<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.
When a stimulus is produced it signifies the production of sensation in the sensory organs. This sensation through the sensory organs (eyes, ears, nose, skin and tongue) is sent to the sensory nerve connected to these sense organs. These sensory nerves send nerve impulses through the nerve fiber to the spinal cord. From the spinal cord the nerve impulse is transferred to motor nerves.
The motor nerve then sends response to the stimulus though the same path to the region from which stimulus was received and thus the body responds through muscular activity. Such as removal of heat from the heated object if heated sensations were received.
Answer:
Red blood.
Explanation:
Red blood is for oxygenated blood, while blue blood is for deoxygenated blood.
The blood in Isabelle's left ventricle would be red, in other words, oxygenated. The left ventricle has oxygenated blood because this blood was first in the right ventricle. Then, it went to the pulmonary arteries, which led the blood to the capillaries close to the alveoli in the lungs. In this area, the deoxygenated blood dropped the CO₂ and took O₂ becoming oxygenated blood. Now, this blood is color-coded red and will go to the pulmonary venules, then to the pulmonary vein, and from there, it will go to the left atrium. Lastly, it will go to the left ventricle to start the systemic circulation, which is the one that distributes the oxygenated blood in the body.
