<u>Answer:</u>
Cyanobacteria start producing pure oxygen around 200 million years ago.
<u>Explanation:</u>
Many scientists believed that Earth did not have any oxygen. Cyanobacteria or the blue green algae are the microbes which produced oxygen for the first time with the help of photosynthesis. This was around 4.5 billion years ago: after Hadean eon.
They were very simple, but they produced oxygen in the early earth’s atmosphere. So, they brought evolution on earth. This “blue-green algae” exists in salt water, rocks and soils and play a major role in maintaining the ecosystem.
Answer: Blindly selecting from a bag filled with blue green red and yellow beads.
Explanation: I looked around on brainly and other websites since you did not provide the choices and I found out this answer. Let me know if it helped!
Answer:
The answer is B, How does gravitropism affect plant growth?
Explanation:
According to Google:
"Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant or fungus in response to gravity pulling on it."
So, since the students put the pots on their sides, and they say that the bean plants bend upwards, then option B is the only logical explanation for the plants' behavior.
Have a BE-A-U-TIIFUL day!! \(^u^\)
