Respiration – Long Answer Questions

Medium Level (Application & Explanation)

Q1. Differentiate between aerobic and anaerobic respiration with examples and outcomes.

Answer:

Aerobic respiration happens in the presence of oxygen.
It breaks glucose into carbon dioxide and water.
It releases more energy as ATP.
Humans and most animals use this pathway during normal and vigorous work.
Anaerobic respiration happens without oxygen.
It forms ethanol + carbon dioxide in yeast, or lactic acid in muscles.
It gives less energy and may cause muscle cramps.
Both types help cells survive in different conditions.

Q2. Explain why ATP is called the “energy currency” of the cell. How is it formed and used?

Answer:

ATP stands for adenosine triphosphate.
It is formed from ADP + Pi during respiration.
Cells use ATP to power muscle contraction and protein synthesis.
ATP also supports nerve impulses and active transport.
When ATP breaks to ADP + Pi, it releases energy quickly.
This energy is immediate and usable by the cell.
So, ATP works like money for energy needs in the cell.
Without ATP, most cell activities would stop.

Q3. Describe gas exchange in plants and animals. Include structures and timing.

Answer:

Plants exchange gases through stomata on leaves.
In the day, plants use CO2 for photosynthesis and release O2.
They also respire all the time, releasing CO2 as waste.
Animals use organs like lungs for gas exchange.
In humans, lungs take in oxygen and release carbon dioxide.
The process keeps body cells supplied with oxygen for respiration.
Gas exchange is essential to make ATP.
It maintains life processes in both plants and animals.

Q4. How do respiratory pigments help oxygen transport? Explain haemoglobin and myoglobin.

Answer:

Respiratory pigments increase the efficiency of oxygen transport.
Haemoglobin in red blood cells binds oxygen in the lungs.
It carries oxygen to tissues for aerobic respiration.
Carbon dioxide dissolves in blood and travels back to the lungs.
Myoglobin in muscles stores oxygen for quick use.
This helps during intense activity or short bursts of work.
Together, they keep tissues oxygen-rich.
They support continuous ATP production.

Q5. Using Activities 5.4 and 5.5, explain how lime water helps detect carbon dioxide from breathing and fermentation.

Answer:

Lime water turns milky in the presence of CO2.
In Activity 5.4, exhaled air makes lime water milky faster.
This happens because we exhale more CO2 after respiration.
In Activity 5.5, yeast fermentation releases CO2 into lime water.
The lime water again turns milky, showing anaerobic respiration.
Fermentation often appears faster due to active yeast.
Both show that CO2 is a product of respiration.
This proves a simple test for detecting carbon dioxide.

High Complexity (Analysis & Scenario-Based)

Q6. A sprinter suddenly feels muscle cramps during a race. Explain the energy pathway changes causing this.

Answer:

During a sprint, muscles demand quick ATP.
Aerobic respiration may not meet this instant need.
Muscles shift to anaerobic respiration for speed.
This makes lactic acid, which causes cramps and pain.
After the race, breathing stays fast to repay oxygen debt.
Extra oxygen helps convert lactic acid back safely.
Training improves oxygen supply and endurance.
It reduces the need for anaerobic bursts.

Q7. You observed fish in an aquarium and compared their breathing with yours. Why do fish breathe faster than humans?

Answer:

Water has less dissolved oxygen than air.
Fish must pass more water over gills to get enough oxygen.
So, their mouth and gill slits move faster.
Humans breathe air, which has more oxygen.
Our lungs can work slower to meet oxygen needs.
The difference shows adaptation to the environment.
Fish and humans have different organs but the same goal.
Both aim to support efficient respiration.

Q8. A friend smokes regularly. Analyse how smoking affects respiration and long-term health.

Answer:

Smoke damages cilia in the respiratory tract.
Without cilia, dust and germs stay in the airways.
This raises the risk of infections and cough.
Long-term smoking can cause COPD and lung cancer.
Damaged lungs take in less oxygen and remove less CO2.
The person feels breathless during normal activities.
Quitting smoking helps cilia recover over time.
It protects overall respiratory health.

Q9. Your class must prove that exhaled air has more CO2 than room air. Design a fair test using lime water and explain expected results.

Answer:

Take two test tubes with fresh lime water.
Bubble room air through one using a syringe.
Bubble exhaled air through the other using a straw.
Keep the time and bubbling rate similar.
The tube with exhaled air turns milky faster.
This shows exhaled air has more CO2 than room air.
It proves that respiration releases carbon dioxide.
Note observations and write a clear conclusion.

Q10. A bakery wants faster dough rising using yeast. Using respiration concepts, suggest steps and justify them.

Answer:

Use fresh yeast in a warm sugar solution.
Keep the dough at a warm temperature (not hot).
Limit oxygen to promote anaerobic respiration.
Yeast will make CO2, which helps dough rise.
The CO2 can be tested by lime water turning milky.
Do not overdo sugar or heat, as yeast may die.
A steady warmth speeds fermentation safely.
This applies the idea of anaerobic respiration in yeast.

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