Biology 3000 Lecture Midterm

Identify a carbohydrate monomer that is absorbed from the digestive tract.

Identify a carbohydrate monomer that is absorbed from the digestive tract.

Glucose

Triglycerides enter the blood circulation as

Chylomicrons

Triglycerides are stored primarily in this type of tissue.

Adipose

Conversion of excess amino acids into carbohydrates and fats during the absorptive state takes place in the

Liver

"Glycogenolysis" refers to the state where

Glucose levels are increased in the blood through the breakdown of glycogen.

"Gluconeogenesis" is the process in which

Glucose levels are increased in the blood by the synthesis of glucose from noncarbohydrate sources.

Which organ is responsible for the synthesis of ketones from fatty acids?

Liver

Which hormone increases the absorption of glucose by the body's cells?

Insulin

Glucose enters cells by

Facilitated transport

Insulin is a product of the

Pancreas

The most common measurement of energy in biological systems is the kilocalorie. This is the amount of energy that would be required to raise the temperature of what quantity of water one degree Celsius?

1,000 g

The energy expenditure of a mammal at rest, in the postabsorptive state, and at a standard temperature is referred to as its

Basal metabolic rate.

Which animal would you predict would have the highest mass-specific metabolic rate?

A hummingbird

Hibernation in small mammals is an example of what specific phenomenon?

Torpor

Leptin is a product of

Adipose tissue.

How do endotherms and ectotherms derive most of their body heat?

Ectotherms derive most of their body heat through their environment, while endotherms derive most of their body heat through metabolic processes.

All of the following are methods used to exchange heat with the environment except

Diffusion

Newborn humans face thermoregulatory challenges as do small mammals. One mechanism they use to generate heat is

Nonshivering thermogenesis in "brown fat."

A consequence of the tendency of the human to gain excess weight is an increased risk of developing high blood pressure, diabetes, cancer, and heart disease.

True

During hibernation, a bear would be expected to be in the postabsorptive state in terms of nutrient utilization.

True

Triglycerides do not need to be chemically altered or broken down to cross the intestinal epithelium.

False

Animals have the ability to generate glucose from proteins during prolonged postabsorptive states.

True

The term "glucose sparing" refers to the increase in fat utilization seen in most tissues and organs during periods of low glucose availability.

True

Individuals with hypothetical "thrifty genes" are proposed to be better at storing fat than individuals without these genetic variants.

True

A mouse and a lizard of identical weight would be expected to have the same total metabolic rate.

False

Predict which food item would be the most effective at increasing an animal's metabolic rate.

Meat

In your study group, your classmates are discussing the relationship between energy expenditure and body size in different animals. There is much confusion as members of the group try to figure this out. How can you explain this to them?

A hummingbird has a larger mass-specific metabolic rate than a horse.

If an organism produces abnormally high levels of leptin, predict what would happen to that organism's weight, and explain why the change would occur.

Weight loss would occur as a result of decreased appetite.

After a meal, ectotherms often situate themselves in a warm and or sunny spot. This can be critical to the health of the animal. Why is this process important?

The digestive process is enzyme-catalyzed. An increase of 10 degrees Celsius can increase the rate of enzyme-driven reactions by 2–3 times the original rate.

The three main forms of nitrogenous wastes found in animals are

Ammonia, urea, and uric acid.

You have a patient who complains of pain in his joints. You ask whether he drinks much water during the day and find out he does not. You therefore suspect his nitrogenous waste is deposited in his joints after it is converted from its usual form of

Urea into uric acid.

What is the correct rank order for relative toxicity (most to least) of the primary nitrogenous wastes generated by different animals?

Ammonia → urea → uric acid

What is the correct rank order for relative amount of water (most to least) required for excretion of the primary nitrogenous wastes generated by different animals?

Ammonia → urea → uric acid

What is the correct rank order for relative energetic cost (most to least) of the primary nitrogenous wastes generated by different animals?

Uric acid → urea → ammonia

Ammonia, urea, and uric acid

Are all nitrogenous wastes.

The total solute concentration of a solution of water and other substances (salts, proteins, etc.) is referred to specifically as its

Osmolarity

What is the path of urine from formation to excretion in the mammalian kidney?

Collecting duct → renal pelvis → ureter → urinary bladder → urethra

What can be said about the transfer of fluid from the glomerulus to Bowman's capsule?

It is mainly a consequence of blood pressure force-filtering the fluid.

What is the path of fluid as it is filtered from the blood and flows through the nephron?

Bowman's capsule → proximal convoluted tubule → loop of Henle → distal convoluted tubule → collecting duct

The bulk of the reabsorption of useful materials by the kidney takes place in the

Proximal convoluted tubule.

Imagine you are examining a small mammal that lives under desert conditions and is water-deprived. You would predict that levels of the antidiuretic hormone (ADH) in its blood would be

High, and that its urine would be more concentrated than its blood.

Sodium and potassium ions can easily diffuse through the lipid bilayer of plasma membranes.

False

Transport of salts against their concentration gradients is energetically expensive.

True

The materials in urine are ONLY those that are filtered from the blood or hemolymph and not reabsorbed by the body following filtration.

False

The blood supply to the loop of Henle also exhibits a countercurrent arrangement.

True

The filtrate that leaves the proximal convoluted tubule is much more concentrated than the blood in humans.

False

Birds store food in a modified portion of the lower esophagus called the

Crop

In the mammalian digestive system, what is the primary site of nutrient absorption?

Small Intestine

Once food is digested, the nutrients must be absorbed by the epithelial cells that line the specialized portions of the alimentary canal. Small, hydrophobic molecules can diffuse down concentration gradients across the membrane. What types of molecules would require ACTIVE TRANSPORT in order to get across?

Minerals, amino acids, salt

In the stomach, food processing continues and secretions from stomach glands aid the initial digestion of

Proteins

The process of emulsification is crucial to the digestion of

Lipids

The diarrhea that is a symptom of diseases like cholera is due to problems in the function of the

Large Intestine

Cows are able to survive on a diet consisting almost entirely of cellulose because

Cows have cellulose-digesting, symbiotic microorganisms in their rumens.

Which are accurate statements about digestion?

• The muscles in the walls of the pharynx and esophagus contribute to swallowing.

• The gizzard contains sand or tiny stones swallowed by the bird.

What is peristalsis?

Smooth muscle contractions that move food through the alimentary canal

One function of HCl secreted in the stomach is to convert pepsinogen into the active enzyme pepsin. Why don't stomach cells simply secrete pepsin instead?

If cells produced active pepsin, they would digest their own cellular proteins.

How does the digestion and absorption of fat differ from that of carbohydrates?

Most absorbed fat enters the lymphatic system, whereas carbohydrates directly enter the blood.

The lacteal, a lymphatic vessel in the center of each intestinal villus, functions in digestion by absorbing

Lipids

Bile is crucial for_________ digestion because of its function in_________.

Fat; Emulsification

Contrary to popular belief, stress is not usually the primary cause of ulcers, and many patients with ulcers do not over-produce acid. What Nobel prize-winning discovery demonstrated a previously unknown cause of ulcers?

The existence of a bacterial infection in the stomachs of most patients with ulcers

Blockage of the common bile duct would be expected to affect

Lipid digestion

Cats cannot synthesize the amino acid taurine. This means that in cats, taurine

is an essential amino acid

Humans are susceptible to scurvy because

They cannot synthesize vitamin C.

How do carnivores and herbivores differ?

Carnivores and herbivores require different enzymes to digest their food.

A digestive cavity in which food enters an opening at one end and passes through the animal in one direction, as it is digested, is called the

Alimentary Canal

Which type of nutrient can pass across epithelial cells without any expenditure of ATP?

Fat

Salivary glands secrete_________ to start the digestion of_________.

Amylase; Starch

In ruminants, cellulose digestion occurs in the

Rumen and reticulum.

The surface area of the small intestine is dramatically increased due to the presence of_________ on the luminal surface.

Villi and microvilli

Surgical removal of the pancreas would

Increase the acidity of the small intestine.

The large intestine concentrates undigested material by

Absorption of salts and water across the epithelial surface of the lumen.

Oral rehydration solutions that contain both salt and glucose are highly effective in treating severe dehydration caused by diarrhea and vomiting. However, glucose or salt alone are not effective. Why?

Sodium transport and glucose transport are coupled in the small intestine so that glucose accelerates absorption of salt and water.

The small intestine releases the hormone secretin in response to acid.

True

In the stomach, proteins are cleaved into amino acids by aminopeptidases.

False

A person whose ancestors were cattle herders is more likely to express the lactase gene as an adult.

True

In omnivores, including humans, the cecum is an important organ for digestion of cellulose.

False

Fat absorbed by the small intestine enters the lymphatic system.

True

The only chyme molecule that is absorbed in significant amounts by the stomach is water.

True

The nervous system can directly affect the activities of the digestive system locally, through the collection of neurons within the walls along the gastointestinal tract. How might the brain exert its regulation of digestion from a distance?

• The sight, smell and taste of food can activate saliva production, stomach activity and digestion before it reaches the stomach.

• Emotional stress or depression may alter appetite patterns.

Animals that use an exoskeleton for movement include

• Crustaceans

• Insects

A creature that does NOT have an endoskeleton is the

Beetle

The human axial skeleton includes

• The vertebral column.

• The sternum.

A group of vertebrates that do not have skeletons made of bone are the

Sharks

The type of muscle that typically surrounds hollow tubes and organs like the stomach is

Smooth muscle

For the hierarchy of skeletal muscle organization, which accurately lists the order of structures from "small" to "big"?

Sarcomere; myofibril; muscle fiber; motor unit

Each skeletal muscle cell constitutes a single

Muscle fiber

The thick filament is composed almost entirely of_________ molecules.

Myosin

During muscular contraction, cross-bridges form between_________and_________.

Actin; Myosin

The primary reservoir for calcium released during excitation-contraction coupling in a skeletal muscle fiber is the

Sarcoplasmic reticulum.

Muscle cells are stimulated by acetylcholine released from the terminals of

Motor neuron axons

When an organism dies, its muscles remain in a contracted state termed rigor mortis for a brief period of time. Contributing most directly to this phenomenon is

The lack of ATP to break cross-bridges between thick and thin filaments.

The streamlined shape of the dolphin, seal, and other swimming animals is most important for

Reducing drag from the water they must swim through.

A notable exception to the evolutionary adaptation of flight is the lack of any flying species within the

Amphibians

The disease osteoporosis involves loss of both mineral and organic components from bones. Factors that may contribute to the development of osteoporosis include

• Prolonged disuse of muscles.

• Lack of calcium and vitamin D in the diet.

• A decline in estrogen following menopause in women.

Skeletal muscle fibers have more than one nucleus.

True

In order for something to be considered a skeleton, it must contain bone or some other hard substance.

False

You would expect to find more mitochondria in glycolytic muscle fibers than in oxidative muscle fibers.

False

Walking or running are more energetically expensive forms of locomotion than either swimming or flying.

True

Why are flexors and extensors considered antagonistic muscles?

Both muscle groups exert only a pulling force when they contract, but they produce opposing movements of the joint.

The skeleton of vertebrates serves several important functions. Among these are

• support and locomotion.

• blood formation.

• protection of organs and soft tissues.

• calcium homeostasis.