Midterm 1 Flashcards
What are the three principal tissue meristems that are laid down during plant embryogenesis?
- Vascular Tissues (procambium)
- Ground Tissues (ground meristem)
- Epidermis (protoderm)
What are examples of specialized tissues and cell types will ground tissue turn into in a leaf?
- mesophyll
- palisade cells
- spongy mesophyll cells
What are examples of specialized tissues and cell types will vascular tissue turn into?
- xylem
- phloem
What are the three categories of ground cell, cell types?
- Parenchyma cells
- Collenchyma cells
- Sclerenchyma cells
What are some features of parenchyma cells?
- thin and flexible cell walls
- living at maturity
- carry on most of the plant’s metabolic functions
- have the ability to differentiate into other cell types under special conditions during repair and replacement of organs after injury
What are some examples of parenchyma cells?
- palisade mesophyll cells
- spongy mesophyll cells
- guard cells
- cortex
- pith
What are some features of collenchyma cells?
- thicker primary cell walls (usually with uneven thickness, typically thicker in “corners”
- living at maturity
- role in support of herbaceous plants (“strings” of celery)
What are the general features of sclerenchyma cells?
- thick secondary cell walls
- dead at functional maturity
- cannot increase in length- occur in parts of the plant which have quit growing in length
What are the two types of sclerenchyma cells?
- Fibers
2. Sclerids
What are the features of fibers?
-long, slender cells with a more or less regular secondary cell wall
What are the features of sclerids?
-shorter cells with an irregular shape
What is the middle lamella?
pectin that glues cells together
What are features of the primary wall?
- laid down first
- mostly cellulose
- resists internal turgor pressure (positive pressure)
- generating stiff cells
What are features of the secondary wall?
- laid down in some cells
- mostly cellulose and lignin
- resists internal negative pressure (collapse_
- strong resistance to rot
Generally how do plants take up water?
by negative pressure
What do pits do?
provide cell wall free connections between cells
What is the function of chloroplasts?
- chlorophyll pigment
- photosynthesis
What is the function of chromoplasts?
-store pigments other than chlorophyll for recognition (petals, flowers)
Where are chromoplasts primarily stored?
in plastids
What are leucoplasts?
- non-pigmented plastids
- primarily in root and storage structures
What are the three types of leucoplasts?
- Amyloplasts
- Elaioplasts
- Proteinoplasts
What do amyloplasts do?
- starch storage
- gravity sensing
- terpene biosynthesis
What do elaioplasts store?
- oil
What do proteinplasts store?
- protein
What are functions of vacuoles?
- store water while concentrating surrounding cytoplasm
- isolate harmful materials
- store waste products
- maintain internal hydrostatic pressure or turgor within the cell
What does the plasmodesma allow intracellular movement of?
- water and other small molecules
- macromolecules such as proteins and mRNAs
When is the primary plasmodesmata formed?
-during cell division
When is the secondary plasmodesmata formed?
-later by enzymes digesting cell wall
What is the plasmodesma?
-cytoplasmic connections between cells
How can the plasmodesmata be closed?
-by synthesis of callose (sugar polymer) in the neck region
How is the plasmodesmata reopened?
-by callose digestion
Why is water status important?
-it is key for growth and photosynthesis
How is surface tension in water created?
-the contractive tendency of water minimizes the interaction with air (that has weak cohesion between molecules)
Why is evaporation in plants important?
-evaporation of water in leaf airspaces cools down the leaf, which is an important mechanism to cope with heat stress
Why is the cohesion of water molecules important for long distance transport of water?
-results in high tensile strength and makes it able to resist tension and negative hydrostatic pressure
What is osmosis?
-diffusion of fluid through a semi-permeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane
