Tag Archives: reproduction

Reproductive Strategies


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Living organisms have evolved many different reproductive strategies to ensure their survival from generation to generation. Scientists sometimes categorize these strategies as “r-selected” (rapid, related to rate) or “K-selected” (related to carrying capacity). You can read a good comparison of r and K-strategies here: Reproductive strategies

Read the ABC Science article: Antechinus go out with a bang and then do “Part B: A case study in reproductive behaviour” on page 150 of your Jacaranda Activity Manual. If you finish, please do the Chapter 12 Review questions and the Activity manual “In Review” for Chapter 12.

Fern Reproduction – Alternation of Generations


1. Watch the Secret Life of Ferns; the Fern Life Cycle and the Fern sporangium catapult on YouTube.

2. Go to The Fern Life Cycle – Student Tutorial and label the Fern Life Cycle diagram as you work through the tutorial.

3. Use this worksheet to create a new task for next year’s Biology class to learn about the Alternation of Generations in ferns.

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This image is a screenshot from the YouTube video “The fern sporangium catapult” showing spores being released from a sporangium and the annulus colored blue, representing the water that is critical to the process of ejecting the spores. Due to the cohesive properties of water molecules and the structure of the annulus, as water evaporates, the sporangium ruptures as the annulus curls back. At a critical point, when water continues to evaporate, there are not enough water molecules to hold the annulus open and the ‘head’ of the sporangium springs back, ejecting the spores.

Term 2 – Week 5: Reproduction (Year 11)


This week in Year 11 Biology we are starting to discuss another body system – the reproductive system. First we will study the concepts of asexual and sexual reproduction and then learn how reproduction occurs in unicellular and multicellular organisms.

Asexual Reproduction – Plants, bacteria and fungi

Draw a diagram to show each of the following types of asexual reproduction:

  • binary fission (eg. bacteria, some algae)
  • budding (eg. yeast, hydra)
  • bulbs (eg. daffodils)
  • runners and rhizomes (eg. strawberries)
  • fragmentation (eg. sea stars, flatworms)
  • spore formation (eg. fungi)
  • parthenogenisis (eg. stick insects, some reptiles)

This YouTube video, Asexual Reproduction, shows budding in Hydra and Anenomes and binary fission in Paramecium, as well as asexual reproduction in Volvox, a green algae.

Sexual Reproduction Handout

Reproductive behaviours of marsupials

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Learning Intention:

Success Criteria:

The Dusky Antechinus (Antechinus swainsonii) is a small dasyurid with an unusual life cycle. “In winter, females make nests in creek banks, often below the surface of the soil, where decayed logs and grass provide cover. The roughly spherical, grass-lined nest chamber has a single opening. Mating is restricted to a short period in winter, and may last up to six hours. All males die within three weeks of the start of mating season. A month after mating, females give birth and six to ten young are carried in an open pouch for about eight weeks. The young are then left in the nest for about three months until they are able to fend for themselves.” (Museum Victoria). Your practical manual has an exercise with graphs showing the changing population of males and females in the Antechinus. Answer the discussion questions and then complete the Biochallenge on page 401.

12: Reproductive Adaptations

Learning Intention: Students will understand the benefits and energy costs of a range of reproductive adaptations. They will compare ‘r’ and ‘K’ strategies and learn how they assist survival of the species.

Success Criteria: Students will be able to describe various reproductive strategies in plants and animals and explain how they assist survival of the species.

Amazing Reproductive Strategies


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Tonight on ABC1 you may have been lucky enough to watch “Life” narrated by David Attenborough. This, the first of three episodes, was about fish – their variety, feeding and reproductive behaviours, habitats and predators.  It began with footage taken in southern Australian waters, of the weedy sea dragon, showing how the male and female court by ‘dancing’ then the female transfers the fertilized eggs to the male, who looks after them until they hatch. The tiny hatchlings wriggle free from the father’s belly-fold and begin to feed, with their yolk sac still attached. The anglerfish has another unusual method of reproduction, in which the male is ‘parasitic’ on the female. The tiny male embeds itself in the female and disintegrates into the female’s flesh, until all that is left is the testes.


Praying mantids exhibit another unusual method of reproduction, in which the male has a good chance of his head being bitten off during mating. If the male happens to lose his rigid grip from atop the female, he is at risk of sexual cannibalism – the female gets a nutritous meal as well as continued copulation, as the nerves that stop copulation are in the head, and the nerves that continue copulation are in the abdomen. Dragonflies and damselflies also display unusual courtship. Eggs may be deposited underwater, drilled into mud, carved into stems, or dropped while in flight.


The green spoonworm (Bonellia viridis) is another species in which the female dominates – in fact you are unlikely to find a male spoonworm at all. The spoonworms begin life as free-swimming larvae, which settle to the bottom of the Mediterranean Sea and slowly develop. If the larvae happen to settle on another female, the female releases a chemical that turns the larvae into a tiny male, which migrates through her mouth into the uterus and assumes a parasitic existence. The female can have up to twenty tiny males inside her genital sac, so she expends no energy looking for a mate, while the male benefits by having a safe and secure space, relying on the female for nutrition.




In a recent article in The Age, “Cheating is risky, but worth it, for female finches”, Adam Carey writes about the reproductive strategies of the beautiful Gouldian Finches, which have an unusually high rate of intra-species incompatability. “Gouldian finches mate two to four times a day during breeding season, but given the opportunity, the female will covertly cuckold her mate, also going to great lengths to keep it a secret. Males will help to incubate eggs and feed chicks, unless the female’s infidelity becomes known, in which case he might abandon the brood.” So what motivates the female to take such a risk? Scientists believe that the female can choose genetically superior mates and maximizes her chance of conceiving healthy offspring by ‘cheating’ on her mate. A superior male can fertilize up to 75% of a female’s eggs, making even one copulation worthwhile.

Mating behaviour in animals – monogamy, polygamy, polygyny and polyandry.

Reproductive Strategies for Survival in Animals


This week we start Chapter 12: Reproductive Strategies for Survival. Reproductive strategies include structual, functional and behavioural adaptations that increase opportunities for fertilization and/or improve survival of offspring. In the animal kingdom there are many different types of reproductive strategies:

  • Type of reproduction (sexual or asexual)
  • Gender system (separate male/female; hermaphrodite; parthenogenesis)
  • Mode of fertilisation (internal or external)
  • Mating system (monogamy; polygamy or promiscuity)
  • Numbers of offspring (r-selected or K-selected)
  • Place of development and source of nutrition for the embryo (oviparity or vivaparity)
  • Investment of parental care into offspring (nil, single parent or both parents, extended family)

Sexual Reproduction

mandarin fish mating

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Today we finished our unit on Reproduction by looking at the variety of strategies that vertebrates use to produce offspring. From broadcast spawning (in most fish) where eggs and sperm are released into the aquatic environment, to the production of amniotic eggs in birds and the vivaporous births of mammals, there are different degrees of resources put into reproduction. Different species of sharks show a variety of different strategies from external egg development (oviparous) to placental live birth (viviparous) to internal egg development with live birth (ovoviviparous) to interuterine cannibalism. Terrestrial organisms require internal fertilisation to protect the gametes from dessication and allow the embryo to form either protected by a shell or within the uterus or womb.

Try this student activity to compare asexual and sexual reproductive strategies. More about reproduction here. Check out the wiki for more activities and information.

Vegetative Reproduction

Vegetative reproduction

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This week we are starting the topic “Reproduction” by looking at vegetative or asexual methods of reproduction. Complete the table titled “Types of Vegetative Reproduction” using your text and activity manual. Plants that are produced by vegetative reproduction are genetically identical to their parent plants, which is a very useful trait for horticulturalists. They may use the following methods:

  • Runners (strawberries, water hyacinth)
  • Cuttings (geraniums, roses)
  • Rhizomes (underground stems, as in ferns, irises, ginger and galangal)
  • Tubers (potatoes0
  • Bulbs (daffodils, tulips, onions)
  • Suckers (undersground stems that arise a distance from the parent plant eg. elm trees and blackberries)

Reproductive behaviours

lyrebird display

Over the next two weeks we will be studying the various reproductive strategies of plants and animals, ranging from the broadcast spawning of coral polyps and boxfish (r-strategy) to the K-strategy of whales and other mammals, in which much energy is expended in gestation and caring for the offspring. The prominent tail feathers of the male lyrebird serve to attract passing females. The male does not put energy into producing eggs or caring for offspring, but puts much energy into growing long tail feathers and putting on reproductive displays.

Quiz on reproductive strategies:

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