1. Which of the following blood vessels carries oxygenated blood away from the lungs?

A. Pulmonary artery
B. Aorta
C. Superior vena cava
D. Inferior vena cava

Correct answer: B

Rationale: The correct answer is B: Aorta. The aorta is the main artery in the body that carries oxygenated blood away from the heart to the rest of the body. The pulmonary artery, option A, carries deoxygenated blood from the heart to the lungs for oxygenation. The superior vena cava, option C, and inferior vena cava, option D, are veins that carry deoxygenated blood from the upper and lower parts of the body, respectively, back to the heart. Therefore, the aorta is the blood vessel that carries oxygenated blood away from the lungs.

2. What is the function of introns in eukaryotic genes?

A. They code for protein sequences.
B. They are involved in gene regulation.
C. They are removed during mRNA processing.
D. They are non-functional remnants of ancient DNA.

Correct answer: C

Rationale: Rationale: A) Introns do not code for protein sequences. Exons are the segments of DNA that code for proteins. B) While introns can indirectly influence gene regulation, their primary function is not directly involved in gene regulation. C) Introns are non-coding regions of DNA that are transcribed into pre-mRNA but are removed during mRNA processing through a process called splicing. This allows only the exons to be included in the mature mRNA that will be translated into proteins. D) While introns were once thought to be non-functional remnants of ancient DNA, research has shown that they can have regulatory functions and play a role in gene expression.

3. 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.

4. What hormone signals the release of digestive enzymes from the pancreas?

A. Gastrin
B. Insulin
C. Glucagon
D. Secretin

Correct answer: D

Rationale: Rationale: A) Gastrin is a hormone that stimulates the release of gastric acid in the stomach, not digestive enzymes from the pancreas. B) Insulin is a hormone produced by the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into cells, but it does not directly signal the release of digestive enzymes from the pancreas. C) Glucagon is another hormone produced by the pancreas that works opposite to insulin by increasing blood sugar levels, but it is not involved in signaling the release of digestive enzymes from the pancreas. D) Secretin is a hormone released by the small intestine in response to the presence of acidic chyme. It stimulates the pancreas to release bicarbonate to neutralize the acidity of the chyme and also triggers the release of digestive enzymes from the pancreas to aid in digestion. Therefore, secretin is the hormone that signals the release of digestive enzymes from the pancreas.

5. 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.

6. What is the protective sac surrounding the testes in the male reproductive system?

A. Vas deferens
B. Scrotum
C. Epididymis
D. Urethra

Correct answer: B

Rationale: The correct answer is B: Scrotum. The scrotum is the protective sac surrounding the testes in the male reproductive system. It houses and protects the testes, helping to regulate their temperature for optimal sperm production. The vas deferens is a duct that carries sperm from the testes to the urethra. The epididymis is a coiled tube where sperm mature and are stored. The urethra is a tube that carries urine from the bladder and semen from the reproductive system. Therefore, the scrotum is the specific structure that directly surrounds and protects the testes in the male reproductive system.