1. According to the passage, thick sediment found in the ancient river deltas of Lake Fryxell
Quote:
This very thickness, however, makes a formal scientific search for signs of - life impracticable.
A. forms layers of deposits laden with dried bacteria that are tens of thousands of years old - mentioned w.r.t Lake Vida not ancient river deltas
B. masks life forms by continuously depositing new layers on top of older ones - mentioned w.r.t Lake Vida not ancient river deltas
C. makes it unlikely that scientists will search there for traces of life -
Correct as can be inferred from the quoted
D. collects liquid water from nearby glaciers warmed by sunlight during the Antarctic summer - Not mentioned in this context, mentioned w.r.t Lake Hoare
E. is devoid of life due to the impenetrable barrier formed by the sediment - a good contender, but just because it is difficult to penetrate doesn't means life doesn't exist at all
2. The passage is primarily concerned with
A. the adaptations of microorganisms that allow them to live in the Dry Valleys' hostile environment - not discussed
B. the relationship between frozen lakes and glaciers which contributes to the availability of fresh water in the Dry Valleys - discussed but not main point
C. evidence of past and present life forms in the extreme conditions of Antarctica's Dry Valleys - the passage intends to say much more than that, through these examples it hypothesizes about possibility of life on Mars
D. the evolutionary histories of ancient lakes and the clues they hold about life in cold, dry ecosystems -
Correct. can be inferred from the 1st & last para, the middle para contributes to the findings of life given in the last para
E. the differences and similarities between ancient river deltas and ancient lakes - though discussed, it is not the main point
3. Based on the information in the passage, scientists looking for life on Mars in conditions similar to those in the Dry Valleys would be most likely to find it in which of the following areas?
Quote:
Dried bacteria in Lake Vida sediment have been dated back tens of thousands of years. Some researchers are hoping that exploration of similar terrain on Mars may yield similar results.
A. former river deltas
B. circumpolar ice fields
C. larger rocks
D. former glaciers
E. former lakebeds -
correct mentioned in the last para
4. Based on the information in the passage, mounds of sediment found at the bottom of Lake Vida are refined by
I. Continual sublimation and ice cover
II. Large pieces of rock decomposing on the lake floor
III. Cracks formed in the ice by sinking rocks and gravel
Quote:
Since smaller rocks, with a larger surface-area-tovolume ratio, get warmer and sink lower than larger rocks, pieces of gravel penetrate by as much as a meter, forming cracks in the ice that cause the finest sediment to sink even deeper.
A. I only
B. I and II
C. III only
CorrectD. II and III
E. I, II, and III