1. What is the main component that gives bones their rigidity and hardness?

A. Collagen
B. Calcium phosphate
C. Cartilage
D. Ligaments

Correct answer: B

Rationale: The main component that gives bones their rigidity and hardness is calcium phosphate, which is a mineral compound found in bone tissue. While collagen is a protein that provides flexibility and strength to bones, it is the calcium phosphate that primarily contributes to the hardness and rigidity of bones. Cartilage is a connective tissue that cushions joints and helps with movement, while ligaments are fibrous tissues that connect bones to other bones. Therefore, calcium phosphate is the correct answer as it directly relates to the rigid and hard nature of bones.

2. What is the functional group present in ethers?

A. Hydroxyl
B. Carbonyl
C. Ether
D. Amine

Correct answer: C

Rationale: Ethers have the functional group -O-, representing an oxygen atom bonded to two alkyl or aryl groups. The other choices are associated with different functional groups.

3. What characteristic unites all organisms in the kingdom Animalia?

A. Multicellularity and heterotrophy
B. Unicellular nature
C. Photosynthesis
D. Cell walls made of chitin

Correct answer: A

Rationale: Rationale: A) Multicellularity and heterotrophy: This is the correct answer because all organisms in the kingdom Animalia are multicellular (composed of multiple cells) and exhibit heterotrophy (obtain nutrients by consuming other organisms). B) Unicellular nature: This is incorrect because organisms in the kingdom Animalia are multicellular, not unicellular. C) Photosynthesis: This is incorrect because organisms in the kingdom Animalia do not perform photosynthesis; they are heterotrophs that obtain nutrients by consuming other organisms. D) Cell walls made of chitin: This is incorrect because organisms in the kingdom Animalia do not have cell walls made of chitin. Chitin is a structural polysaccharide found in the cell walls of fungi, not animals.

4. Which condition is characterized by inflammation of the inner lining of the stomach?

A. Gastroesophageal reflux disease (GERD)
B. Diverticulitis
C. Ulcerative colitis
D. Gastritis

Correct answer: D

Rationale: The correct answer is D, gastritis. Gastritis refers to the inflammation of the inner lining of the stomach, which can be caused by various factors such as excessive alcohol consumption, prolonged use of NSAIDs, or bacterial infections like H. pylori. Gastroesophageal reflux disease (GERD) is characterized by the backflow of stomach acid into the esophagus, not inflammation of the stomach lining. Diverticulitis is inflammation of small pouches that can develop in the colon, while ulcerative colitis is inflammation in the large intestine. Therefore, gastritis best fits the description of inflammation in the inner lining of the stomach.

5. The lymphatic system works closely with which other body system to fight infections?

A. Respiratory system
B. Digestive system
C. Immune system
D. Nervous system

Correct answer: A

Rationale: The correct answer is the Respiratory system. The lymphatic system and the respiratory system work closely together to fight infections. The respiratory system helps to filter out pathogens and other harmful substances from the air we breathe, while the lymphatic system produces and transports white blood cells (lymphocytes) that play a key role in the immune response against infections. This collaboration helps the body to defend against respiratory infections and maintain overall health.

6. Which type of muscle is found in the walls of hollow organs, such as the stomach and intestines, and is responsible for involuntary contractions to propel substances through the organs?

A. Cardiac muscle
B. Smooth muscle
C. Skeletal muscle
D. Striated muscle

Correct answer: b

Rationale: The correct answer is B: Smooth muscle. Smooth muscle is found in the walls of hollow organs like the stomach and intestines. It is responsible for involuntary contractions to move substances through these organs. Unlike skeletal muscle (answer C) and cardiac muscle (answer A), smooth muscle is not under voluntary control. Striated muscle (answer D) is a term that refers to both skeletal and cardiac muscle due to their striped appearance under a microscope, but smooth muscle does not have this striped appearance.