Question

Fossilized stromatolites

(A) formed around deep-sea vents.

(B) resemble structures formed by bacterial communities that are found today in some shallow marine bays.

(C) provide evidence that plants moved onto land in the company of fungi around 500 million years ago.

(D) contain the first undisputed fossils of eukaryotes.

Short answer

1. The statement "formed around deep-sea vents." isfalse.

2. The statement "resemble structures formed by bacterial communities that are found today in some shallow marine bays." istrue.

3. The statement "provide evidence that plants moved onto land in the company of fungi around 500 million years ago." is false.

4. The statement "contain the first undisputed fossils of eukaryotes." is false.

Step-by-step solution

Fossilized stromatolites

Over three billion years old, stromatolites are the world's oldest fossils. For more than 2 billion years, they dominated life on Earth and are thought to be the primary oxygen source in the atmosphere.

Explanation of option (A)

A hydrothermal vent is a crack on the seafloor that discharges geothermally heated water. In the deep ocean, hydrothermal vents sustain distinct ecosystems and their populations of species.

Thus, the stromatolites are not formed around the deep-sea vents.

Therefore, the given statement is false.

Explanation of option (B)

Generally, modern stromatolites are found in hypersaline lakes and marine lagoons since animals cannot graze excessively salty water. Stromatolites arise when sediments in shallow oceans become entangled with biofilms of microorganisms such as cyanobacteria.

Thus, stromatolites resemble the bacterial structure formed on the marine bay.

Therefore, the given statement is true.

Explanation of option (C)

Algae are the nearest living relatives of the first land plants, and they thrive in watery environments, such as rivers and the ocean. These creatures may extract water and nutrients from the environment. Stromatolites provide evidence about the photosynthetic cyanobacteria.

Thus, these fossils do not provide evidence about first land plants.

Therefore, the given statement is false.

Explanation of option (D)

Scientists determined that eukaryotes such as primitive amoeba-like creatures must have evolved 2.7 billion years ago because eukaryotes are the only species on Earth capable of producing chemical molecules like sterol. The earliest fossil of a eukaryotic cell is Grypania spiralis, a multicellular alga.

Thus, stromatolites are not the first actual fossils of eukaryotes.

Therefore, the given statement is false.