Answer:
B. presence of oxygen in the atmosphere
Explanation:
I took the same test and got it right
<span>Cartilage. Cartilage primarily tissue consists of chondrocytes, specialized cells that form a matrix of collagen and other proteins. Cartilage tissue is found at joints between long bones, and also comprises other structural areas in the body such as vertebrae, bronchial tubes, the outer ear, the nose, and in between ribs.</span>
It has four main components: plasma, red blood cells, white blood cells, and platelets. Blood has many different functions, including: transporting oxygen and nutrients to the lungs and tissues. forming blood clots to prevent excess blood loss.
Answer:
30...365; observe the ratio.
Although the actual questions are missing from your ask, here's how you can tell.
If the study will be messed up (added bias) through interaction with the subjects the study should be observational. For example if a biologists wanted to study the eating habits of wild birds in the tropics, they would need to do an observational study. if they did a controlled experiment, the birds will change their eating habits based on human interaction, thus making the study invalid.
If the study requires specific measurements, close monitoring, or contact and interaction with the subjects the study should be a controlled experiment. For example, if a scientist wanted to test out a new drug, the health of patients would need to be closely monitored.
