True! because if you have more than one variable, you aren’t going to know which variable changed the dependent variable.
Answer: B
Explanation:
Ammonia is so toxic that it can be transported and excreted only in large volumes of very dilute solution. As a result most terrestrial animals simply don't have access to sufficient water to routine excrete ammonia.
The main advantage of urea is its very low toxicity. Animals can transport urea in the circulatory system and store it safely in high concentrations. Also much less water is loss when a given quantity of nitrogen is excreted in a concentrated solution of urea than would be in a dilute solution of ammonia.
Answer:
The independent variable are the vitamins .
The dependent variable are the rats.
Explanation:
The vitamins are the independent variable because they are are controllable. You can control how many vitamins the rats will be given.
The answer is mitochondria because mitochondria is involved in cellular respiration.
Each enzyme is comprised of covalently linked amino acids...enzymes are proteins