Bio notes quiz 3 - bio PDF

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The earliest two clades have NO SEEDS 1. Lycophytes 2. Monilophytes (Seedless vascular plants) Lycophytes  The first plants to have evolved true roots and a basic vascular system.  Means water uptake can happen through the plants  Not true leaves (only weakly Vascularised. (Microphyll) Monilophytes  (ferns and fern allies)  Mark the appearance of true LEAVES.  Even though leaves are small, they are well vascularised. Gymnosperms and angiosperms  The benefit of the seed allows for the increased protection of the embryo.  Seed= embryo+ food supply+ protective coat. FEATURES SHARED BY ALL SEED PLANTS: 1. Reduced gametophyte and dominant sporophyte  Begins with sporophyte been dependent on gametophyte for nutrition before it evolved with sporophyte becoming dominant, and more dominant as it evolved again. 2. Heterospory  Most seedless plants are homosporous (homo = same)  ALL seed plants are heterosporous (heteros= different)  HETEROSPORY IN SEED PLANTS o Sporophyte produces 2 types of spores: o Large female spores= megaspores o Small, male spores= microspores  Male sporangia through meiosis produce male spores = microspores  Female sporangia through meiosis produce

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female spores = megaspores 3. Ovules Seed plants retain the megaspore within the sporophyte in an ovule. Female sporangium = megasporangium Female spore = megaspore ---> becomes female gametophyte ---> produces eggs (gametes) 4. Pollen Male spore=microspore ----> becomes a pollen grain (male gametophyte enclosed within pollen wall) In seed plants, a microspore develops into a pollen grain, containing the male gametophyte Pollen grains are the vehicle for carrying sperm to eggs. Pollen grains, coated with sporopollenin, can withstand desiccation for long periods Pollen grains remove the dependence on water to transport the gametes.

THE 4 PHYLA OF SEED PLANTS WITHOUT FLOWERS ARE GYMNOSPERMS Gymnosperms are naked seed plants  Ovule is naked at pollination  Reproductive structures are called cones  Males cones have pollen (bearing sperm)  Female cones have ovules (bearing eggs)when these are fertilised by sperm, they bear seeds. 1. 

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Cycadophytes Probably the most ancient of all extant seed plants Thrived with the dinosaurs in the Mesozoic Look like ferns however can differentiate as ferns do not have seeds. Cycad cones are borne on separate male and female plants- cycads are dioecious

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Ginkgophytes Once widely distributed worldwide. Now only one species Ginkgo biloba The leaves are twolobed Ginkgo's are dioecious but are wind pollinated.

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Coniferophytes These are the largest gymnosperm phylum and the most diverse and widespread  In the Northern hemisphere, conifers dominate entire ecosystems  Largest Vascular plants  Include Oldest vascular plants  Conifers (softwoods) are one of the most widely used commercial timbers worldwide. 4. Gnetophytes  Possibly the closest living relatives of flowering plants  The only gymnosperms to have vessels in their xylem (efficient water transport)  3 extant genera Gymnosperms + angiosperms= seed plants Protective coat + food supply enables DORMANCY  A stage in life cycle where:  Metabolic rates slows down  Growth and development are suspended. 

Three key innovations of angiosperms – Flowers, fruits, vessels That enabled the transport of pollen, seeds and water Flowers – Sepals, petals, stamens, carpels Pollen Vectors – Water, wind = undirected Animal = directed Natural selection –

Natural selection has favoured flower colours and shapes and scents that are successful in attracting pollinators Mutualism – The relationship between flowering plants and their pollinators is mutually beneficial ADAPTIVE RADIATION  A single lineage produces a large number of decendent species that are adapted to a wide range of habitats = great diversity Monocots – Primary 1 cotyledon Parallel venation Vascular tissue scattered Root system usually fibrous Pollen grain with 1 opening Multiples of 3 -

Eudicots – primary and secondary 2 cotyledons Network/branches Vascular tissue usually arranged in rings Taproot Pollen grain with 3 openings Floral organs in multiples of 4-5 The tree types of plant tissue: o Dermal o Ground o Vascular

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Functions: storage, photosynthesis, support, Protection Parenchyma Collenchyma Sclerenchyma o Fibers o Sclereids Vascular Tissue – tracheid and vessels 2 types: 1. Xylem 2. Phloem Xylem – takes water and mineral nutrients up Hollow tubes Tracheid Vessels – Angiosperms have both tracheids and vessels Lignin – Fills spaces in cell walls Provides a matrix for cellulose Hydrophobic Lignin is the defining feature of vascular tissue Phloem – (sugars/hormones) takes sugars and hormones down conducts food through sieve tubes sieve tube = overlapping end to end connected by sieve areas sieve tubes = areas containing large pores Two main parts of a plant: = Are the above ground (Co2 and light and below ground (water and mineral nutrients Roots, shoots and leaves, reflects increasing specialisation to terrestrial life

Dermal Tissue – The epidermis, covers external surfaces of the plant body Protects inner cells from the environment, one cell layer thick, covered by a cuticle. Stoma  guard cells Epidermis covers all external surfaces of the plant Ground Tissue –

APICAL MERISTEMS  Grow from the tips (grow in length).  Shoots grow up  Roots grow down  Cells of apical meristems are delicate.  Could be damaged very easily from exposure to the sun  Apical meristems are protected by leaves.  Root apical meristem could be rubbed of from

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soil been too dry and the growth of soil. It is protected by the root cap. They produce PRIMARY TISSUES. The growth they stimulate forms the primary plant body.

LATERAL MERISTEMS  Grow from the side (Grow in width).  Secondary growth  Cork cambium o Produces bark o Grows and pushes towards the outside.  Vascular cambrium o Produces the vascular tissue of the plant (xylem phloem. o Produces Pholem towards the outside o Produces xylem towards the inside.  The tissues form the bulk of the trunks, branches, and larger roots (secondary tissues)  Forms the secondary plant body. COHESION = The attractive force between molecules of the same substance  Water molecules have a high polarity.  Water molecules are like magnets o They stick to each other  CREATES high surface tension (can resist breaking) ADHESION  They stick to the sides of xylem tissue  Water adheres to the surface of narrow pipes o Stronger then the forces of gravity Cohesion + tension + adhesion allow water to move upwards in an unbroken column. Photosynthesis needs to be occurring at the top of the leaf for this to occur....