Important Questions Test: Respiration in Organisms - Class 7 MCQ

- The equation for aerobic respiration is: Glucose + Oxygen → CO₂ + H₂O + Energy.
- In this process, glucose (a sugar) reacts with oxygen.
- Oxygen is essential for breaking down glucose to release energy.
- The byproducts of this reaction are carbon dioxide and water.
- Therefore, in the equation, X represents oxygen, making it crucial for sustaining life through energy production.

The given equation represents fermentation or anaerobic respiration. In the equation Y represents yeast.

When structure diaphragm relaxes and curve upwards air is forced out of the lungs.

Option (a):

• X: Tadpole (breathes through gills) 
• Y: Whale (breathes through lungs) 
• Z: Earthworm (breathes through skin) 
  This option is correct.

During exhalation or expiration we breathe out air rich in carbon dioxide.

Hair traps dust particles in our nose.

The trachea, commonly known as the windpipe, is a tube about 4 inches long and less than an inch in diameter in most people. The trachea begins just under the larynx (voice box) and runs down behind the breastbone (sternum). The trachea then divides into two smaller tubes called bronchi: one bronchus for each lung.
The diaphragm is an unpaired, dome shaped skeletal muscle that is located in the trunk. It separates the thoracic and abdominal cavities from each other by closing the inferior thoracic aperture. The diaphragm is the primary muscle that is active in inspiration.

In the given experimental setup when the rubber sheet is pushed upwards air is forced out.

When rubber sheet is pulled downwards, air enters into the balloon.

• The tracheal system is a network of tubes that transport air directly to the tissues.
• Cockroaches and other insects use this system for respiration, allowing efficient gas exchange.
• Earthworms respire through their skin, fish use gills, and frogs have lungs and skin for gas exchange.
• Thus, among the options, only the cockroach relies on the tracheal system for respiration.

In muscle cells partial breakdown of glucose produces lactic acid.

Food is broken down in the absence of oxygen to form alcohol, carbon dioxide and energy in anaerobic respiration.

Aerobes are organisms that require oxygen for their survival and growth. Cats, dogs, and human beings are examples of aerobes as they rely on aerobic respiration to generate energy.

Parts of Respiratory System includes:

• External nostrils – For the intake of air.
• Nasal chamber – which is lined with hair and mucus to filter the air from dust and dirt.
• Pharynx – It is a passage behind the nasal chamber and serves as the common passageway for both air and food.
• Larynx – Known as the soundbox as it houses the vocal chords, which are paramount in the generation of sound.
• Epiglottis – It is a flap-like structure that covers the glottis and prevents the entry of food into the windpipe.
• Trachea – It is a long tube passing through the mid-thoracic cavity.
• Bronchi – The trachea divides into left and right bronchi.
• Bronchioles – Each bronchus is further divided into finer channels known as bronchioles.
• Alveoli – The bronchioles terminate in balloon-like structures known as the alveoli.
• Lungs – Humans have a pair of lungs, which are sac-like structures and covered by a double-layered membrane known as pleura.

• When we breathe in air.
• Air enters lungs and there is an increase in the size of the chest.