Topic 9.3 Reproduction in Angiosperms

8/3/2019 Topic 9.3 Reproduction in Angiosperms

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Topic 9.3


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Angiosperms are the flowering plants

They make seeds

They are different than gymnosperms (likepine trees) because gymnosperms makeseeds without making flowers.

Remember that the angiosperms can bedivided into the monocots and dicots


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http://www.wisc-online.com/objects/index_tj.asp?objID=BIO1305
http://www.wisc-online.com/objects/index_tj.asp?objID=BIO1305http://www.wisc-online.com/objects/index_tj.asp?objID=BIO1305http://www.wisc-online.com/objects/index_tj.asp?objID=BIO1305http://www.wisc-online.com/objects/index_tj.asp?objID=BIO1305http://www.wisc-online.com/objects/index_tj.asp?objID=BIO1305http://www.wisc-online.com/objects/index_tj.asp?objID=BIO1305http://www.wisc-online.com/objects/index_tj.asp?objID=BIO1305http://www.wisc-online.com/objects/index_tj.asp?objID=BIO1305


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9.3.1 Draw and label a diagram

showing the structure of a

dicotyledonous animal-pollinated

flower


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9.3.2 Distinguish between

pollination fertilization and seeddispersal


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Pollination: the process by which pollenis placed on the female stigma

Fertilization: the process by which thesperm of the plant unites with the egg

Seed dispersal:the process by which the

embryo (protected in the seed) isdispersed to distant locations

http://www.youtube.com/watch?v=zbQ1jWl3AOM
http://www.youtube.com/watch?v=zbQ1jWl3AOMhttp://www.youtube.com/watch?v=zbQ1jWl3AOMhttp://www.youtube.com/watch?v=zbQ1jWl3AOMhttp://www.youtube.com/watch?v=zbQ1jWl3AOM


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Yellow Book

Pollination in Plants page 297-304


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9.3.3 Draw and label a diagram

showing the external and internal

structure of a nameddicotyledonous seed


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embryo - developing plant still insidethe seed. The embryo has cotyledons(embryonic leaves), a root cap, a foodsource and a plumule (shoot).

micropyle - the small pore in a seedthat that allows water absorption

embryo shoot(hypocotyl)- the partof the stem of a sprouting plant that isabove the root and below the stalk ofthe cotyledon (seed leaves)

seed coat (testa) - seed coat is theouter, protective layer covering the

seed seed leaf (cotyledon) - the

embryonic leaf within a seed embryo root (radicle)- will become

the root of the plant

Testa

Embryo leaves

Embryo shoot

Embryo root

Micropyle

Cotyledon


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9.3.4 Explain the conditions

needed for the germination of atypical seed


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Germination is the development of a seedinto in functioning plant.

Oxygen, water and a suitable temperatureis needed for germination.


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Oxygen is need in aerobic respiration toproduce ATP so the plant has the energyneeded to germinate.


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Water is taken in and rehydrates the seedcausing it to swell up. This cracks the testaand enzymes are activated which begin

breaking down large molecules.


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Temperature needs to be suitable for thetype of seed that is germinating. Someseed require a period of low temperaturefollowed by one of high temperature to

break dormancy (ensures seeds do notgerminate until winter has passed).


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Germination is a very uncertain time in aplants life cycle and many seeds do not

produce a viable plant because of threats

to the fragile seedling such as harshweather, predators and parasites.


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9.3.5 Outline the metabolic

processes during germination ofa starchy seed


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1. Water is absorbed and it

activates the cotyledon cells2. The plant synthesizes gibberellin

(a plant growth substance)

3. The gibberellin causes theenzyme amylase to be produced

4. Amylase breaks down the seedsinto maltose

5. The maltose diffuses to the

embryo where it will be used forenergy release and growth


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Yellow Book

Germination in Plants page 305-306


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9.3.6 Explain how flowering is

controlled in long-day and short-

day plants including the role ofphytochrome


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Plants are able to detect the presence of light,its direction, wavelength and even intensity

Photoperiodismis a plants response to light

due to the length of day and night Plants must flower when pollinators are

available and when resources are abundant


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Long day plants Blooms whendays are thelongest and nightsthe shortest

Radishes,spinach, lettuce

Short day plants Blooms in latespring, latesummer andautumn when

days are shorter

Poinsettas, aster,andchrysanthemums

Day-neutral plants Flower withoutregard to daylength

Roses, dandelionsand tomatoes


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Photoperiodicty is the term used todescribe a plants response to the length ofthe night.

Plants use a special blue-green pigmentknown as phytochrome to regulate theirphotoperiodism.

Watch this mini lecture to get a basicunderstanding

http://www.youtube.com/watch?v=v3jdrSWxJ64&feature=relmfu
http://www.youtube.com/watch?v=v3jdrSWxJ64&feature=relmfuhttp://www.youtube.com/watch?v=v3jdrSWxJ64&feature=relmfuhttp://www.youtube.com/watch?v=v3jdrSWxJ64&feature=relmfuhttp://www.youtube.com/watch?v=v3jdrSWxJ64&feature=relmfu


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Phytochrome is a photoreceptor thatexists in two forms or states.

There is an active form known as Pfr and

an inactive form known as Pr.


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Long day plants are stimulated to flowerwhen Pfr is present in the right amount

Short day plants are inhibited by Pfr and

will flower when it is not present


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Long dark period and short days allowsmore Pfr to revert back to Pr - this is whenshort day plant flowers

Long days and short nights producesincreased Pfr this stimulates the long dayplant to flower

Pfr acts as a promoter of flowering in longday plants and inhibits flowering in shortday plants


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This step here occurs rapidly in the light and slowly in the dark


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Many experiments were done on this topic

You should be able to explain theseexperiments


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In short-day plants the length ofthe night (darkness) is the criticalfactor

If it is too short, the plant wontflower

If a long enough time period isinterrupted by a flash, it wont

flower Why? The flash restarts the time

period


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In long-day plants the lengthof the night (darkness) is alsothe critical factor

If it is too long, the plant wont

flower

If a long time period is

interrupted by a flash, it willflower


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http://bcs.whfreeman.com/thelifewire/content/chp39/3902002.html

http://highered.mcgraw-

hill.com/sites/9834092339/student_view0/chapter41/animation_-

_phytochrome_signaling.html
http://bcs.whfreeman.com/thelifewire/content/chp39/3902002.htmlhttp://bcs.whfreeman.com/thelifewire/content/chp39/3902002.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter41/animation_-_phytochrome_signaling.htmlhttp://bcs.whfreeman.com/thelifewire/content/chp39/3902002.htmlhttp://bcs.whfreeman.com/thelifewire/content/chp39/3902002.html


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Yellow Book

Photoperiodism in Plants page 277-288


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Topic 9.3 Reproduction in Angiosperms

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