Question 1

How do microorganisms contribute to the carbon cycle?

Accepted Answer

Microorganisms decompose organic matter through aerobic respiration, releasing carbon dioxide into the atmosphere. Photosynthetic organisms then use this carbon dioxide to produce organic compounds, completing the carbon cycle. This process is essential for recycling carbon and maintaining ecosystem balance.

Question 2

What role do nitrogen-fixing bacteria play in soil enrichment?

Accepted Answer

Nitrogen-fixing bacteria like Rhizobium form symbiotic relationships with legumes, converting atmospheric nitrogen into ammonia and ammonium ions that plants can absorb. This process significantly enriches soil nitrogen content, promoting plant growth and agricultural productivity without requiring synthetic fertilizers.

Question 3

How do microbes reduce biological oxygen demand in wastewater treatment?

Accepted Answer

During secondary treatment, microorganisms break down organic pollutants in sewage, significantly reducing biological oxygen demand (BOD). This microbial degradation minimizes environmental impact and ensures cleaner water systems before discharge into natural water bodies.

Question 4

What is bioremediation and how do microbes accomplish it?

Accepted Answer

Bioremediation uses microorganisms' metabolic capabilities to degrade harmful substances. Species like Pseudomonas putida degrade hydrocarbons from oil spills, while fungi such as Aspergillus niger remove heavy metals through biosorption, transforming environmental toxins into less harmful compounds.

Question 5

How do microbes contribute to biofuel production?

Accepted Answer

Yeasts ferment sugars into ethanol, a widely used biofuel, while anaerobic bacteria decompose organic matter to produce methane-rich biogas. These microbial processes provide renewable energy alternatives to fossil fuels, supporting global energy sustainability and reducing environmental impact.

Question 6

What is the role of phosphate-solubilizing bacteria in soil fertility?

Accepted Answer

Bacteria like Pseudomonas fluorescens solubilize insoluble phosphate minerals by secreting organic acids, increasing phosphorus availability in soil. This process enhances soil fertility and nutrient cycling, supporting plant growth and agricultural productivity in ecosystems.

Question 7

How do denitrifying bacteria return nitrogen to the atmosphere?

Accepted Answer

Denitrifying bacteria like Pseudomonas reduce nitrates to nitrogen gas (N₂), releasing nitrogen back into the atmosphere. This process completes the nitrogen cycle, balancing soil nitrogen levels and preventing excessive nutrient accumulation in ecosystems.

יישומים סביבתיים של מיקרואורגניזמים