Fact 1: All life relies on a relatively narrow range of pH, or acidity.  Fact 2: All organisms have life cycles.  Given the two facts above, answer the question "what relies on a relatively narrow range of acidity?" with the following options:  - weathering  - mammals  - density  - Most plants  - organisms  - animals  - barnacles  - volume
organisms

Fact 1: Uneven heating of the Earth 's surface cause wind.  Fact 2: Wind belts arise because of the uneven heating of Earth s surface by the Sun.  Given the two facts above, answer the question "What does uneven heating by the Sun cause?" with the following options:  - harm  - energy  - corn  - Injury  - cracks  - wind  - deadly  - sweat
wind

Fact 1: All plants have a characteristic life cycle that includes alternation of generations.  Fact 2: All ferns are shade plants.  Given the two facts above, answer the question "What has a characteristic life cycle that includes alternation of generations?" with the following options:  - humans  - leaves  - Oak  - dogs  - Trees  - cacti  - amoeba  - ferns
ferns

Fact 1: Sound can be used for communication by animals.  Fact 2: Sound Sound waves are mechanical waves.  Given the two facts above, answer the question "What can be used for communication by animals?" with the following options:  - books  - Electrical energy  - electromagnetic energy  - nails  - chemical messengers  - mechanical waves  - encoded information  - ice

mechanical waves