Jan. 30th (Exam One) Flashcards
What is the purpose of the periderm?
Why is it needed?
It serves as a protective covering especially during secondary growth in woody plants.
Its primary purpose is to replace the epidermis which becomes quite inadequate as the plant grows laterally.
The periderm is needed because as the plant grows the original outer layer, epidermis, becomes unable to keep up with the plants growth.
What are cork cells?
Are they alive at maturity?
They are the dead cells that compose the outer part of the periderm.
They die after they are produced by the lateral meristem (cork cambium).
What is the bulk of the tissue in herbaceous plants?
Ground tissue
What are the three types of ground tissue?
- Parenchyma
- Collenchyma
- Sclerenchyma
Describe the parenchyma of the ground tissue.
What are its functions?
This layer contains cells that have relatively thin cell walls.
- Storage
- Photosynthesis
- Tissue repair
Describe the Collenchyma of the ground tissue.
What are its functions?
This layer contains cells that have unevenly thickened walls that contain cellulose and pectin (non-lignified)
Functions:
- Support
- Flexibility
Describe the sclerenchyma of the ground tissue.
What are its functions?
This layer contains cells that have evenly thickened, lignified cell walls - they are dead at maturity.
Functions.
- Strength
- Rigidity
What are the types of Vascular Tissue?
Does vascular tissue growth represent primary or secondary growth?
- Primary Xylem
- Primary Phloem
It represents primary growth
Another good name for vascular tissue is __________________________.
This makes up the bulk of the tissue in what type of plant?
Conducting tissue
Vascular tissue makes up the bulk of the tissue in woody plants.
Describe the Primary Xylem of the vascular tissue.
What are its functions?
This is a tissue layer that contains non-living cells that are lignified at maturity.
Xylem contains specialized water conducting cells called (Tracheids) and (Vessel Elements)
Tracheids - longer and thinner
Vessel Elements (only really angiosperms) are shorter and wider.
Functions:
- Transports minerals and water upwards from the root system.
- Provides structural support
Describe the Primary Phloem of the vascular tissue.
What are its functions?
This is a tissue layer that contains living cells at maturity and is non-lignified.
This tissue layer has specialized cells called sieve tube members and companion cells.
The primary phloem functions to transport sugars and other organic nutrients from the photosynthetic tissues to the rest of the plant.
How are the conducting cells of the xylem different than the sieve tube members and the companion cells of the phloem?
Xylem is non-living at maturity and transports water passively - is is highly lignified.
Phloem is living at maturity and transports sugars and other organic nutrients actively - it is not lignified.
What are the function of stems?
They are to support the plant structurally as well as facilitate the plant competing for sunlight with other plants.
What is the difference between herbaceous and woody dicot stems?
Herbaceous - these lack secondary growth and really only grow from their apical meristems. They usually only live for one season, because their stems are soft and green
Woody Dicot - these have secondary growth and become thicker and thicker as time goes on. The
Describe the vascular cambium.
Inner or outer lateral meristem?
What does it make?
This is the inner lateral meristem.
It produces:
- Secondary xylem to the inside.
- Secondary phloem to the outside
- Parenchyma in both directions
What is responsible for making the annual rings of spring and summer wood?
What is the difference between the two types?
Secondary Xylem
Springwood - tracheids are larger and the vessel elements have thinner walls allowing for better water transport.
Summerwood - tracheids are smaller and the vessel elements have thicker walls allowing for more structural support.
What is responsible for making the periderm (the corky outer layer)?
Hint: the other lateral meristem…
The cork cambium
What three things is bark composed of?
- Cork cambium
- Periderm (from cork cambium)
- Secondary phloem (from vascular cambium)
Define Dendrochronology.
Why is it important?
(2 reasons)
This is the study of tree rings.
Importance:
- It can tell us stuff about the climate, weather, and ecology at different times
- If we are lucky to get a tree that was preserved, it can tell us about what could have been happening long ago.
In a longitudinal section of a root, what covers the root apical meristem?
What are the three zones from top to bottom?
The root cap.
Zones:
1. Zone of differentiation
2. Zone of elongation
3. Zone of division
What is the general function of the mesophyll?
Situated between the upper and lower epidermis, the mesophyll (two types) is critical in photosynthesis and gas exchange.
What is the palisade mesophyll and its functions?
What is the spongy mesophyll and its functions?
Where are each of them located?
The palisade mesophyll is the upper layer of mesophyll, near the upper epidermis. It is rich in columnar cells that are packed with chloroplasts; this is the main site for photosynthesis.
The spongy mesophyll is the lower layer of mesophyll near the lower epidermis. It contains loosely packed cells that have large intercellular spaces. It facilitates gas exchange of CO2 and O2.
Why did the difference in the types of mesophyll evolve?
It evolved because it maximized the efficiency of photosynthesis and gas exchange.
Where are carnivorous plants found?
They are found in areas like bogs, wetlands, coastal areas and parts of tropical rainforests where the nutrient level in the soil is low (phosphorus and nitrogen) and the acidity is high.
What is the reason for the adaptation of carnivorous plants?
They must find a way to get the essential nutrients.
Areas where they inhabit have non-carnivorous plants that are competing like mad for nutrients, so they can avoid this competition, by utilizing specific niches like eating insects etc..
How do the following carnivorous plants catch their prey?
- Venus Fly Trap
- Sundew
- Pitcher plant
- Has guard hairs to prevent escape
- Has glandular hairs that produce a sticky glue
- The leaves of pitcher plants are modified into tubular, pitcher-shaped structures that act as traps.
