1. The endocrine system communicates through chemical messengers called:

A. Enzymes
B. Hormones
C. Antibodies
D. Neurons

Correct answer: B

Rationale: The correct answer is B: Hormones. The endocrine system communicates through hormones, which are chemical messengers produced by various glands in the body. These hormones are released into the bloodstream and travel to target organs or tissues to regulate a wide range of bodily functions. Enzymes (A) are biological molecules that catalyze chemical reactions, not chemical messengers for communication within the body. Antibodies (C) are involved in the immune system's response to foreign substances. Neurons (D) are part of the nervous system and communicate through electrical impulses rather than chemical messengers like hormones.

2. Two objects with different masses collide. What happens to their momentum after the collision?

A. Increases for both objects
B. Decreases for both objects
C. Remains the same for both objects
D. Can increase for one and decrease for the other

Correct answer: C

Rationale: In an isolated system (no external forces), the total momentum

3. The phrase "massive open online courses" (MOOCs) refers to

A. Online learning platforms designed specifically for students with disabilities.
B. University-level courses freely available to anyone with an internet connection.
C. Interactive training modules aimed at developing job-specific skills and knowledge.
D. Online resources offering personalized learning experiences tailored to individual needs.

Correct answer: B

Rationale: MOOCs by definition are open and accessible courses, aligning with B.

4. What do isotopes of the same element have in common?

A. Identical number of protons and neutrons.
B. Identical chemical properties.
C. Identical number of electrons.
D. Identical mass number.

Correct answer: A

Rationale: Identical number of protons and neutrons - Isotopes have the same atomic number but different mass numbers due to varying neutron counts.

5. Differentiate between epithelial and connective tissue.

A. Epithelial tissue is exclusively found in the lungs, while connective tissue supports tendons.
B. Both are composed of cells, but epithelial tissue lines surfaces and glands, while connective tissue binds other tissues.
C. Epithelial tissue is more vascularized, while connective tissue is responsible for muscle contraction.
D. Epithelial tissue is the largest tissue type, while connective tissue is the smallest.

Correct answer: B

Rationale: Epithelial tissue covers surfaces and lines organs, while connective tissue provides support and structure throughout the body. Both are composed of cells, but their functions and locations differ.