Plants. and their classi.ication

Transcription

1 + Plants and their classi.ication

2 +Why are plants important? n Photosynthesis Carbon dioxide + water + energy à sugar + oxygen 6CO 2 + 6H 2 O à C 6 H 12 O 6 + 6O 2 n Food (green tea, fruits, seeds, roots, vegetables) n Biofuel n Pharmaceuticals

3 +Distinguishing characteristics n Multicellular eukaryotes? n Photoautotrophs? n Cell wall composed of cellulose? n Chlorophyll for photosynthesis? n BUT other organisms have these features too e.g. red seaweed, euglenoids, dino.lagellates

4 +Furthermore... n Charophyceans (algal group closely related to plants) and plants have: A. Rosette cellulose- synthesizing complexes on plasma membranes n This suggests that the cellulose cell wall is a distinct evolution from protists B. Enzymes in peroxisomes C. Sperm cell similarity D. Similarity in cell division

5 +However, n Plants develop from embryos protected by tissues of the parent plant n Life cycle of plants is alternation of generations n Some plants have vascular tissue. n Vascular tissue channels within plant for transport n Xylem transports water and dissolved minerals upward from root to shoot n Phloem transports sugars from leaves to other parts of plant where photosynthesis doesn t occur

6 +Terrestrial Plants * n Apical meristems n Multicellular- dependent embryos within tissues of the female parent n Alternation of generations n Walled spores produced in sporangia n Multicellular gametangia n Adaptations for water conservation, water transport n Secondary metabolic pathways producing lipids, carbohydrates etc

7 +Bringing it back to Grade 11

8 +Alternation of Generations Terms: Diploid (2n) 2 sets of chromosomes Haploid (1n) 1 set of chromosomes Sporophyte diploid plant that produces haploid spores Gametophyte haploid plant that produces haploid gametes 1 st generation is a haploid plant and the 2 nd generation that follows is a diploid plant How is this different from humans?

9 +Vascularization Xylem cells are hollow and therefore dead cells at maturity

10 +Evolution of plants

11 +Bryophytes MOSSES LIVERWORTS HORNWORTS

12 +Bryophytes n Non- vascular plants n Lack true roots, stems, and leaves n Include mosses, liverworts, and hornworts n Gametophyte is the dominant generation in their life cycles n Generally live in aquatic environment so sperm can swim to female organ for fertilization n Uses: n dried peat from bogs as fuel n peat moss as soil additive

13 +Life Cycle of Moss

14 +Evolution of Vascular Plants n Tracheophytes: plants with vascular tissue (xylem and phloem) to transport nutrients n First appeared on Earth 360 million years ago What is the significance of the development of vascular tissue?

15 +Pteridophytes: Seedless Vascular Plants LYCOPHYTA club mosses PTEROPHYTA - horsetails

16 +Pteridophytes n n n n n Phylum Lycophyta and phylum Pterophyta (ferns, whisk ferns, and horsetails) Different evolutionary origin from each other Sporophyte dominant life cycle Lycophytes only the small ones have survived over time many are tropical and grow on trees as epiphytes epiphytes use other organisms to grow on but are not parasites Pterophyta sphenophytes (horsetails) have brushy appearance found in marshy places alongside streams and sandy road- sides

17 +Ferns vascular, non- seed n species n Most diverse in tropics but found elsewhere too

18 +Life Cycle of Ferns

19 +Seed- Producing Vascular Plants n What is the evolutionary signi.icance of seeds? Encasing for plant embryo that provides nutrients and allows dispersal without drying out n Two main types: a. gymnosperms b. angiosperms

20 +Gymnosperm n Naked seeds n Lack enclosed chambers (ovaries) n Develop instead on the surfaces of specialized leaves called sporophylls n Four phyla: ginko, cycads, gnetophytes, conifers

21 +Ginkgophyta n Ginko biloba is the only surviving species! n Thought to improve memory

22 +Cycads n Not palms but look like them

23 +Gnetophyta n Have vessel elements (which transport water within the plant) as found in.lowering plants

24 +Conifers Did you know? Sequoia tree in California weighs about metric tons equivalent to 14 blue whales or people!

25 +Life Cycle of a Pine

26 +Angiosperms n Seed producing, vascular AND.lowering! n What is the evolutionary advantage to.lowers? Attract animals and spread seeds farther n Divided into two types: monocot and dicot

27 +Angiosperms

28 + Life Cycle of An Angiosperm

29 +Structure of a Flower Stamen male reproductive structure Anther contains pollen Filament Pistil female reproductive structure Ovary contains ovules which can develop into seed Stigma sticky tip Style

30 +How Angiosperms Reproduce Step 1 Pollination Pollen lands on stigma Self- pollination vs. cross pollination Step 2 Fertilization Meeting of pollen and ovule (male and female gametes) via pollen tube to form zygote Step 3 Seed dispersal Zygote develops into seed Surrounding ovary forms into fruit. Seed dispersal to reduce competition during growth

31 +How Angiosperms Reproduce

32 +Homework n Read section 3.1 n Questions pg.64 #1-7,9,12