Acquiring Energy #6: Heterotrophs, Autotrophs, Photosynthesis Graphs

Question 1

Heterotrophs

Answer 1

Heterotrophs: Organisms that obtain energy by consuming energy-rich organic compounds of organisms and detritus (non-living material)

Question 2

Autotrophs

Answer 2

Autotrophs: Organisms that assimilate sunlight energy through photosynthesis or assimilate environmental inorganic chemical compounds through chemosynthesis

Assimilate: Take in and convert energy/nutrients into form that organism can use for growth, maintenance, and other life processes

Example:
- Some Plants
- Animals
- Fungi
- Bacteria/Archaea

Question 3

Chemoautotrophs

Answer 3

Chemoautotrophs: Organism that takes inorganic chemicals and transforms it into energy

Example: Bacteria/Archaea

Question 4

Photoautotrophs

Answer 4

Photoautotrophs: Organisms that carry out photosynthesis (sunlight energy, carbon dioxide, water converted into organic materials used in cellular functions)

Example:
- Plants
- Bacteria/Archaea

Question 5

Photosynthesis Graphs: Limiting Factor

Answer 5

First Section (increasing slope):
- Light = limiting factor
- Rate increases proportionately with increase in light intensity
- Increase in rate = linear at lower light intensities

Question 6

Photosynthesis Graphs: Light Saturation

Answer 6

Second Section (flattening slope):
- Light saturation
- No further light will increase photosynthesis rate
- Another factor has become limiting
- Rate becomes constant
- Either [CO2] or temperature needs to be raised to increase rate any further

Question 7

Photosynthesis Graphs: Maximum Net Photosynthesis Rate

Answer 7

Highest Point (y-axis):
- Maximum rate of net photosynthesis

Question 8

Photosynthesis Graphs: Light Saturation Point

Answer 8

Highest Point (x-axis):
- Light saturation point
- Intensity at which additional increases in light do not increase photosynthesis

Question 9

Photosynthesis Graphs: Light Compensation Point

Answer 9

X-Intercept:
- Light compensation point
- Photosynthesis rate = respiration rate
- Low light intensities above LC point = rate increases linearly to light intensity
- Higher light intensities = departs from linearity to eventually achieve light saturation

Question 10

Photosynthesis Graphs: Respiration Rate

Answer 10

Y-Intercept:
- Respiration rate
- Below 0

Question 11

Sunflowers: Adjusting to Light Intensity Changes

Answer 11

Sunflowers:
- Can change: behaviour, leaf morphology, physiology (to improve low light photosynthetic efficiency)
- Can NOT: increase carbon uptake to substitute for reduced solar energy