Structural Support And Force Transfer Flashcards
Function of guard cells
Change shape to open or close an opening in the epidermis known as a pore.
Function of the stomata (sing. Stoma)
Allows carbon dioxide to enter to photosynthetically active tissues
Trichomes function
Minimize water loss and regulating gas exchange in shoots
Depending on species:
1. Keeps surface cool by reflecting sunlight
2. Provide barbs or store toxic compounds
3. Trap and digest insects
Most photosynthesis, as well as most carbohydrate storage, takes place in __________________.
Ground tissue
What three distinct tissue types make up ground tissue?
- Parenchyma
- Collenchyma
- Sclerenchyma
Parenchyma cells
- Are totipotent
- Filled with chloroplast on leaves (main site of photosynthesis)
- In other organs, store starch granules
- Important in plant healing wounds
- Important for asexual reproduction via stolons and rhizomes
Collenchyma cells
- Overall shape is longer and thinner
- Cells walls tend to be thicker
- Even mature cells can stretch and elongate
- Provide structural support for plants
Scleremchyma
- Produce thick secondary cell wall
- With a relatively thin primary cell wall
- Cell wall contains lignin and cellulose
- For supporting stems and other plant structures
- Two types: fibre and sclereids
- Usually dead by maturity
Fibre sclerenchyma
- Extremely elongated
- Important in the manufacture of paper, ropes, and fabrics
Sclereids
- relatively short
- variable shapes
- function: protection
- form the tough coat of seeds and thick shells of nuts
Function and types of vascular tissue systems?
- Xylem - conducts water and dissolved ions from root system to shoot system
- Phloem - conducts sugar, amino acids, chemical signals, and other substances. Done in both directions; roots to shoots and shoots to roots.
Types of cells found in the xylem structure
- Tracheids - water conducting cells found in all vascular plants
- Vessel elements - conducting cells found in angiosperms
Tracheids
- Long, slender cells with tapered ends
- Has pits, gaps in secondary cell wall where there is only a primary cell wall.
- Since they are dead, pits have no cytoplasm
- Water moves up tracheids or side to side via the pits from cell to cell
Vessel elements
- Are shorter and wider than tracheids
- Addition to pits, have perforations - openings that lack both primary and secondary cell wall.
- In some species, may lack a cell wall
- Form open pipes called vessels
- Conducts water more efficiently than tracheids, because their width and perforations offer less resistance to flow
Types of Phloem cells
- Sieve-tube elements
2. Companion cells
Sieve-tube elements
- Long, thin cells that have perforated ends called sieve plates
- Conducts sugars and other nutrients
- Lack nuclei and most organelles
- Connected to numerous companion cells through plasma desmata
Companion cells
- Connected to sieve-tube elements by plasmodesmata
- Provide materials to maintain the cytoplasm and plasma-membrane of sieve-tube elements
- Involved in loading and unloading carbohydrates and other nutrients into and out of sieve-tube elements
Primary growth
- extends the reach of of roots and shoots
- increasing Plants ability to absorb photons and acquire CO2, water, and ions
Secondary growth
- increases the width of the plant body
- increasing the amount of connecting tissue available
- providing structural support for extensive primary growth
- produces wood
Differences between cambium (lateral meristem) and apical meristem
- Cambium forms a cylinder that runs the length of a root or stem and is made up of a single layer of meristematic cells.
In contrast, apical meristems are localized at root tips and shoot tips and are dome shaped. - In a cambium, cells divide in a way that increases width of roots in shoots.
In an apical meristem cells divide in a way that extends root and shoot tips.
What are the two types of cambium in plants that undergo secondary growth?
- Vascular cambium
- located between secondary xylem and secondary phloem
- generates new layers of cells inside and outside; inside cells push outside cells increasing the girth of the plant - Cork cambium
- located near perimeter of the stem and root
- produces new cells to the outside
Lenticels
Small, spongy openings in the bark that allow gas exchange
What is striated muscle?
Muscle cells where the actin and myosin filaments are aligned in rows forming sarcomeres, giving the cells and tissue a banded appearances
Types of muscle tissue
- Smooth muscle
- Cardiac muscle
- Skeletal muscle
Smooth muscle
- Cells are unbranched
- Tapered at each end
- Organized into thin sheets (often)
- Involuntary contraction
Unstriated - appears smooth
Cardiac muscle
- Makes up the walls of the heart, responsible for pumping blood throughout the body.
- Contains sarcomeres and are striated
- Have unique branched structures connecting end-end via specialized regions called, intercalated disks
- these discs are important for flow of electron signals and heartbeat coordinations
Skeletal muscle
- Long, unbranched muscle fibers.
- Packed with myofibrils, each containing thousands of sarcomeres
- Striated
- Usually attached to skeleton
- Distinguished from smooth and cardiac muscle by being voluntary.
Skeletal-Fiber Types
- Slow muscle fibers
- Fast muscle fibers
- Intermediate muscle fibers
Slow muscle fibers
- appear red because contains high [conc] of myoglobin, an iron-bearing pigment
- contracts slowly because myosin hydrolyses ATP at a slow rate
- have lots of mitochondria - fatigue slowly
- aerobic respiration supplies ATP
Fast muscle fibers
- appear white because they have a low myoglobin [conc].
- contract rapidly - myosin hydrolyses ATP at rapid rates
- fatigue rapidly because primary source of ATP is glycolysis rather than aerobic respiration.
Fun fact: contracts up to three times faster than slow muscle fibre
Intermediate muscle fibers
- appear pink or red
- contracts at intermediate speeds
- derive ATP from both glycolysis and aerobic respiration
Types of skeletal-fibre organization
- Parallel
2. Pennate
Parallel
Small cross section = small force
Long length = large length change
Pennate
Large cross section = large force
Small length = small length change
Main function of skeletal systems
- Protection
- Maintenance of body posture
- Re-extension of shortened muscle
- Transfer of muscle forces
Types of skeletal systems
- Hydrostatic skeletons - use the hydrostatic pressure of enclosed body fluids or soft tissue to support body.
- Endoskeleton - have rigid structures inside the body
- Exoskeleton - have rigid structures on the outside of the body
How do hydrostatic skeletons move?
Alternating contraction of longitudal and circumferential muscles pass down animals in waves, called peristalsis, allowing movement forward or backwards
Bones
- human adult body contains 206
- made of cells that contain calcium phosphate
- bones meet up at articulation (joints)
Cartilage
-made up of cells scattered in gelatinous matrix of polysaccharides and protein fiber
Tendons
Connects muscles to bones
Ligaments
- Made of collagen
- Bind bones to other bones
How Do Exoskeletons work?
Same as endoskeleton but use pennate muscles
