Botany SAT II Review

Things to know that we’ve already covered… Plant cell structure (Chapter 4) Photosynthesis (Chapter 7) Angiosperm reproduction and double fertilization ( )

2 major divisions of land plants I. Non vascular plants II. Vascular plants

I. Non vascular plants (bryophytes) No vascular tissue Small, inhabiting shady, moist areas Include mosses, liverworts, hornworts

II. Vascular Plants Have vascular tissue - tubelike, elongated cells through which water (xylem) and sugars (phloem) are transported. Has true roots, stems and leaves. Grow in a variety of environments-why?

2 major divisions of VASCULAR plants I. Seedless plants II. Seed plants

I. Seedless plants Must have a moist environment in which to grow. Includes Club Mosses- Lycophyta Horsetails/Sphenophyta, Ferns/Pterophyta All reproduce by forming spores. Let’s move on to the other division of vascular plants…

Reproduce by seeds. A seed is an embryo with a food supply (endosperm) enclosed in a tough, protective coat. II. Seed plants

2 major divisions of VASCULAR SEED plants I. Gymnosperms II. Angiosperms

I. Gymnosperms Most are conifers (cone-bearing trees) Seeds are formed in cones Plants contain some “female” cones that make spores and some “male” cones that make pollen

Anthophyta = Flowering Plants Seeds are protected within flowers and develop inside fruit. This is the most successful group of plants. Why? II. Angiosperms

2 major divisions of VASCULAR PROTECTED SEED/FLOWERING plants. I. Monocots II. Dicots

Angiosperms: Divided into two classes, based on the number of seed leaves (cotyledons) within the seed. Monocots: (non-wood) grasses, lilies, palms Dicots: Shrubs, trees, herbs and flowers.

Dicot and monocot stems 14

Summary AngiospermsGymnosperms

Chapter 31 Plant structure, reproduction, and development

Body plant – roots, stems, and leaves 17

General Tissue types Dermal tissue – outer protective covering Vascular tissue – xylem and phloem Ground tissue – between epidermis and vascular 18

Vascular tissue Xylem – Conducts water and minerals upward in the plant – Dead at maturity – do not consume water Phloem – Carries sugars that have been produced in the leaves and/or stems. – Barely alive – require ATP from companion cells to assist in transport

Transporting water up the xylem (Chapter 32) Root pressure Capillary action Transpiration-cohesion theory – Water evaporates from the leaf surface – Water molecules are connected to each other by hydrogen bonds – Water is pulled up the xylem from the root 20

Transporting sugar through the phloem (Chapter 32) Sucrose is pumped into phloem cells at the source Water enters from the adjacent xylem cells via osmosis The sugar solution is forced down the phloem cells under pressure. 21

Leaf structure Mesophyll is between epidermis layers – Palisade layer is more ordered to maximize photosynthesis – Spongy layer is more diffuse, leaving space for gas movement 22

Stomata Pores in the leaf surface Regulated by guard cells 23

Growth Primary growth – Apical meristem on root and shoot extend the vertical length of the plant

Growth Secondary growth – Lateral meristems increase the girth of woody plants – Vascular cambium One cell thick, between primary xylem and phloem Produces new secondary xylem (inside) and phloem (outside) each year Growth is not continuous throughout the year, creating rings

Growth Secondary growth – Cork cambium Forms cork (bark), which replaces the epidermis (from original shoot) Forms protective covering for root and shoot

Reproduction - Alternation of generations 27

Alternation of generations Sporophyte – Main body of the angiosperm plant Immature male gametophyte = pollen grain Mature male gametophyte = pollen tube Female gametophyte = egg sac – Enclosed in the ovule – the ovule is a section of the ovary 28

Double fertilization The pollen tube enters the ovule One nucleus fertilizes the center two nuclei Results in triploid (3n) endosperm nucleus 29

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Asexual reproduction – Vegetative propagation Tubers (like potatoes) – underground storage equipped with buds on the surface Runners (like strawberries) – horizontal stems that can give rise to new roots and shoots Bulbs – underground buds (contains several buds that can be new plants) Grafting – two young plants are joined

Chapter 33 Plant hormones and behaviors 32

One group of hormones stimulates growth and development Auxin – origin: apical meristem of the shoots – Stimulates cell elongation in stems – Retards cell elongation in roots. Gibberellins – origin: buds and leaves – Breaks dormancy in buds by stimulating mitosis – Stimulates mitosis in developing leaves Cytokinins – origin: roots – Works with auxins to stimulate cell division – Delay aging (used on freshly cut flowers) 33

The other group stimulates aging and death or dormancy Abscisic acid (inhibitors) – Retards growth – Causes dormancy in seeds Ethylene – Causes fruit ripening – May work along with auxin to retard elongation of root cells – Causes leaf falling 34

Phototropism Plants bend toward light – auxin migrates to the dark side, elongating those cells 35

Gravitropism Response to gravity – roots grow downwards, shoots grow upwards 36

Thigmotropism Response to touch – caused by changes in water pressure – Coiling around a support – Tree trunks grow thicker in response to winds

Photoperiodism – flowering regulated by light Short day plants (long night plants) – Flower in early spring or autumn (when nights are longer) Long day plants – Flower in summer (when nights are shorter) Day neutral plants – Flowering begins when the plant has a certain number of branches and flowers until frost 38