Which of the following true statements best supports the endosymbiotic theory? select one: a. all mitochondria have circular dna. b. all eukaryotic cells have ribosomes. c. all eukaryotic cells have dna. d. all mitochondria function as powerhouses to the cell.

Barbara is converting 78°f to degrees celsius. first, she subtracts 32 from 78. what is the next step?

Researchers randomly divide participants into groups. each group takes a different amount of omega-3 fatty acid supplements daily for a month. one group receives a placebo. the researchers measure the impact on cholesterol levels in the blood. what is the purpose of random assignment in this experiment? a, to produce treatment groups with similar characteristics b, to ensure that all people with high cholesterol have an equal chance of being selected for the study c, to increase the accuracy of the research results and prevent skewness in the data

Consider the model of the oxygen cycle on earth. the majority of earth's oxygen reservoirs are found in the a) atmosphere. b) biosphere. c) hydrosphere. d) lithosphere.