Mechanisms of reproduction – HSC Biology

  • Explain the mechanisms of reproduction that ensure the continuity of a species, by analysing sexual and asexual methods of reproduction in a variety of organisms, including but not limited to:
    • animals: advantages of external and internal fertilisation
    • plants: asexual and sexual reproduction
    • fungi: budding, spores
    • bacteria: binary fission
    • protists: binary fission, budding


In order for a species to continue, it must replicate. This allows for the next generation to replace the current one. The two ways an organism can replicate can be separated into sexual and asexual reproduction.

Sexual reproduction requires to organisms of opposite sex in order for an offspring. Since this involves the combination of genetic material from both parents, the offspring will have features which resemble both parents. This, however, is more energy inefficient and fewer offspring. However, the parents will usually raise and support the young – increasing the likelihood of survival.

Asexual reproduction only requires a single organism for reproduction. It is therefore more rapid and energy favorable since the individual doesn’t have to spend time looking for a mate. The offspring are identical to the parent – which is not favorable in the event of a selective pressure as it could wipe out the entire species due to lack of genetic variation.

Animals can reproduce internally or externally. Internal reproduction involves growing the organism within the parent e.g for humans, child in a mother. This increases the likelihood of survival for the child and allows for a more controlled and nutrient rich environment – this is more common for land dwelling creatures. Where as salmon lay eggs which grow and hatch wildly. This will increase the number of offspring, however, the environment isn’t as regulated and the chance of death is greater.

Plants can reproduce asexually e.g clone or sexually e.g flowers


Fungi reproduce asexually from budding which is an asexual method of reproduction which involves the organism developing an extrusion which buds off to form a new organism. Additionally, fungi release spores which can be sexual or asexual – these are carried in the wind and deposited on new surface allowing a new fungi to grow from this. Below is a diagram showing fungi sexual and asexual reproduction – don’t worry about all the details.

Characteristics of Fungi | Boundless Biology

Source: Lumen learning


The petri dish below shows bacteria reproducing via binary fission, this is when a bacterium splits into two. This asexual reproduction can occur every 20 minutes allowing bacteria to rapidly populate areas.


Protists can be found in pond water, they asexually reproduce via binary fission and budding.


Sexual vs asexual reproduction

  • animals: sexual reproduction
  • plants: asexual and sexual reproduction
  • fungi: budding, spores
  • bacteria: binary fission
  • protists: binary fission, budding


Question 1.

Compare and contrast sexual and asexual reproduction, using examples when one would be more favorable then the other. [4 marks]

Question 2.

Outline the method of reproduction for:

  • animals: [1 mark]
  • plants: [2 marks]
  • fungi: [2 marks]
  • bacteria: [1 mark]
  • protists: [2 mark]

Question 3. [6 marks]

Evaluate whether sexual or asexual reproduction is more favorable for the continuation of a species.

Question 4. [3 marks]

Explain why internal reproduction is better then external reproduction for land dwelling animals.

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