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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?

Roots absorb minerals and water from the soil constantly. The suction force is created by evaporation of water from leaves. It helps water to... View Article

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

Waste Process Organ Carbon dioxide Exhalation Lungs Undigested food Egestion Anus and large intestine Urine Excretion Kidney Sweat... View Article

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?

a) The periodical filtering of blood through artificial kidney is termed as 'Dialysis'. A kidney can filter 100-150 quarts of blood every day. If... View Article

(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?

(a) The pulmonary artery is the only artery that carries carbon dioxide-rich blood. A pulmonary artery is a set of blood vessels that are related... View Article

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 a reason for your answer.

The possible situations could be a) The plant will die because without the root hairs, the root will not able to absorb nutrients and water.... View Article

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 is 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.

The arranged statements are: a) Blood containing useful and harmful substances reaches the kidneys for filtration. b) Useful substances are... View Article

Name the organ which is located in the chest cavity with its lower tip slightly tilted towards the left.

Heart The heart is a blood-pumping organ of the human circulatory system.The human heart is one of the most important organs responsible for... View Article

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?

A septum is a diving wall which is present between the the left side and the right side of the heart, which does not allow mixing of blood when... View Article

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?

The artery have thick elastic walls and arteries receives blood in high pressure directly from the left ventricle. Because of the high pressure... View Article

Aquatic animals like fish excrete their wastes in gaseous form as (a) Oxygen (b) Hydrogen (c) Ammonia (d) Nitrogen

c) Ammonia Aquatic animals perform the procedure of 'Excretion' depending on the availability and unavailability of water. They excrete their... View Article

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

c) Suction force Roots absorb minerals and water from the soil constantly. The suction force is created by evaporation of water from the... View Article

In which of the following parts of the human body are sweat glands absent? (a) Scalp (b) Armpits (c) Lips (d) Palms

c) Lips Sweat glands are present in scalp, armpits, and palms but not in lips. So, lips do not secrete sweat. Sweat glands are absent in the... View Article

The absorption of nutrients and exchange of respiratory gases between blood and tissues takes place in – (a) veins (b) arteries (c) heart (d) capillaries

d) Capillaries Exchange of gases, nutrients, and waste between blood and tissue occurs in the capillaries. Capillaries are tiny vessels that... View Article

They are pipe-like, consisting of a group of specialized cells. They transport substances and form 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

d) Phloem tissue Phloem is also important as the xylem tissues for the vascular system of plants. The main activity of this tissue is to... View Article

The muscular tube through which stored urine is passed out of the body is called – (a) kidney (b) ureter (c) urethra (d) urinary bladder

C) Urethra A hollow tube is located between 'Urinary Meatus' and 'Urinary Bladder' is termed as Urethra. A tube in the kidney through which... View Article

A food stall owner was preparing dough for making bhaturas. He added a pinch of yeast and sugar to the dough and left it in a warm place. After few hours, the dough had risen. There was a sour smell too. (a) Why did the dough rise? (b) Why did the dough smell sour? (c) Why was sugar added to the dough? (d) What would have happened if the dough was kept in the refrigerator, soon after it was prepared?

a) Yeast are the single cell organisms which perform anaerobic respiration. The dough rose because of the release of carbon dioxide which is a... View Article

Observe Figure carefully and answer the following questions. (a) Which process is being tested in the activity? (b) What is the result of the activity? Give reasons.

a) As the air is being released from the nose, the process of exhalation is being tested here. b) In the first case i.e. test tube A only water... View Article

Observe Figure carefully and answer the following questions. (a) In which jar, will the amount of CO2 be the highest and why? (b) In which jar, will the amount of CO2 be the lowest and why?

In jar A only plant is present and plants take up the carbon dioxide present the atmospheric air. In jar B along with the plant, mice are also... View Article

Paheli participated in a 400 m race competition held at her school and won the race. When she came home she had mixed feelings of joy and pain as she had cramps in her leg muscles. After a massage, she was relieved of the pain. Answer the following questions related to the situation. (a) What can be the possible reasons for the pain in her legs? (b) Why did she feel comfortable after a massage?

a) During heavy exercise like running a deficiency of oxygen is created in the muscle cells. This deficiency leads to anaerobic respiration in... View Article

Insects and leaves of a plant have pores through which they exchange gases with the atmosphere. Can you write two points of differences between these pores with respect to their position, number and extension into the body?

Spiracles are the tiny pores present in the insects like cockroaches which help in gaseous exchange whereas stomata are the openings present on... View Article

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