The main function of the heart in the human body is to:

• pump blood throughout the body

• digest food

• control body temperature

• filter waste from the blood

The part of the cell that controls its activities and contains DNA is:

• Cytoplasm

• Nucleus

• Cell membrane

• Mitochondria

Plants take in which gas during photosynthesis?

• Oxygen

• Carbon Dioxide

• Nitrogen

• Hydrogen

What gas do humans breathe out that plants need?

• Oxygen

• Nitrogen

• Carbon Dioxide

• Hydrogen

The difference between a plant cell and an animal cell is:

• Plant cells have a cell wall, while animal cells do not.

• Animal cells have chloroplasts, while plant cells do not.

• Both plant and animal cells have a cell wall.

• Plant cells lack a nucleus, while animal cells have one.

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. Which of the following is an example of an ecosystem?

• A desert

• A computer

• A car

• A book

What are the three main stages of the life cycle of a butterfly?

• Egg, Larva, Adult

• Egg, Pupa, Adult

• Egg, Larva, Pupa

• Larva, Pupa, Adult

What is a food chain? Name three levels in order.

• A sequence of organisms each dependent on the next as a source of food; producers, consumers, decomposers

• A network of interconnected food webs; primary, secondary, tertiary

• A linear sequence of organisms; herbivores, carnivores, omnivores

• A system of interdependent food chains; predators, prey, scavengers

Natural selection is a process by which:

• organisms with favorable traits survive and reproduce

• all organisms survive regardless of traits

• organisms with unfavorable traits reproduce more

• environmental changes do not affect organisms

One reason an animal might go extinct is:

• habitat loss

• overpopulation

• abundant food supply

• favorable climate conditions