In humans, structures that release digestive secretions directly into the small intestine include both the

A. stomach

B. gall bladder

C. villi

D. lacteals

B) gall bladder

- Correct: Bile, which aids in the emulsification of fats in the small intestine, is stored and concentrated in the gall bladder before being released into the small intestine. When fatty foods enter the small intestine, the gall bladder contracts and releases bile into the duodenum (the first part of the small intestine). Bile helps to break down large fat globules into smaller droplets, a process known as emulsification, which increases the surface area for the action of digestive enzymes, such as lipase, facilitating the digestion and absorption of fats.

A) stomach

- Incorrect: Bile is not released from the stomach. The stomach primarily secretes gastric juices containing hydrochloric acid and pepsinogen to aid in the digestion of proteins.

C) villi

- Incorrect: Villi are finger-like projections in the lining of the small intestine that increase its surface area for nutrient absorption but do not release bile.

D) lacteals

- Incorrect: Lacteals are lymphatic vessels found in the villi of the small intestine that absorb dietary fats and fat-soluble vitamins. They do not release bile.

A. diarrhea

B. appendicitis

C. gallstones

D. ulcers

D) ulcers

- Correct: The decrease in hydrochloric acid secretion resulting from the surgical cutting of a branch of the nerve regulating stomach secretions would be most helpful to an individual with ulcers. Ulcers are sores or lesions that develop in the lining of the stomach, small intestine, or esophagus due to factors such as infection with Helicobacter pylori bacteria, prolonged use of nonsteroidal anti-inflammatory drugs (NSAIDs), or excessive alcohol consumption. Hydrochloric acid plays a significant role in the formation and exacerbation of ulcers by increasing the acidity of the stomach, which can irritate and erode the lining of the gastrointestinal tract. Therefore, reducing hydrochloric acid secretion can help alleviate the symptoms and promote healing of ulcers.

A) diarrhea

- Incorrect: Decreasing hydrochloric acid secretion would not directly address the underlying causes of diarrhea, which may be related to infections, dietary issues, or other factors affecting gastrointestinal motility and water absorption.

B) appendicitis

- Incorrect: Appendicitis is inflammation of the appendix, a small pouch located near the junction of the small and large intestines. Decreasing hydrochloric acid secretion would not directly affect the development or treatment of appendicitis.

C) gallstones

- Incorrect: Gallstones are hardened deposits that form in the gallbladder and can obstruct the flow of bile. Decreasing hydrochloric acid secretion would not directly address the formation or treatment of gallstones, as they are primarily composed of cholesterol or bilirubin, not affected by changes in stomach acid levels.

A. They form proteins needed in the stomach.

B. They form the acids that break down food.

C. They change food substances into molecules that can pass into the bloodstream and cells.

D. They change food materials into wastes that can be passed out of the body.

C) They change food substances into molecules that can pass into the bloodstream and cells.

- Correct: Digestive enzymes secreted by the pancreas play a crucial role in breaking down complex food molecules into smaller, absorbable molecules that can pass through the walls of the small intestine and into the bloodstream. These smaller molecules include carbohydrates broken down into simple sugars, proteins broken down into amino acids, and fats broken down into fatty acids and glycerol. Once these molecules are absorbed into the bloodstream, they can be transported to cells throughout the body to provide energy and support various metabolic processes.

A) They form proteins needed in the stomach.

- Incorrect: Digestive enzymes do not form proteins needed in the stomach. Proteins are broken down into amino acids by digestive enzymes, but the enzymes themselves do not form proteins.

B) They form the acids that break down food.

- Incorrect: Digestive enzymes do not form acids. Acids such as hydrochloric acid are secreted by the stomach and aid in the breakdown of food, particularly proteins, but they are not formed by pancreatic enzymes.

D) They change food materials into wastes that can be passed out of the body.

- Incorrect: While digestive enzymes help break down food materials, their primary function is to convert these materials into absorbable molecules rather than wastes. The conversion of food into waste products occurs primarily through processes in the digestive tract and is facilitated by enzymes as part of digestion, but it is not the direct role of pancreatic enzymes.

A. Specific enzymes break down proteins into amino acids.

B. Specific hormones break down proteins into simple sugars.

C. Specific hormones break down proteins into complex starches.

D. Specific enzymes break down proteins into simple sugars.

A) Specific enzymes break down proteins into amino acids.

- Correct: This is the correct answer. Proteins are broken down into their constituent amino acids by specific enzymes during the process of digestion. Enzymes like pepsin in the stomach and various proteases in the small intestine facilitate this breakdown.

B) Specific hormones break down proteins into simple sugars.

- Incorrect: Hormones are not directly involved in breaking down proteins into simple sugars. Hormones are signaling molecules that regulate various processes in the body, including metabolism, but they don't directly participate in the breakdown of proteins into sugars.

C) Specific hormones break down proteins into complex starches.

- Incorrect: Hormones do not break down proteins into complex starches. Proteins are broken down into amino acids by enzymes, not hormones. Starches are complex carbohydrates and are broken down into simple sugars by enzymes like amylase, not proteins.

D) Specific enzymes break down proteins into simple sugars.

- Incorrect: Proteins are not broken down into simple sugars. They are broken down into amino acids by specific enzymes. Simple sugars come from the breakdown of carbohydrates, not proteins.

A. a polypeptide

B. a coenzyme

C. a substrate

D. an inorganic catalyst

B) a coenzyme

- Correct: Vitamin B1, also known as thiamine, functions as a coenzyme in cell respiration. Coenzymes are small molecules that assist enzymes in catalyzing biochemical reactions. In the case of thiamine, it serves as a coenzyme for several enzymes involved in the metabolism of carbohydrates, particularly in the citric acid cycle (Krebs cycle) and the pentose phosphate pathway, which are essential processes in cell respiration. Thiamine helps in the conversion of carbohydrates into energy, ultimately facilitating ATP production.

A) a polypeptide

- Incorrect: Polypeptides are chains of amino acids linked by peptide bonds, and they serve as the building blocks of proteins. Vitamin B1 is not a polypeptide itself but rather a small organic molecule.

C) a substrate

- Incorrect: Substrates are molecules upon which enzymes act to catalyze biochemical reactions. Vitamin B1 is not a substrate but rather a cofactor (coenzyme) that assists enzymes in catalyzing reactions.

D) an inorganic catalyst

- Incorrect: Inorganic catalysts are typically metallic ions or small inorganic molecules that facilitate chemical reactions but are not part of the reaction products. Vitamin B1 is an organic molecule derived from thiazole and pyrimidine rings and is not classified as an inorganic catalyst.

A. red meat and poultry

B. fresh fruits and vegetables

C. eggs and milk products

D. animal fat and plant oil

B) fresh fruits and vegetables

- Correct: Fresh fruits and vegetables are excellent sources of roughage, also known as dietary fiber. These foods provide insoluble fiber, soluble fiber, or a combination of both, which adds bulk to the stool and promotes healthy digestion. Insoluble fiber, found in foods like leafy greens, celery, and broccoli, helps to move food through the digestive tract, preventing constipation. Soluble fiber, found in foods like apples, oats, and beans, can help lower cholesterol levels and regulate blood sugar levels.

A) red meat and poultry

- Incorrect: While red meat and poultry are good sources of protein and other nutrients, they are not significant sources of dietary fiber or roughage. These foods do not contribute to the fiber content of the diet.

C) eggs and milk products

- Incorrect: Eggs and milk products are valuable sources of protein, vitamins, and minerals, but they are not significant sources of dietary fiber or roughage. These foods do not provide the fiber needed for healthy digestion.

D) animal fat and plant oil

- Incorrect: Animal fat and plant oils are sources of dietary fat, which is important for providing energy and essential fatty acids in the diet. However, they do not contain significant amounts of dietary fiber or roughage. These foods do not contribute to the fiber content of the diet.

A. reproductive and excretory

B. digestive and respiratory

C. respiratory and immune

D. digestive and reproductive

The digestive system provides materials in the form of nutrients from food, such as carbohydrates, fats, and proteins. These nutrients are broken down during digestion and absorbed into the bloodstream.

The respiratory system provides oxygen, which is necessary for cellular respiration, the process by which ATP (adenosine triphosphate) is produced in cells. Oxygen is inhaled into the lungs and diffuses into the bloodstream to be transported to cells throughout the body.

A. emulsification

B. excretion

C. absorption

D. peristalsis

Emulsification is a process by which large fat globules are broken down into smaller droplets. This process is facilitated by substances called emulsifiers, with bile being one of the most common emulsifiers in the human body.

A. glucose

B. protein

C. starch

D. oxygen

B) protein

- Correct: After an organism consumes meat, the organic molecules present in the meat, such as amino acids and lipids, are broken down through the process of digestion. These molecules are then absorbed into the bloodstream and transported to various cells throughout the body. In the cells, these molecules are used as building blocks for synthesizing new proteins. Proteins are essential macromolecules involved in numerous cellular functions, including structural support, enzymatic activity, and regulation of cellular processes. Therefore, many of the organic molecules originally contained in the meat would be found in newly formed molecules of protein within the organism's cells.

A) glucose

- Incorrect: Glucose is a simple sugar that is primarily derived from the digestion of carbohydrates. While some amino acids obtained from the digestion of protein can be converted into glucose through gluconeogenesis, the majority of amino acids are used for protein synthesis, not glucose production.

C) starch

- Incorrect: Starch is a complex carbohydrate found in plants. It is not typically present in meat, and it is not directly synthesized from the organic molecules obtained from meat consumption.

D) oxygen

- Incorrect: Oxygen is a gas essential for cellular respiration but is not synthesized from the organic molecules obtained from meat consumption. Oxygen is mainly obtained through breathing and is used in cellular respiration to generate ATP, the energy currency of the cell.

A. meat and eggs

B. fruits and vegetables

C. minerals and milk

D. water and vitamins

B) fruits and vegetables

- Correct: Fruits and vegetables contain the greatest amounts of sugars and starches in the human diet. Both fruits and vegetables are rich sources of carbohydrates, including natural sugars, fiber, and starches. These carbohydrates provide a readily available source of energy for the body. Examples of fruits with natural sugars include apples, bananas, and grapes, while starch-containing vegetables include potatoes, corn, and peas.

A) meat and eggs

- Incorrect: Meat and eggs are primarily sources of proteins and fats, not sugars and starches. They contain minimal amounts of carbohydrates.

C) minerals and milk

- Incorrect: Minerals are inorganic compounds essential for various physiological functions, and milk is a source of proteins, fats, and carbohydrates (mainly lactose, a sugar). While milk contains some sugars, fruits and vegetables typically contribute more significant amounts of sugars and starches to the diet.

D) water and vitamins

- Incorrect: Water and vitamins are essential components of the diet, but they do not contain sugars and starches. Water is a vital component for hydration, and vitamins are organic compounds required for various biochemical processes in the body.