Q: Answer the question

Which human body system produces the hormones that regulate growth?
OPTIONS:
- skeletal
- digestive
- circulatory
- endocrine

A: endocrine

Q: Answer the question

Which type of organism is the best at fixing nitrogen?
OPTIONS:
- bacteria
- fungi
- protists
- animals

A: bacteria

Q: Answer the question

The iron in iron-rich red soils may not be in a form that can be taken up by tree roots. As a result, leaves and needles may look yellow. Some trees release acids that convert iron in soil to a usable form. This change in soil chemistry is a type of which process?
OPTIONS:
- deposition
- weathering
- precipitation
- photosynthesis

A:
weathering