Question

In which set of organisms does external fertilization occur
A. Echinodermata and mosses
B. Hemichordata and ferns
C. Amphibians and algae
D. Reptiles and gymnosperms

Answer 1

Hint: External fertilization is the process in which male and female gametes are released in the medium and male and female gametes fuse in the medium to produce the fertilized egg, known as zygote.

Complete Answer:
- Medium or environment in which externally fertilizing organisms release their gametes is generally water, which protects eggs from desiccation. And they release gametes generally in spawning and fertilization takes place.
- In this process the chances of the fuse of male and female gametes are very low thus, the amount of male and female gametes released is very high. Also, gametes are targeted by the predators as well because they are open unprotected in the medium.
- This mode of reproduction helps in the production of genetic variations, produce large number of infants. But some drawbacks are: Many gametes are not utilized and left unfertilized. Predators have high chances of attacking on gametes and desiccation of zygote or eggs may also take place.
- Examples of organisms which have this mode of reproduction are lower organisms such as amphibians, which releases their eggs and sperm in the water and fertilization takes place.
- Similarly, in case of algae, the microgamete and macrogamete fuses outside the body of algae in the water medium and fertilization takes place.

Thus, we can say that option ‘C’ that is, amphibians and algae is the correct option.

Note: Gymnosperms are plants without flowers and reproduce through sexual reproduction but with internal fertilization process. And mosses reproduce with spore formation; they don’t have flowers for reproduction.