Match List I with List II.
List I (Compound)
A. Carbon monoxide
B. Sulphur dioxide
C. Polychlorinate

Q: Why does CO bind to haemoglobin instead of oxygen?

Carbon monoxide has a molecular structure that allows it to bind to the iron atom in haemoglobin with an affinity about 300 times stronger than oxygen. Once bound, it doesn't easily let go, blocking oxygen transport.

Q: How exactly does SO2 cause stiffness in flower buds?

High concentrations of SO2 disrupt the plant's cellular metabolism and degrade chlorophyll. This chemical stress leads to the hardening and stiffness of the delicate tissues in flower buds, causing them to fall off.

Q: What are PCBs and where do they come from?

Polychlorinated biphenyls (PCBs) are man-made organic chemicals consisting of carbon, hydrogen, and chlorine atoms. They were used in electrical, heat transfer, and hydraulic equipment before being banned due to their toxicity and carcinogenic properties.

Q: Can plants really clean the air of nitrogen oxides?

Yes! Certain plants like Pyrus (pear), Pinus (pine), and Quercus (oak) have enzymes that can absorb and metabolise nitrogen oxides from the air, effectively using them as a nitrogen source for growth.

Q: Is photochemical smog related to these pollutants?

Absolutely. Oxides of nitrogen (NOx) are primary precursors to photochemical smog. When they react with volatile organic compounds in the presence of sunlight, they form secondary pollutants like ozone and PAN.

Question

Match List I with List II.
$\begin{array}{ll} 	ext{List I (Compound)} & 	ext{List II (Effect/affected species)} \ 	ext{A. Carbon monoxide} & 	ext{I. Carcinogenic} \ 	ext{B. Sulphur dioxide} & 	ext{II. Metabolised by pyrus plants} \ 	ext{C. Polychlorinated biphenyls} & 	ext{III. Haemoglobin} \ 	ext{D. Oxides of nitrogen} & 	ext{IV. Stiffness of flower buds} \end{array}$
Choose the correct answer from the options given below :

Options:

(A) A $ightarrow$ III, B $ightarrow$ IV, C $ightarrow$ I, D $ightarrow$ II

(B) A $ightarrow$ IV, B $ightarrow$ I, C $ightarrow$ III, D $ightarrow$ II

(C) A $ightarrow$ I, B $ightarrow$ II, C $ightarrow$ III, D $ightarrow$ IV

(D) A $ightarrow$ III, B $ightarrow$ IV, C $ightarrow$ II, D $ightarrow$ I

Sigma Percentile · Accepted Answer

Welcome to the fascinating and sometimes alarming world of Environmental Chemistry! Today, we are going to act as environmental detectives. Our mission? To match some of the most notorious pollutants with their specific biological and ecological footprints.

This isn't just about memorizing facts; it's about understanding how the chemicals we release into the atmosphere interact with living systems. Let's break down our list of suspects one by one.

### The Invisible Threat: Carbon Monoxide

First on our list is Carbon monoxide, or $ 	ext{CO} $. This gas is infamous for being a silent killer. But why is it so dangerous?

Imagine you inhale $ 	ext{CO} $. It rushes into your bloodstream and encounters haemoglobin, the protein responsible for transporting oxygen to your cells. Here is the catch: haemoglobin loves carbon monoxide. In fact, its affinity for $ 	ext{CO} $ is about 300 times greater than its affinity for oxygen!

When $ 	ext{CO} $ binds to haemoglobin, it forms a highly stable complex called **carboxyhaemoglobin**. This effectively locks up the haemoglobin, preventing it from carrying oxygen. The result is oxygen starvation at the cellular level. Therefore, Carbon monoxide directly affects **Haemoglobin**. This gives us our first match: $ 	ext{A} ightarrow 	ext{III} $.

### The Plant Killer: Sulphur Dioxide

Next up is Sulphur dioxide, or $ 	ext{SO}_2 $. While $ 	ext{CO} $ targets animals, $ 	ext{SO}_2 $ is particularly devastating to plant life.

When plants are exposed to high concentrations of $ 	ext{SO}_2 $ in the air, it disrupts their internal metabolic processes. One of the most visible and tragic effects is on their reproductive cycle. The gas causes the **stiffness of flower buds**.

Because the buds become stiff and brittle, they eventually fall off the plant before they can bloom. This severely impacts the plant's ability to reproduce. So, Sulphur dioxide is the culprit behind the stiffness of flower buds. We have our second match: $ 	ext{B} ightarrow 	ext{IV} $.

### The Toxic Legacy: PCBs

Moving on, we encounter Polychlorinated biphenyls, commonly known as PCBs. These are synthetic organic chemicals that were once widely used in industrial applications, particularly as insulating fluids in electrical transformers.

However, we later discovered their dark side. PCBs are highly persistent in the environment and accumulate in the food chain. More alarmingly, extensive research has proven that they are **carcinogenic**.

This means they have the potential to cause cancer in both humans and animals. Due to their severe toxicity, their production has been banned globally, but they still linger in the environment. Thus, PCBs are matched with their carcinogenic nature: $ 	ext{C} ightarrow 	ext{I} $.

### Nature's Air Purifiers: Oxides of Nitrogen

Finally, we look at the Oxides of nitrogen, often referred to as $ 	ext{NO}_x $. These are major components of smog and acid rain, primarily produced by vehicle emissions and industrial processes.

But here is a fascinating twist: nature has developed its own defense mechanism against them. Certain species of plants act as natural sinks for these pollutants.

Plants such as *Pinus*, *Juniparus*, *Quercus*, *Vitis*, and specifically **Pyrus** (pear trees), have the remarkable ability to **metabolise nitrogen oxides**. They absorb these gases through their leaves and incorporate the nitrogen into their own metabolism. It's a beautiful example of nature trying to heal itself. Therefore, Oxides of nitrogen are metabolised by pyrus plants: $ 	ext{D} ightarrow 	ext{II} $.

### Bringing It All Together

We have successfully interrogated all our suspects. Let's review our findings:
- Carbon monoxide ($ 	ext{A} $) binds to Haemoglobin ($ 	ext{III} $).
- Sulphur dioxide ($ 	ext{B} $) causes Stiffness of flower buds ($ 	ext{IV} $).
- Polychlorinated biphenyls ($ 	ext{C} $) are Carcinogenic ($ 	ext{I} $).
- Oxides of nitrogen ($ 	ext{D} $) are Metabolised by pyrus plants ($ 	ext{II} $).

Looking at our options, this sequence perfectly aligns with option (a). By understanding the unique chemical behavior of each pollutant, we didn't just solve a problem—we uncovered the intricate connections within our ecosystem!

Select Answer:

Visualized Solution

Analyzing the Pollutants

Carbon Monoxide ( $CO$ )

Sulphur Dioxide ( $SO_{2}$ )

Polychlorinated Biphenyls (PCBs)

Oxides of Nitrogen ( $NO_{x}$ )

Final Conclusion

The Sigma Insight: Atmospheric Pollution

The Invisible Threat

The Plant Killer

The Toxic Legacy

Nature's Air Purifiers

Bringing It All Together

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