1. Unit 7 Chapters 22-25 Biology
Plants
Unit 7 Chapters 22-25
Biology

2. Origin of Plants Evolved from organisms similar to green algae
First evidence in the fossil record was around 500 million years ago
Did not have any leaves
Psilophytes – earliest known plant fossil

3. Plant Characteristics
A multicellular eukaryote
Produce its own food (glucose) by way of photosynthesis
Use chlorophyll (green pigment)
Thick cell walls made of cellulose
Cuticle – waxy waterproof coating on the stems and leaves

4. Needed for survival Sunlight Water and Minerals Gas exchange
Used in photosynthesis to produce food
Water and Minerals
Gas exchange
Require oxygen for cellular respiration and carbon dioxide for photosynthesis
Movement of water and nutrients
Use specialized tissues (vascular tissue)

5. Plant Life Cycle Alternation of generation
Two alternating phases, a diploid phase and a haploid phase
Sporophyte
Diploid phase that reproduces by asexual spores
Gametophyte
Haploid phase that reproduces sexually by producing gametes that fuse together by fertilization

7. Classification of Plants
4 groups that are based on:
Water-conducting tissues
Seeds
Flowers
Bryophyte (Nonvascular)
Ferns and allies (Seedless vascular )
Gymnosperm (Seed vascular)
Angiosperm (Seed vascular flowering plant)

8. Bryophytes Nonvascular Plants
Life cycle depends on water for reproduction
Draws up water by osmosis
Include: mosses, liverworts, and hornworts

9. Bryophyte Types Mosses Liverworts Most common bryophyte
Rhizoids – long, thin cells that anchor them in the ground and absorb water and minerals from the soil
Liverworts
Gemmae – small multicellular reproductive structures used in asexual reproduction

10. Bryophyte Life Cycle Gametophytes Sporophyte
Dominant recognizable stage
Carries out most of the plant’s photosynthesis
Antheridia – produce the sperm (male)
Archegonia – produce the egg (female)
Sporophyte
Depends on the gametophyte for water and nutrients

11. Vascular Plants
Contain specialized tissue that conducts water and nutrients throughout the plant (vascular tissue)
Tracheids – tubular cells that are specialized to conduct water; dead at maturity
Xylem – transport subsystem that carries water upward from the roots
Phloem – transports solutions of nutrients and carbohydrates produced in photosynthesis
Sieve tube element – main phloem cells that are surrounded by companion cells

12. Vascular Plants
Roots – underground organs that absorb water and minerals
Stems – supporting structures that connect roots and leaves; carry water and nutrients between them
Leaves – photosynthetic organs that contain one or more bundles of vascular tissue (veins)

13. Ferns and Allies: Seedless Vascular Plants
Include club mosses, horsetails, and ferns
Ferns
Rhizomes – creeping or underground stems
Fronds – large leaves of ferns.
Life cycle of ferns
Diploid sporophyte is the dominant stage
Sporangia – tiny containers of haploid spores
Sori – group or cluster of sporangia

15. Seed Plants Divided into 2 groups Gymnosperms
Bear their seeds directly on the surfaces of cones
Include: conifers, cycads and ginkgoes
Angiosperms (Flowering plants)
Bear their seeds within a layer of tissue that protects the seed
Include: grasses, flowering trees and shrubs, and all wildflowers and cultivated flowers

16. Adaptations of Seed Plants
Reproduce free from water by the use of:
Flowers and cones
Cones are the seed bearing structure of gymnosperms
Flowers are the seed bearing structures of angiosperms
Transfer of sperm by pollination
Pollen grain – tiny structure that contains the entire male gametophyte
Pollination – transfer of pollen to the female structure; can be transferred by wind, insects or small animals

17. Adaptations of Seed Plants
Protection of embryos in seeds
Seed – an embryo of a plant that is encased in a protective covering (seed coat) and food supply (cotyledons); may have structures that aid in its dispersal
Embryo – an organism in its early stage of development

18. Angiosperms – Flowering Plants
Flowers
Reproductive organ; contains ovaries that surround and protect the seed
Fruit
Wall of tissue surrounding the seed
Used to attract animals to disperse their seeds

19. Parts of a Flower Sepals and Petals Stamens Pistil (carpels)
Outermost floral parts that protect the developing bud
Petals – brightly colored to attract vectors
Stamens
Male reproductive part
Consists of a thin stalk (filament) and an oval sac that consist of pollen grains at the top (anther)
Pistil (carpels)
Female reproductive part
Consist of a broad base (ovary) that contain one or more ovules, the stalk that comes from the ovary (style), and a sticky portion at the top (stigma) where pollen grains land

21. Diversity of Angiosperms
2 types: named for the number of cotyledons in the plants embryo
Monocots (monocotyledon)
Corn, wheat, lilies, orchids, and palms
Dicots (dicotyledon)
Roses, clover, tomatoes, oaks, and daisies

22. Comparison of Monocots and Dicots
Single cotyledon
Parallel veins
Flower parts are multiples of 3
Vascular bundles are scattered
Fibrous roots
Dicots
Two cotyledon
Branched veins
Flower parts are multiples of 4 or 5
Vascular bundles are arranged in rings
Taproot

24. Diversity of Angiosperms
Life spans are divided into 3 categories:
Annuals
Flowering plant that complete a life cycle within one growing season
Marigolds, petunias, and pansies
Biennials
Complete their life cycle in two years
Primrose, parsley, and celery
Perennials
Flowering plants that live for more than two years
Asparagus, many grasses, palm trees, maple trees, and honeysuckle

25. Seed Plant Structure 3 principal organs: Roots Stems Leaves
absorb water and dissolved nutrients
anchor plants in the ground
Protect the plants against bacteria and fungi
Hold plant upright against wind and rain
Stems
Transports nutrients between the leaves and the roots
Leaves
Photosynthetic systems of the plant

26. Seed Plant Structure 3 plant tissue systems: Dermal tissue
Outer covering of a plant
Consist of a single layer of epidermal cells
Vascular tissue
transport system
composed of xylem and phloem
Ground tissue
Cells that lie between the dermal and vascular tissues
Functions in storage, adds flexibility and strengthens the plant
Ground tissue consist of mainly parenchyma which contains chloroplast in the leaves; Collenchyma – help support and give flexibility; Sclerenchyma – extremely thick and rigid cell that helps strengthen the plant

27. Plant Growth Most plants have an open or indeterminate type of growth
i.e. they grow as long as they live
Meristems – clusters of tissue that are responsible for growth throughout the plants life
Meristematic tissue – undifferentiated cell that are produced by the meristems
Apical meristem – increase the length of stems and roots

28. Roots
Function: anchor the plant and absorb water and dissolved nutrients from the soil
2 main types of roots:
Taproot
Found mainly in dicots
Primary root is long and thick
Secondary roots remain small
Example: oak and hickory trees
Fibrous root
No single root grows larger than the rest
Help prevent erosion
Example: grasses

29. Roots Root structure and growth
Root hairs – tiny cellular projections that increase the surface area through which water can be absorbed
Cortex – spongy layer of ground tissue underneath the epidermis
Root cap – protects the root as it forces its way through the soil

31. Stems 3 important functions: Nodes – point of leaf attachment
Produce leaves, branches, and flowers
Hold leaves up to the sunlight
Transport substances between roots and leaves
Nodes – point of leaf attachment
Internodes – regions between nodes
Buds – contain undeveloped tissue that can produce new stems and leaves

33. Stems
Monocot and Dicot Stems

34. Stems
Growth of stems:
Primary growth – growth in which the plant increase in height; occurs at the apical meristems; takes place in all seed plants
Secondary growth – growth in which the stem increases in width; occurs in the lateral meristem
Vascular cambium – produces vascular tissue
Cork cambium – produces the outer covering of stems (bark)

35. Leaves
Structure is optimal for absorbing light and carrying out photosynthesis
Blade – thin, flattened sections of the leaf that is attached to the stem by a thin stalk (petiole)
Functions:
Photosynthesis, transpiration, and gas exchange

36. Leaves Transpiration – the loss of water through the leaves
Gas exchange occurs in the
Stomata – porelike opening in the underside of the leaf
Each stoma consist of two guard cells that control the opening and closing of the stomata

38. Transport in Plants Capillary action
The tendency of water to rise in a thin tube
Adhesion – is the attraction between unlike molecules; property that causes capillary action

39. Plant Hormones Auxins – stimulate cell elongation
Cytokinins – stimulate cell division (growth)
Gibberellins – produce dramatic increases in size in the stems and fruit
Ethylene – stimulates fruits to ripen

40. Plant Responses Tropisms – plant responses to external stimuli
Gravitropism – plant responses to the forces of gravity
Phototropism – tendency of a plant to grow toward light
Thigmotropism – response of plants to touch

41. Plant Adapted for Specific Habitats
Xerophytes – plants that live in the desert biome
Epiphytes – plants that are not rooted in soil but grow directly on other plants