Don\'t answer the list above I posted it as a reference thanks ( answer the ques

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Don't answer the list above I posted it as a reference thanks ( answer the question 6.. a to c)

Name Demonstration 6: Specialized organ systems for internal fertilization. Using your textbook or the World Wide Web for reference, complete Figures 6-7 and 6-8 by labeling them with the letters listed for each reproductive organ listed below. Also, with a one- sentence description for each organ describe how each organ enables internal fertilization. a. Seminal vesicle b. Urethra (for anatomical reference) c. Scrotum d. Prostate e. Bulbourethral gland f. Testes g Erectile tissue h. Penile body, glands, and prepuce i. Vas deferens j. Epididymis k. Cervix 1. Vagina m. Major vestibular gland n. Vaginal opening o. Labia minora p. Labia majora q. Ovary r. Ovaduct s. Uterus t. Clitoral body, glans, and prepuce -INTRODUC TION TO ANIMAL REPRODUCTION, FERTILIZATION, AND DEVELOPMENT

Explanation / Answer

6a. No

Sea urchin undergoes external fertilization, where male sea urchin lying in elevated sealevel release the sperm and gametes fertilize the eggs of the female sea urchins which lie deep in the ocean. Sea urchin have four (for irregular sea urchins) gonads or five gonads (for regular sea urchins). The parts mentioned above are applicable for internal fertilization in higher mammals and not applicable to sea urchins whose fertilization is simple and external

6b. From the list,Testes in male urchin and ovaries and female urchin are absoultely essential.

The other one could be urethra for male (gonopore in seaurchins which is common for both male and female) and vaginal opening in female

But it should be remembered that, they are not so well developed as those in higher animals in sea urchins. Gonads in sea urchins are rudimentary and basic.

Male and female are externally indistinguishable. They have four to five gonads called as Roe, which are present in both male and female sea urchins. They have a gonopore to release the gametes and muscles which support the duct to release the gametes. Male sea urchins release the sperms and female release the eggs

6c. External fertilization evolved first and Internal ferilization evolved later.

External fertilization is simple and does not need complex reproductive organs and mechanisms making it the first in evolution. Survival rate of the organisms produced through external fertilization is low due to harsh environmental conditions, predators and external fertilization involves production of more number of gametes which is not conservative, and it always needs medium like water for the gametes to travel which is an external factor.

External fertilization is induced by other external parameters like temperature of water, pH of water, salinity and length of day all of which plays the deciding role in fertilization. In a nutshell, external fertilization is less conservative and affected by number of other factors which may or may not be in the favor of the organism. This led to the development of specialized reprodcutive organs and evolution of internal fertilization which is more controlled and conservative process.

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