1. What type of molecule forms the cell membrane and controls what enters and exits the cell?

A. Proteins
B. Carbohydrates
C. Lipids
D. Nucleic acids

Correct answer: C

Rationale: The correct answer is C: Lipids. The cell membrane is primarily composed of a double layer of lipids called phospholipids. These phospholipids have a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails, which arrange themselves to form a barrier that controls the passage of substances in and out of the cell. While proteins are also present in the cell membrane and play important roles in transport and cell signaling, lipids are the main structural component responsible for the selective permeability of the membrane. Carbohydrates are typically found on the outer surface of the membrane and are involved in cell recognition and communication. Nucleic acids are not a major component of the cell membrane; they are primarily responsible for storing and transmitting genetic information within the cell.

2. Which of the following is NOT a good scientific practice?

A. Which of the following is NOT a good scientific practice?
B. Selecting data that supports a desired outcome and ignoring contradictory evidence.
C. Peer-reviewing research findings before publication.
D. Replicating experiments to confirm results and validate findings.

Correct answer: B

Rationale: Scientific objectivity requires considering all data, regardless of whether it aligns with initial expectations. Selective bias can lead to inaccurate conclusions.

3. 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.

4. Which of the following is the main function of the liver?

A. To produce bile, which helps digest fats
B. To store energy in the form of glycogen
C. To produce proteins that help to clot blood
D. To detoxify harmful substances in the body

Correct answer: D

Rationale: Rationale: A) The liver does produce bile, which helps in the digestion of fats, but this is not its main function. Bile is stored in the gallbladder and released into the small intestine to aid in the digestion and absorption of fats. B) While the liver does store energy in the form of glycogen, this is not its main function. Glycogen is a form of glucose storage that can be broken down into glucose when the body needs energy. C) The liver does produce proteins that help to clot blood, such as fibrinogen and prothrombin, but this is not its main function. These proteins are essential for the blood clotting process to prevent excessive bleeding. D) The main function of the liver is to detoxify harmful substances in the body. The liver processes and removes toxins, drugs, alcohol, and other harmful substances from the bloodstream, making them less harmful and

5. Which of the following is the main function of the stomach?

A. To store food and break it down into smaller pieces
B. To absorb nutrients into the bloodstream
C. To produce enzymes that help digest food
D. To eliminate waste products from the body

Correct answer: A

Rationale: Rationale: The main function of the stomach is to store food that has been ingested and mechanically break it down into smaller pieces through the process of churning and mixing with gastric juices. This mechanical breakdown, along with the action of stomach acid and enzymes, helps to initiate the digestion of food before it moves on to the small intestine for further digestion and absorption of nutrients. Absorption of nutrients into the bloodstream primarily occurs in the small intestine, not the stomach. The production of enzymes that help digest food primarily occurs in the pancreas and small intestine, not the stomach. The elimination of waste products from the body primarily occurs through the large intestine and rectum, not the stomach.

6. Which type of glial cell provides structural support and insulation for neurons in the central nervous system?

A. Schwann cells
B. Astrocytes
C. Oligodendrocytes
D. Microglia

Correct answer: C

Rationale: The correct answer is C: Oligodendrocytes. Oligodendrocytes are a type of glial cell found in the central nervous system that provide structural support and insulation for neurons by forming myelin sheaths around axons. Schwann cells, on the other hand, are found in the peripheral nervous system. Astrocytes play a role in nutrient transfer and maintaining the blood-brain barrier. Microglia are responsible for immune defense and clearing debris in the CNS. Therefore, oligodendrocytes are specifically responsible for providing structural support and insulation for neurons in the central nervous system.