Astudent wants to answer the question "does adding calcium powder to soil make pea plants grow faster? " she adds calcium powder to the soil of 12 plants and does not add it to the soil of a second group of 12 plants. she measures the growth of all of the plants in each group for a month. which statement best summarizes the factors that need to be controlled in this experiment?
a) all plants should be the same age and health and be given equal amounts of water and sunlight.
b) all plants should be placed in separate, equal-sized pots on the same table, where they receive the same amount of sunlight.
c) all plants should be watered in the morning at the same time each day, and given the same amount of soil and sunlight.
d) all plants should be the same health and be given equal amounts of water, calcium, and sunlight.

The diagram below represents a marine food web and a process that can harm the human population. each circle represents an organism and the smaller dots inside them represent a toxic substance. what is being represented and how does it harm the population? the diagram represents biological half-life, in which toxins build up in organisms higher up on the food chain, and this can negatively impact humans who consume the organisms and the toxic substance. the diagram represents biomagnification, in which toxins build up in organisms higher up on the food chain, and this can negatively impact humans who consume the organisms and the toxic substance. the diagram represents the process by which different organisms prey upon each other; this can impact the human population by reducing the number of organisms that do not contain the toxin. the diagram represents the way that toxins are metabolized by living organisms, with those at greater trophic levels able to metabolize more efficiently than those at lower levels. this means that those at higher tropic levels are safer for humans to consume compared to the organisms at lower trophic levels.

What causes the force that pushes magma from the magma chamber through the pipe and vent of a volcano?

Question#29: why does the tropical ocean have a greater temperature range than the temperate ocean?