Question

Oospore produced without sexual reproduction is

• A. Sporozoite
• B. Aboospore
• C. Zoolospore
• D. Tropospore

Hint:

The prefix "ab-" or "ap-" in biological terms often denotes "away from," "absence of," or "without."
Hence, an "oospore" produced "without" standard fertilization is designated as an "aboospore."

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Oospores are thick-walled, sexually derived resting spores produced by members of the Oomycota (water molds and downy mildews).
However, under certain physiological or environmental conditions, similar thick-walled resting structures can develop parthenogenetically without the fusion of male (antheridial) and female (oogonial) nuclei.

Step 2: Detailed Explanation:
In standard sexual reproduction of oomycetes, an antheridium transfers male nuclei into the oogonium containing one or more oospheres.
The fusion of these haploid gametic nuclei produces a diploid, thick-walled oospore designed to survive unfavorable environmental conditions.
When the sexual process is bypassed, and the oosphere develops directly into a resting spore without fertilization, the resulting structure is called an "aboospore" (sometimes referred to as an apospore or parthenogenetic oospore).
This parthenogenetic development represents an evolutionary mechanism to ensure survival when compatible mating types or physiological stimuli for sexual reproduction are absent.
Let us analyze the alternative options:
- A sporozoite is a motile, infective stage in the life cycle of certain spore-forming protozoans (such as the malaria parasite Plasmodium).
- A zoospore (or zoolospore) is a flagellated, asexual motile spore produced in aquatic environments, lacking a thick protective wall.
- A tropospore is a hypothetical or highly specific developmental term not associated with oomycete resting spores.
Therefore, the correct term for a parthenogenetically produced oospore is an aboospore.

Step 3: Final Answer:
An oospore produced without undergoing sexual fertilization is termed an aboospore.