1. Define asexual reproduction as the process resulting in the production of genetically identical offspring from one parent.

Asexual reproduction results in daughter nuclei that have an identical replica of the genes of their parent nuclei. The definition is already given in the prompt!

  1. Discuss the advantages and disadvantages to a species of asexual reproduction.

Advantages:

  • Species can multiply faster, as no courting is required – only one parent needed for asexual reproduction.
  • Species can colonise new habitats faster and more efficiently.
  • In case of a mutation that is advantageous towards survival, e.g. a new gene giving rise to an enzyme that allows resistance to a drug, the effect on the population can be seen without much delay. What I mean is, you have the new mutant cell, that has an advantage over the other cells, thanks to a gene mutation. Within the hour, you’ll have thousands of these new mutant cells, so the failure of this drug to eradicate these cells becomes obvious. For this kind of effect to be seen in organisms that rely on sexual reproduction takes years or decades.

Disadvantages:

  • Because the genetic makeup of daughter cells are identical to that of their parent cells, species that rely on asexual reproduction have very little variation. The only way variation can occur is through gene mutations.
  • Due to limited variation, such a species has a limited chance of survival in different or changing environmental conditions, because all of them will only be adapted to a particular set of ‘normal’ conditions.
  • The species will not evolve as efficiently as sexually reproducing species.
  • If an organism experiences a gene mutation resulting in a disadvantageous trait arises, it will be easier for it to produce offspring and pass on its disadvantageous gene, as it doesn’t require a sexual partner.
  • Due to its rapid multiplication rate, a mutation leading to a disadvantageous trait will rapidly achieve a large effect on its population, provided the disadvantaged organisms survive long enough to reproduce.
  1. Define sexual reproduction as the process involving the fusion of haploid nuclei to form a diploid zygote and the production of genetically dissimilar offspring.

That’s a pretty self-explanatory point.

  1. Discuss the advantages and disadvantages to a species of sexual reproduction.

Advantages:

  • Gives rise to variation.
  • Due to variation, the species has a higher chance of survival in different or changing conditions.
  • This makes it easier for it to colonise new habitats.
  • As variation is the driving force of evolution, evolution occurs efficiently.
  • A negative mutation takes longer to inflict a significant effect on a population, or may never be passed on to the next generation.

Disadvantages:

  • Takes a long time to court.
  • Takes a while to colonise new habitats, so survival of species is harder to ensure.
  • Requires two parents which can be difficult to achieve when there is a disparity in the number of males and females of the species in the area.
  • In the same way a negative mutation may not be passed on to the next generation because the parent couldn’t mate/ the gamete containing the bad gene wasn’t fertilised, positive or favourable genes may not be passed on.
  • It produces fewer offspring than asexual reproduction (this point ties in with the point about the colonisation of new habitats taking a while).

 

Notes submitted by Sarah.

Click here to go to the next topic.

Click here to go to the previous topic.

Click here to go back to the Science menu.