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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... 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... 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... 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... View Article

Whenever we feel drowsy or sleepy, we start yawning. Does yawning help us in any way?

When we feel drowsy, rate of breathing is decelerated, that means enough oxygen is not supplied to lungs, it makes... View Article

On a very cold morning, Boojho and Paheli were talking with each other as they walked down to their school. They observed that the air coming out of their mouth looked like smoke. They were amused and wondered how it happened. Help them find the answer.

On a cold day, the warm and moist air exhaled by us condenses into mist when it comes in contact... View Article

On average, an adult human being at rest breathes 15–18 times per minute. The breathing rate, however, may differ under different conditions. Arrange the following activities given in the box in order of increasing breathing rates and give a reason for your answer. (sleeping, cycling, brisk walk, watching T.V.)

Sleeping > Watching > T.V. > Brisk Walk > Cycling The breathing rate becomes faster when we are working. The... View Article

Which gas present in the air is essential for aerobic respiration? What is the role of oxygen during respiration?

Aerobic respiration occurs in the presence of oxygen gas or O2. Oxygen oxidizes the food and breaks it into smaller... View Article

Pick the odd-one-out from each of the groups given below on the basis of respiratory organs. Give a reason for your answer. (a) cockroach, grasshopper, snail, ant (b) lizard, cow, earthworm, snake (c) crocodile, whale, dolphin, fish (d) snake, tadpole, crow, goat

Answer: The respiratory system is an organ system responsible for exchanging gases in animals. It is the system that uses... View Article

Fill in the blanks with suitable words. (a) The roots of a plant take up oxygen from the trapped between the particles. (b) Diaphragm forms the _ of the chest cavity. (c) Exchange of gases in the leaves takes place with the help of . (d) Cockroaches breathe with the help of air tubes called _____.

a) The roots of a plant take up oxygen from the air trapped between the soil particles. The roots use up the oxygen... View Article

Mark the following statements as True or False. Exhaled air has more percentage of CO2 than inhaled air.

True Explanation The percentage of CO2 in inhaled air is 0.04% whereas in exhaled air it is 4.4%. Therefore, we... View Article

Mark the following statements as True or False. Insects have spiracles on the lower surface of the body.

False Explanation Insects have spiracles on the sides of the body. Spiracles are openings or tiny pores on the surface... View Article

Mark the following statements as True or False. (a) Oxygen breaks down glucose outside the cells of organisms.

False Explanation Oxygen breaks down glucose inside the cells of organisms.. At first, glucose-containing 6 carbon molecules are broken in... View Article

Earthworms and frogs breathe through their skin because of which the skin of both the organisms is (a) moist and rough. (b) dry and rough. (c) dry and slimy. (d) moist and slimy.

(d) moist and slimy. Explanation Earthworm and frogs both breathe through their skin because of which their surface becomes moist... View Article

Fish breathe with the help of gills which are richly supplied with blood vessels. The gills help the fish to (a) take in oxygen from the air. (b) take in oxygen dissolved in water. (c) absorb nutrients present in water. (d) release waste substances in water.

(b) take in oxygen dissolved in water. Explanation Fishes use gills for the exchange of gases. As the water enters... View Article

Breathing is a process that (i) provides O2 to the body. (ii) breaks down food to release energy. (iii) helps the body to get rid of CO2. (iv) produces water in the cells. Which of the following gives the correct combination of functions of breathing? (a) (i) and (ii) (b) (ii) and (iii) (c) (i) and (iii) (d) (ii) and (iv)

c) (i) and (iii) Explanation Breathing is the process of inhaling oxygen into the body and exhaling carbon dioxide out... View Article

Yeast is used in the wine and beer industries because it respires (a) aerobically producing oxygen. (b) aerobically producing alcohol. (c) anaerobically producing alcohol. (d) anaerobically producing CO2.

(c) anaerobically producing alcohol. Explanation Yeast respires anaerobically to produce ethanol and CO2. Due to this property, it is used... View Article

Sometimes when we do heavy exercise, anaerobic respiration takes place in our muscle cells. What is produced during this process? (a) alcohol and lactic acid (b) alcohol and CO2 (c) lactic acid and CO2 (d) lactic acid only

d)Lactic acid only Explanation While doing heavy exercise such as running, cycling, weightlifting, etc., we need high energy which creates... View Article

In towns and cities, generally, the bore wells have to be dug very deep to get water as compared to bore wells dug in villages. Give suitable reasons.

The reason is that the excessive use of water which depletes the groundwater. Towns and cities have asphalted roads and... View Article

Gardeners gently dig up the soil around the roots of garden herbs (plants) frequently. Give reasons.

Gardeners gently dig up the soil around the roots of garden herbs (plants) frequently because: It helps the plant roots... View Article

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