transpiration, which is the evaporation of water from the leaves and other aerial parts of the plant. As water evaporates, it creates a negative pressure (suction force) within the xylem channels. This pressure differential helps to pull water up from the roots to the leaves and other parts of the plant, even against gravity. This mechanism is similar to drinking water with a straw – as you suck the air out, the liquid rises. In trees, transpiration creates a continuous water column and a pressure differential that draws water upwards from the roots to the topmost leaves.
Question 18- Match the parts of the heart in Column I with the direction of flow of blood in Column II.
| Column I | Column II |
|---|---|
| (i) Right ventricle | (a) Pushes blood into the pulmonary artery. |
| (ii) Pulmonary veins | (b) Take deoxygenated blood from the heart to lungs. |
| (iii) Left atrium | (c) Receives blood from different parts of the body. |
| (iv) Pulmonary arteries | (d) Bring oxygenated blood from lungs to the heart. |
| (v) Left ventricle | (e) Pushes blood into the aorta. |
| (vi) Right auricle | (f) Receives deoxygenated blood from the pulmonary veins |
Answer-
- (i) Right ventricle – (a) Pushes blood into the pulmonary artery.
- (ii) Pulmonary veins – (d) Bring oxygenated blood from lungs to the heart.
- (iii) Left atrium – (f) Receives deoxygenated blood from the pulmonary veins.
- (iv) Pulmonary arteries – (b) Take deoxygenated blood from the heart to lungs.
- (v) Left ventricle – (e) Pushes blood into the aorta.
- (vi) Right auricle – (c) Receives blood from different parts of the body.
Explanation-
- (i) The Right ventricle contracts to push blood into the pulmonary artery to send it to the lungs for oxygenation.
- (ii) The Pulmonary veins are the vessels that bring oxygen-rich blood from the lungs back to the heart, specifically to the left atrium.
- (iii) The Left atrium receives the oxygenated blood from the pulmonary veins.
- (iv) The Pulmonary arteries are the only arteries that carry deoxygenated blood, which they transport from the right ventricle to the lungs.
- (v) The Left ventricle is the chamber that pushes blood into the aorta, which then distributes it throughout the body.
- (vi) The Right auricle (or right atrium) receives deoxygenated blood from the body through the superior and inferior vena cava and pumps it into the right ventricle.
In the matching, some statements required slight corrections to be accurate-
- (iii) Left atrium should be matched with “Receives oxygenated blood from the lungs,” which is the function of the pulmonary veins (d) in Column II.
- (vi) Right auricle, which is another term for the right atrium, should be matched with “Receives blood from different parts of the body,” indicating its role in receiving deoxygenated blood.
Question 19- Group the following terms based on the categories given-
- root hairs
- xylem
- urethra
- arteries
- kidneys
- veins
- atria
- capillaries
- heart
- ureter
- phloem
- urinary bladder
Categories-
- (a) Circulatory system of animals
- (b) Excretory system in humans
- (c) Transport of substances in plants
Answer-
(a) Circulatory system of animals
- Arteries- These are blood vessels that carry oxygen-rich blood away from the heart to the body.
- Veins- Veins are blood vessels that carry oxygen-poor blood back to the heart.
- Atria- The two upper chambers of the heart (singular- atrium) receive blood – the right atrium from the body and the left atrium from the lungs.
- Capillaries- These are tiny blood vessels where the exchange of oxygen, carbon dioxide, and other substances between blood and tissues occurs.
- Heart- The organ that pumps blood throughout the body.
(b) Excretory system in humans
- Urethra- The tube through which urine is discharged from the bladder out of the body.
- Kidneys- Organs that filter waste from the blood and produce urine.
- Ureter- The duct by which urine passes from the kidney to the bladder.
- Urinary bladder- A muscular sac in which urine is stored before it is excreted.
(c) Transport of substances in plants
- Root hairs– They are extensions of root epidermal cells that help absorb water and nutrients from the soil.
- Xylem– Vascular tissue in plants responsible for the transport of water and dissolved minerals from the roots to the rest of the plant.
- Phloem- Vascular tissue responsible for the transport of nutrients, particularly sugars made by photosynthesis, to all parts of the plant.
Explanation- In the circulatory system of animals, the heart acts as the pump to send blood through the vessels. Arteries, veins, capillaries, and the atria of the heart are all integral components of this system. In the excretory system in humans, the kidneys filter waste from the blood to produce urine, which is then transported to the bladder via the ureters, stored, and eventually expelled through the urethra. In plants, xylem and phloem are specialised tissues that transport water, minerals, and food throughout the plant, with root hairs playing a crucial role in water and mineral uptake from the soil.
Question 20. Fill in the Blanks-
The blood vessels that carry oxygen-rich blood from the heart to all parts of the body are called _____________.
Answer- Arteries
Explanation- Arteries are the blood vessels that transport oxygenated blood away from the heart to the body’s tissues. Their thick elastic walls allow them to withstand the high pressure of blood pumped out by the heart.
The blood vessels that carry carbon dioxide-rich blood from all parts of the body back to the heart are called _____________.
Answer- Veins
Explanation– Veins are the vessels that return deoxygenated blood back to the heart. They have thinner walls than arteries and valves that ensure blood flows in only one direction towards the heart.
The blood vessels with thinner walls that allow the exchange of gases and nutrients between the blood and tissues are called _____________.
Answer- Capillaries
Explanation– Capillaries are extremely thin blood vessels where the exchange of oxygen, carbon dioxide, nutrients, and waste products between blood and body tissues occurs.
The type of blood vessels that have thick elastic walls to cope with the high pressure of blood directly pumped from the heart are called _____________.
Answer- Arteries
Explanation- Arteries have thick, elastic walls to accommodate and maintain the high pressure at which blood is pumped from the heart throughout the body.
Blood flows at high pressure in _____________.
Answer- Arteries
Explanation- The blood is under high pressure in the arteries because it is being pumped out forcefully by the heart to reach all body tissues.
The vessels that have valves to prevent the backflow of blood are called _____________.
Answer- Veins
Explanation- Veins contain valves that prevent the backflow of blood, helping maintain a one-way flow back to the heart, especially important as the pressure in veins is lower than in arteries.
The smaller vessels into which arteries divide are called _____________.
Answer- Arterioles
Explanation- Arteries branch out into smaller vessels known as arterioles, which then lead to the capillary networks that supply blood to the body’s tissues.
The vessels formed when capillaries join together are called _____________.
Answer- Venules
Explanation- Capillaries merge to form small vessels known as venules, which in turn combine to form veins, completing the circuit of blood back to the heart.
Question 21. While learning to ride a bicycle Boojho lost his balance and fell. He got bruises on his knees and it started bleeding. However, the bleeding stopped after some time.
(a) Why did the bleeding stop?
Answer- The bleeding stopped due to the blood clotting process.
Explanation- When Boojho fell and bruised his knees, the blood vessels in that area were damaged. The body responds to such injury by initiating a blood clotting process. Platelets, which are components of blood, gather at the site of injury to form a plug. These platelets release chemicals that start the clotting process, resulting in the formation of a fibrin clot which stops further bleeding.
(b) What would be the colour of the wounded area and why?
Answer- The colour of the wounded area would initially be red due to bleeding and then turn blue or purple as a bruise develops. Explanation- The red coloration is due to the presence of red blood escaping from the damaged vessels. As the bruise develops, the area may turn blue or purple due to the breakdown of haemoglobin in the clotted blood under the skin, which can lead to a discoloration as it is absorbed back into the body.
(c) Which type of blood cells are responsible for clotting of blood?
Answer- Platelets are responsible for the clotting of blood. Explanation- Platelets, also known as thrombocytes, are the type of blood cells that play a key role in blood clotting. When a blood vessel is injured, platelets adhere to the site of injury and release clotting factors. These factors, along with other proteins in the blood plasma, such as fibrinogen, work together to form a fibrin clot that seals wounds and stops bleeding.
Class 7 Science- Chapter 11- Transportation in Animals and Plants – Complete Notes
NCERT Solutions for Class 7 Science Chapter 11-Transportation in Animals and Plants
Rapid Revision – Class 7 Science- Chapter 11- Transportation in Animals and Plants
Class 7 – Science- Chapter 11-Transportation in Animals and Plants Question Answer (Solved MCQs)
