Biology: Digestion and Nutrition
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Questions and Answers

What is the role of bile in the small intestine?

  • To aid in digestion and absorption of fats (correct)
  • To activate proteases
  • To destroy functional red blood cells
  • To neutralize acidic chyme

    • Where does most digestion occur in the small intestine?

  • Duodenum (correct)
  • Jejunum
  • Ileum
  • Stomach

    • What is the function of the epithelial lining of the duodenum?

  • To produce acidic digestive enzymes
  • To absorb fatty acids and monoglycerides
  • To produce alkaline digestive enzymes
  • To produce several digestive enzymes (correct)

    • What is the role of the pancreas in the small intestine?

    <p>To produce proteases trypsin and chymotrypsin</p> Signup and view all the answers

    What is the function of villi epithelial cells in the small intestine?

    <p>To absorb fatty acids and monoglycerides</p> Signup and view all the answers

    What is the role of chylomicrons in the small intestine?

    <p>To transport fatty acids and monoglycerides</p> Signup and view all the answers

    What is the main function of the jejunum and ileum in the small intestine?

    <p>Absorption of nutrients and water</p> Signup and view all the answers

    What is the role of the liver in the small intestine?

    <p>To produce bile</p> Signup and view all the answers

    Where does the breakdown of glucose polymers initiated by salivary amylase take place?

    <p>Mouth</p> Signup and view all the answers

    What is the function of mucus in saliva?

    <p>Lubricates food</p> Signup and view all the answers

    What is the role of the epiglottis during swallowing?

    <p>Blocks entry to the trachea</p> Signup and view all the answers

    What is the pH of gastric juice in the stomach?

    <p>Low, around 2</p> Signup and view all the answers

    What is the function of pepsin in gastric juice?

    <p>Breaks down proteins</p> Signup and view all the answers

    What is the role of parietal cells in the stomach?

    <p>Secrete hydrogen and chloride ions</p> Signup and view all the answers

    What is the function of chief cells in the stomach?

    <p>Secrete pepsinogen</p> Signup and view all the answers

    What prevents chyme from entering the esophagus during digestion?

    <p>Sphincters</p> Signup and view all the answers

    What is the primary function of lysosomes in intracellular digestion?

    <p>To fuse with food vacuoles to release hydrolytic enzymes</p> Signup and view all the answers

    Which of the following is a characteristic of extracellular digestion?

    <p>The breakdown of food particles occurs outside of cells</p> Signup and view all the answers

    What is the primary function of the gallbladder in the mammalian digestive system?

    <p>To store and concentrate bile</p> Signup and view all the answers

    What is the difference between a gastrovascular cavity and a complete digestive tract?

    <p>The presence of an alimentary canal with two openings</p> Signup and view all the answers

    Which stage of feeding is characterized by the uptake of nutrients by cells?

    <p>Absorption</p> Signup and view all the answers

    What is the primary function of the salivary glands in the mammalian digestive system?

    <p>To produce digestive enzymes that break down carbohydrates</p> Signup and view all the answers

    Which of the following is a characteristic of intracellular digestion?

    <p>Food particles are engulfed by phagocytosis and broken down by hydrolytic enzymes</p> Signup and view all the answers

    What is the primary function of the pancreas in the mammalian digestive system?

    <p>To produce digestive enzymes that break down proteins and carbohydrates</p> Signup and view all the answers

    What is the primary mechanism by which sponges capture food particles?

    <p>Phagocytosis</p> Signup and view all the answers

    In cnidarians, where does digestion take place?

    <p>Gastrovascular cavity</p> Signup and view all the answers

    What is the common characteristic of animals with bilateral symmetry in terms of digestion?

    <p>Complete digestive system with an entrance and an exit</p> Signup and view all the answers

    What is unique about the digestive system of mammals?

    <p>Complex digestive system with a mouth, esophagus, stomach, small intestine, and large intestine</p> Signup and view all the answers

    What is the stage of feeding characterized by the breakdown of food into smaller molecules?

    <p>Digestion</p> Signup and view all the answers

    In which stage of feeding do cells absorb nutrients through endocytosis?

    <p>Absorption</p> Signup and view all the answers

    What is the process by which unused substances are discarded in sponges?

    <p>Exocytosis</p> Signup and view all the answers

    What is the mechanism by which enzymes break down food in cnidarians?

    <p>Exocytosis</p> Signup and view all the answers

    What is the primary function of energy in animals?

    <p>To support growth and maintenance</p> Signup and view all the answers

    Which of the following is NOT a macronutrient?

    <p>Vitamins</p> Signup and view all the answers

    What is the primary source of energy for herbivores?

    <p>Plants</p> Signup and view all the answers

    During which process do animals obtain energy?

    <p>Digestion</p> Signup and view all the answers

    What is the primary consequence of energy imbalance?

    <p>Health problems</p> Signup and view all the answers

    What is the role of omnivores in the energy cycle?

    <p>They obtain energy from plants and animals</p> Signup and view all the answers

    What is the primary function of the mucous cells in the stomach?

    <p>To produce mucus for protection from acid and enzymes</p> Signup and view all the answers

    What is the purpose of the neutralization reaction in the duodenum?

    <p>To neutralize the acidic pH from the stomach with basic alkaline secretions</p> Signup and view all the answers

    What is the primary function of the glycoproteins in saliva?

    <p>To provide lubrication and protection to the mouth and esophagus</p> Signup and view all the answers

    What is the primary role of the epithelial lining of the small intestine in relation to fat absorption?

    <p>To increase the surface area for absorption through villi</p> Signup and view all the answers

    What is the primary function of the triglycerides in fat absorption?

    <p>To be broken down into fatty acids and monoglycerides for absorption</p> Signup and view all the answers

    What is the primary function of the lacteal in fat absorption?

    <p>To transport absorbed fatty acids and monoglycerides to the bloodstream</p> Signup and view all the answers

    What is the primary function of the chylomicrons in fat absorption?

    <p>To package triglycerides, phospholipids, cholesterol, and proteins for transport</p> Signup and view all the answers

    What is the primary function of the bolus in the mouth?

    <p>To mix food with saliva for formation of a manageable food mixture</p> Signup and view all the answers

    What is the primary advantage of bulk feeding over particle feeding?

    <p>Getting a lot of energy in one act</p> Signup and view all the answers

    Which of the following animals uses a lure to attract prey?

    <p>Angler fish</p> Signup and view all the answers

    What is the primary function of tool use in animals?

    <p>To obtain food that would be difficult or impossible to obtain otherwise</p> Signup and view all the answers

    Which of the following groups of animals is known for their high hunting effectiveness?

    <p>African wild dogs</p> Signup and view all the answers

    What is the primary benefit of group feeding in animals?

    <p>Increased food capture efficiency</p> Signup and view all the answers

    Which of the following is an example of deception in feeding strategies?

    <p>Angler fish using a lure to attract prey</p> Signup and view all the answers

    What is the primary difference between bulk feeding and particle feeding?

    <p>The size of the food particles</p> Signup and view all the answers

    Which of the following is NOT an advantage of bulk feeding?

    <p>Increasing the speed of digestion</p> Signup and view all the answers

    What is the primary function of essential amino acids in animals?

    <p>To serve as building blocks for proteins</p> Signup and view all the answers

    What is the primary difference between complete and incomplete proteins?

    <p>The presence of all essential amino acids</p> Signup and view all the answers

    What is the primary function of vitamins in animals?

    <p>To facilitate chemical reactions</p> Signup and view all the answers

    What is the primary consequence of iron overload in animals?

    <p>Hemochromatosis</p> Signup and view all the answers

    What is the primary stage of food processing where nutrients are absorbed into the bloodstream?

    <p>Absorption</p> Signup and view all the answers

    What is the primary function of essential fatty acids in animals?

    <p>To serve as building blocks for lipids</p> Signup and view all the answers

    What is the primary difference between fat-soluble and water-soluble vitamins?

    <p>The ability to be stored in the body</p> Signup and view all the answers

    What is the primary consequence of a diet lacking essential nutrients?

    <p>Malnutrition</p> Signup and view all the answers

    What is the primary function of the large intestine in the digestive system?

    <p>Water absorption and waste elimination</p> Signup and view all the answers

    Which type of feeder is characterized by the consumption of large amounts of food at one time?

    <p>Bulk feeder</p> Signup and view all the answers

    What is the primary function of gastrin in the digestive system?

    <p>To prepare the stomach for digestion</p> Signup and view all the answers

    What is the primary function of the rumen in the digestive system of ruminants?

    <p>To break down undigested plant material</p> Signup and view all the answers

    What is the primary function of the cephalic phase of digestion?

    <p>To prepare the stomach for digestion</p> Signup and view all the answers

    What is the primary function of the hormone secretin in the digestive system?

    <p>To stimulate the release of pancreatic juices</p> Signup and view all the answers

    What is the primary function of the hormone CCK in the digestive system?

    <p>To stimulate the release of bile and pancreatic juices</p> Signup and view all the answers

    What is the primary function of the gut flora in the large intestine?

    <p>To break down undigested plant material</p> Signup and view all the answers

    What is the primary function of the hormone leptin in regulating body weight?

    <p>To reduce appetite</p> Signup and view all the answers

    What is the primary function of insulin in regulating glucose levels in the blood?

    <p>To convert glucose to glycogen</p> Signup and view all the answers

    Study Notes

    Digestion and Nutrition

    • There are three types of nutrients: those that can be made in the body, those obtained only by eating plants, and those obtained only by eating animals.

    Digestion Forms

    • Digestion involves four stages: ingestion, digestion, absorption, and elimination.
    • Intracellular digestion occurs when food particles are engulfed by phagocytosis, and then fuse with lysosomes containing hydrolytic enzymes.
    • Extracellular digestion occurs outside of cells, in compartments that are continuous with the outside of the animal's body, and can be found in animals with simple body plans.
    • More complex animals have a complete digestive tract or alimentary canal, which can have specialized regions for digestion and absorption.

    Mammalian Digestive System

    • The mammalian digestive system consists of an alimentary canal and accessory glands that secrete digestive juices.
    • Accessory glands include salivary glands, pancreas, liver, and gallbladder.
    • The small intestine is the longest section of the alimentary canal, and is the major organ of digestion and absorption.

    Digestion in the Small Intestine

    • The small intestine is divided into three parts: duodenum, jejunum, and ileum.
    • The pancreas produces proteases trypsin and chymotrypsin that are activated in the duodenum.
    • Bile from the liver and gallbladder aids in digestion and absorption of fats.
    • The epithelial lining of the duodenum produces several digestive enzymes, and enzymatic digestion is completed as peristalsis moves the chyme and digestive juices along the small intestine.
    • Most digestion occurs in the duodenum, while the jejunum and ileum function mainly in absorption of nutrients and water.

    Absorption of Fats

    • Villi epithelial cells absorb fatty acids and monoglycerides, and recombine them into triglycerides.
    • These fats are coated with phospholipids, cholesterol, and proteins to form water-soluble chylomicrons.
    • Chylomicrons are transported into a lacteal, a lymphatic vessel in each villus, and delivered to large veins that return blood to the heart.

    Digestion in the Mouth

    • Salivary glands deliver saliva to lubricate food and initiate breakdown of glucose polymers.
    • Teeth chew food into smaller particles, and saliva contains mucus, a viscous mixture of water, salts, cells, and glycoproteins.
    • The tongue shapes food into a bolus and provides help with swallowing.

    Digestion in the Stomach

    • Gastric juice has a low pH of about 2, which kills bacteria and denatures proteins.
    • Gastric juice is made up of hydrochloric acid (HCl) and pepsin, a protease that cleaves proteins into smaller peptides.
    • Parietal cells secrete hydrogen and chloride ions separately into the lumen of the stomach.
    • Chief cells secrete inactive pepsinogen, which is activated to pepsin when mixed with hydrochloric acid in the stomach.
    • Mucus protects the stomach lining from gastric juice.

    Types of Digestive Strategies

    • Digestive strategies involve four stages: ingestion, digestion, absorption, and elimination.

    Sponges

    • Sponges are primitive animals with simple bodies made up of cells, but no tissues, organs, or organ systems.
    • They are filter feeders, using incurrent canals to bring in small particles of food, including decaying bodies.
    • Coanocytes capture food particles through phagocytosis, forming a food vacuole.
    • Enzymes in vesicles break down food into smaller molecules, which are then used by the cell or shared with other cells.
    • Unused substances are discarded through exocytosis, and metabolic wastes like CO2 diffuse through the plasma membrane.

    Cnidarians

    • Cnidarians, like cnidarians and comb jellies, have extracellular digestion, where food is broken down outside of cells.
    • Ingestion occurs through a mouth, and digestion takes place in the gastrovascular cavity.
    • Enzymes are released into the cavity through exocytosis, breaking down food into smaller particles.
    • Cells lining the cavity absorb nutrients through endocytosis, and unused materials are discarded through exocytosis.

    Bilaterally Symmetrical Animals

    • Animals with bilateral symmetry, like segmented worms, arthropods, and birds, have a complete digestive system with an entrance (mouth) and an exit (anus).
    • Ingestion occurs through the mouth, and digestion takes place in the digestive system, often with mechanical breakdown (e.g., chewing mandibles, gizzard).
    • Absorption occurs along the intestine, and excretion occurs through the anus.
    • Variations include a crop for storing food, a cloaca for reproductive and excretory systems, and structures like the gizzard for mechanical breakdown.

    Mammalian Digestive System

    • Mammals have a complex digestive system, with a mouth, esophagus, stomach, small intestine, and large intestine.
    • Ingestion occurs through the mouth, and mechanical digestion occurs with teeth.
    • Chemical digestion occurs in the stomach with enzymes, and accessory glands aid in digestion.
    • Absorption occurs in the small intestine, and the large intestine recycles water before excretion through the anus.

    Energy and Nutrition

    • Energy is vital for animals to survive, thrive, and maintain bodily functions
    • Animals obtain energy by consuming other organisms or plants, which provide energy for growth and maintenance

    Macronutrients

    • Carbohydrates, lipids, and proteins are the three primary macronutrients essential for energy and growth
    • These macronutrients provide energy and support various bodily functions, including growth and maintenance

    Energy Sources

    • Plants are the primary energy source for many animals, serving as a food source for herbivores
    • Herbivores, such as cows and deer, obtain energy by consuming plants
    • Carnivores, such as lions and tigers, obtain energy by consuming other animals
    • Omnivores, such as humans and bears, obtain energy by consuming both plants and animals

    Digestion and Absorption

    • Digestion breaks down nutrients into smaller molecules, releasing energy for the body
    • Absorption involves the uptake of these molecules into the bloodstream, providing energy for the body
    • Energy is obtained from nutrient breakdown during digestion and absorption, supporting bodily functions

    Importance of Energy

    • Energy is crucial for survival, growth, and maintenance of bodily functions
    • Energy is necessary for physical activity, supporting muscle movement and exercise
    • Energy imbalance can lead to health problems, such as obesity, diabetes, and malnutrition

    Mammalian Digestive System

    • Mammals have fewer compartments in their digestive system compared to other vertebrates
    • The digestive system consists of the mouth, esophagus, stomach, and intestines (small and large) for digestion, absorption, and excretion

    Mouth

    • The mouth is the first stage of digestion
    • Salivary glands produce saliva containing amylase, mucous, water, salts, and glycoproteins
    • Amylase breaks down polysaccharides into smaller polysaccharides and disaccharides
    • Mucous helps food move through the esophagus
    • Formation of bolus occurs in the mouth

    Esophagus

    • The esophagus is responsible for the passage of food to the stomach
    • The epiglottis, a valve, prevents food from entering the respiratory tract

    Stomach

    • The stomach has gastric pits, which are finger-like projections
    • Parietal cells in the stomach secrete hydrogen ions and chloride ions
    • Chief cells are the majority of cells in the stomach
    • Mucous cells produce mucus for protection
    • The stomach has a pH of 2 due to hydrochloric acid, which breaks down proteins and activates pepsinogen
    • Pepsin, a protease, breaks down protein molecules into smaller polypeptides

    Small Intestine

    • The small intestine is the main place for chemical digestion
    • The small intestine is divided into three sections: duodenum, jejunum, and ileum
    • The duodenum is where food from the stomach mixes with digestive materials from the pancreas, liver, gallbladder, and small intestine lining cells
    • A neutralization reaction occurs in the duodenum (acidic pH 2 + basic alkaline secretions)
    • The pancreas produces a variety of enzymes, including protease, amylase, and lipase
    • Enzymes are activated in the duodenum
    • Bile, produced by the liver and stored in the gallbladder, is responsible for the digestion and absorption of fats
    • Epithelial cells lining the small intestine produce digestive enzymes, such as amylase and carboxy peptidase

    Fat Absorption

    • Villi on epithelial cells increase the surface area for absorption
    • Triglycerides are broken down into fatty acids and monoglycerides
    • Absorption occurs into cells, where triglycerides are reformed and packaged into chylomicrons
    • Chylomicrons contain triglycerides, phospholipids, cholesterol, and proteins
    • Chylomicrons are released into lacteal, a lymphatic vessel, for transport to the blood and eventually to the heart and body parts

    Feeding Strategies

    • Particle feeding: collecting small particles, often dead organisms, for essential nutrients.
    • Bulk feeding: consuming large items, such as prey, for a lot of energy.

    Modifying Food Supply

    • Leaf-cutter ants: collecting leaves, carrying them underground, and allowing fungi to break down cellulose into protein-rich food.
    • Aphid-hurting ants: collecting aphids, protecting them from enemies, and benefiting from sweet, sugary secretions (honeydew).

    Traps and Deception

    • Spiders: setting up webs, traps, and using deception to catch prey.
    • Ant lions: creating funnel traps in sand and sucking juices from trapped insects using modified mandibles.
    • Angler fish: using a lure on their dorsal fin to attract prey and swallowing them whole.
    • Deception: some animals use deception to attract prey, such as moths attracted to a spider's silk and pheromone imitation.

    Tool Use

    • Chimps: using sticks to extract termites from mounds.
    • Egyptian vultures: using rocks to crack open ostrich eggs.
    • Tool use: using an object to obtain food that would be difficult or impossible to obtain otherwise.

    Group Feeding

    • Advantages of group feeding: increased food capture efficiency, reduced search area, and lower risk of predation.
    • Examples of group feeding: lions, hyenas, wild dogs, dolphins, grey whales, and Harris hawks.
    • Strategies of group feeding: cooperation, communication, and coordination to hunt and catch prey.

    Comparison of Hunting Effectiveness

    • Lions: 50% hunting effectiveness, often scavenging instead of hunting.
    • Hyenas: 70% hunting effectiveness, using coursing to chase and exhaust prey.
    • African wild dogs: 90% hunting effectiveness, using stamina to chase and exhaust prey.
    • Harris hawks: group hunting in the desert, using perched and flying birds to catch prey.

    Animal Nutrition

    • Animals require energy, building blocks, and essential nutrients like vitamins and minerals to survive.
    • There are three types of animals: herbivores, carnivores, and omnivores, each with unique nutritional needs.

    Protein Nutrition

    • There are 20 amino acids, with 9 essential amino acids that cannot be synthesized by animals.
    • Complete proteins (meat, eggs, cheese) provide all essential amino acids, while plant proteins are incomplete.

    Lipid Nutrition

    • Animals can synthesize fatty acids, but must obtain essential fatty acids from their diet.
    • Essential fatty acids are unsaturated and cannot be synthesized by animals.

    Vitamin and Mineral Nutrition

    • There are 13 vitamins, which are organic molecules required for chemical reactions.
    • Vitamins can be fat-soluble (stored in the body) or water-soluble (excess excreted).
    • Minerals are inorganic molecules required for various bodily functions.

    Nutritional Deficiencies

    • Malnutrition occurs when the diet lacks essential nutrients.
    • Undernutrition occurs when the diet lacks sufficient energy or nutrients.
    • Examples of nutritional deficiencies: hemochromatosis (iron overload), neural tube defects (folic acid deficiency).

    Digestive System

    • There are four stages of food processing: ingestion, digestion, absorption, and elimination.
    • Types of feeders: suspension feeders, substrate feeders, fluid feeders, and bulk feeders.

    Mouth and Esophagus

    • Mouth: mechanical digestion (teeth, tongue) and salivary glands (saliva, amylase).
    • Esophagus: peristalsis (muscular contractions) and epiglottis (blocks trachea during swallowing).

    Stomach

    • Gastric juices: hydrochloric acid, pepsin, and mucus.
    • Parietal cells produce hydrogen and chloride ions, and chief cells produce pepsinogen.

    Small Intestine

    • Longest section of the elementary canal, where most digestion and absorption occur.
    • Pancreatic juices (enzymes, bicarbonate) and bile salts aid in digestion.
    • Villi increase surface area for absorption.

    Large Intestine

    • Absorbs water and electrolytes, and houses gut flora for fermentation of undigested plant material.
    • Cecum is a specialized region for fermentation.
    • Colon, rectum, and anus are involved in waste elimination.

    Ruminants and Digestion

    • Ruminants, such as cows, have a mutualistic relationship with microorganisms to break down undigested plant material.
    • The cow's digestive system involves the rumen, reticulum, omasum, and abomasum.

    Feedback Circuits and Digestion

    • Feedback circuits regulate digestion and energy storage based on available food and nutrients.
    • The nervous system and endocrine system work together to control digestion.
    • Hormones regulate digestion, such as gastrin, secretin, and CCK.

    Hormones and Digestion

    • Gastrin is released in the stomach to prepare gastric juices for digestion.
    • Secretin and CCK are released in the small intestine to break down food and neutralize acidic chyme.
    • CCK also helps to release bile to break down fats.

    Energy Storage and Cellular Respiration

    • Excess energy is stored in the liver and muscle cells as glycogen.
    • Excess energy beyond that is stored in adipose tissue as fat.
    • Insulin and glucagon are hormones that help to regulate glycogen breakdown and glucose formation.

    Glucose Regulation and Homeostasis

    • Insulin helps to convert glucose to glycogen when blood sugar levels are high.
    • Glucagon breaks down glycogen to glucose when blood sugar levels are low.
    • This feedback loop helps to maintain homeostasis of glucose levels in the blood.

    Regulation of Body Weight

    • Hormones such as leptin, ghrelin, insulin, and PYY help to regulate appetite and body weight.
    • Leptin reduces appetite when present, but its decrease can increase appetite.
    • Ghrelin triggers hunger feelings, while insulin and PYY help to suppress appetite.

    Evolution and Body Weight

    • The ability to maintain body weight is important for survival in times of famine.
    • Examples of species that have adapted to maintain body weight, such as the pygmy birds, demonstrate the importance of this trait in evolution.

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    This quiz covers the processes of digestion, nutrition, and absorption in living organisms. It includes stages of feeding, intracellular digestion, and sources of nutrients.

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