Cell Communities Flashcards
Name the three different types of land plants.
- Avascular (Bryophytes) - Mosses, liverworts and hornworts.
- Vascular (but seedless) - Ferns, clubmosses and horsetails.
- Seed plants - Angiosperms and gymnosperms.
State five common features of a plant.
- Multicellular.
- Apical meristems.
- Cell wall is used for support and rigidity.
- They have specialised reproductive organs.
- Spores or seeds with specialised walls which stop them from drying out.
State three features of apical meristems.
- Localised regions of dividing cells.
- Result in primary growth (length).
- Produces three primary meristems which develop into three tissue types.
What class of growth does lateral meristems result in?
Secondary (girth).
Define dermal tissue.
Outer protective covering.
Define vascular tissue.
Root and shoot transport.
Define ground tissue.
Any tissue that isn’t dermal or vascular.
What are the three basic plant organs?
- Roots.
- Stem.
- Leaves.
Describe the structure of leaves.
It has variable morphology, comprising flat blade and petiole (leaf stalk). It contains veins (vascular tissue) which is parallel in monocots and is a network in dictos.
Describe the function of leaves.
It is the main photosynthetic organ. It also provides support, protection, storage and reproduction.
What is the dermal tissue of a root, stem and leaf?
Epidermis.
What are the two ground tissues of a root, stem and leaf?
- Cortex and pith.
2. Mesophyll.
What are the three vascular tissues of a root, stem and leaf?
- Phloem.
- Xylem.
- Vascular bundles.
Describe the structure of stems.
It has alternating nodes (leaf attachment points) and internodes.
Describe the function of stems.
- To support leaves, flower and fruit.
- To transport between root and shoot.
- Activity at apex leads to primary growth.
- Storage of nutrients.
- Some photosynthesis.
- Asexual reproduction (stolons).
Describe the structure of roots.
Dicots - main taproot and lateral roots.
Monocots - mass of fibrous roots.
Describe the functions of roots.
- Anchors plants in soil. Prop and buttress roots improve support.
- Absorbs minerals and water.
- Stores carbohydrates.
What are the four functions of the epidermis?
- Protection against damage and pathogen.
- Reflects excess solar radiation.
- Cuticle reduces water loss.
- Defence against insect herbivory.
Define periderm.
Replaces epidermis in old stem/root regions of woody plants.
What three layers form in early secondary growth?
- Cork cambium.
- Cork cells deposit suberin in walls then die.
- Phelloderm which is the inner layer of living parenchyma.
Define xylem.
Water conducting tissue.
State four features of tracheary elements (TE).
- Dead at maturity.
- Elongated with lignified walls.
- Linked by pits/perforation plates.
- Its main role is to conduct water and minerals.
What does fibres and lignified tracheary element provide?
Support.
What does xylem parenchyma provide?
A storage role and living cells.
Define tracheary elements.
Xylem elements without plates in angiosperms only.
Define phloem.
Photosynthate conducting tissue.
State five features of conducting cells.
- Long, narrow sieve cells (gymnosperms).
- Linked sieve tube members (angiosperms).
- They are living cells with reduced contents.
- The nucleus and ribosomes of companion cell serve both cells.
- Perforated sieve plates link cells.
In roots and stems, what is the ground tissue internal to vascular tissue known as?
Pith.
In roots and stems, what is the ground tissue external to vascular tissue known as?
Cortex.
What two types of tissue are ground tissue in leaves?
- Spongy mesophyll.
2. Palisade mesopyhll.
State four features of parenchyma.
- Thin, flexible walls as there is no secondary wall.
- Large central vacuole.
- Contain plastids.
- Ability to divide and differentiate.
In what four places are parenchyma found?
- Cortex and pith of stem.
- Mesophyll of leaves.
- Flesh of fruits.
- Reproductive structures.
What four metabolic functions does parenchyma carry out?
- Photosynthesis in mesophyll.
- Storage e.g. amyloplasts store starch.
- Regeneration/wound healing (meristematic).
- Support e.g. in stems.
State a feature of collenchyma.
Thick primary walls with no lignin, this it is soft and stretchy.
State a function of collenchyma.
Flexible support for growing tissues.
What two places are collenchyma found?
- Stems, petioles and young organs.
2. As elongated strands or cylinders beneath epidermis.
State two features of sclerenchyma.
- Thick, lignified secondary walls.
2. May be dead at maturity.
State a function of sclerenchyma.
It supports non-growing plant parts.
What are the two types of sclerenchyma?
- Fibres - Long, thin cells in bundles.
2. Sclereids - Short, irregular shape.
What two places are sclerenchyma found?
- Fibres in stems.
2. Sclereids in seed coats and pear flesh.
State four functions of cell walls.
- Cell protection.
- Maintains cell shape.
- Holds plant up against gravity.
- Avoids excess water uptake.
What is a secondary cell wall composed of and what does this mean for its structure?
It is composed of cellulose and lignin. This makes the wall rigid.
What is the structure of a primary cell wall like?
It is thin, flexible and mainly composed of cellulose.
Define middle lamellae.
Adhesive pectins between cells.
Define gap junctions.
Cytoplasmic channels between cells in animal tissues.
State two features of plasmodesmata.
- They perforate the cell wall.
2. They encompass a cytoplasmic sleeve, desmotubule (SER) and cell membrane.
What is the purpose of cell junctions?
They allow exchange of ions, proteins, mRNA and virus DNA.
State three reasons why plant roots anchor plants to one spot.
- They must defend themselves against herbivory.
- They must deter competitors.
- They must attract pollinators.
Define metabolites.
Intermediates/products of metabolism.
Define secondary metabolites.
They deter herbivores.
Define determinate growth. What type of cell does this happen to?
Growth stops at a certain size. This happens to animal cells.
Define indeterminate growth. What type of cell does this happen to?
Growth throughout life. This happens to plant cells.
Explain two reasons why indeterminate growth acts as plant defence.
- Possible due to meristems:
- Mitotically active regions.
- Produce new undifferentiated tissue. - Allows recovery from damage.
