Which of these ingredients in saliva is responsible for activating salivary amylase?

A. mucus

B. phosphate ions

C. chloride ions

D. urea

Answer Explanation:

b) phosphate ions

- Correct: Phosphate ions are responsible for activating salivary amylase. Saliva contains salivary amylase (also known as alpha-amylase or ptyalin), which is an enzyme that catalyzes the hydrolysis of starch into maltose and other smaller carbohydrates. However, salivary amylase is only activated in the presence of certain ions, particularly phosphate ions. These ions help to stabilize the enzyme's structure and facilitate its enzymatic activity. Therefore, phosphate ions play a crucial role in the function of salivary amylase.

a) Mucus

- Incorrect: Mucus in saliva serves primarily as a lubricant and protective barrier for the oral mucosa and facilitates swallowing. It does not directly activate salivary amylase

c) Chloride ions

- Incorrect: Chloride ions are electrolytes present in saliva, but they do not directly activate salivary amylase. Instead, they help maintain the osmotic balance and pH of saliva.

d) Urea

- Incorrect: Urea is a waste product found in urine and is not directly involved in the activation of salivary amylase.

Therefore, the Correct Answer is B.

Q #1: Chemical digestion of carbohydrates begins in the

A. esophagus

B. stomach

C. duodenum

D. oral cavity

Answer Explanation

D. oral cavity

- Correct: Chemical digestion of carbohydrates begins in the oral cavity. Salivary glands in the mouth secrete saliva, which contains an enzyme called amylase. Amylase breaks down complex carbohydrates (such as starch) into simpler sugars (such as maltose) through hydrolysis. This process initiates the digestion of carbohydrates before the food bolus reaches the stomach or small intestine.

A. esophagus

- Incorrect: The esophagus is primarily involved in the propulsion of food from the mouth to the stomach through peristaltic contractions. It does not play a significant role in the chemical digestion of carbohydrates.

B. stomach

- Incorrect: While the stomach plays a role in the digestion of proteins through the action of gastric juices containing pepsin and hydrochloric acid, it does not contribute significantly to the digestion of carbohydrates. In fact, the acidic environment of the stomach may temporarily inhibit the activity of salivary amylase.

C. duodenum

- Incorrect: The duodenum is the first part of the small intestine where the majority of chemical digestion occurs. While the duodenum receives pancreatic enzymes and bile that aid in the digestion of carbohydrates, proteins, and fats, the initial chemical digestion of carbohydrates primarily occurs in the oral cavity with the action of salivary amylase.
Q #2: Which of the following organs is supported by a layer of adventitia rather than serosa?

A. esophagus

B. stomach

C. small intestine

D. large intestine

Answer Explanation

a) esophagus

- Correct: The esophagus is supported by a layer of adventitia rather than serosa. The adventitia is a connective tissue layer that covers organs and structures that are not located within the peritoneal cavity. In the case of the esophagus, it lies behind the trachea and heart and passes through the diaphragm before connecting to the stomach. Since it is located outside the peritoneal cavity, it is covered by adventitia instead of serosa, which is the visceral peritoneum that covers organs within the abdominal cavity.

b) stomach

- Incorrect: The stomach is supported by a layer of serosa, which is the visceral peritoneum covering organs within the abdominal cavity.

c) small intestine

- Incorrect: The small intestine is supported by a layer of serosa, which is the visceral peritoneum covering organs within the abdominal cavity.

d) large intestine

- Incorrect: The large intestine is supported by a layer of serosa, which is the visceral peritoneum covering organs within the abdominal cavity.
Q #3: Which of these statements about the pharynx is true?

A. It extends from the nasal and oral cavities superiorly to the esophagus anteriorly.

B. The oropharynx is continuous superiorly with the nasopharynx.

C. The nasopharynx is involved in digestion.

D. The laryngopharynx is composed partially of cartilage.

Answer Explanation

d) The laryngopharynx is composed partially of cartilage.

- True: The statement that the laryngopharynx is composed partially of cartilage is true. The pharynx, commonly known as the throat, is a muscular tube that extends from the base of the skull to the level of the sixth cervical vertebra. It serves as a passageway for both air and food. The pharynx is divided into three regions: the nasopharynx, oropharynx, and laryngopharynx.

a) It extends from the nasal and oral cavities superiorly to the esophagus anteriorly.

- False: The pharynx extends from the nasal and oral cavities superiorly to the esophagus and larynx inferiorly, not anteriorly.

b) The oropharynx is continuous superiorly with the nasopharynx.

- False: The oropharynx is continuous inferiorly with the oral cavity, not superiorly with the nasopharynx. The nasopharynx is continuous superiorly with the nasal cavity.

c) The nasopharynx is involved in digestion.

- False: The nasopharynx is primarily involved in respiration and the passage of air. It contains the openings of the auditory tubes and tonsils but is not directly involved in digestion.

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Which of these ingredients in saliva is responsible for activating salivary amylase?

More Questions on TEAS 7 Science

Q #1: Chemical digestion of carbohydrates begins in the

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Q #2: Which of the following organs is supported by a layer of adventitia rather than serosa?

Answer Explanation

Q #3: Which of these statements about the pharynx is true?

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