NAS2 Challenge Exam Questions and Answers (With
Correct Solutions) Latest 2025/2026
Levels of Organization: - chemical, cellular, tissue, organ, organ system, organismal
Survival Needs - nutrients, oxygen, water, appropriate temperature, atmospheric pressure
Requirements for Life - maintaining boundaries, movement, responsiveness, digestion, metabolism,
excretion, reproduction, growth
Homeostasis - ability to maintain relatively stable internal conditions even though the outside world
changes continuously
Basic Mechanisms - receptor, control centre, effector
Negative Feedback Mechanisms - most common homeostasis control mechanism; the net effect is
that the original output of the system shuts off the original stimulus or reduces the intensity
Positive Feedback Mechanisms - cause the level of a variable to change in the same direction as an
initial change
Ionic bond - chemical bond between atoms formed by the transfer of electrons
Covalent bond - shared electrons between atoms
Hydrogen bond - hydrogen shares a pair of electrons with another atom
Nonpolar - electrically balanced molecules
Polar - non symmetrical molecules that contain electrically unbalanced atoms (water)
Correct Solutions) Latest 2025/2026
Levels of Organization: - chemical, cellular, tissue, organ, organ system, organismal
Survival Needs - nutrients, oxygen, water, appropriate temperature, atmospheric pressure
Requirements for Life - maintaining boundaries, movement, responsiveness, digestion, metabolism,
excretion, reproduction, growth
Homeostasis - ability to maintain relatively stable internal conditions even though the outside world
changes continuously
Basic Mechanisms - receptor, control centre, effector
Negative Feedback Mechanisms - most common homeostasis control mechanism; the net effect is
that the original output of the system shuts off the original stimulus or reduces the intensity
Positive Feedback Mechanisms - cause the level of a variable to change in the same direction as an
initial change
Ionic bond - chemical bond between atoms formed by the transfer of electrons
Covalent bond - shared electrons between atoms
Hydrogen bond - hydrogen shares a pair of electrons with another atom
Nonpolar - electrically balanced molecules
Polar - non symmetrical molecules that contain electrically unbalanced atoms (water)
