D. <span>controlled
is the right answer because a</span><span>n </span>experiment<span> in which an observer tests a hypothesis by looking for changes carried by alterations to a variable.</span>
Copper is considered to be a non-renewable resource as it takes a long amount of time for the copper deposits to form.
This is the exact answer:
Bacteria are helpful because they produce oxygen, which our bodies need to breathe, and they help us to digest the food we eat. Bacteria are also helpful because they are used in medicine to help us overcome disease. Bacteria are harmful because they can cause tooth decay and illnesses that can be either common or quite serious.
Humans get there energy primarily from glucose I believe. We break down glucose to get ATP (Adenosine Triphosphate) which is then used to supply energy to our cells in order to function.
Answer:
External respiration: CO2 diffuses into the blood
Explanation:
External respiration is also called the pulmonary gas exchange. It refers to the diffusion of O2 from the air in the alveoli of the lungs to blood in pulmonary capillaries and diffusion of CO2 in the opposite direction from the capillary blood into the alveolar air. External respiration in the lungs is responsible for oxygenation of deoxygenated blood coming from the right side of the heart. The oxygenated blood is then returned to the left side of the heart.
