Topic 9.4: Reproduction in Plants

Essential Idea:  Reproduction in flowering plants is influenced by the biotic and abiotic environments.

At SHS, Topic 9.4 is taught in the following class unit(s):

• Communities and Ecosystems (unit 24)
• Angiosperm Reproduction (unit 38)

Statements & Objectives:

9.4.U1  Flowering involves a change in gene expression in the shoot apex.​

• Compare the vegetative and reproductive phases of the angiospermatophyta life cycle.
• State that flowers are produced from a shoot apical meristem.
• State two abiotic factors that may trigger flowering.
• Compare the timing of flowering in short-day plants and long-day plants.
• Outline the process by which changes in gene expression trigger flowering.

9.4.U2  The switch to flowering is a response to the length of light and dark periods in many plants.​

• State the role of the pigment phytochrome.
• Describe the conversions between the two forms of phytochrome.
• Describe role of phytochrome in controlling flowering in long and short day plants.

9.4.U3  Success in plant reproduction depends on pollination, fertilization and seed dispersal.

• ​Define pollination, fertilization and seed dispersal.
• State the changes to the ovule and ovary that result from fertilization.
• List mechanisms of seed dispersal.

9.4.U4  Most flowering plants use mutualistic relationships with pollinators in sexual reproduction.​

• Define mutualism.​
• Explain an example of mutualism between a flowering plant and its pollinator.

9.4.A1  Methods used to induce short-day plants to flower out of season.

• State how plants can be manipulated to force flowering out of season.

​9.4.S1  Drawing internal structure of seeds.

• Draw and label the structure of seeds, including:
  • Embryo root
  • Embryo shoot
  • Cotykedons
  • Testa
  • Micropyle
  • Hilum
• State the function of the different parts of the seed. ​

9.4.S2  Drawing of half-views of animal-pollinated flowers.

• Draw and label an animal pollinated flower, including:
  • Nectar-secreting glands
  • Petals
  • Sepals
  • Anthers
  • Filaments
  • Carpel
  • Stigma
  • Style
  • Ovary
  • Ovule
• State the function of the different parts of the animal-pollinated flower. ​

9.4.S3  Design of experiments to test hypothesis about factors affecting germination.​

• Define germination.
• Outline why water, oxygen and warmth are required for germination.
• Outline the role of gibberellin during germination.
• Write five example problem questions for experiments that could test factors affecting germination.

9.4.NOS  Paradigm shift-more than 85% of the world’s 250,000 species of flowering plant depend on pollinators for reproduction. This knowledge has led to protecting entire ecosystems rather than individual species.

• Contrast traditional conservation efforts with newer strategies of conservation.

In the News:

• Unexpected ‘Germline’ Plant Cells May Shield New Generations (2019-08-05)
• Honeybees Are Hurting. What Else Can Pollinate Our Food? (2018-08-21)
• When the seed becomes a plant, it has 48 hours to survive (2018-08-02)
• For one tropical tree, effective seed dispersal relies especially on elephants (2018-07-18)
• Botanical life in close up (2018-07-02)
• ​Lizards, mice, bats and other vertebrates are important pollinators, too (2018-04-04)
• Duck faeces shed light on plant seed dispersal (2018-02-05)
• When did flowers originate? (2018-02-05)
• ​Flower petals have ‘blue halos’ to attract bees (2017-10-18)
• Tree hitched a ride to island (2014-06-18)
• Calcium and reproduction go together like the birds and the bees (2014-08-22)
• Solving Crimes With Pollen, One Grain Of Evidence At A Time (2015-04-25)
• Hips, haws and drupes: when is a nut not a nut? (2016-11-10)
• ‘This is amazing!’ African elephants may transport seeds farther than any other land animal (2017-04-10)
• Watching their Dust:   Photographing Players in Pollination (2017-04-24)
• Nocturnal pollinators go dark under street lamps (2017-08-02)
• Headbanging Aussie bee takes a heavy metal approach to pollination (2015-12-14)
• Sweet success: how bees choose which pollen to collect (2016-07-12)
• The Beautiful Tricks of Flowers (TED, 2011)
• What's In It For The Corpse Flower To Smell Like Death? (2016-10-25)
• Biggest producer of coffee could see bean-growing land shrink nearly 90% by 2050 (2017-09-11)
• ​WE CAN SAVE INDIVIDUAL SPECIES — BUT CAN WE SAVE ENTIRE ECOSYSTEMS? (2016-02-23)
• A stinging report: Climate change a major threat to bumble bees (2017-09-29)