Sexual and Asexual Reproduction Quiz
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Questions and Answers

What is one major conclusion regarding the cost of sexual reproduction?

  • Sexual species have equal contributions from both genders.
  • Mating is typically less risky than asexual reproduction.
  • Males and females have the same potential for population growth.
  • Finding a mate is often time-consuming and risky. (correct)

    • Which principle explains the advantage of sexual reproduction in dealing with parasites?

  • Natural selection principle
  • Red Queen principle (correct)
  • Muller’s ratchet
  • Lottery principle

    • What is the reason behind the persistence of sexual reproduction despite its costs?

  • It provides long-term mutational advantages by reducing harmful mutations. (correct)
  • It only benefits males in the population.
  • It reduces the population size significantly.
  • It ensures that offspring are identical to the parents.

    • Under what environmental condition is sexual reproduction suggested to be more beneficial?

    <p>Unpredictable environments that require diversity.</p> Signup and view all the answers

    What does Muller’s ratchet refer to in the context of evolutionary biology?

    <p>The tendency for deleterious mutations to accumulate in the absence of sex.</p> Signup and view all the answers

    What is a primary benefit of sexual reproduction compared to asexual reproduction?

    <p>It generates new multilocus combinations of alleles.</p> Signup and view all the answers

    Which of the following describes anisogamous species?

    <p>Species that have two distinct mating types or sexes.</p> Signup and view all the answers

    What does the size-advantage model of sex reproduction suggest?

    <p>Reproductive success can change based on size and environmental factors.</p> Signup and view all the answers

    How has the method of reproduction evolved over billions of years?

    <p>Eukaryotic sex emerged around 1.2 billion years ago.</p> Signup and view all the answers

    Which of the following accurately describes the characteristics of obligately asexual species?

    <p>They reproduce exclusively without sexual reproduction.</p> Signup and view all the answers

    Study Notes

    Sex and Recombination

    • Sex generates new combinations of alleles throughout entire genome.
    • Over the human genome, there are more than 10^600 possible combinations of alleles.
    • Offspring are genetically distinct from their parents and usually each other.

    Asexual Reproduction

    • Many species can reproduce without sex.
    • Obligately asexual species reproduce only asexually.
    • Facultatively sexual species can reproduce sexually or asexually.
    • Obligately asexual species can reproduce only asexually.

    Sexual Reproduction

    • Sexually reproducing species may be isogamous (equal sized gametes) or anisogamous (gametes either small & motile or large & immobile).
    • Some species can self-fertilize, others cannot.
    • Isogamous species may have no distinct mating types, or many different mating types.
    • Anisogamous species usually have two sexes; individuals can be dioecious (separate sexes) or monoecious (hermaphrodites).

    Monoecy (Hermaphrodism)

    • Monoecy (hermaphrodism) can be simultaneous or sequential.
    • The Size-advantage model of sex suggests that reproductive success is linked to size.

    Origins of Sex

    • 3.5 BYA: the first cells reproduced asexually
    • 2 BYA: bacteria start exchanging genes (parasex).
    • 1.2 BYA: eukaryotic sex appears (specialized gametes, formed by meiosis, fuse to create a diploid zygote).
    • Today: most multicellular organisms reproduce sexually at least some of the time.
    • Obligately asexual animals are rare and extinction-prone.

    Bdelloid Rotifers

    • Bdelloid rotifers have been obligately asexual for more than 40 million years and still haven't gone extinct.

    Costs of Sex

    • Finding a mate is time-consuming and often risky.
    • In most sexual species, only females grow the population.
    • Only half of alleles are passed to offspring.

    Benefits of Sex

    • Sexual recombination helps to get rid of harmful mutations.
    • Without sex, deleterious mutations accumulate in the population (Muller's Ratchet).

    Immediate Benefits of Sex

    • Sexual reproduction is advantageous in unpredictable environments (lottery principle).
    • Sexual reproduction is advantageous in environments with lots of parasites (Red Queen principle).

    Take-homes

    • There are many ways to be asexual and many ways to be sexual.
    • Sex is costly, risky, and inefficient, but still very widespread.
    • The benefits of sex outweigh the costs.

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    Description

    Test your knowledge on the mechanisms of sexual and asexual reproduction. Explore the distinctions between isogamous and anisogamous species, and understand the complexities of genetic combinations generated through sexual reproduction. This quiz will challenge your understanding of reproduction strategies across different species.

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