1. Epithelial tissue, which covers surfaces, is further classified based on the number of cell layers. Simple epithelium has:

A. No layers
B. One layer
C. Two to several layers
D. Many tightly packed layers

Correct answer: B

Rationale: The correct answer is B: 'One layer.' Simple epithelium is characterized by having a single layer of cells. This type of epithelial tissue is found in areas where diffusion, filtration, or absorption are primary functions. Simple epithelium allows for efficient exchange of substances across the cell layer due to its thin structure and close proximity to underlying tissues. Examples of locations where simple epithelium is found include the lining of blood vessels (endothelium) and air sacs of the lungs (alveoli). In contrast, stratified epithelium consists of multiple layers of cells and is commonly found in areas that require protection against mechanical or chemical stress, such as the skin and the lining of the esophagus.

2. How is the density of a substance calculated?

A. Mass / Volume
B. Volume / Mass
C. Mass x Volume
D. None of the above

Correct answer: A

Rationale: Density is the mass per unit volume of a substance.

3. Simple columnar epithelium lining the small intestine is crucial for:

A. Movement
B. Support
C. Absorption
D. Insulation

Correct answer: C

Rationale: The correct answer is C: Absorption. The simple columnar epithelium lining the small intestine is crucial for absorption due to its structure and function. It has microvilli that increase the surface area available for nutrient absorption. This epithelium also contains specialized cells like goblet cells that secrete mucus to protect the lining and aid in the movement of materials. Movement (choice A) is more related to muscle tissue rather than epithelial tissue. Support (choice B) is usually provided by connective tissue rather than epithelial tissue. Insulation (choice D) is not a function of the simple columnar epithelium in the small intestine.

4. What is the name of a condition where the immune system mistakenly attacks healthy body tissues?

A. Allergy
B. Autoimmune disease
C. Immunodeficiency
D. Sepsis

Correct answer: B

Rationale: The correct answer is B: Autoimmune disease. This condition occurs when the immune system mistakenly targets and attacks healthy tissues in the body, leading to inflammation and tissue damage. Autoimmune diseases can affect various organs and systems in the body, such as rheumatoid arthritis, lupus, and multiple sclerosis. Allergies (A) involve the immune system overreacting to harmless substances, but they do not involve attacking healthy tissues. Immunodeficiency (C) refers to a weakened immune system that is less able to fight off infections. Sepsis (D) is a life-threatening condition caused by the body's response to an infection, not an autoimmune reaction.

5. What is the main topic of the passage?

A. Benefits of bioremediation in cleaning oil spills.
B. Dangers of microplastics to marine ecosystems.
C. History of plastic production and its global impact.
D. Comparison of different waste management strategies.

Correct answer: B

Rationale: The passage focuses on the specific issue of microplastics in the marine environment and their harmful effects.

6. What happens during a physical change in matter?

A. A new substance with different properties is formed
B. The chemical composition of the substance changes
C. The original substance can be recovered by physical means
D. Energy is either released or absorbed

Correct answer: C

Rationale: During a physical change in matter, the original substance undergoes a change in its physical state or appearance without any change in its chemical composition. This means that the original substance can be recovered by physical means, such as melting, freezing, boiling, or condensing. No new substance is formed (option A), the chemical composition remains the same (option B), and energy changes can occur but are not a defining characteristic of a physical change (option D).