Final exam Bio

What are the major body-plan functions?

Gas exchange, feeding, transport, sensory and nervous functions, and locomotion.

What are the major evolutionary lineages?

Bacteria, Protists, Plants, Fungi, Basal animals, Protostomes, and Deuterostomes.

What were the major steps in the origin of life?

The evolution of information replication, metabolic pathways creating organic molecules, energy transformation systems, and lipid membranes defining cell boundaries.

Why are insects limited in size?

Larger insect bodies experience oxygen depletion in tracheal tubes unless tracheal density increases dramatically.

What is the empirical size limit for insects?

Beetles reach a maximum of around 16 cm because over 90% of their leg volume becomes tracheae.

How do cephalochordates perform gas exchange?

They rely entirely on gas exchange across their body surface.

How do cephalochordates feed?

They use ciliary feeding through pharyngeal gill slits.

What type of circulatory system do cephalochordates have?

They have a closed circulatory system but lack a true heart and respiratory pigments.

Why did organisms evolve two pumps for gas exchange?

To minimize diffusion distance and to maximize partial pressure gradients for oxygen and carbon dioxide.

What are external gills used for?

They provide high surface area exposed to water for gas exchange, as seen in aquatic salamanders.

What is cutaneous respiration?

Gas exchange through the skin, which occurs in frogs and many larval fishes.

Why do some aquatic animals gulp air?

They gulp air in low-oxygen waters to supplement gas exchange.

What are accessory air-breathing organs?

Esophageal or pharyngeal outgrowths that act as primitive lungs or swim bladders.

What is positive pressure ventilation?

A breathing mechanism used by gar, lungfish, and amphibians in which buccal pumping forces air into the lungs.

How does positive pressure breathing work?

Buccal muscles push air into the lungs, and exhalation occurs mostly passively.

What are faveoli?

Small honeycomb-like chambers in lungs that increase surface area for gas exchange in many non-mammalian tetrapods.

What is negative pressure ventilation?

A breathing system used by amniotes that draws air into the lungs by expanding the thoracic cavity.

How does negative pressure breathing work?

Expansion of the thorax decreases internal pressure, pulling air into the lungs.

How do lepidosaurs ventilate their lungs?

They expand their body wall using rib muscles, and their lungs contain faveoli.

How do mammals ventilate their lungs?

They use a diaphragm and intercostal muscles to expand the thorax and draw air in.

Are mammalian lungs attached to the ribs?

No; lungs are not attached to the ribs and expand only through pressure changes.

How many alveoli are in human lungs?

About 300 million alveoli with dense capillary networks.

How does gas exchange occur in the lungs?

Gas exchange occurs solely by diffusion across thin respiratory membranes.

What are the end products of carbohydrate digestion?

Monosaccharides.

What are the end products of protein digestion?

Amino acids.

What are the end products of nucleic acid digestion?

Nitrogenous bases, sugars, and phosphates.

What are the end products of lipid digestion?

Glycerol and fatty acids.

What is the evolutionary transition in respiratory structures?

The transition occurred from aquatic gills to lungs and then to alveoli or parabronchi.

What is a pneumothorax?

A condition where air enters the pleural cavity, causing loss of surface tension and collapse of the lung.

What are perfluorocarbons?

Liquids with extremely high oxygen solubility used for potential oxygen delivery.

What is the phylogenetic axis of gas exchange diversity?

It reflects independent evolution of respiratory organs across different lineages.

How does size influence gas exchange?

Body size affects surface-area-to-volume ratios, which influence gas exchange efficiency.

How does metabolic rate affect gas exchange?

Higher metabolism increases oxygen demand and requires more efficient respiratory systems.

How does medium influence gas exchange efficiency?

Whether an organism breathes air or water strongly affects the efficiency of gas exchange.

What is the energy source in transport systems?

The sun or food provides the energy that drives biological systems through heat or metabolism.

What is the function of pumps in biological systems?

They generate pressure gradients, such as hearts creating blood pressure or evaporation creating tension in plants.

What structures function as ducts or vessels?

Structures like xylem and blood vessels convey fluids along pressure or osmotic gradients.

What is the role of regulators in transport systems?

They adjust flow rates, such as pacemaker cells in animals or stomata in plants.

What is the purpose of valves in biological systems?

They control the direction of fluid flow, such as heart valves or leaf pores.

What types of fluids serve as transport media?

Fluids such as blood, sap, and water with dissolved ions serve as transport media in organisms.

What are unlocalized pumping mechanisms?

They include ciliary beating, peristalsis, and general muscle contractions.

What are localized pumping mechanisms?

They include animal hearts and plant leaves, functioning as pressure or suction pumps.

What is osmotic flow?

The movement of water into regions with higher solute concentration.

What is pressure flow?

The movement of water toward regions of lower pressure or higher tension.

What gradient drives upward water movement in plants?

Water potential is highest in the soil and lowest in the leaves and air, creating an upward gradient.

What creates the “push from below” in root pressure?

Active transport of ions into the xylem draws in water osmotically, producing positive pressure known as root pressure.

Why is warm water bad for oxygen availability?

Because gas solubility decreases as temperature increases, so warm water holds much less oxygen.

What does Henry’s Law state about gas dissolving in water?

If the dissolved gas concentration is below equilibrium concentration (C < Ceq), gas dissolves into the liquid.

What does Henry’s Law state about gas leaving water?

If the dissolved gas concentration is above equilibrium concentration (C > Ceq), gas bubbles out of the liquid.

How does low pH affect hemoglobin?

Low pH causes hemoglobin to release more oxygen.

What is single circulation in fish?

A system where blood passes through the gill capillaries first, loses pressure, and then flows to the body.

Why is single circulation limiting for fish?

Because the pressure drop across the gills leaves low residual pressure for tissue perfusion.

What adaptations help fish compensate for low pressure after the gills?

They have large gills and countercurrent exchange to maximize oxygen uptake.

What is special about lungfish circulation?

Lungfish have a mix of gill and lung circulation, allowing them to breathe air and water.

What does the ductus arteriosus do in lungfish?

It connects pulmonary and systemic flows, allowing flexible routing of blood.

Why is laminar flow important in lungfish circulation?

It minimizes mixing of oxygenated and deoxygenated blood.

What is double circulation with a single ventricle in amphibians?

A 3-chambered heart with two atria and one ventricle that partially separates pulmonary and systemic blood.

What is a disadvantage of amphibian circulation?

Some mixing of oxygenated and deoxygenated blood occurs in the single ventricle.

What is an advantage of amphibian circulation?

Partial separation of pressures allows higher systemic blood flow.

What is a partial septum in reptile hearts?

A structure dividing the ventricle partially, reducing mixing between pulmonary and systemic blood.

Why is the partial septum an intermediate evolutionary form?

Because it precedes the fully divided 4-chambered heart seen in mammals and birds.

How many chambers do mammals and birds have in their hearts?

They have a fully divided four-chambered heart with no blood mixing.

What does the right side of the mammalian heart do?

It pumps deoxygenated blood to the pulmonary circuit at low pressure.

What does the left side of the mammalian heart do?

It pumps oxygenated blood to the systemic circuit at high pressure.

Do mammals and birds have any arterial mixing between circuits?

No; there is complete separation between pulmonary and systemic flows.

What is the role of the placenta in fetal circulation?

The placenta provides oxygen, allowing the fetus to bypass the lungs.

What are the two major fetal shunts?

The foramen ovale and the ductus arteriosus.

What is the function of the foramen ovale?

It allows blood to flow from the right atrium to the left atrium, bypassing the lungs.

What happens if the foramen ovale fails to close at birth?

It can cause mixing of blood and lead to cyanosis.

What is the function of the ductus arteriosus?

It connects the pulmonary artery to the systemic arteries, bypassing the lungs.

What happens if the ductus arteriosus does not close?

It can result in heart failure due to abnormal blood flow.

Why must both fetal shunts close at birth?

To establish separate pulmonary and systemic circuits needed for normal adult circulation.

How many hearts do cephalopods have?

They have three hearts: one systemic heart and two branchial hearts.

What type of circulation evolved independently in cephalopods?

They independently evolved double circulation.

Why is double circulation beneficial in cephalopods?

It allows a boost in pressure after gas exchange, improving tissue perfusion.

How do invertebrate vessels regulate flow?

Their vessels constrict or dilate to change resistance and redirect blood flow.

What unifies stomatal opening, sucrose transport, kidney filtration, neuronal signaling, and nutrient absorption?

They are all driven by electrochemical gradients.

What cotransport mechanism do plants and fungi primarily use?

They use H⁺ cotransport, such as the H⁺/sucrose symporter.

What cotransport mechanism do animals primarily use?

They use Na⁺ cotransport, such as the Na⁺/glucose symporter.

What was the digestive innovation first seen in cnidarians?

They were the first to evolve extracellular digestion using hydrolytic enzymes in a gut cavity.

What major digestive innovation evolved in bilaterians?

Bilaterians evolved complete digestive tracts with regional specialization.

What are the functional regions of a complete digestive tract?

Mechanical breakdown, storage, enzyme secretion, absorption, and elimination.

What is prey capture and ingestion?

The process of obtaining food, which varies by lineage depending on ecology and anatomy.

What is mechanical reduction in digestion?

The physical breakdown of food using structures such as teeth, mandibles, or gizzards.

What is the function of storage organs like the crop or stomach?

They store food for intermittent feeding and allow sterilization with HCl.

What happens during chemical digestion?

Enzymes hydrolyze polymers into absorbable monomers.

What occurs during nutrient absorption?

Small molecules cross membranes into the body via transport proteins.

What is elimination in digestion?

The removal of undigested waste from the body.

What type of stomach do ruminants have?

Ruminants have a four-chambered stomach consisting of the rumen, reticulum, omasum, and abomasum.

How do ruminants digest cellulose?

They rely on symbiotic microbes in the rumen and reticulum to digest cellulose.

Why do ruminants chew cud?

They regurgitate and re-chew partially digested food to increase surface area for microbial digestion.

Why are ruminants efficient at extracting energy?

Their microbial symbionts produce vitamins and help extract nutrients from low-quality diets.

What is the primary site of digestion and absorption?

The small intestine is the primary site of digestion and nutrient absorption.

What does the pancreas secrete into the small intestine?

It secretes bicarbonate to neutralize acid, amylases for sugars, proteases for peptides and amino acids, and lipases for fats.

What does NaHCO₃ do in digestion?

It neutralizes acidic chyme entering the small intestine.

What do pancreatic amylases do?

They break down carbohydrates into simple sugars.

What do pancreatic proteases do?

They break peptides into amino acids.

What do pancreatic lipases do?

They digest fats into monoglycerides and fatty acids.

What is the main function of the large intestine?

It reabsorbs water and minerals from remaining food waste.

What additional function does the large intestine have?

It houses microbiota that produce vitamins such as vitamin K and biotin.