Plant and Cell Architecture Flashcards
Model organisms
Plants with short generation times and small genomes
Genomes
The sum of their genetic information
Major unifying principles of plants
- ultimate solar collectors-convert light energy to chemical energy
- sessile; evolved to grow towards essential resources (light, water, and mineral nutrients)
- structurally reinforced to support mass toward sunlight against the pull of gravity
- mechanisms to move water and minerals from soil to sites of photosynthesis and growth
- lose water continuously but have evolved mechanisms for avoiding desiccation
- develop embryos that derive nutrients from the mother plant
Plants (embryophytes)
Share the evolutionarily derived traits for surviving on land that are absent in algae
Nonvascular plants (bryophytes)
Mosses, hornworts, and liverworts
Vascular plants (tracheophytes)
Consist of non-seed plants (ferns and their relatives) and seed plants (gymnosperms and angiosperms)
Gymnosperms
- Seed plants “naked seed”
- include conifers, cycads, ginkgo, and gnetophytes
- 800 species known
Conifers
- Largest group of gymnosperms which include such commercially important forest trees as pine, fir, spruce, and redwood
- “cone bearers”
Angiosperms
- “vessel seed”
- evolved about 145 million years ago
- include 3 major groups: monocots, eudicots, and basal angiosperms
Flowering plants
- angiosperms
- major anatomical innovation is the flower
Alternation of generations
Plants alternate between two distinct multicellular generations to complete their life cycle
-one generation is diploid (two copies of each chromosome 2N) and the other is haploid (one copy of each chromosome 1N)
Gametes
Egg and sperm
Meiosis
Cell division resulting in a reduction of the number of chromosomes from 2N to 1N
Spores
The products of meiosis in diploid plants
Sporophytes
Diploid plant forms are called this
Gametophyte
A new haploid multicellular individual
Pollen
Bees carry around the male gametophyte which is a multicellular structure that produces sperm cells
Two separate generations in the plant life cycle
The diploid, spore-producing sporophyte generation and the haploid, gamete-producing gametophyte generation
Megaspores
Develop into the female gametophyte
Microspores
Develop into the male gametophyte
Monoecious
- “one house”
- has flowers that produce both male and female gametophytes
Dioecious
- “two houses”
- male and female flowers occur on separate individuals
Megastrobili
Female cones
Microstrobili
Male cones
Double fertilization
Two sperm produced, only one of which fertilizes the egg
The other sperm fuses with two nuclei in the female gametophyte to produce the 3N endosperm, the storage tissue for the angiosperm seed
Ferns and mosses
Sporophyte generation gives rise to spores that grow into adult gamteophytes that differentiate into male and female structures, the male antheridium and the female, archegonium
Prothallus
- in ferns, the gametophyte is this small monoecious
- has antheridia and archegonia that divide mitotically to produce motile sperm and egg cells
Stem
Grows upward and supports the above ground part of the plant
Root
Anchors the plant and absorbs nutrients and water, grows down below the ground
Leaves
Primary function is photosynthesis
Nodes
Leaves grow out laterally from the stem
Shoots
Leaves and stems together
Internode
The region between two nodes
Primary plant axis
The main stem and taproot
Plasma membrane (also called plasmalemma)
Outer fluid boundary of the living cytoplasm of plant cells
Cytoplasm
All of the organelles and cytoskeleton suspended within the cytosol
Cytosol
The water-soluble and colloidal phase residing within the plasma membrane
Nucleoplasm
The internal compartment of the membrane-bounded nucleus in eukaryotes
Cell wall
Plants cells further enclosed by this rigid, cellulosic wall
Middle lamella
Prevents cell migrations and has each cell wall cemented to its neighbors
Primary cell walls
Typically thin (less than 1 micrometer) and characteristic of young, growing cells
Secondary cell walls
Thicker and stronger than primary walls and are deposited on the inner surface of the primary wall after most cell enlargement has ended
Lignin
Secondary cell walls owe their strength to this
A brittle, gluelike material