Ans: (F)
Question: The two-chambered heart of some backboned aquatic animals is part of their:
Options:
- (A) aerobic capacity
- (B) three-chambered heart
- (C) biological diversity
- (D) it keeps an organism warm
- (E) the body's largest organ
- (F) circulatory system
- (G) salmon
- (H) swimming system
CoT: Fish have a circulatory system with a two-chambered heart. Fish are backboned aquatic animals. Some backboned aquatic animals have a circulatory system with a two-chambered heart.

Ans: (D)
Question: What uses playing as just one of many ways to learn how to behave?
Options:
- (A) athletes
- (B) Toys
- (C) sharks
- (D) Humans
- (E) Video games
- (F) exercise
- (G) people
- (H) A.I
CoT: Playing is just one of many ways that mammals and other animals learn how to behave. After all, seals are mammals just as humans are mammals. Playing is just one of many ways that humans and other animals learn how to behave.

Ans: (H)
Question: What direction does something that has oxygen-rich blood go?
Options:
- (A) mouth of rivers
- (B) the body's largest organ
- (C) move to different locations
- (D) Earth orbiting the Sun
- (E) Move to another area
- (F) to move people
- (G) animal transport
- (H) Away from the heart
CoT: Arteries generally carry oxygen-rich blood. Arteries carry blood away from the heart. Something that brings blood away from the heart carries oxygen-rich blood.

Ans: (D)
Question: What detects hybrids of the substance that helps assemble proteins?
Options:
- (A) orchids
- (B) sensory neurons
- (C) peachleaf willow
- (D) luminometer
- (E) A computer
- (F) animals
- (G) A Greek letter
- (H) scattered light
CoT: DNA contains genetic instructions for proteins, and RNA helps assemble the proteins. RNA hybrids are then detected by a luminometer. A luminometer detects hybrids of the substance that helps assemble proteins.