Solution idea: Some arthropods have special excretory structures. Insects are the largest group of arthropods. Some insects have special excrectory structures.
Q: What can have special excretory systems?
Options:
- (A) feces
- (B) barnacles
- (C) animals
- (D) cacti
- (E) fungi
- (F) wings
- (G) soil
- (H) insects
A: (H)

Solution idea: Mutations may change the structure of a chromosome or just change a single nucleotide. DNA is made up of nucleotides. Mutations change DNA.
Q: What do mutations do to dna?
Options:
- (A) It expands
- (B) Damages them
- (C) negative
- (D) Moisturize it.
- (E) Help it.
- (F) Destroy it.
- (G) It decreases
- (H) Change it.
A: (H)

Solution idea: Heterotrophs are living things that cannot make their own food. Proteins are an essential nutrient for heterotrophs . Living things that can't make their own food need protein.
Q: What do things that cannot make their own food need as a nutrient?
Options:
- (A) Energy
- (B) metal
- (C) animals
- (D) mud
- (E) Energy.
- (F) protein
- (G) prototype
- (H) fungi
A: (F)

Solution idea: Arteries generally carry oxygen-rich blood. Arteries carry blood away from our heart. Oxygen-rich blood is carried away from our heart.
Q: Oxygen-rich blood is carried where?
Options:
- (A) it keeps an organism warm
- (B) mouth of rivers
- (C) The area was once underwater
- (D) running and lifting
- (E) the body's largest organ
- (F) away from the heart
- (G) Earth orbiting the Sun
- (H) four limbs
A: (F)