A prezygotic barrier prevents (a) the union of egg and sperm (b) reproductive success by an interspecific hybrid (c) the development of the zygote into an embryo (d) allopolyploidy from occurring (e) changes in allometric growth
Introduction: The biological species concepts define species as the group of members which can interbreed among themselves and produce fertile offspring. It explains the integrity of a species is maintained by reproductive isolation. The prezygotic barriers are the important role players to prevent interspecies breeding.
Answer to Problem 1TYU
Correct answer: A prezygotic barriers prevent the fertilization process by the union of egg and sperm of two different species. Hence, the correct answer is option (a).
Explanation of Solution
Reason for correct answer:
The reproductive isolation by prezygotic barriers prevents the event of fertilization of the gametes of the gametes of two different species. The prezygotic barrier as its name suggests is the barrier having several mechanisms to discourage different species including closely related species to not to mate with each other and become reproductively isolated.
Option (a) is given as “the union of egg and sperm”.
The union of egg and sperm is prevented by the prezygotic barrier. Hence, the correct answer is option (a).
Reasons for incorrect answer:
Option (b) is given as, “reproductive success by an interspecific hybrid”.
The prezygotic barrier as the name suggests is a barrier which prevents the formation of zygote. Instead, the reproductive success of an interspecific hybrid is checked by the means of postzygotic barriers. Hence, option (b) is incorrect.
Option (c) is given as, “the development of the zygote into an embryo”.
The development of the zygote into an embryo is checked by the means of reproductive failure mechanism which is a part of postzygotic barriers instead of the prezygotic barrier. Hence, option (c) is incorrect.
Option (d) is given as, “allopolyploidy from occurring”.
The prezygotic barriers do not prevent allopolyploids instead of postzygotic barriers along with selection pressure checks allopolyploidy. Hence, option (d) is incorrect.
Option (e) is given as, “changes in allometric growth”.
The changes in allometric growth are a result of adaptive evolutionary modifications of pre-existing characters of the same species whereas prezygotic barriers prevent fertilization and mating between two different species. Hence, option (e) is incorrect.
Hence, the options (b), (c), (d), and (e) are incorrect.
A prezygotic barrier is an isolation mechanism which prevents fusion of male and female gametes (sperm and egg).
Want to see more full solutions like this?
Chapter 20 Solutions
Biology (MindTap Course List)
- Is parental care of a species a factor that affects embryological development? If so, how?arrow_forwardWhat are zygotes and other cells carrying two matching sets of chromosomes?arrow_forwardUnder what conditions should natural selection favor production of many offspring versus the production of a few well-provisioned offspring?arrow_forward
- What are the physical similarities exist between each of the embryos? How does the pattern of embryological development provides evidence which supports common ancestry?arrow_forwardCan conjoined (Siamese) twins be dizygotic twins in light of the theory that conjoined twins result from incomplete division of the embryo?arrow_forwardDo all dioecious species have a homogametic and a heterogametic sex? 1. Yes, because dioecious means that two types of gametes are produced, even in hermaphroditic species. 2. Yes, because all sex-determining systems include heterogametic and homogametic sexes. 3. Yes, because in dioecious organisms, either the XX-XY or the ZZ-ZW system determines sex. XY and ZW individuals are heterogametic. XX and ZZ individuals are homogametic. 4. No, because hermaphrodites and species that reproduce asexually are dioecious. 5. No, because dioecious means that the sexes are separate, regardless of how sex is determined. In some dioecious species, sex is determined by a single gene.arrow_forward
- .If you removed the ZPA from a limb bud and then placed a bead soaked in Sonic hedgehog in the middle of the bud, what would be the most likely result?arrow_forwardWhy must the life cycle of sexually reproducing species alternate between haploid and diploid stages? A) Mitosis must occur at some point in the life cycle to prevent a doubling of chromosomes in each generation. B) Meiosis must occur at some point in the life cycle to prevent a doubling of chromosomes in each generation. C) Mitosis must occur at some point in the life cycle to prevent a reduction of chromosomes in each generation. D) Meiosis must occur at some point in the life cycle to prevent a reduction of chromosomes in each generation.arrow_forwardWho proposed the theory of recapitulation ? Who is known as the Father of taxanomy? What is called coacervates? What is protobiont? Which ancestral called direct ancestry of human?arrow_forward
- What would happen if one cell was removed or damaged at the 2-cell stage of sea urchin embryo development? What about if one cell was removed at the 4-cell stage? At the 8-cell stage? How about if two cells were separated after the first cleavage and allowed to develop on their own?arrow_forwardWhich reproductive barrier is most likely to prevent interbreeding between a polyploid species and its diploid sister species?arrow_forwardWould you expect more or less similarity between embryos from distantly related species? Explain and provide examples.arrow_forward
- Biology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage LearningHuman Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage LearningBiology Today and Tomorrow without Physiology (Mi...BiologyISBN:9781305117396Author:Cecie Starr, Christine Evers, Lisa StarrPublisher:Cengage Learning