Question

State two conditions necessary for external fertilisation and external development to succeed

Answer 1

External fertilization is a male organism's sperm fertilizing a female organism's egg outside of the female's body.[1]Internal fertilization, on the other hand, is the occurrence of internal insemination as the mode of combining sperm and egg.[2] External fertilization occurs in water or a moist area because it gives the sperm external mobility to get to the egg.[3] While in the water, the sperm and ova can shed simultaneously to fertilize the egg.[3] The release of eggs and sperm into the water is known as spawning.[4]When females spawn, they release a batch of eggs into a spot of their choice or just into the water, as in bottom dwelling or sessile species and all of the males start to release sperm that are in close proximity.[4] Within vertebrates, it is the amphibians and fish that use external fertilization.[5] When it comes to invertebrates, most are benthic, sessile, or benthic sessile combined animals such as coral, sea anemones, and tube dwelling polychaetes.[3] The benthic zone is the lowest level of the ocean where organisms called benthos reside.[6] An organism that is sessile does not have the ability to move or be mobile.[7] Benthic marine plants such as algae also go through external fertilization to reproduce.[3] Overall, environmental factors and the timing have a heavy influence over the success of external fertilization.In external fertilization some of the eggs laid by the animals gets wasted due to huge rainfall, floods etc.

Answer 2

The external fertilization is a process of fusion of male and female gametes in conditions outside the female body. It usually takes place in water.

Explanation:

• For external fertilization water body and free floating gametes like sperms and ovum are necessary.
• The external fertilization process is used by the fishes.
• In external fertilization the female releases the eggs and the male releases the sperms in the same environment this process occurs during spawning.
• The sperms land over the eggs and fertilize them in the water body.
• This technique has disadvantages that it exhibit low fertilization success as fertilization does not take place frequently and the eggs are eaten up by the predators.

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