Plant cells produce oxygen in the process of photosynthesis at the cellular level. this causes plants at the organism level to perform which function? a. cell division b. reproduction c. waste elimination d. cellular respiration

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

Group control group #1 experimental group yes yes yes control group #2 no new drug orange juice bed rest no yes no yes ves which of the following is the best explanation of why a second control group was included in this experiment? o a. to provide the volunteers in the study with something to drink o b. to prove that the common cold cannot be cured c. to confuse anyone who is trying to steal their new drug and sell it as their own invention o d. to researchers conclude that results are related to the new drug and not to the orange juice submit e previous

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins