Question

Which forms of life were dominant in the Mesozoic era?(1 point)
Responses

birds
birds

mammals
mammals

reptiles
reptiles

one-celled animals

Answer 1

Which characteristic defines the Paleozoic era?(1 point)
Responses

Mammals and other warm-blooded animals became dominant.
Mammals and other warm-blooded animals became dominant.

Animals with shells and hard parts were dominant for the first time.
Animals with shells and hard parts were dominant for the first time.

Simple, one-celled life forms were dominant.
Simple, one-celled life forms were dominant.

Reptiles became dominant after a mass extinction.

Answer 2

Which option orders the events chronologically, from earliest to latest.(1 point)
Responses

Photosynthesizing bacteria release oxygen into the sea. Oxygen concentrations increase in the atmosphere. Many new animal species evolve. Single-celled organisms increase atmospheric methane concentrations.
Photosynthesizing bacteria release oxygen into the sea. Oxygen concentrations increase in the atmosphere. Many new animal species evolve. Single-celled organisms increase atmospheric methane concentrations.

Single-celled organisms increase atmospheric methane concentrations. Photosynthesizing bacteria release oxygen into the sea. Oxygen concentrations increase in the atmosphere. Many new animal species evolve.
Single-celled organisms increase atmospheric methane concentrations. Photosynthesizing bacteria release oxygen into the sea. Oxygen concentrations increase in the atmosphere. Many new animal species evolve.

Single-celled organisms increase atmospheric methane concentrations. Oxygen concentrations increase in the atmosphere. Photosynthesizing bacteria release oxygen into the sea. Many new animal species evolve.
Single-celled organisms increase atmospheric methane concentrations. Oxygen concentrations increase in the atmosphere. Photosynthesizing bacteria release oxygen into the sea. Many new animal species evolve.

Many new animal species evolve. Single-celled organisms increase atmospheric methane concentrations. Photosynthesizing bacteria release oxygen into the sea. Oxygen concentrations increase in the atmosphere.

Answer 3

How did the success of photosynthetic bacteria change Earth’s atmosphere?(1 point)
Responses

increased hydrogen concentration
increased hydrogen concentration

increased oxygen concentration
increased oxygen concentration

decreased hydrogen concentration
decreased hydrogen concentration

decreased oxygen concentration

Answer 4

The dominant forms of life in the Mesozoic era were **reptiles**. This era, often referred to as the "Age of Reptiles," is characterized by the prevalence of dinosaurs and other reptiles.

Answer 5

The characteristic that defines the Paleozoic era is that **animals with shells and hard parts were dominant for the first time.** This era saw the emergence of many marine life forms with hard exoskeletons during events like the Cambrian Explosion.

Answer 6

The correct chronological order of the events from earliest to latest is:

**Photosynthesizing bacteria release oxygen into the sea. Oxygen concentrations increase in the atmosphere. Many new animal species evolve. Single-celled organisms increase atmospheric methane concentrations.**

This sequence reflects the progression of oxygen production by bacteria leading to increased atmospheric oxygen, which then allowed for the evolution of more complex life forms.

Answer 7

The success of photosynthetic bacteria changed Earth’s atmosphere by resulting in **increased oxygen concentration**. These bacteria produced oxygen as a byproduct of photosynthesis, significantly altering the composition of the atmosphere and paving the way for the evolution of aerobic organisms.