Examine a slide of Rhizopus, sexual reproductive structures. Draw and label the Rhizopus sexual reproductive structures. Identify the gametangia and zygospore. Make sure to draw and label these structures on this page.
(a) 667 um Rhizopus sporangia As Rhizopus under the light microscope.
The dark structures are zygospores, which are produced during sexual reproduction. zygospore diploid (2N) haploid (N) meiosis fertilization sporangium sexual spores (N) germination of zygospore + strain gametes (N) strain sporangium sporangium sporangiophore spores hyphae asexual + strain strain gametangia mycelium
The Correct Answer and Explanation is :
To examine the sexual reproductive structures of Rhizopus and identify the key components such as gametangia and zygospores, let’s first look at the two images you’ve referenced. In Rhizopus, sexual reproduction occurs through the formation of specialized structures such as gametangia, zygospores, and sporangia.
Image Breakdown:
- Zygospores: These are dark, thick-walled structures that result from the fusion of two gametes during fertilization. Zygospores are diploid (2N) and are produced after meiosis occurs within them. Zygospores are the product of sexual reproduction and are capable of germinating under suitable conditions.
- Gametangia: These are specialized structures that form at the tips of hyphae of opposite mating strains. There are two types of gametangia: male and female. They fuse during sexual reproduction to form the zygospore. Gametangia are haploid (N).
- Sporangia: These structures are part of the asexual reproductive cycle of Rhizopus. They are responsible for producing haploid (N) spores. The spores are released from the sporangium into the environment, where they can germinate and grow into new mycelium. The sporangiophore is the stalk that supports the sporangium.
Labeling the Diagram:
- Zygospores: Dark, thick-walled, and diploid (2N) structures formed from the fusion of gametangia.
- Gametangia: These are the haploid (N) structures formed at the tips of specialized hyphae from opposite strains. When the gametangia meet, they fuse to form the zygospore.
- Sporangium: These are asexual reproductive structures where spores are produced. The spores are haploid (N).
- Sporangiophore: The stalk that supports the sporangium.
- Hyphae: These are the filaments that make up the mycelium of Rhizopus. They are involved in both asexual and sexual reproduction.
Explanation of the Reproductive Cycle:
- Asexual Reproduction: The primary method of reproduction in Rhizopus is asexual. Under favorable conditions, the mycelium produces sporangia. These sporangia release haploid spores, which germinate and grow into new mycelium. This process is quick and efficient, helping the organism colonize new environments.
- Sexual Reproduction: Under unfavorable conditions, Rhizopus switches to sexual reproduction. Two compatible mating strains of Rhizopus produce gametangia at the tips of their hyphae. The gametangia fuse, resulting in the formation of a zygospore. The zygospore is diploid (2N) and undergoes meiosis, producing new haploid spores. This genetic recombination increases genetic diversity, which can be beneficial for the organism’s survival in fluctuating environments.
In summary, the key reproductive structures of Rhizopus are the sporangium for asexual reproduction, and the gametangia and zygospores for sexual reproduction. Understanding the distinction between these structures and the stages of reproduction is crucial for identifying the organism’s reproductive cycle under the microscope.