*Question*
Q: Cellular respiration and photosynthesis are important parts of which cycle? Read this paragraph and choose the correct option from the provided answers: Cellular respiration and photosynthesis are important parts of the carbon cycle. The carbon cycle is the pathways through which carbon is recycled in the biosphere. While cellular respiration releases carbon dioxide into the environment, photosynthesis pulls carbon dioxide out of the atmosphere. The exchange of carbon dioxide and oxygen during photosynthesis ( Figure below ) and cellular respiration worldwide helps to keep atmospheric oxygen and carbon dioxide at stable levels. Choices: - vapor cycle - greenhouse effect - water cycle - carbon cycle A:
**Answer**
carbon cycle

*Question*
Q: The fact that all animals have certain traits in common shows that they share what? Read this paragraph and choose the correct option from the provided answers: There is great variation among species that make up the animal kingdom. Some of this variation is shown in Figure below . Despite the variation, there are a number of traits that are shared by all animals. The fact that all animals have certain traits in common shows that they share a common ancestor. How did such a diverse group of organisms evolve? What traits do all animals share? Read on to find out. Choices: - a common gene - a common brain - a common planet - a common ancestor A:
**Answer**
a common ancestor

*Question*
Q: What are surface currents mainly caused by? Read this paragraph and choose the correct option from the provided answers: Surface currents are like streams flowing through the surface of the ocean. They are caused mainly by winds. Earth's rotation influences their direction. This is called the Coriolis effect. Surface currents may affect the climate of nearby coasts. Choices: - lightning - waves - rains - winds A:
**Answer**
winds

*Question*
Q: How many valves are in the heart? Read this paragraph and choose the correct option from the provided answers: So how is the blood kept from flowing back on itself? Valves ( Figure below ) in the heart keep the blood flowing in one direction. The valves do this by opening and closing in one direction only. Blood only moves forward through the heart. The valves stop the blood from flowing backward. There are four valves of the heart. Choices: - one - six - two - four A:
**Answer**
four