Question

The passage is primarily concerned with:

• A. the possibility of life on Mars
• B. selecting sites for landers on Mars
• C. research on Mars
• D. findings of Christopher McKay on Mars
• E. algae found on Mars
• A. Virus and space
• B. Bacteria
• C. Lichen
• D. Algae
• J. Microbes
• A. If any bacteria are alive today on Mars, they must have survived from the time before the planet cooled.
• B. Space photographs of Martian craters should reveal to the explorers signs of life there.
• C. Bacteria frozen into permafrost at the Martian South Pole may be viable.
• D. On digging up, more than 3 million years old Siberian permafrost has revealed bacteria.
• O. Algae could have existed on Mars.

Answer 1

The Correct Option is A

The given passage is focused on the possibility of life on Mars. The main topic discussed by scientists, particularly those from NASA, revolves around the conditions under which life might exist on Mars and compares these with Earth's ultra-cold regions. The passage explores the potential for discovering life forms like bacteria or lichens on Mars. It discusses the possibility of fossilized evidence in Mars' ancient lake beds and the viability of bacteria in permafrost conditions. Below is a step-by-step analysis of how we arrive at the correct answer:

1. Evidence of Life Forms: The passage begins by suggesting scientists' belief that if life exists on Mars, it is likely to be in the form of bacteria in permafrost or lichens within rocks. This theme aligns with exploring the possibility of life on Mars.
2. Comparative Analysis: Christopher McKay and other scientists use Earth's ultra-cold environments as models to hypothesize about life-sustaining conditions on Mars. This comparison emphasizes the potential for Martian life, supporting the theme of life's possibility.
3. Discussion on Algae: The narrative includes speculation about ancient Martian lakes and the potential fossilization of algae indicative of past life. Although this involves selecting sites for research, the underlying purpose is to find life evidence on Mars.
4. Concluding Insight: Toward the end, McKay's statement about the universe being "lousy with algae" if found on Mars indicates the broader implications for the existence of life, thus underscoring the main subject of the passage—life's possibility on Mars.

In contrast, while site selection for landers, research on Mars, and McKay's findings are relevant subtopics, they serve as expanded discussions under the broader theme of exploring life on Mars. Therefore, the correct answer is clearly: the possibility of life on Mars.

Each option in the question plays a part in the passage, but only one truly encapsulates the overarching focus, which is crucial for correctly answering reading comprehension questions in exams.

Answer 2

The question asks which of the given options is the least likely form of primitive life to exist on Mars, according to the comprehension passage. Let's examine each option with reference to the passage:

1. Bacteria: The passage states that scientists believe that if life exists on Mars, it is most likely in the form of bacteria. Therefore, bacteria are a likely form of life on Mars.
2. Lichen: The passage explains that lichens have been found within Antarctic rocks and are considered a potential form of life on Mars. Thus, lichens are a plausible form of life on Mars.
3. Algae: The passage mentions the possibility of finding fossilized algae in ancient dried-out lake beds on Mars. Hence, algae is considered as a possible form of life.
4. Microbes: Microbes generally include bacteria and other microscopic organisms. The comprehension suggests that such small organisms might exist in Mars' extreme conditions, making microbes a likely candidate for Martian life.
5. Virus and space: The passage does not suggest viruses as a potential form of primitive life on Mars. Although viruses are microscopic, they are not mentioned as a viable form of life in the context of the passage. Additionally, "space" in combination with viruses doesn't align with the passage's context about life forms.

Based on the comprehension, the least likely form of primitive life to exist on Mars is Virus and space, making it the correct answer.

Answer 3

To determine which statement is not true, we need to analyze each option based on the information provided in the comprehension passage about the possibility of life on Mars:

1. The statement "If any bacteria are alive today on Mars, they must have survived from the time before the planet cooled" is supported by the passage. The passage mentions that bacteria alive today would have survived from before the planet cooled, more than 3 billion years ago. Therefore, this statement is true.
2. The statement "Space photographs of Martian craters should reveal to the explorers signs of life there" is the one being questioned. The passage discusses photographing Martian lake beds from spacecraft to look for signs of past life, not current life in craters. Therefore, finding signs of life through space photographs of craters is less plausible according to the passage, making this statement potentially untrue.
3. The statement "Bacteria frozen into permafrost at the Martian South Pole may be viable" is aligned with the passage, where McKay expresses optimism that such bacteria might be viable. Hence, this statement is true.
4. Regarding "On digging up, more than 3 million years old Siberian permafrost has revealed bacteria," the passage confirms this by mentioning bacteria found in Siberian permafrost. Hence, this statement is true.
5. The statement "Algae could have existed on Mars" is also supported by the passage. It discusses the possibility of fossilized Martian algae and mentions structures such as stromatolites. Therefore, this statement is true.

Based on the analysis, the statement about space photographs revealing signs of life in Martian craters is not supported by the passage, making it the correct answer to the question.