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Ch. 28- Vascular Plants: Tissues and Growth & Ch. 30- Plant…

- - - - The stem's primary function is to elongate and orient the shoot in order to maximize photosynthesis by the leaves
      - The stem also functions to elevate reproductive structures for wider range of dispersal
      - Stem Structures:
        
        Nodes: the points at which leaves are attached
        
        Internodes: the stem segments between nodes
        
        Apical bud: the bud at the tip of a plant stem, also called a terminal bud that grows upwards or downwards
        
        Axillary bud: structure that has the potential to form a lateral shoot, or branch; grows laterally
  - - - Stems are responsible for photosynthesis, gas exchange, heat dissipation, and for defense against pathogens and herbivores
      - Leaf Structures:
        
        Leaves have a blade and a stalk, called the petiole, that joins the leaf to the stem at a node
        
        Veins that transport the supplies for photosynthesis to the leaf and the products of photosynthesis away to the rest of the plant
      - Leaf Tissues:
        
        Mesophyll: contains cells specialized for photosynthesis
        
        Stomata: allows for gas exchange between environmental air and photosynthetic cells in leaf
        
        Guard cells: regulate opening and closing of stomata
        
        Vascular tissue (xylem and phloem): transports nutrients and photosynthetic products
  - - - There are 2 types of root systems:
        
        Taproot System
        
        Has one main vertical root, called the taproot, that penetrates soil deeply and helps prevent plant from toppling over
        
        Have lateral roots branching off from taproot that are responsible for absorption
        
        The taproot allows for the plant to grow tall
        
        Fibrous Root System
        
        Has a mat of thin roots spreading out below the soil surface
        
        Has many small roots that spread out from the stem
      - Root Terms:
        
        Adventitious: describes a plant organ that grows in an unusual location
        
        Root hairs: thin finger-like extensions of root epidermal cells
- - - - 2 Types of Tissues:
        
        Xylem which transports water and dissolved minerals up from roots into shoots
        
        Phloem which transports sugars to roots and sites of growth
      - Vascular tissue of a root or stem is known as stele
        
        In roots a vascular cylinder is present which is a solid central bundle of vascular tissue
        
        In stems and leaves vascular bundles are present which separate strands of xylem and phloem
  - - - Structures:
        
        Pith: ground tissue that is internal to vascular tissue
        
        Cortex: ground tissue that is external to the vascular tissue
- - - - Apical Meristem
        
        Located at the tip of roots and shoots and axillary buds of shoots
        
        Enables growth in length (aka primary growth, which produces almost all the plant body in nonwoody plants)
      - Axillary Meristem
        
        The structure that has the potential to form a lateral shoot, or branch; grows laterally
    - - Non-woody plants: plants that have an epidermis and cuticle
      - Woody plants: plants that have a periderm in older regions of stems and roots which provides more protection
      - Apical Dominance: Phenomenon in which an active apical bud inhibits growth from nearby axillary buds through plant hormones
- - - - Abiotic pollination : wind
      - Biotic pollination: insects, bats, and birds
        
        Examples of pollinators include: bees, moths, blowflies, hummingbirds, and long-nosed bats
      - Self-fertilizing: ensures every ovule will develop into a seed
        
        Can be bad because it does not increase genetic diversity
        
        To prevent self-fertilization plants can:
        
        Some species lack either carpels or stamens in flower
        
        Some plants have stamens and carpels that mature at different times or are structurally arranged to discourage self-fertilization
        
        Self-incompatibility: ability of plant to reject its own pollen and pollen of closely related individuals
- - - - Lateral Meristem
        
        Enables growth in thickness
        
        One part is the vascular cambium which adds layers of vascular tissue (secondary xylem and phloem)
        
        The other part is the cork cambium which replaces epidermis with thicker, tougher periderm
      - Xylem which transports water and dissolved minerals up from roots into shoots
      - Phloem which transports sugars to roots and sites of growth
      - Periderm which is the corky outer layer of a plant stem formed in secondary thickening or as a response to injury or infection
- - - - Ovule = integument + tissues it encloses
  - - - The female gametophyte development begins when I cell in the megasporangium, called the megasporocyte, enlarges and undergoes meiosis to produce 4 haploid megaspores. Only 1 of the 4 megaspores survives, the other 3 degenerate. After this, the nucleus of the megasporocyte divides 3 times without cytokinesis creating 1 cell that has 8 haploid nuclei. The cell is divided by membranes creating an embryo sac consisting of 4 parts: antipodal cells, 2 polar nuclei, synergids, and a haploid egg (n).
        
        For male gametophyte formation, the microsporocytes that undergo meiosis each produce 4 haploid microspores. The microspores then undergo mitosis producing pollen grains that are haploid. The pollen grains consist of a generative cell and a tube cell. The generative cell divides to form 2 sperm, which pass into the tube cell during gametophyte maturation.
        
        When male gametocyte matures, generative cell passes into tube cell. The microsporangium then breaks open allowing the pollen to be released, meaning the pollen grain can be transferred to the stigma completing the process of pollination. Once this happens, the tube cell quickly produces the pollen tube while the generative cell divides producing 2 sperm cells. The pollen tube grows through style and into the ovary triggering the death of 1 synergid. This provides entry for the sperm into the ovary.
        
        Double fertilization occurs. (See process in separate bullet point.)
        
        After double fertilization occurs, the zygote develops into an embryo which is packaged with food into a seed creating the endosperm. The seed may be enclosed in fruit made from the ovary.
    - - Defined as the union of two sperm cells with different nuclei of female gametophyte
        
        During this process, 1 sperm fertilizes the egg to become an embryo, while the other sperm fertilizes 2 polar nuclei to become the endosperm. This ensure that the endosperm develops only in ovules where the egg has been fertilized preventing the wasting of nutrient on infertile ovules.
        
        The steps of double fertilization are as follows:
        
        After the pollen lands on the stigma it germinates and the generative cell begins forming the pollen tube. The tube cell lengthens the pollen tube, which forms around the ovary. The generative cell then splits to form 2 sperm cells. The pollen tube penetrates the ovule through the micropyle and the tube cell disintegrates. The sperm cells then enter the ovule allowing for fertilization of the egg and endosperm.
- - - - 2 Forms in Angiosperms:
        
        Fragmentation: detached fragment of plant that can develop into a new plant
        
        Apomixis: plants can sometimes produce seeds without pollination or fertilization