Nutrient Transport and Absorptioon

What condition would most likely reduce water movement through xylem?

Low soil moisture (since water cannot move through dry environment).

rhizobal bacteria

nitrogen fixing bacteria that lives in symbiosis with legumes

What creates high pressure potential at the source end of phloem in the pressure flow model?

Active transport of sucrose into phloem, followed by water uptake.

How does water contribute to the movement of sugar into phloem?

Creating a pressure gradient that pushes sugar solution (high at source, low at sink).

Adaptation for herbivores animals.

Specialized chambers like rumen and cecum for microbial fermentation.

Why is concurrent flow not as efficient as countercurrent flow?

Concurrent flow allows less diffusion because the concentration gradient is constantly decreasing.

Difference between open and closed circulatory systems?

Open uses hemolymph; closed systems have blood contained within vessels.

Blood is oxygenated in lungs, then goes where?

Left atrium, then to the rest of the body.

In ventricular systole, which valves are open?

Semilunar valves.

What do AV valves do?

Prevent backflow of blood from ventricles to atria.

What does the QRS complex on ECG signify?

Ventricular depolarization.

What are legume species known for?

Nitrogen-fixing bacteria.

Within the legume root, what does nitrogenase do?

Produced by rhizobium to convert nitrogen gas into a usable form.

What does leghemoglobin do in legume roots?

Regulates the amount of oxygen produced by the plant.

What happens if a legume is incapable of producing leghemoglobin?

It will not efficiently carry out nitrogen fixation.

Pressure-flow hypothesis of phloem transport?

Sugar moves from sieve tube elements near source to lower pressure in companion cells near sinks.

Unloading of sucrose from companion cells into sink cells vacuoles happens through?

Sucrose H+ cotransporters.

What happens in individuals malnourished and low on solutes?

The solute concentration in the venous side of the capillary beds drops below the concentration.

Increasing levels of CO2 in blood does what to pH?

Decreases pH, which decreases hemoglobin's affinity for binding oxygen.

What are vegetarians at a deficiency for?

Amino acids (present in meat).

Essential nutrients?

Amino acids, nutrients, fatty acids, minerals, vitamins.

Why are carbohydrates not considered essential?

Because we can synthesize them from other sources.

Role of sodium in the body?

Muscle contraction and neuron function.

Topics related to the circulatory system?

EKG, cardiac cycle, circulatory systems.

Enzymes in the digestive system?

Amylase, pepsin, lipase, bile salts.

Junction between small and large intestine?

Cecum, where herbivores digest cellulose.

What is the charge of clay?

Negatively charged, holds onto positively charged ions.

What do carnivorous plants require?

Additional minerals.

Effect of old growth on new growth?

Nitrogen-fixing so new growth suffers.

Characteristics of sandy soils?

Lots of O2, little water since it passes through easily.

What is an electrochemical gradient?

Difference in charge and concentration across a membrane.

If protons are continuously pumped outside of cell, what happens?

Outside becomes more positively charged; anions move outside due to attraction; cations move outside.

What requires direct expenditure from plants?

Proton pump.

How do fungi acquire nitrogen aside from air?

From proteins in decaying organic matter.

What is diffusion?

Movement down gradient.

Why can nitrifying bacteria impact soil nutrients?

They transform biologically available nitrogen to a form that washes out of soil easily.

What drives transpiration?

Evaporation in combination with cohesion and tension in the plant water column from leaf cell to root hair.

What is the apoplast pathway?

Outside the cell, via the cell wall (no filter by selectively permeable membrane).

What is the symplast pathway?

Through the shared cell cytoplasm, via plasmodesmata.

What is transmembrane movement?

Through the cell membrane, via water channels.

What decreases water potential in soil?

Decreases in uptake of water by root hairs and thus decrease the flow of water in xylem.

How does high solute concentration in desert plants help absorb water?

Lowers the plant’s solute potential, allowing water to move into the plant.

What increases the rate of transpiration?

Drier air and low atmospheric pressure.

What is root pressure?

A high pressure potential driven by accumulation of ions and water by osmosis.

What model explains movement of water up tall trees?

Cohesion and tension model, does not require energy like ATP.

What is capillarity?

Adhesion of water molecules to sides of xylem cells, cohesion of water molecules to each other, and surface tension (against gravity).

Where are amylases produced?

Mouth and pancreas.

Where are bile salts produced?

Liver (stored in gall bladder).

Where is pepsin produced?

Stomach.

Where are trypsin and chymotrypsin produced?

Pancreas.

Where is lipase produced?

Mouth, stomach, and pancreas.

What do both mouth and pancreas produce?

Amylases, which break down carbohydrates.

Advantage of a double circulatory system?

Oxygenated blood can return to the heart for additional pumping before going to systemic flow.

What does the rate of sugar transport in a plant depend on?

Difference in turgor pressure between source and sink and rate of photosynthesis.

What is a complete digestive tract?

No possible mixing of food and waste.

Difference in fluid transport between xylem and phloem?

Phloem requires energy input and runs on positive pressure; xylem does not require energy and runs on negative pressure.

What is the relationship between movement of water in xylem and pressure-flow hypothesis?

Sugar solute moves from area of high concentration at source to an area of lower concentration near sink cells; water flows from xylem into phloem due to high sugar solute concentration.

What happens to hemoglobin binding when one O2 is bound?

Hemoglobin is more likely to bind to oxygen.

What occurs to the hemoglobin-saturation curve when pH decreases?

Shifts to the right.

What promotes oxygen release from hemoglobin?

A decrease in pH in body tissue.

What happens to hemoglobin's likelihood of releasing O2 with an increase in pH?

It is less likely to release O2.

Why are some nutrients considered essential?

Animals are not able to synthesize them.

How do mycorrhizal fungi produce nutrients?

Through decomposition.

How do rhizobia bacteria produce nutrients?

By fixing nitrogen from air.

What affects new growth in plants initially?

Nutrients that the plant cannot easily move from older tissues to new ones.

What occurs with plant growth in soil?

Cations present (cation exchange) and oxygen availability is low.

What is required for plant acquisition of nutrients from soil?

A proton gradient is required for the acquisition of both cations and anions.

What happens to water potential when solute potential decreases?

Water potential increases.

What is the nature of solute potential?

Always negative.

What is the nature of pressure potential?

Always positive.

What occurs when a plant removes solutes?

Solute potential increases and water potential increases.

Where is the lowest water potential in a plant typically found?

Where water is evaporating from leaf stomata (air spaces in the leaves).

What is a sugar sink at the end of the growing season?

Roots sending sugar for storage as they prepare for dormancy.

What is a sugar source at the start of the growing season?

Roots supplying sugars stored for new growth.

What is the pressure flow hypothesis of phloem transport?

High pressure at the source to low pressure at the sink.

How does xylem transport water?

Moves water upward via tension, not pressure, and occurs due to negative pressure.

Advantage of single over complete digestive tract?

Single opening needed to facilitate both ingestion and elimination.

What enzymes are found in the stomach?

Pepsin, amylase, gastric lipase.

What enzyme is produced in the liver?

Bile salts.

What is Fick's law related to?

Thin membrane, short distance, large area, large difference in pressure on either side.

Which vertebrates have the least efficient respiratory system due to crosscurrent flow?

Mammals.

What is an open circulatory system?

Hemolymph that flows freely within a cavity, not separated from interstitial fluid.

What is a closed circulatory system?

Blood within vessels, distinct from interstitial fluid.

Where does gas exchange occur?

Only at capillaries.

What do veins do?

Carry blood away from the heart, both oxygenated and deoxygenated.

What do arteries do?

Carry blood towards the heart.

What is vasodilation?

Increased blood speed in vessels.

What are osmoconformers?

Organisms that adjust to their environment's osmolarity and do not expend much energy on osmoregulation.

What are osmoregulators?

Organisms that actively maintain their internal osmolarity regardless of the external environment and require more energy.

What is the energy requirement for excretion of ammonia?

Requires very little energy to produce since it is highly soluble.

What is countercurrent exchange?

Filtration by mammalian kidneys and heat transfer between veins and arteries.