Difference Between Zoospore and Zygote

The main difference between zoospore and zygote is that zoospore is a motile asexual spore of algae, fungi, and protozoans whereas zygote is the fertilized ovum, the result of the fusion of haploid gametes.

Zoospore and zygote are structures that are capable of developing into new individuals of the same species. Zoospore is a result of asexual reproduction while zygote is a result of sexual reproduction. Zoospores can be either haploid or diploid while the zygote is always diploid.

Key Areas Covered

1. What is a Zoospore
     – Definition, Characteristics
2. What is a Zygote
     – Definition, Characteristics
3. What are the Similarities Between Zoospore and Zygote
     – Outline of Common Features
4. What is the Difference Between Zoospore and Zygote
     – Comparison of Key Differences

Key Terns: Asexual Reproduction, Gametes, Sexual Reproduction, Zoospore, Zygote

What is a Zoospore

Zoospore refers to the motile, asexual spore of algae, fungi, and protozoans. The production of zoospores occurs in a sac called sporangium at the end of the aerial hyphae. They can swim by means of a flagellum. Protoplasm rapidly divides internally to produce zoospores. Thereby, zoospores are a type of endospores. The spores are unicellular and hyaline. Also, they lack cell walls. Since they lack cell walls, zoospores are not resistant to unfavorable conditions. 

Figure 1: Zoospores inside Sporangium

The endogenous food reserves serve as the energy source for the locomotion. Zoospores respond to environmental conditions, determining the conditions for encystation.

What is a Zygote

Zygote refers to the diploid cell resulted from the fusion of haploid gametes. In humans, the gametes contain 23 chromosomes. During fertilization, the somatic chromosomes number, 46 is regenerated. In plants, the zygote is formed inside the female gametophyte. In fungi, the karyogamy of two haploid cells forms the zygote. 

Figure 2: Zygote

After the formation, the zygote rapidly divides by mitosis, forming new cells that develop into different structures of the new individual.

Similarities Between Zoospore and Zygote

• Zoospore and zygote are reproductive structures.
• They consist of a single cell.
• Both of them can be diploid.

Difference Between Zoospore and Zygote

Definition

Zoospore: Motile, asexual spore of algae, fungi, and protozoans

Zygote: Diploid cell resulted from the fusion of haploid gametes

Occur in

Zoospore: Algae, fungi, and protozoans

Zygote: Higher organisms

Production

Zoospore: Formed inside the zoosporangium

Zygote: Formed by the fusion of gametes

Result of

Zoospore: Asexual reproduction

Zygote: Sexual reproduction

Ploidy

Zoospore: Can be either haploid or diploid

Zygote: Diploid

Mobility

Zoospore: Flagellated and mobile

Zygote: Immobile

Dispersal

Zoospore: Take part in dispersal

Zygote: Does not take part in dispersal

Conclusion

Zoospore is a motile asexual spore of algae, fungi or protozoans. Zygote is the result of the fusion of gametes during sexual reproduction. Both zoospore and zygote are single-celled reproductive structures. The main difference between zoospore and zygote is the type of reproduction from which they formed.

Reference:

1. “Zoospore.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., Available here
2. “Zygote.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 23 Dec. 2014, Available here

Image Courtesy:

1. “Phytophthora parasitica sporangia and zoospores” By Supattra Intavimolsri Department of Agriculture, Thailand – PaDIL, a source of images designed for Biosecurity and Biodiversity.(CC BY 3.0 au) via Commons Wikimedia
2. “Zygote1” By Nina Sesina – (CC BY-SA 4.0) via Commons Wikimedia