Why are there so many variations of human skin color

Most of the energy needed for all the processes on earth comes directly or indirectly from the sun. There is no medium or material connecting the sun to the earth.

Which of the following statements is true regarding specialization among cells? a. All cells specialize to some degree. b. Specialization leads to greater autonomy among cells. c. Specialized cells may lose the ability to reproduce. d.

Why are the fish able to survive in the pond? 1) The fish use carbon dioxide produced by the plants. 2) The fish use oxygen produced by the plants. 3) The plants use oxygen produced by the fish. 4) The plants use chlorophyll produced by the fish.

Microfilariae occur during which stage of heartworm larvae? first second third fourth

Which of the following does inhaling agents such as coal dust cause? a. tuberculosis b. pneumonia c. bronchitis d. pulmonary fibrosis e. pulmonary tuberculosis

According to the law of supply and demand, what would occur if the supply of oil decreased, but the demand remained the same? A) Oil prices would increase B) Oil prices would decrease C) Oil usage would increase D) Oil usage would decrease

Which of the following is the largest available source of fresh surface water

Why does tempreture increase when the amount of carbon dioxide or methane in the earth system increase?

Which of the following is the definition for specifiction

Which water depth had the biggest difference in survival rates for embryos with UV-B protection versus embryos without UV-B protection? (A) 0 cm (B) 100 cm (C) 50 cm (D) 10 cm