Question | Answer |
Many of the adaptations that appear to have emerged after land plants diverged from their algal relatives facilitated ___ and ___ on dry land. | - survival
- reproduction |
Plants have a hierarchical organization consisting of ___, ___, and ___. | - organs
- tissues
- cells |
Different ___ generate new cells for primary and secondary growth. | meristems |
The presence of land plants has enabled other life-forms – including animals – to survive on land. What does that mean? What do animals get from plants? | - photosynthetic organisms like plants produce oxygen and food (like carb.s)
- animals benefit from both products
- the roots of plants also create habitats by stabilizing soil |
What are the four key traits of land plants? | - alternation of generations and multicellular, dependent embryos
- walled spores produced in sporangia
- multicellular gametangia
- apical meristems |
The life cycles of all land plants alternate between two generations of multicellular organisms: ___ and ___. Each generation gives rise to the other. | - gametophytes
- sporophytes |
alternation of generations | - a life cycle in which there is both a multicellular diploid form (sporophyte) and a multicellular haploid form (gametophyte)
- characteristic of plants and some algae |
What exactly is a sporophyte and what does it produce? | - [in organisms (plants and some algae) that have alternation of generations,] the multicellular diploid form that results from the union of gametes (and development of the zygote)
- produces haploid spore by meiosis |
What exactly is a gametophyte and what does it produce? | - [in organisms (plants and some algae) that have alternation of generations,] the multicellular haploid form that develops from a spore via mitosis
- produces haploid gametes by mitosis |
Where is meiosis occurring during the alternation of generations? | in sporophytes during the production of spores |
What process is giving rise to gametes during the alternation of generations? | mitosis in the gametophyte |
What process is giving rise to the zygote during the alternation of generations? | union of two different haploid gametes; fertilization |
Where is the embryo developing during the alternation of generations? | multicellular plant embryos develop from zygotes that are retained within the tissues of the "female" parent (a gametophyte) |
What is a sporangium? Where are sporangia found? | - a multicellular organism in which meiosis occurs and haploid cells develop
- part of the sporophytes where spores are made
- (like gonads are parts of us where gametes are made) |
By what process do sporangia produce spores? What does the spore wall do? | - spores are produced via meiosis
- the spore wall is tough and resistant to harsh environments (allows 'em to be dispersed through dry air w/o harm)
- the cell membrane by itself is not enough to hold in water and protect spores outside of sporangia |
archegonium | - arche = origin
- the "female" gametangium (multicellular plant structure)
- a moist chamber in which gametes develop
- like ovaries in humans |
antheridium | - the "male" gametangium (multicellular plant structure)
- a moist chamber in which gametes develop
- like testes in humans |
By what process are eggs and sperm produced? Where does fertilization take place? | - mitosis
- sperm is released into the environment, travels to archegonium to fertilize the eggs |
Where does the embryo develop? | within an archegonium |
In liverworts, female and male gametophytes are separated. How do sperm get to eggs? | - sperm are released from antheridia
- when it rains, drops hit the male gametophytes
- sperm get in the water and are splashed onto female gametophytes
- they can then swim to the archegonia and eggs |
How does a plant get its food? Where does that happen? | - photosynthesis
- mostly in leaves, can be in stems too |
How does a plant get its water and mineral nutrients? Where does that happen? | - from the soil
- in the root system |
apical meristem | - apex = tip
- embryonic plant tissue in the TIPS of roots and buds of shoots
- the dividing cells of an apical meristem enable the plant to grow in length |
What is growth like in plants compared to animals? | - plants (mostly...): indeterminate growth, cells enlarge, happens at apical meristems, cells differentiate
- animals (mostly): determinate growth, cell number increases, happens in most tissues, cells lose ability to differentiate |
How are growing tips protected? | - the root apical meristem is protected from the time it emerges by the root cap; sloughed off
- “stemlike” tissue bends as a seedling emerges to minimize the force on the shoot tip
- sheaths of tissue can form a protective tube around emerging shoots |
Plants have a hierarchical organization consisting of ___, ___, and ___. | - organs
- tissues
- cells |
tissue | an integrated group of cells with a common structure, function, or both |
organ | a specialized center of body function composed of several different types of tissue |
What are roots and what are their functions? | - an organ in vascular plants
- absorb water, nutrients, and oxygen
- transport those to shoot system
- anchor the plant
- store food (starch) |
taproot | a main vertical root that develops from an embryonic root and gives rise to lateral (branch) roots |
What are lateral (branch) roots and what do they do? | - roots that arise from established roots, such as the taproot
- increase surface area |
What are root hairs and what do they do? | - tiny extensions of root epidermal cells, growing just behind the root tips
- increases surface area even more for absorption of water and minerals |
What are prop roots and what do they do? | - modified roots
- aerial roots that arise from stems
- they penetrate the soil from various directions to help support tall, top-heavy plants (especially when the soil is shallow and unstable)
- ex. hala or mangroove trees |
What are storage roots and what do they do? | - modified roots
- roots that are specially modified for storage of starch and water
- they usually grow underground for protection from plant-eating animals
- ex. beets, carrots |
What are strangling aerial roots and what do they do? | - modified roots
- sent down from the tops of tall trees and become rooted in the soil
- the roots surround the host trunk, eventually strangling the bark and killing the host tree |
What are pneumatophores and what do they do? | - modified roots
- "air roots"
- roots that come out of the water
- enable the root system to obtain oxygen |
What are buttress roots and what do they do? | - modified roots
- large, shallow roots common in tropical areas because most nutrients are only available at the surface level
- extensive root system also provides larger surface area for absorption and architectural support for the large trees |
What do plants use oxygen for? | - to produce energy when there is no sunlight (they respire just like animals do)
- respiration combines oxygen and the food created during photosynthesis to produce usable energy
- one of the byproducts of respiration is CO2 |
What are stems and what are their functions? | - organs in vascular plants that consist of alternating systems of nodes and internodes
- support, raise and separate the leaves to expose them to sunlight
- raise reproductive structures to facilitate dispersal of pollen (wind, bees) and fruit (birds) |
node | a point along the stem of a plant at which leaves are attached |
internode | a segment of a plant stem between the points where leaves are attached |
axillary bud | - a structure that has the potential to form a lateral shoot, or branch
- the bud appears in the angle formed between a leaf and a stem |
apical bud | - a bud at the tip (apex) of a plant stem
- also called a terminal bud
- grows vertically |
apical dominance | - the tendency for growth to be concentrated at the tip of a plant shoot, because the apical bud partially inhibits axillary bud growth via hormones
- clipping the apical bud causes a plant to grow more laterally/bushy instead of vertically |
What are rhizomes and what do they do? | - modified, underground stems
- horizontal shoots that grow just below the surface
- vertical shoots emerge from axillary buds on the rhizome
- ex. ginger |
What are stolons and what do they do? | - modified stems
- horizontal shoots that grow along the surface
- these "runners" enable a plant to reproduce asexually as plantlets form at nodes along each runner
- ex. strawberry plant |
What are tubers and what do they do? | - modified stems
- enlarged ends of rhizomes or stolons specialized for storing food
- ex. potatoes
- the "eyes" of a potato are clusters of axillary buds that mark the nodes |
What are leaves and what are their functions? | - the main photosynthetic organ of vascular plants
- carry out photosynthesis
- protect the plant
- carry out gas exchange (through stomata) |
blade | the flattened portion of a typical leaf |
petiole | - the stalk of a leaf
- joins the leaf to a node of the stem
- (not all plants have these) |
simple leaf | - has a single blade (not divided into leaflets)
- can be lobed |
compound leaf | - blade consists of multiple leaflets
- can tell its one leaf because there will only be one axillary bud at the base |
What are tendrils and what do they do? | - modified leaves that cling to supports
- some plants have weak stems, so the need tendrils to grow vertically
- after a tendril has "lassoed" a support, it will form a coil that brings the plant closer to the support |
What are spines and what do they do? | - modified leaves
- protect the plant from predators
- plants that have spines, like cacti, carry out photosynthesis in the stem |
What are storage leaves and what do they do? | - modified leaves that layer and attach to a short stem
- store food
- the most common storage product is starch
- ex. onion |
What are reproductive leaves and what do they do? | - modified leaves
- produce adventitious plantlets that fall off the leaf and take root in the soil
- asexual reproduction |
The basic plant organs (roots, stems, and leaves) are composed of ___, ___, and ___ tissues. | - dermal
- vascular
- ground |
dermal tissue system | - the plant's outer protective covering
- first line of defense against physical damage and pathogens |
epidermis | - the dermal tissue system of nonwoody plants, usually consisting of a single later of tightly packed cells
- protects the plant
- helps with water retention |
cuticle | a waxy covering on the surface of stems and leaves that prevents desiccation (drying out) of terrestrial plants |
periderm | the protective coat that replaces the epidermis in woody plants during secondary growth, formed of the cork and cork cambium |
trichomes | - hair-like outgrowths of the shoot epidermis
- some are spiky or produce unpleasant tastes/odors to protect against predators
- others reduce water loss and reflect excess light |
What are the functions of the vascular tissue system? | to carry out long-distance transport of materials between the root and shoot systems |
xylem | - vascular plant tissue consisting mainly of tubular dead cells that conduct most of the water and minerals upward from the roots to the rest of the plant
- ONE WAY SYSTEM (root system -> stomata) |
phloem | - vascular plant tissue consisting of living cells arranged into elongated tubes that transport sugar and other organic nutrients throughout the plant
- from photosynthetic to not
- TWO WAY SYSTEM (SOURCE TO SINK) |
What are the functions of the ground tissue system? | - tissue that's not vascular or dermal
- filler tissue, but also includes various cells specialized for functions such as storage, photosynthesis, and support |
pith | ground tissue that is internal to the vascular tissue |
cortex | ground tissue that is between the vascular and dermal tissue |
parenchyma cells | - (para=beside/near, enchym=pour in)
- a relatively unspecialized plant cell type that carries out most of the metabolism, synthesizes and stores organic products, and develops into a more differentiated cell type
- living cells |
collenchyma cells | - (coll=neck, enchym=pour in)
- a flexible plant cell type that occurs in strands or cylinders that support young parts of the plant without restraining growth
- living cells |
sclerenchyma cells | - (scler=hard, enchym=pour in)
- a rigid, supportive plant cell type possessing thick secondary walls strengthened by lignin at maturity
- cells die at maturity |
tracheid | - a long, tapered water-conducting cell found in the xylem of nearly all vascular plants
- functioning tracheids are no longer living
- narrower than vessels |
vessel | - a continuous water-conducting micropipe found in the xylem of plants
- wider than tracheids |
sieve tube elements | - living cells that conduct sugars and other organic nutrients in the phloem
- connected end to end, they form sieve tubes |
companion cells | - plant cells that are connected to sieve tube elements by plasmodesmata and whose nucleus and ribosomes may serve one or more adjacent sieve tube elements
- regulates flow of nutrients |
Different ___ generate new cells for primary and secondary growth. | meristems |
indeterminate growth | a type of growth characteristic in plants in which the organism continues to grow as long as it lives |
determinate growth | a type of growth characteristic of most animals and some plant organs (flowers and leaves) in which growth stops after a certain size is reached |
apical meristem | - embryonic plant tissue in the tips of roots and buds of shoots
- the dividing cells of an apical meristem enable the plant to grow in length |
primary growth | - growth produced by apical meristems, lengthening roots and stems
- all plants have primary growth |
secondary growth | growth produced by lateral meristems, thickening the roots and shoots of woody plants |
lateral meristems | - a meristem that thickens the roots and shoots of woody plants
- eg. vascular and cork cambium |
cork cambium | a cylinder of meristematic tissue in woody plants that replaces the epidermis with thicker, tougher cork cells |
Epidermal cells are replaced by ___ and then ___. | - periderm
- cork |
vascular cambium | a cylinder of meristematic tissue in woody plants that adds layers of secondary vascular tissue called secondary xylem (wood) and secondary phloem |