Uhm... I believe you mean a situation when we examine a relation between two variables. In this case all other conditions must remain as constant as possible because they could affect a result and then the conclusions could be false. ie. you examine a relation between temperature and frequency of cell division/organism's activity, then you should stabilize air pressure, food composition, bacterial flora in experimental room... etc. of course when you conduct research in a field, ie. ecological research you can't do any of that but then you are obliged to explain possible aberrations of your results in an article's discussion.
They change into pupae for most of winter
Telescopes on Earth and in orbit around Earth provide scientists with information about our solar system. That information is used to plan where spacecraft fly and where they “point their cameras.” NASA and other agencies send robotic spacecraft to fly by, orbit, or land on other planets and moons.
<span>Observing animal tracks is an example of direct observation, which is used to estimate population size. True</span>
Mercury is a barren planet with little atmosphere. In many regards it is similar to our own moon. However, it is also very close to the Sun, so humans will have to set up bases in craters or near the Poles to avoid being blinded.