Biology 1500 -unit 4 Exam Questions
and All Actual Answers 2026 Updated.
Explain how the circular processes of photosynthesis and cellular respiration result in the cycling
of carbon within ecosystems. - Answer increase in Photosynthesis relative to Cellular
respiration will rise O2. all carbon in organic molecules comes from products of Photosynthesis.
the carbon gets put back into air by being consumed by animals/decomposers and released in
the form of CO2.
Explain the two reasons for an imbalance in this cycle that led to the increasedO2 during the
Carboniferous. - Answer -the land was dominated by bogs and plants, there were lots of
photosynthesis, but lots of carbon was buried instead of undergoing CR, -because early trees
used lignin instead of cellulose as structural material, no decomposers could break this down, so
dead trees fell into bogs that had no O2 for CR and the buried carbon became our fossil fuels.
Describe the hypothesized reasons for the decline in O2 during the late Permian - Answer
there was a drier climate so there was a reduction in PS, decomposition facilitated by sandy
sediments, fungi evolved to be able to break down lignin, so reduction in burial of C and O2
levels dropped because more C enters CS
xplain the importance of Lignin and Lignin Decomposition on the rise and fall ofO2 levels during
the Carboniferous - Answer when lignin present you have more O2 released into atmosphere
& coal formation & bigger plants.
lignin decomposition will remove the excess O2 from atmosphere and go back into organic
carbons & no coal formation.
Explain where most of the matter in organic carbons comes from - Answer most mater in
organic carbons come from the products of photosynthesis and plants.
Recall the elevation of Mt. Everest - Answer between 8,800 and 8,900 (8,850)
Recall the reason for 'death-zone' and where a death zone occurs - Answer insufficient
oxygen
Recall the migration path of Bar Headed Geese and which feat makes itremarkable - Answer
The elevation at which they fly. (Higher the elevation the lower the oxygen)
Know the functions of the mammalian respiratory system - Answer 1) Supply oxygen to cells
2) Rid body of Carbon Dioxide
, List the steps in mammalian respiration - Answer 1. Air travels down the larynx
2. Through the trachea
3. And into the lungs
4. Then air passes through the branching bronchi
5. Reaches the respiratory bronchioles
gas exchange - Answer movement of oxygen from air into blood, and of Carbbon Dioxide
from blood into air.
Total Volume - Answer the amount of air that moves in an out of the longs per breath when
breathing normally.
Vital Capacity - Answer amount of air moving in and out of the lungs when exercising
vigorously
Alveoli - Answer parts of the lungs across which gaes are exchanged
Ventillation - Answer movement of air between the outside world. The gas exchange surface.
Describe how the structure of our respiratory system facilitates gas exchange - Answer the
gas exchange occurs in the lungs between the alveoli and tiny blood vessels called capillaries.
Explain what residual lung volume refers to and why it exists - Answer amount of air left in
the lungs after exhaling (this is never exchanged)-Prevents lungs from collapsing-Prevents large
fluctuations in respiratory gases-Keep the alveoli open even after maximum expiration
Compare the atmosphere we breathe (at sea level) and the atmosphere in ourlungs, and explain
the reason for the difference. - Answer Atmosphere: PO2= 21 kPa PCO2= .04 kpa
Inside lung: PO2= 13-15 kpa PCO2=5-6 kpa
-lung atmosphere is different from outside atmosphere, depending on the volume of gas
exchanged.
-O2 demand -> higher O2 levels in lung
-O2 damage -> lower O2
Describe the differences in atmospheric gases between sea level and theHimalayas. - Answer
Sea level: 100 kpa available
Mt. Everest: 33.7 kpa available
and All Actual Answers 2026 Updated.
Explain how the circular processes of photosynthesis and cellular respiration result in the cycling
of carbon within ecosystems. - Answer increase in Photosynthesis relative to Cellular
respiration will rise O2. all carbon in organic molecules comes from products of Photosynthesis.
the carbon gets put back into air by being consumed by animals/decomposers and released in
the form of CO2.
Explain the two reasons for an imbalance in this cycle that led to the increasedO2 during the
Carboniferous. - Answer -the land was dominated by bogs and plants, there were lots of
photosynthesis, but lots of carbon was buried instead of undergoing CR, -because early trees
used lignin instead of cellulose as structural material, no decomposers could break this down, so
dead trees fell into bogs that had no O2 for CR and the buried carbon became our fossil fuels.
Describe the hypothesized reasons for the decline in O2 during the late Permian - Answer
there was a drier climate so there was a reduction in PS, decomposition facilitated by sandy
sediments, fungi evolved to be able to break down lignin, so reduction in burial of C and O2
levels dropped because more C enters CS
xplain the importance of Lignin and Lignin Decomposition on the rise and fall ofO2 levels during
the Carboniferous - Answer when lignin present you have more O2 released into atmosphere
& coal formation & bigger plants.
lignin decomposition will remove the excess O2 from atmosphere and go back into organic
carbons & no coal formation.
Explain where most of the matter in organic carbons comes from - Answer most mater in
organic carbons come from the products of photosynthesis and plants.
Recall the elevation of Mt. Everest - Answer between 8,800 and 8,900 (8,850)
Recall the reason for 'death-zone' and where a death zone occurs - Answer insufficient
oxygen
Recall the migration path of Bar Headed Geese and which feat makes itremarkable - Answer
The elevation at which they fly. (Higher the elevation the lower the oxygen)
Know the functions of the mammalian respiratory system - Answer 1) Supply oxygen to cells
2) Rid body of Carbon Dioxide
, List the steps in mammalian respiration - Answer 1. Air travels down the larynx
2. Through the trachea
3. And into the lungs
4. Then air passes through the branching bronchi
5. Reaches the respiratory bronchioles
gas exchange - Answer movement of oxygen from air into blood, and of Carbbon Dioxide
from blood into air.
Total Volume - Answer the amount of air that moves in an out of the longs per breath when
breathing normally.
Vital Capacity - Answer amount of air moving in and out of the lungs when exercising
vigorously
Alveoli - Answer parts of the lungs across which gaes are exchanged
Ventillation - Answer movement of air between the outside world. The gas exchange surface.
Describe how the structure of our respiratory system facilitates gas exchange - Answer the
gas exchange occurs in the lungs between the alveoli and tiny blood vessels called capillaries.
Explain what residual lung volume refers to and why it exists - Answer amount of air left in
the lungs after exhaling (this is never exchanged)-Prevents lungs from collapsing-Prevents large
fluctuations in respiratory gases-Keep the alveoli open even after maximum expiration
Compare the atmosphere we breathe (at sea level) and the atmosphere in ourlungs, and explain
the reason for the difference. - Answer Atmosphere: PO2= 21 kPa PCO2= .04 kpa
Inside lung: PO2= 13-15 kpa PCO2=5-6 kpa
-lung atmosphere is different from outside atmosphere, depending on the volume of gas
exchanged.
-O2 demand -> higher O2 levels in lung
-O2 damage -> lower O2
Describe the differences in atmospheric gases between sea level and theHimalayas. - Answer
Sea level: 100 kpa available
Mt. Everest: 33.7 kpa available
