134. Choose the correct option to fill up the blanks:
___________ nourish the host coral as well as help it deposit its skeleton. They perform ________
and pass on some of the _____________ they make to the coral.
A. hermatypic corals, scavenging, organic matter
B. scleractinian, respiration, calcium
C. ahermatypic corals, synthesis, calcium
D. Zooxanthellae, photosynthesis, organic matte

Detailed Explanation:

Coral reefs, among the most diverse and vital ecosystems on the planet, thrive with the help of a unique symbiotic relationship between corals and zooxanthellae—microscopic algae that live within the coral’s tissue. This partnership is not only crucial for the survival of corals but also plays a vital role in maintaining the health and structure of coral reefs.

Zooxanthellae are photosynthetic algae that live within the cells of coral polyps. They perform photosynthesis, a process that allows them to convert sunlight into energy. During this process, zooxanthellae produce organic matter, mainly glucose, which is then transferred to the coral host as a nutrient source. This nutrient exchange is key to the survival of corals, as the organic matter produced by zooxanthellae provides much of the energy required by the corals to build their calcium carbonate skeletons and sustain growth.

In return, corals provide zooxanthellae with a safe environment, access to sunlight through the transparent coral tissue, and waste products such as carbon dioxide and nitrogen, which are beneficial for the algae’s photosynthetic process.

Answer to the Question:

The correct answer is: D. Zooxanthellae, photosynthesis, organic matter

Zooxanthellae nourish the host coral and help it deposit its skeleton. They perform photosynthesis and pass on some of the organic matter they make to the coral. This process is central to the health of coral reefs and the overall functioning of the marine ecosystem.