Which of the following best describes topsoil? A.
Topsoil is made entirely of minerals weathered from the underlying parent material.
B.
Topsoil is made entirely of decomposed organic remains.
C.
Topsoil is made of humus and mineral particles weathered from the soil's parent material.
D.
Topsoil is made of humus and clay minerals washed down from the layer above the topsoil.

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.

What are some of the immune functions of the lymphatic system? a. cleaning red blood cells from the blood and creating lymph fluids b.transporting lymph to the tissues and creating lymph fluids c.removing infectious agents and making white blood cells d.making red blood cells and removing infectious agents

Which chemical reaction shows photosynthesis? a. water + carbon dioxide + sunlight → oxygen + glucose b. carbon + oxygen → carbon dioxide c. hydrogen + oxygen → water d. nitrogen + hydrogen → ammonia