Chapter 1 Quiz 4 (2nd Secondary Biology)

Intestinal villi are finger-like projections in the small intestine that increase the surface area for absorption of nutrients. They possess microvilli, which further increase the surface area. Additionally, they are supplied with blood capillaries and lacteal vessels, which help in the absorption of nutrients. Therefore, the statement that they only participate in the absorption of fats is not true, as they play a crucial role in the absorption of various nutrients, not just fats.

In the epithelial cells of the villi, fatty acids and glycerol may recombine. This is because the villi are responsible for absorbing nutrients from the small intestine into the bloodstream. Fatty acids and glycerol are the components of dietary fats, and they are broken down during digestion. Once inside the epithelial cells of the villi, they can be recombined to form triglycerides, which are then packaged into chylomicrons and transported to the lymphatic system for further distribution throughout the body.

The main function of lacteals in the villi is the absorption of fatty acids and glycerol. Lacteals are specialized lymphatic capillaries found in the small intestine villi. They play a crucial role in the absorption of dietary fats. When fats are broken down into fatty acids and glycerol during digestion, they are absorbed by the lacteals and transported through the lymphatic system to the bloodstream. This allows the body to utilize these essential nutrients for energy and other metabolic processes.

The correct answer is "All of the above" because the main functions of the digestive system include ingestion (taking in food), digestion (breaking down food), secretion (releasing enzymes and other substances), pushing food forwards (peristalsis), absorption (taking in nutrients), and defecation (eliminating waste).

Metabolism involves all of the processes that break down and build up molecules in the body. This includes both anabolic processes, which build up larger molecules from smaller ones, and catabolic processes, which break down larger molecules into smaller ones. Therefore, the correct answer is that metabolism involves all of these processes.

After absorption, amino acids can undergo various processes. Some amino acids are recycled to make new proteins, which is essential for growth and repair in the body. Additionally, some amino acids are used as a source of energy, providing fuel for various metabolic processes. Lastly, amino acids can also be used to synthesize nitrogen-containing compounds, such as neurotransmitters, hormones, and nucleotides. Therefore, all of the given options are correct, as amino acids can be utilized in these different ways after absorption.

In anabolic reactions, the cell increases in size within very narrow limits. Anabolic reactions involve the synthesis of complex molecules from simpler ones, requiring energy input. This process allows the cell to grow and build new structures. However, the increase in size is limited to maintain the cell's functionality and prevent excessive growth.

Glucose molecules are absorbed by the capillaries in the villi of the small intestine. From there, they enter the hepatic portal vein, which carries blood to the liver. In the liver, glucose is processed and stored as glycogen or released into the bloodstream. The hepatic vein then carries the blood, including glucose, from the liver to the inferior vena cava. Finally, the blood travels from the inferior vena cava to the heart, where it is pumped to the rest of the body.

When you eat a large meal, the catabolic activity called digestion takes the biomolecules you consumed and breaks them down into smaller molecules. Catabolic refers to the process of breaking down larger molecules into smaller ones, which is exactly what happens during digestion.

Fatty acids do not reach the bloodstream directly. They are first broken down into smaller molecules called glycerol and fatty acids. The glycerol is converted into glucose, which can then enter the bloodstream. The fatty acids are transported to the liver, where they are used for energy or stored as fat. Therefore, while amino acids, glucose, and vitamin B can directly enter the bloodstream, fatty acids require additional steps before they can be utilized by the body.

Absorption refers to the process of moving food components from the lumen of the gastro-intestinal tract into body cells. This process allows nutrients, such as carbohydrates, proteins, and fats, to be taken up by the body and used for various functions. Absorption occurs primarily in the small intestine, where nutrients are transported across the intestinal wall and into the bloodstream. From there, they can be delivered to cells throughout the body to support growth, repair, and energy production.

Catabolism refers to the breakdown of complex molecules into simpler ones, usually accompanied by the release of energy. Hydrolysis is a specific type of catabolic reaction where a molecule is broken down by the addition of water. In this reaction, a water molecule is split into hydrogen and hydroxide ions, which are then used to break the bonds of the molecule being catabolized. Therefore, hydrolysis reaction is an example of catabolism.

When glucose is absorbed into the body but is not immediately needed for energy, it is stored in the form of glycogen. The liver and muscle cells are responsible for storing this excess glucose as glycogen. The liver acts as a storage site for glycogen and can release glucose into the bloodstream when needed. Muscle cells also store glycogen and use it as a source of energy during physical activity. Therefore, both muscle cells and the liver store glucose as glycogen, providing a readily available source of potential energy when needed.

The food particles shown in the figure are absorbed by the epithelial mucosal cell of the villi. These absorbed nutrients are then transferred through the lymphatic vessel to the lymphatic system. The lymphatic system plays a crucial role in the absorption and transportation of fats and fat-soluble vitamins. It also helps in filtering and removing waste products from the body. Therefore, the correct answer is the lymphatic system.

Fatty acids can be used in catabolic processes that generate energy through the process of beta-oxidation. They can also be used in anabolic processes to create phospholipids, which are important for cell membranes. Fatty acids and glycerol are stored in adipose fat in the form of triglycerides for later use as an energy source. However, fatty acids cannot be directly converted into glucose through a process called gluconeogenesis. Glucose is primarily synthesized from non-carbohydrate sources such as amino acids and glycerol. Therefore, the statement that fatty acids can be used to make glucose is incorrect.

The correct sequence of steps involved in the process of the Human Digestive System is as follows:
1. Ingestion: The process of taking in food through the mouth.
2. Digestion: The breakdown of food into smaller molecules by mechanical and chemical processes in the stomach and small intestine.
3. Absorption: The process by which nutrients from digested food are taken into the bloodstream through the lining of the small intestine.
4. Assimilation of food: The utilization of absorbed nutrients by cells for growth, repair, and energy production.
5. Defecation: The elimination of undigested waste materials from the body through the rectum and anus.

The oxidation of free fatty acids actually releases energy in the form of ATP. This process is an important source of energy for cells, especially during times of fasting or prolonged exercise. Therefore, the statement that oxidation of free fatty acids requires energy is incorrect.

Anabolism is the correct answer because it refers to the process by which absorbed food molecules are used to build and repair tissues in the body. This process involves the synthesis of complex molecules from simpler ones, such as the conversion of glucose into glycogen for storage in the liver. Anabolism is an essential part of metabolism and is responsible for the growth and maintenance of the body's cells and tissues.

In each villus, all of the following statements are true except for "There is an outer covering of multi-layers epithelial cells." The villi in the small intestine have a single layer of epithelial cells, not multiple layers. The other statements are correct. The lacteal is surrounded by blood capillaries, products of digestion are transferred to the blood and lymph, and there are microvilli present on the epithelial cells.

The villi are small finger-like projections in the small intestine that increase the surface area for absorption. Vitamin D and glycerol are absorbed in structure (B) because they are both lipid-soluble substances. Vitamin C and minerals are absorbed in structure (A) because they are water-soluble substances.

Defecation involves both voluntary and involuntary muscles of the rectum and the anal sphincter. The voluntary muscles are under conscious control and allow us to initiate the process of defecation when we feel the urge to go to the bathroom. The involuntary muscles, on the other hand, work automatically and help to propel the feces out of the rectum and through the anal sphincter. This combination of voluntary and involuntary muscle contractions ensures the effective elimination of waste from the body.

Villi are small finger-like projections in the small intestine that increase the surface area for absorption of nutrients. They contain capillaries, which are tiny blood vessels. These capillaries help in the absorption of nutrients from the digested food in the small intestine and transport them into the circulatory system. Therefore, the function of villi is to move nutrients into the circulatory system via capillaries.

Once the absorbed amino acids pass through the cell membrane in the villi, they are released into the intestinal blood stream. From there, they are transported to the liver by the hepatic portal vein. This vein carries nutrient-rich blood from the intestines to the liver for processing and detoxification before it is distributed to the rest of the body.

Fatty acids and glycerol are absorbed by the lacteals of the villi. Lacteals are specialized lymphatic capillaries found in the small intestine. They are responsible for absorbing dietary fats and fat-soluble vitamins. The villi are small, finger-like projections on the inner lining of the small intestine that increase the surface area for absorption. The fatty acids and glycerol are transported through the lymphatic system and eventually enter the bloodstream.

The absorption process involves the uptake of nutrients from the digestive system into the bloodstream. Fat-soluble vitamins (A, D, E, and K) are actually absorbed along with dietary fats, not proteins. They require the presence of fats for proper absorption.

The rectum is the structure in the digestive system where waste material is compressed into a solid form before being eliminated from the body. It acts as a temporary storage site for feces until they can be expelled through the anus. The rectum plays an important role in the elimination of waste and maintaining the overall health and functioning of the digestive system.

The correct answer states that emulsified fats and vitamin A are found in (B), while vitamin C and glucose are found in (A). This means that emulsified fats and vitamin A are the food materials resulting from digestion that are found in option (B), while vitamin C and glucose are the food materials resulting from digestion that are found in option (A).

The yellow color of the stools in a young infant is due to bile pigments that have passed through the bile juice. Bile is produced by the liver and stored in the gallbladder. It is released into the small intestine to aid in the digestion and absorption of fats. Bile pigments, such as bilirubin, give bile its yellow color. When these pigments are not fully broken down and absorbed in the small intestine, they can pass through the digestive system and give the stools a yellowish color.

The synthesis of ATP is an anabolic reaction because it involves the building of ATP molecules from smaller molecules, which requires energy input. Anabolic reactions are responsible for the synthesis of complex molecules from simpler ones, and they typically require energy. In this case, the energy is stored in the ATP molecules for later use. The breaking down of ATP, on the other hand, is a catabolic reaction because it involves the breakdown of ATP molecules into smaller molecules, releasing energy in the process.

The thin wall of the villi in the small intestine enables a shorter diffusion path for the absorption of nutrients. This means that the nutrients can easily pass through the thin wall and be absorbed into the bloodstream more efficiently. The shorter diffusion path allows for quicker and more effective absorption of nutrients, ensuring that the body receives the necessary substances for energy and growth.

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Butter takes a different route during absorption compared to the other food substances listed. While bread, egg white, and honey are all primarily absorbed in the small intestine, butter is primarily absorbed in the stomach. This is because butter is high in fat, and fat digestion begins in the stomach with the help of an enzyme called gastric lipase. The fat in butter is broken down into smaller molecules called fatty acids and glycerol, which can then be absorbed through the stomach lining.

Active transport is the process by which cells use energy to move molecules across a membrane against their concentration gradient. This allows the transfer of digested food from the intestine into the bloodstream. Membrane diffusion, on the other hand, refers to the movement of molecules across a membrane from an area of higher concentration to an area of lower concentration. This process also aids in the transfer of digested food into the bloodstream. Therefore, both active transport and membrane diffusion are involved in the transfer of digested food to the blood and lymph.

Water is mostly absorbed in the colon. The colon, also known as the large intestine, is responsible for the final stages of water absorption in the digestive system. After the small intestine has absorbed most of the nutrients from food, the remaining waste material enters the colon. The colon absorbs water and electrolytes from this waste material, helping to form solid stool. This process is important for maintaining proper hydration and preventing excessive water loss in the body.

The products of starch digestion are absorbed through active transport to blood capillaries. Active transport is a process that requires energy to move molecules against their concentration gradient. In this case, the products of starch digestion are actively transported from the small intestine into the bloodstream through the blood capillaries. This allows for efficient absorption of nutrients into the body.

Glucose is absorbed in the small intestine through a process called secondary active transport, where sodium ions are actively transported out of the cell, creating a concentration gradient that drives the uptake of glucose into the cell. This process is facilitated by a protein called the sodium-glucose cotransporter (SGLT). Therefore, the correct statement is that absorption of glucose is associated with sodium uptake (2ry active transport).

The large intestine is responsible for absorbing water and electrolytes from the remaining indigestible food material, forming feces. The lining of the epithelial wall having many convolutions increases the surface area for absorption. The mucosa layer secretes mucus to facilitate the smooth passage of feces. The presence of bacteria in the large intestine helps in breaking down undigested food remains into simple substances. However, the expulsion of feces outside the body is not an adaptation of the large intestine, but rather a function of the anal muscles.