1. What is the main function of calcitonin, a hormone produced by the thyroid gland?

A. Stimulate metabolism and heat production
B. Increase calcium absorption from the intestines
C. Enhance bone growth and development
D. Lower blood calcium levels

Correct answer: D

Rationale: The correct answer is D: 'Lower blood calcium levels.' Calcitonin is a hormone produced by the thyroid gland that helps regulate calcium levels in the blood. It works by inhibiting the breakdown of bone, which in turn lowers the amount of calcium released into the bloodstream. This process helps to decrease blood calcium levels when they are too high. Options A, B, and C are not functions of calcitonin; instead, they are more closely associated with other hormones such as thyroid hormones, vitamin D, and growth hormone, respectively.

2. Which of the following functional groups is present in carboxylic acids?

A. Carbonyl
B. Hydroxyl
C. Carboxyl
D. Aldehyde

Correct answer: C

Rationale: Carboxylic acids contain the carboxyl functional group (-COOH). The other choices are associated with different functional groups.

3. Which of the following types of muscle tissue is found attached to bones and allows for voluntary movement?

A. Smooth muscle
B. Cardiac muscle
C. Skeletal muscle
D. Connective tissue

Correct answer: C

Rationale: The correct answer is C: Skeletal muscle. Skeletal muscle is the type of muscle tissue that is attached to bones and allows for voluntary movement. This type of muscle is under conscious control, meaning we can choose to contract or relax these muscles to produce movement. Smooth muscle (option A) is found in the walls of internal organs and is not under voluntary control. Cardiac muscle (option B) is found in the heart and also functions involuntarily. Connective tissue (option D) primarily provides support and structure to the body but does not directly enable movement like skeletal muscle does.

4. What is the name of the muscular ring that controls the passage of food from the esophagus to the stomach?

A. Pyloric sphincter
B. Cardiac sphincter
C. Ileocecal valve
D. Sphincter of Oddi

Correct answer: B

Rationale: The correct answer is B: Cardiac sphincter. The cardiac sphincter, also known as the lower esophageal sphincter, is the muscular ring located at the junction between the esophagus and the stomach. It controls the passage of food from the esophagus into the stomach by opening and closing to prevent reflux of stomach contents back into the esophagus. The other options are incorrect: A) The pyloric sphincter is located at the junction between the stomach and the small intestine, controlling the passage of food from the stomach into the small intestine. C) The ileocecal valve is located between the small intestine and the large intestine. D) The Sphincter of Oddi is located in the duodenum and regulates the flow of bile and pancreatic juice into the small intestine. Therefore, the correct answer is B because it specifically relates to the passage of food from the esophagus to the stomach.

5. Which sentence uses the comparative degree of an adjective correctly?

A. This movie is good, but the other one is better.
B. She is the tallest player on the team.
C. He worked hardest than everyone else.
D. My coffee is hotter than yours.

Correct answer: A

Rationale: Option A uses "better" to compare the quality of two movies.

6. What is the term for an organism with two different alleles for a gene?

A. Homozygous
B. Heterozygous
C. Dominant
D. Recessive

Correct answer: B

Rationale: An organism with two different alleles for a gene has a mixed genotype and may exhibit either the dominant or recessive trait depending on the specific gene and its alleles.