Problem 1 - Campbell Biology

Question

Fossilized stromatolites (A) formed around deep-sea vents. (B) resemble structures formed by bacterial com- munities 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.

Step-by-Step Solution

Answer

Option B

Step 1: Understand the Question

The question is asking for the correct statement about fossilized stromatolites.

Step 2: Analyze Each Option

Review what each option states about fossilized stromatolites:

Step 2.1: Option A

Option A states that fossilized stromatolites formed around deep-sea vents. This is incorrect; stromatolites are typically found in shallow water environments.

Step 2.2: Option B

Option B states that fossilized stromatolites resemble structures formed by bacterial communities found today in some shallow marine bays. This is correct. Stromatolites are formed by cyanobacteria in shallow waters.

Step 2.3: Option C

Option C states that fossilized stromatolites provide evidence that plants moved onto land in the company of fungi around 500 million years ago. This does not relate to stromatolites but to other fossil types.

Step 2.4: Option D

Option D states that fossilized stromatolites contain the first undisputed fossils of eukaryotes. This is incorrect as stromatolites are associated with cyanobacteria, which are prokaryotes, not eukaryotes.

Step 3: Conclude the Correct Answer

Having analyzed all options, the correct statement about fossilized stromatolites is found in Option B.

Key Concepts

cyanobacteria

Cyanobacteria are a group of photosynthetic bacteria that are as old as life itself. These microorganisms play a crucial role in the formation of stromatolites.

They are prokaryotic, meaning they lack a nucleus or any other membrane-bound organelles. Cyanobacteria are often found in aquatic environments and utilize sunlight through photosynthesis to produce energy.

In the context of stromatolites, cyanobacteria layer themselves together in shallow waters, trapping sediments which gradually form the rock-like structures we see today. Their ability to photosynthesize significantly contributed to the oxygenation of Earth's early atmosphere.

shallow marine bays

Shallow marine bays provide the perfect environment for the formation of stromatolites. These areas are typically warm, sunlit, and rich in minerals, making them ideal for photosynthetic organisms like cyanobacteria.

In modern times, similar structures or living stromatolites can still be found in places like Shark Bay, Australia. These shallow water environments allow cyanobacteria to interact closely with the sediment and form layered structures. The consistency of these shallow marine conditions is key for the growth process of stromatolites, adapting over millions of years.

prokaryotes

Prokaryotes are single-celled organisms that lack a nucleus. Cyanobacteria are a classic example of prokaryotes.

Prokaryotes are distinguished by their simpler cell structure compared to eukaryotes. They have genetic material that is not enclosed in a nuclear envelope.

In the case of stromatolites, prokaryotic cyanobacteria use their simple yet effective cellular machinery to photosynthesize and trap sediments. Understanding the role of prokaryotes helps us appreciate how these simple organisms have contributed to Earth's geological and atmospheric history over billions of years.

paleobiology

Paleobiology is the study of ancient life through the examination of fossil records. It helps scientists understand the evolution of organisms and their interactions with the environment.

Stromatolites are significant to paleobiology because they provide insights into early life on Earth. They represent some of the oldest known fossils, dating back over 3.5 billion years.

By studying fossilized stromatolites, paleobiologists can gather information on the Earth’s early biosphere and the organisms that shaped it. This field merges principles of both geology and biology to reconstruct ancient ecosystems and evolutionary history.