Exploring Prokaryotes: Bacteria and Archaea

What are prokaryotes?

• The largest and most complex organisms on earth

• The smallest, simplest, and oldest organisms on earth

• Organisms with a nucleus

• Organisms with linear DNA

Answer explanation

Prokaryotes are the smallest, simplest, and oldest organisms on Earth. They lack a nucleus and have circular DNA, distinguishing them from more complex eukaryotic organisms.

Which of the following is NOT a shape that bacteria can have?

• Spheres

• Spirals

• Cubes

• Rods

Answer explanation

Bacteria typically have three main shapes: spheres (cocci), rods (bacilli), and spirals (spirilla). They do not form cube shapes, making 'Cubes' the correct answer as it is NOT a shape that bacteria can have.

What is the primary role of decay bacteria in the ocean?

• To produce oxygen

• To decompose dead material and recycle nutrients

• To cause red tides

• To form fossils

Answer explanation

Decay bacteria play a crucial role in the ocean by decomposing dead material, which helps recycle nutrients back into the ecosystem. This process is essential for maintaining the health of marine environments.

Tags

NGSS.MS-LS2-3

Which pigment is NOT found in cyanobacteria?

• Chlorophyll

• Phycocyanin

• Phycoerythrin

• Carotene

Answer explanation

Cyanobacteria contain chlorophyll, phycocyanin, and phycoerythrin, which are essential for photosynthesis. Carotene, while a common pigment in many plants, is not typically found in cyanobacteria.

What are stromatolites?

• Fossils formed by cyanobacteria

• A type of archaea

• A shape of bacteria

• A pigment in cyanobacteria

Answer explanation

Stromatolites are layered structures created by the activity of cyanobacteria, which trap sediments and form fossilized remains over time. This makes 'Fossils formed by cyanobacteria' the correct choice.

Which of the following statements is true about archaea?

• They are eukaryotes

• They are the most complex form of life

• They are often extremophiles

• They have linear DNA

Answer explanation

The correct statement is that archaea are often extremophiles, meaning they thrive in extreme environments. They are not eukaryotes, are not the most complex life forms, and typically have circular DNA, not linear.

What is the significance of cyanobacteria in Earth's history?

• They are the first organisms to have a nucleus

• They were the first photosynthetic organisms and produced oxygen

• They are the largest organisms in the ocean

• They are responsible for all red tides

Answer explanation

Cyanobacteria are significant because they were the first photosynthetic organisms, producing oxygen as a byproduct. This process dramatically changed Earth's atmosphere and paved the way for the evolution of aerobic life.

Tags

NGSS.HS-ESS2-7

Which of the following is NOT a kingdom of prokaryotes?

• Bacteria

• Archaea

• Protista

• None of the above

Answer explanation

Protista is not a kingdom of prokaryotes; it consists of eukaryotic organisms. Bacteria and Archaea are the two kingdoms of prokaryotes.

What type of DNA do prokaryotes have?

• Linear DNA

• Circular DNA

• Double-stranded RNA

• Single-stranded DNA

Answer explanation

Prokaryotes typically have circular DNA, which is distinct from the linear DNA found in eukaryotes. This circular structure allows for efficient replication and is a key characteristic of prokaryotic organisms.

What is the age of the oldest fossils of archaea?

• 2.5 billion years

• 3.8 billion years

• 1.5 billion years

• 4.5 billion years

Answer explanation

The oldest known fossils of archaea date back to approximately 3.8 billion years ago, making this the correct answer. Other options, while significant, do not represent the earliest evidence of archaea.