New York State Chemistry RegentsNew York State Earth Science Regents

 
Living Environment Regents August 2010 Question 17 PDF Print E-mail
Friday, 27 May 2011 12:47
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Correct answer: (4) decreased biodiversity within species

The asexual reproduction exhibited by animals, like some genera of fishes, amphibians, and lizards, is called parthenogenesis. It is a process in which the egg develops without being fertilized. Sharks undergo a complex form of parthenogenesis that involves the doubling of chromosomes after meiosis to create diploid offsprings. Since crossing over of chromosomes did not occur between two different individuals, there is no recombination of genetic material that is responsible for diversity among species.

Incorrect answers:

(1) increased gene recombinations

No genetic recombination occurs during the asexual reproduction because there is no crossing over of chromosomes between two different individuals.

(2) increased number of males produced

During parthenogenesis in sharks, all the offsprings produced are females due to their X-Y sex-determination system, wherein female chromosomes are represented as XX. Thus, no male sharks (with XY chromosome) will be conceived due to the absence of Y chromosome.

(3) decreased number of eggs used

During asexual reproduction, eggs are still used. The eggs turn into diploid offsprings when the chromosomes double after meiosis. Thus, there is no change in the number of eggs used during reproduction.
Last Updated on Friday, 27 May 2011 12:50
 

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