_ bind to allergens.
Options:
- (A) to stay warm
- (B) mammals
- (C) fur and fat
- (D) animals
- (E) protect them
- (F) Most plants
- (G) Antibodies
- (H) Chemical energy
--
Let's think first: Antibodies are large, Y-shaped proteins that recognize and bind to antigens. Allergens are also called Antigens. Antibodies bind to allergens.... So the answer is [(G)]

What may become unbalanced if the rate of breathing is too fast or too slow?
Options:
- (A) meiosis
- (B) rain levels
- (C) photosynthesis
- (D) blood acidity
- (E) an organism's body
- (F) Veins and arteries.
- (G) kinetic energy
- (H) swamp vegetation
--
Let's think first: Blood pH may become unbalanced if the rate of breathing is too fast or too slow. Acidity is measured with a pH meter or with pH paper strips. Blood acidity may become unbalanced if the rate of breathing is too fast or too slow.... So the answer is [(D)]

Some producers use what physical feature to use energy and inorganic molecules?
Options:
- (A) leaves
- (B) sunlight
- (C) solar energy
- (D) sun
- (E) resevoir
- (F) chemicals
- (G) mitosis
- (H) trees
--
Let's think first: Producers use energy and inorganic molecules to make food. Leaves make food for the plant. Some producers have leaves to help use energy and inorganic molecules.... So the answer is [(A)]