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.
Answer:
Describe how oxygen gas is produced during photosynthesis?
Photosynthesis entails the reaction between carbondioxide and water which gives glucose and evolve oxygen
Explanation:
there is a zero percent chance do to the sterilization and cleaning of all equipment as well as it being illegal to reuse needles in hospitals
Answer:
The correct option is the number 2. Cystic fibrosis
Explanation:
Cystic fibrosis is a hereditary disease that affects the glands that produce mucus, sweat and digestive juices, this genetic disorder makes the secretions more sticky and thick, they accumulate and produces blockage in the tubes, ducts and passages, in particular in the lungs and pancreas.
The mucus block the ducts that carry digestive enzymes from the pancreas to the small intestine. Without these digestive enzymes, the intestines are not able to completely absorb nutrients in the food. The result is often, little increase in weight and growth, intestinal obstruction, particularly in newborns (ìleo meconium), among others.
Cystic fibrosis also affects the epithelial cells of the sweat glands, children suffering from this disorder may have a kind of salt layer on the skin. They can also lose abnormally high amounts of salt when they sweat on hot days.
