Data Were Collected from the Heterocysts of a Nitrogen-Fixing Cyanobacterium

question 2

Multiple Choice

Data were collected from the heterocysts of a nitrogen-fixing cyanobacterium inhabiting equatorial ponds. Study the graph and choose the most likely explanation for the shape of the curve.

• A) Enough oxygen (O₂) enters heterocysts during hours of peak photosynthesis to have a somewhat inhibitory effect on nitrogen fixation.
• B) Atmospheric nitrogen (N₂) levels increase at night because plants are no longer metabolising this gas, so they are not absorbing this gas through their stomata.
• C) Heterocyst walls become less permeable to nitrogen (N₂) influx during darkness.
• D) The amount of fixed nitrogen that is dissolved in the pond water in which the cyanobacteria are growing peaks at the close of the photosynthetic day (1800 hours).

---

Definitions:

Greater Rewards

Greater rewards are more substantial or significant benefits or compensations offered or received as a result of achieving higher goals or performing exceptionally well.

Pleasant to Occupy

Describes a space or environment that is enjoyable and comfortable to be in.

Talcott Parsons

An American sociologist known for his development of a general theoretical system for the analysis of society called structural functionalism.

Goal Attainment

is the process or strategy of reaching a desired outcome or objective, often discussed within the context of organizational behavior and social action.