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Life Processes - Respiration

Grade 10CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Respiration is a metabolic process involving the breakdown of food (glucose) to release energy in the form of ATPATP (Adenosine Triphosphate).

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The first step of respiration is Glycolysis, which occurs in the cytoplasm, where a 66-carbon Glucose molecule is broken down into two 33-carbon molecules of Pyruvate.

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Aerobic Respiration: Occurs in the presence of O2O_2 in the mitochondria. It yields a high amount of energy (3838 ATPATP) and produces CO2CO_2 and H2OH_2O.

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Anaerobic Respiration: Occurs in the absence of O2O_2. In yeast (fermentation), it produces Ethanol (C2H5OHC_2H_5OH) and CO2CO_2. In human muscle cells, during vigorous exercise, it produces Lactic Acid, leading to muscle cramps.

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Human Respiratory System: Air enters through nostrils, passes through the pharynx, larynx, and trachea (shielded by cartilaginous rings) into the bronchi and bronchioles, finally reaching the Alveoli.

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Alveoli: Balloon-like structures that provide a massive surface area for the diffusion of gases (O2O_2 and CO2CO_2) between the lungs and blood capillaries.

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Hemoglobin: A respiratory pigment present in Red Blood Cells (RBCsRBCs) that has a high affinity for O2O_2, transporting it from lungs to tissues. CO2CO_2 is more soluble in water and is mostly transported in the dissolved form in plasma.

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Breathing Mechanism: During inhalation, the diaphragm flattens and ribs are lifted, increasing the chest cavity volume and decreasing pressure, causing air to rush into the lungs.

📐Formulae

Glucose (6-carbon)→CytoplasmPyruvate (3-carbon)+Energy\text{Glucose (6-carbon)} \xrightarrow{\text{Cytoplasm}} \text{Pyruvate (3-carbon)} + \text{Energy}

Pyruvate→In Presence of O2 (Mitochondria)6CO2+6H2O+38 ATP\text{Pyruvate} \xrightarrow{\text{In Presence of } O_2 \text{ (Mitochondria)}} 6CO_2 + 6H_2O + 38 \text{ ATP}

Pyruvate→In Absence of O2 (Yeast)2C2H5OH+2CO2+2 ATP\text{Pyruvate} \xrightarrow{\text{In Absence of } O_2 \text{ (Yeast)}} 2C_2H_5OH + 2CO_2 + 2 \text{ ATP}

Pyruvate→Lack of O2 (Muscle Cells)Lactic Acid+Energy\text{Pyruvate} \xrightarrow{\text{Lack of } O_2 \text{ (Muscle Cells)}} \text{Lactic Acid} + \text{Energy}

ADP+Phosphate→EnergyATPADP + \text{Phosphate} \xrightarrow{\text{Energy}} ATP

💡Examples

Problem 1:

Why is the rate of breathing in aquatic organisms much faster than that seen in terrestrial organisms?

Solution:

Aquatic organisms utilize O2O_2 dissolved in water. Since the concentration of dissolved O2O_2 is significantly lower than the concentration of O2O_2 in the atmosphere (21%21\%), aquatic organisms must breathe faster to intake sufficient oxygen for their metabolic needs.

Explanation:

This is an adaptation to compensate for the low availability of oxygen in the aqueous medium compared to the terrestrial environment.

Problem 2:

Write the chemical equation for the breakdown of glucose in the case of insufficient oxygen in human muscle cells.

Solution:

C6H12O6→Cytoplasm2CH3CH(OH)COOH (Lactic Acid)+EnergyC_6H_{12}O_6 \xrightarrow{\text{Cytoplasm}} 2CH_3CH(OH)COOH \text{ (Lactic Acid)} + \text{Energy}

Explanation:

When the demand for energy is high and O2O_2 supply is limited (e.g., sprinting), pyruvate is converted into lactic acid instead of CO2CO_2 and H2OH_2O. The accumulation of lactic acid causes muscle fatigue and cramps.

Problem 3:

How are the lungs designed in human beings to maximize the area for exchange of gases?

Solution:

Within the lungs, the passage divides into smaller and smaller tubes (bronchioles) which finally terminate in balloon-like structures called Alveoli. The walls of the Alveoli contain an extensive network of blood vessels.

Explanation:

If the alveolar surface were spread out, it would cover about 80 m280 \text{ m}^2. This massive surface area ensures efficient and rapid diffusion of O2O_2 into the blood and CO2CO_2 out of the blood.