In this problem we will explore some of the many ways that mutations in two different genes can interact to produce different Mendelian ratios. Consider a hypothetical insect species that has red eyes. Imagine mutations in two different unlinked genes that can, in certain combinations, block the formation of red eye pigment yielding mutants with white eyes. In principle, there are two different possible arrangements for two biochemical steps responsible for the formation of red eye pigment. The two genes might act in series such that a mutation in either gene would block the formation of red pigment. Alternatively, the two genes could act in parallel such that mutations in both genes would be required to block the formation of red pigment.

Further complexity arises from the possibility that mutations in either gene that lead to a block in enzymatic activity could be either dominant or recessive. If the crosses is made between a wild type insect with red eyes and a true breeding white eyed strain with mutations in both genes. Such considerations yield the Pathways in parallel with recessive mutations in both genes, determine the phenotype of the F1 progeny and the expected phenotypic ratio of red to white eyed insects in the F2.

#Question id: 11069

#Unit 7. System Physiology – Animal

A 22-year-old woman inhales as much air as possible and exhales as much air as she can producing the spirogram shown in the figure. A residual volume of 1.0 L was determined using the helium dilution technique. What is her functional residual capacity (in liters)?

#Question id: 11070

#Unit 7. System Physiology – Animal

A patient has a dead space of 150 ml, functional residual capacity of 3 L, tidal volume of 650 ml, expiratory reserve volume of 1.5 L, a total lung capacity of 8 L, respiratory rate of 15 breaths/min. What is the alveolar ventilation?

#Question id: 11071

#Unit 7. System Physiology – Animal

At the end of inhalation, with an open glottis, the pleural pressure is

#Question id: 11072

#Unit 7. System Physiology – Animal

The following diagram shows pulmonary airway resistance expressed as a function of pulmonary volume. Which relationship best describes the normal lung?

#Question id: 11073

#Unit 7. System Physiology – Animal

The respiratory passageways have smooth muscle in their walls. Which of the following best describes the effect of acetylcholine and epinephrine on the respiratory passageways?

#Question id: 11074

#Unit 7. System Physiology – Animal

A 30-year-old woman performs a valsalva maneuver about 30 min after eating lunch. Which of the following best describes the changes in pulmonary and systemic blood volumes that occur in this woman?