Mastering Bio

Consider a tree that is 50 m tall and is transpiring roughly 90 liters of water each day. Approximately how many calories will the tree use to transpire this quantity of water?

0 calories

A population is growing exponentially and its instantaneous growth rate (r) is 0.02. Would the number of individuals added to the population (rN) be greatest at a population size (N) of 20, 500 or 1000?

1000 (rN would be greatest at the highest N)

Atmospheric pressure at sea level is equal to a column of 760 mm Hg. Oxygen makes up 21 percent of the atmosphere by volume. The partial pressure of oxygen (PO2) in such conditions is _____.

160 mm Hg

At the summit of a high mountain, the atmospheric pressure is 380 mm Hg. If the atmosphere is still composed of 21percent oxygen, then the partial pressure of oxygen at this altitude is about _____.

80 mm Hg

Altitude sickness occurs when a hiker ascends to altitudes where the density of oxygen is low. Carbonic anhydrase inhibitors cause less movement of carbonic acid toward carbon dioxide production and are used as a prophylactic treatment of altitude sickness. How does this treatment decrease the symptoms of high altitude sickness?

An increase in blood acidity leads to an increase in ventilation.

Based on the accompanying figure, showing fetal (A) and adult (B) oxygen-hemoglobin saturation curves, which of the following conclusions is TRUE?

At 50 percent saturation, fetal blood will have a higher affinity for oxygen than adult blood will

Predict how Antarctic icefish can transport enough oxygen in their blood to meet their needs even though they lack hemoglobin.

Cold water carries more oxygen than warm water does. The oxygen is simply dissolved in the blood.

When you are jogging, your muscles are using more oxygen and releasing more carbon dioxide into the blood than when you are at home on the couch. Which of the following would occur during your jog?

The medullary respiratory center would detect rising carbon dioxide levels.

Which of the following statements comparing respiration in fish and in mammals is correct?

The movement of the respiratory medium in mammals is bidirectional, but in fish it is unidirectional.

A significant increase in the amount of interstitial fluid surrounding the capillary beds of a human's lungs will cause _____.

a decrease in the amount of oxygen moving from the lungs into the blood

The flow of xylem from root to leaf in a tall tree is principally due to ________________.

a decrease in water potential in the leaves due to evaporation

When water moves from soil into the vascular tissues inside the root, it can take three possible pathways. Of these, the apoplastic route is _____.

between cells and through cell walls

Breathing is primarily regulated by ________.

carbon dioxide concentration and pH sensors

The transport of a water column up a very tall tree can be explained by _____.

cohesive and adhesive forces of the water column under evaporative tension

In plants there are three types of tissues or tissue systems. Which of these is not one of the tissue systems?

companion cells

Most of the carbon dioxide produced by humans is ________.

converted to bicarbonate ions by carbonic anhydrase, an enzyme in red blood cells

The water lost during transpiration is a side effect of the plant's exchange of gases. However, the plant derives some benefit from this water loss in the form of ________.

evaporative cooling and mineral transport

What important role does the Casparian strip play in the movement of water through plants?

forces water to move through the cytoplasm of living endodermal cells as it makes its way from the soil to the xylem

Water potential () can be thought of as the tendency for water to move from one place to another. In plants, it is made up mainly of solute potential and pressure potential. Hypothetical plant cells A and B are adjacent to each other. The solute potential (S) of cell A is 0.35 MPa, and its pressure potential (P) is +0.15 MPa. The solute potential (S) of cell B is 0.30 MPa, and its pressure potential (P) is +0.05 MPa. In which direction will net water movement occur?

from cell A to cell B

Consider Figures 42.17 and 42.18. "Affinity" is a biochemical concept that describes the relative strength or relative tendency for something to bind to its binding partner, in this case oxygen to hemoglobin. Think about affinity intuitively, in the sense of needing a higher substrate concentration (oxygen) to get to the same point on the Y-axis (say 50% saturation). Would you say the higher pH (pH 7.4 in Figure 42.17) and fetal hemoglobin (Figure 42.18) have higher or lower affinities than their counterparts (pH 7.2 and adult hemoglobin)?

higher pH and fetal hemoglobin have higher affinities

A key aspect of cooperative binding by hemoglobin is that ___________.

it permits rapid uptake of oxygen in the lungs and greater delivery of oxygen once blood reaches capillaries in the body's tissues -. Cooperative binding is critical to the high rate of oxygen transport in the circulatory system.

Fick's law of diffusion describes the factors that influence the diffusion of respiratory gases across biological membranes like gills and lungs. Diffusion rate = k × A × (P2 P1)/D. Natural selection is LEAST likely to act upon which variable in Fick's law?

k

The Bohr shift on the oxygen-hemoglobin dissociation curve is produced by changes in _____.

pH

Carbon dioxide enters the inner spaces of the leaf through the _____.

stoma

Air rushes into the lungs of humans during inhalation because ________.

the rib muscles and diaphragm contract, increasing the lung volume and decreasing the pressure within the lungs

Loss of water from the aerial parts of plants is called ________.

transpiration

he function of sieve-tube elements is to _____.

transport sugars throughout the plant

As an undergraduate research assistant, your duties involve measuring water potential in experimental soil-plant-atmosphere systems. Assume you make a series of measurements in a system under normal daylight conditions, with stomata open and photosynthesis occurring. Which of the following correctly depicts the trend your measurement data should follow if the cohesion-tension mechanism is operating?

ψatmosphere < ψleaves < ψroots < ψsoil