1.6 Domain Eukarya: Kingdom Plantae
a) Describe alternation of generation as the unique characteristics of Plantae b) State the classification of Plantae into four groups : i. Bryophytes ii. Pteridophytes iii. Gymnosperms iv. Angiosperms
❑ Multicellular eukaryotes ❑ Photosynthetic autotrophs that utilize chlorophylls to trap light energy for the process of photosynthesis ❑ Primary food storage : starch ❑ Cell wall : cellulose ❑ Have 2 generations : Alternation of generations
“A life cycle in plants involved the alternation between 2 generations of distinct multicellular stage: sporophyte (diploid/2n) and gametophyte (haploid/n) generation” ❑ Sporophyte generation which produce haploid spores by meiosis ❑ Starts with a mature sporophyte (2n) which produces haploid spores by meiosis, a process which results in a reduction of the number of chromosomes by a half ❑ The spores germinate and grow into a gametophyte(n) ❑ Gametophyte generation which produce haploid gametes by mitosis ❑ At maturity, the gametophyte(n) produces gametes by mitosis, which does not alter the number of chromosomes ❑ Two gametes fuse to produce a zygote, which develops into a diploid sporophyte (2n)
a) Describe the unique characteristics of Bryophytes b) State the classification of Bryophytes into three (3) divisions / phyla : i. Phylum Hepatophyta (Marchantia sp.) ii. Phylum Bryophyta (Polytrichum sp.) iii. Phylum Anthocerophyta (Anthoceros sp.) c) State the terrestrial adaptation for bryophytes.
❑ Most primitive terrestrial plants ❑ Habitat : damp, shady places (highland area) ❑ Non-vascular plants ❑ No true stems, leaves & root ❑ Have rhizoids (attach to the soil) ❑ Gametophyte generation is dominant ❑ Gametes develop within gametangia. ❑ Male gametangium: antheridium produces antherozoid ❑ Female gametangium: archegonium produces oosphere ❑ Sporophytes are smaller & shorter lived and depend on the gametophytes for the water and nutrients.
1) Water conservation by waxy cuticle ❑ In some bryophytes, epidermis of leaves and other aerial parts is coated with cuticle to prevent excessive loss of water by evaporation ❑ Thus, preventing the bryophytes from being desiccated (drying out) 2) Presence of multicellular gametangium ❑ Gametes are produced within gametangia. ❑ Gametangia has a layer of sterile (nonreproductive) cells that surrounds and protects the gametes. ❑ Diploid zygote develops into embryo within the female gametangium to protect embryo during its development.
3)Multicellular, dependent embryo ❑ Diploid zygote develops into diploid embryo by mitosis within the archegonium ❑ Gametophyte carry out photosynthesis and provide developing embryo with nutrients and water ttps://status.libretexts.org. 4) Walled spores produced in sporangium ❑ Walls of haploid spores contain sporopollenin (exine) ❑ make the walls tough and resistant to harsh environments ❑ enable the wind-carried spores to disperse through air without being desiccated ❑ The outer tissues of sporangium protect spores until they are released into air
a) Describe the unique characteristics of Pteridophytes b) State the classification of Pteridophytes into two divisions / phyla: i. Lycophyta (Lycopodium sp., Selaginella sp.) ii. Pterophyta (Dryopteris sp.)
❑ Seedless vascular plants. ❑ Have true roots, stem (rhizome) & leaves (frond) ❑ True roots with lignified vascular tissue. • xylem : tracheid only • phloem : sieve tube only ❑ Larger size than Bryophytes ❑ Distinct alternation of generation • sporophyte (2n) generation is dominant ❑ Habitat : found in place of low light intensity in the tropical & subtropical regions ❑ Reproductive system : still dependent on water for fertilization ❑ Ferns reproduce sexually by producing spores https://www.biologypages.info/F/Ferns.html
Classification of Pteridophytes ii) Phylum Pterophyta e.g.Dryopteris sp. 2 phyla : i) Phylum Lycophyta e.g. Lycopodium sp. e.g. Sellaginella sp. https://alchetron.com/Lycopodium https://www.wordnik.com/words/Selaginella http://www.sharnoffphotos.com/nature/wild_plants /wild_plantsDF/dryopteris_sp.html 13
a) Describe the unique characteristics of Gymnosperms b) State the classification of Gymnosperms into four (4)divisions (phyla) : i. Phylum Cycadophyta (Cycas sp.) ii. Phylum Pinophyta / Coniferophyta (Pinus sp.) iii. Phylum Ginkgophyta (Ginkgo sp.) iv. Phylum Gnetophyta (Gnetum sp.)
❑ Seed is not enclosed within ovary ❑ Reproductive organ : cone consist of the sporophylls that are spirally arranged. ❑ Sporophyte is dominant ❑ Leaves with a waxy coating : To help conserve water ❑ Ovules contain the female gametophyte ❑ Water is not required during fertilization ❑ Presence of vascular tissue ❖ Xylem : tracheid only ❖ Phloem : sieve tube only *except for Gnetophyta
https://www.ornamentaltrees.co.uk/ginkgo-biloba-tree-p384 https://www.verywellmind.com/ ginkgo-biloba-for-anxiety-89334 https://www.pinterest.com/pin/521010250623999646/
a) Describe the unique characteristics of Angiosperms (Phylum Anthophyta)
❑ Have flowers as reproductive organ ❑ Seed is enclosed within ovary ❑ Have complex vascular tissues ❖ xylem consists of tracheids & vessels ❖ phloem consists of sieve tubes & companion cell ❑ Sporophyte is dominant ❑ Double fertilization occurs producing the nutritive triploid endosperm ❑ Fruits are formed which serves as protection and means of dispersal for the seeds
https://en.wikipedia.org/wiki/Mangifera_indica https://plantstomata.wordpress.com/2016/11/27/stomatal-structures-in-zea-mays-monocots/ 19
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