Chapter 21,24,27- The Evolution of PLants PDF

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This note covers concepts for chapter 21, 24, and 27 the evolution of plants ...

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Chapter 21, 24, 27 The Evolution of Plants: Ancestral protist give rise to what types of species/organisms? o Plants, animals, and fungi all evolved from an ancestral protist

How did chloroplasts FIRST evolved? Why were they critical to the evolution of plants? o Chloroplasts first evolved from primary endosymbiosis of a cyanobacterium. o Not only were they critical to the evolution of plants, they are also important to all life on land because this structure provided nutrient support. First clades to branch after primary endosymbiosis are all aquatic à ? o Algae

What characteristics do all land plants share? o Produce their own food using sunlight o Contain chloroplast à organelles that carry out photosynthesis o Cell wall that is composed of cellulose Features of Plants: o Plants are sessile o They are generally land based with the exception of sea grasses o Have roots (algae do not) o All plants are multicellular; (some algae are unicellular) o Undergo alternation of generations

Survival on land was facilitated by the evolution among plants of numerous adaptions à o Cuticle: a waxy coating that slows water loss o Stomata: closable openings that regulate gas exchange and water loss o Gametangia: multicellular organs that enclose gametes and prevent them from drying out o Embryos: young plants contained within a protective structure o Spores: with thick walls containing a polymer that prevents drying and resists decay o Mycorrhizae: mutually beneficial associations with fungi that promote nutrient uptake from the soil All plants undergo a reproduction theme known as à o Alternation of generations: plants alternate between haploid and diploid generations.

How does plant reproduction differs from animal reproduction? o In plants: ⇒ Gametes are produced by mitosis ⇒ Gametophytes are haploid (1n) and reproduce sexually ⇒ Sporophytes are diploid (2n) and reproduce asexually o In humans: ⇒ Gametes are produced by meiosis Transition to land required what? o Required evolution of water retention and gravity adaptations

What has changed over the course of plant evolution?

What happened to gametes over the course of evolution? o Gametophyte (1n) has been reduced o Sporophyte (2n) has become MORE prominent What plants fall under Bryophytes (nonvascular land plants)? o Liverworts o Mosses o Hornworts Features of Bryophytes: o Earliest plants à nonvascular o 475-450 mya o Lack roots and tissue for transporting water and nutrients o Seedless o Grow only in moist environments o Stay close to the ground because… ⇒ Unable to transport water high up due to gravity o Next evolutionary step: transport water against gravity What plants fall under Monilophytes (Seedless vascular plants)? o Ferns o Horsetails Features of Monilophytes? o First vascular plant à specialized tissues for transport o Vascular tissue keeps stem rigid o Seedless o Next evolutionary step: a vascular system to transport fluids against gravity

Vascular systems is the next evolutionary step à o Water is transported up against gravity by the vascular system of a plant ⇒ Can grow tall o Still close to water because its seedless characteristic o Ferns are plants descended from the the first vascular plants A vascular system consists of ____ and _____, arranged in _______? o Xylem on the INSIDE o Phloem on the OUTSIDE ⇒ As xylem moves up, phloem moves down ⇒ As xylem moves nutrients in, phloem moves out A mechanism that in which water from roots is transported UP the xylem to the leaves (site of photosynthesis)? o Transpiration How does water move from roots to leaves? o Uses concentration gradient to move water against gravity

This nutrient is produced by photosynthesis in leaves then transported in plant via a structure known as? o Sugar is produced in leaves and transported via phloem.

Following vascular systems, the next evolutionary advance is what? o Evolution of seeds ⇒ Replaced seedless vascular plants as most dominant plants on earth What plants fall under gymnosperms? o Cycads o Ginkgos o Gnetophytes o Conifers Features of gymnosperms? o Seed bearing plants à “naked” seeds o Typically held in cones What is one benefit of development of seeds? o Free plants from requiring very moist areas…. increasing diversity Features of Gymnosperm: o Female cones have eggs o Male cones contain pollen (sperm) ⇒ Pollen carried by wind, then fertilize the egg and become embryo What is the major function of embryo in gymnosperm? o Embryo encased in seed ⇒ Embryo contains nutrients and tough outer protective coating

Major evolutionary innovations happen in which type of plants? o Angiosperms Features of Angiosperms: o about 150 mya o first flowering plants “vessel seed” à ex: roses, cacti o replaced gymnosperms as most dominant plants on earth o Seed bearing plants o Seeds in fruit o Flowering à major evolutionary innovations (synapomorphies) Following evolution of seeds, the next evolutionary advance is what? o Flowers and fruits

Animals are involved in angiosperms, why? o Flowers recruit animals to help spread pollen ⇒ This is why flowers have bright colors, enticing scents to attract animals o Such structures used to attract pollinators are …. ⇒ petals and sepals Groups of flowers are referred to as? o Inflorescences ⇒ All parts of flowers derived from modified leaves Which factor increases the reproductive success of angiosperms? o Flowers and fruits This type of flowers has BOTH megasporangia and microsporangia: o Perfect flowers This type of flowers has BOTH flower types à male and female: o Imperfect flowers Species such as corn or birch, both female and male flowers occur on the same plant, this is? o Monoecious Male and female flowers are produced on different plants (never both)? o Dioecious

How does double fertilization occur in angiosperms? o Each pollen grain contains two male gametes: ⇒ one combines with egg to form diploid zygote ⇒ other one comines with two haploid nuclei of the female gametophyte to form a triploid cell o Triploid cell gives rise to the endosperm, which nourishes the embryonic sporophyte during its early development. Besides double fertilization, this type of reproduction is MORE TARGETED? o Animal aided pollination

What relationship do plants and animals have during the process of pollination? o Symbiotic relationship ⇒ Animal distributes pollen for plant ⇒ Plant in return provides food source (nectar) The seed components of angiosperm: Cereal grains (wheat): ⇒ Endosperm, embryo, and seed coat Refined foods: ⇒ Lack embryo and seed coat

Where do fruits develop from, what is the function of fruit? o They are developed from ovaries AFTER fertilization o Functions à protect seeds, aid in dispersal Where would you find vegetables at? o Everything else, leaves, roots, etc.

What is one additional mechanism for seed dispersal? o Via fruit ⇒ Fruit if consumed by animals § They digest the fruit flesh § Excrete the seeds What happens when angiosperms lose their leaves in cold climates in winter (deciduous plants)? o Enter a dormant state o Lose leaves will provide potential source for water loss, leaves will die from cold Prior to losing their leaves, what do angiosperms do to prep for this event? o Recycle proteins before leaves fall off o Chlorophyll breaks down ⇒ Revealing anthocyanins, and carteniods Evolutionary relationships among the Angiosperms:

The two largest angiosperm clades include: Monocots: one cotyledon Includes grasses, cattails, lilies, orchids, and palms

Eudicots: two cotyledons Include the vast majority of familiar seed plants

Without the presence of a CNS, how do plants sense and respond to the environment: o Gravitropism o Phototropism ⇒ this mechanism is done by via a hormone named IAA, which enables plants to grow in desired direction o Thigmotropism ! ! ! ! ! ! ! ! ! ! ! ! ! ! The trunks of this group of organisms are connected by the same root system and are ALL genetically identical: o Clonal organisms

FUN fact …...