Answer: d. in the body can operate at a mechanical advantage or mechanical disadvantage, depending on specific location.
Explanation:
A first-class lever is defined as the force in which fulcrum is present in the center and the load and effort on each side of the fulcrum. First class lever moves over a large distance to move the load to a smaller distance.
First-class lever can be operated at mechanical advantage or disadvantage that it can aid in work by changing the direction of the force and by increasing the efficiency. As the the fulcrum is between the load and the effort so the length of the effort arm divided by the length of the effort arm.
If the fulcrum is closer to the effort, it will operated at mechanical disadvantage and vice versa.
Example of first class levers includes scissors, a claw hammer, a see-saw and a weighing balance.
Hence, the correct option is D.
Laurasia and Gondwanaland. I know that last one seems weird but it’s true
Photosynthesis
Photosynthetic bacteria use the energy of the sun to make their own food. In the presence of sunlight, carbon dioxide and water are turned into glucose and oxygen. The glucose is then turned into usable energy. Glucose is like the "food" for the bacteria. An example of photosynthetic bacteria is cyanobacteria, as seen in the opening image. These bacteria are sometimes called blue-green algae, although they are not algae, due to their numerous chlorophyll molecules.
Decomposers
Bacteria known as decomposers break down wastes and dead organisms into smaller molecules. These bacteria use the organic substrates they break down to get their energy, carbon, and nutrients they need for survival.
Chemotrophs
Bacteria can also be chemotrophs. Chemosynthetic bacteria, or chemotrophs, obtain energy by breaking down chemical compounds in their environment. An example of one of these chemicals broken down by bacteria is nitrogen-containing ammonia. These bacteria are important because they help cycle nitrogen through the environment for other living things to use. Nitrogen cannot be made by living organisms, so it must be continually recycled. Organisms need nitrogen to make organic compounds, such as DNA
Where i got the information https://www.ck12.org/biology/bacteria-nutrition/lesson/Bacteria-Nutrition-MS-LS/
The scientific method describes the steps you use during an experiment