Read the passage given below and answer the four questions that follow:-
Microorganisms were discovered in tiny cracks within 2-billion-year-old rock in South Africa, making it the oldest rock known to host life. This finding offers insights into Earth's early life and the search for extraterrestrial life.
Deep within Earth's crust, billions of resilient microbes survive in extreme isolation, far removed from sunlight, oxygen, and food sources, growing at a glacial pace over thousands or millions of years. Previously, the oldest microbial traces were found in 100- million-year-old seafloor sediments. However, Yohey Suzuki and his team at Tokyo University have pushed this record back by 2 billion years.
They extracted a 30-cm cylindrical rock core from the Bushveld Igneous Complex in South Africa, a 2-billion-year-old volcanic region. Upon slicing the core, they found microbial cells in tiny fractures. DNA staining and imaging with advanced microscopes confirmed the microbes were indigenous, with intact cell walls, suggesting they were active.
The researchers hypothesise that the microorganisms were carried into the rock via water shortly after its formation. Clay deposits in the fractures may have provided nutrients. These microbes, primitive in evolutionary terms, offer clues about Earth's earliest life forms and their evolution.
The study also has implications for Mars exploration. Suzuki notes similarities between the Bushveld rocks and Martian rocks, suggesting the same techniques could identify life on Mars.
"This underscores the deep subsurface as a crucial environment for microbial life," says Manuel Reinhardt from the University of Göttingen, while noting that microorganisms colonised the rocks after crack formation; the timing needs investigation.
What implication does the study have for Mars exploration?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Techniques used on Earth's rocks can help detect life in Martian subsurface rocks.
Suzuki notes similarities between the Bushveld rocks and Martian rocks and suggests that the same techniques could identify life on Mars. The methods used to find microbes deep in old rock on Earth could be used on Martian rock below the surface.
Why the Other Options are Incorrect?
Option 1: Mars lacks geological structures similar to those on Earth. — Incorrect. Contradicted: the passage calls Martian rocks similar to the Bushveld rocks.
Option 2: Life on Mars, if present, would only exist on its surface. — Incorrect. Contradicted: the study points to the deep subsurface as a home for microbes, not the surface.
Option 4: Microorganisms on Mars are likely much younger than those on Earth. — Incorrect. Not mentioned: the passage makes no comparison of ages between life on Mars and on Earth.