Lecture 8- The plant body Flashcards
97% of angiosperms belong to which two clades?
Monocots and eudicots
What features distinguish monocots?
Narrow leaves Veins in leaves- parallel One cotyledon Flower parts in multiples of three Primary vascualr bundle scattered
What features distinguish eudicots?
Broad leaves Veins in leaves are net like Two cotyledons Flower parts in multiples of 4 or 5 Primary vascular bundle in a ring
The remaining species of angiosperms resemble which of the two major clades more closely?
Eudicots
Give examples of monocot plants
Grasses, lilies, palms, orchids
Give examples of eudicot plants.
Soy beans, roses, sunflowers, maples
What are angiosperms?
Vascular plants characterized by double fertilization, a triploid endosperm, seeds enclosed in modified leaves called carpels
Flowering plants possess what three types of vegetative (non-reproductive) organs?
Roots, stems, leaves
What two basic systems are all organs organised into?
Shoot system and root system
What does the shoot system consist of?
Stems, leaves and flowers
What are nodes and internodes?
Nodes are points of attachment of stem to leaf, and the stem regions between successive nodes are internodes
What is the function of the stem?
To hold and display the leaves to the sun and provide connections for transport of materials between roots and leaves
What is the function of the leaves?
Photosynthesis
What is the function of the root system?
To anchor the plant in place and provide nutrition
What does the structure of vegetative organs include?
The overall shape, morphology
and the anatomy- the arrangement of component cells and tissues
What are the two principle types of root systems?
Taproot system- single, large, deep growing primary root accompanied by less prominent lateral roots- common in most eudicots
Monocots- fibrous root system- numerous thin roots, roughly equal in diameter
What are adventitious roots?
Roots that arise above ground from points along the stem- these can form when a piece of shoot is cut or broken from the plant and placed in water or soil. This enables the cutting to establish its self as a new plant- vegetative reproduction
What is a bud?
An embryonic shoot
What is the difference between an axillary bud and an apical bud?
Axillary buds are where each leaf meets a stem and can develop into a new branch. Apical buds are at the tip of stems or branches and produces upwards and outwards growth or develop into flowers
Some stems are highly modified. Explain how this is demonstrated by a potato, desert plants and runners.
The tuber of a potato is an underground stem.
Desert plants have large, water-retaining stems.
Runners in strawberry plants and Bermuda grass are horizontal stems from which roots grow at intervals. If links are broken, individual plants can grow on either side.
What is a blade and how is it attached to the plant?
A blade of a leaf is a thin, flat structure, attached to the stem by a stalk called a petiole.
How do leaves maximize the amount of sunlight that they receive during the day?
Some leaves track the sun over the course of the day- moving to constantly face it
Why may some leaves on the same plant have different shapes?
Genetic, developmental and environmental factors
What are the two types of leaf structure?
Compound leaves- consist of multiple leaflets arranged along an axis or central point. Simple leaves consist of a single blade. Doubly compound leaves is the result of further division of the axis.
What determines the shape of a leaf?
Differential growth of the leaf veins and the tissue between the veins determines overall shape of blade or leaflet
What types of modifications can occur to leaves during development in order to become specialised?
- Modified to become storage depots for energy rich functions (onion bulb)
- Water storage- such as in succulents
- Tendrils- support the plant by wrapping around other structures or plants (peas)
Define tissue
An organised group of cells that have features in common and that work together as a structural and functional unit- organised into tissue systems
What are the three tissue systems in plants?
Vascular tissue
Dermal tissue
Ground tissue
These extend through the plant in a concentric arrangement
What tissues does the vascular tissue system consist of?
Xylem (water and mineral ions)
Phloem (carbohydrates)
What is the function of the xylem?
Transport, storage and support
What is the purpose of the phloem?
Transport carbohydrates from the source (site of production) to the sink (the site of utilization or storage)
What is the dermal tissue system?
The outer covering of the plant
What does the dermal tissue system consist of?
Epidermis- thin layer of cells- contains specialized guard cells that form stomata
The epidermis secretes wax covered cutin- Cuticle.
Woody plants have a periderm- protective covering.
What is the function of stomata?
Gas exchange
What is the function of the cuticle?
Prevent water loss from stems and leaves
What is the function of ground tissue?
Storage, support, photosynthesis, production of defensive and attractive substances.
During early embryonic development, a plant establishes the basic body plan. What two patterns contribute to the plant body plan?
The arrangement of cells and tissues along the main axis from root to shoot
The concentric arrangement of the tissue systems
What does the growing stem consist of?
Modules, or units, laid down one after another, consisting of a node with its attached leaf/leaves and the internode below that node and the axillary buds at the base of the internode.
Branches may be thought of as a module.
In what ways do branches grow differently to animal limbs?
They grow one after another (limbs grow simultaneously during development).
Branches differ from one another (number of leaves, degree of branching)
These branches are long lived, lasting years to centuries
Root systems are branching structures, lateral roots are semi-independent. How do they grow?
As the root system grows, penetrating and exploring the soil environments, roots may die and others may grow.
What are the two types of plant body?
Primary plant body and secondary plant body
What does the primary plant body consist of?
All non-woody parts of the plant. Monocots in particular consist entirely of primary plant body.
What is the secondary plant body?
Wood and bark, seen in trees and shrubs. These tissues are laid down as stems and roots thicken and continues to grow throughout the life of the plant.
What are meristems?
Localized regions of cell division in plants
These retain the ability to produce new cells indefinitely.
Describe the growth of primary and secondary plant body.
Tissues of secondary plant body are laid down as the stems and roots thicken, the primary plant body includes the leaves, flowers and all parts of the body that were laid down before the thickening began. The secondary plant body grows and thickens throughout its lifetime. The primary plant body also continues to grow, lengthening the shoot and root systems and forming new leaves.
What are initials?
Cells that perpetuate meristems- they are actively dividing cells in the meristem. When the initial divides, one daughter cell divides into another meristem and the other differentiates into a specialized cell.
What are the two types of growth than can occur?
Determinate growth- growth of the individual ceases when the adult state is reached- seen in some plant parts, such as flowers, leaves and fruits.
Indeterminate. Generated from specific regions of active cell division and expansion, seen in roots and stems.
What are the two types of meristems that contribute to growth and development of a plant?
Apical meristems- give rise to the primary plant body
Lateral meristems- give rise to the secondary plant body
Where are apical meristems located and what effect do they have on plant growth?
In the tips of roots and stems and in buds.
Primary growth leads to elongation of shoots and roots and the formation of organs.
Cell division of meristems leads to cell expansion and differentiation.
What are the two kinds of apical meristems?
Shoot apical meristems: supply the cells that extend stems and branches
Root apical meristems: supply cells that extend roots
What do apical meristems give rise to?
A set of cylindrical primary meristems that produce the primary tissues of the plant body
What are the three types of primary meristems and what tissue systems do they give rise to?
Protoderm: dermal tissue system
Ground meristem: ground tissue system
Procambium: Vascular tissue system
What are the two types of lateral meristems?
Vascular cambium
Cork cambium
What is the vascular cambium?
A cylindrical tissue consisting of vertically elongated cells that divide frequently. It supplies the cells of the secondary xylem and phloem, which eventually become wood and bark.
What is the cork cambium?
The cork cambium produces mainly waxy-walled cork-cells which supplies some of the cells that become bark.
What is wood?
Secondary xylem.
What is bark?
Everything external to the vascular cambium. This is the secondary phloem and the periderm.
What is the periderm?
Cork and the cork cambium.
What happens as a tree grows in diameter?
The outermost layers, including the epidermis, dry and crack off. The cork cambium produces new protective walls, called the periderm, with walls impregnated with suberin
Why does the cork cambium produce a periderm?
Without it, the tree would be exposed to potential damage including excessive water loss and invasion by microorganisms.
What is the oldest known individual plant?
A bristlecone pine- 4900 years old
What is leaf anatomy adapted for?
To carry out photosynthesis
Gas exchange
Limit water loss
Exporting products of photosynthesis to the rest of the plant
The mesophyll is made up of two zones of photosynthetic parenchyma cells. What are the two zones of mesophyll? What else is within the mesophyll?
Palisade mesophyll (upper layers)(elongated shape) Spongy mesophyll (lower layers) (irregular shaped) Lots of air space for the diffusion or carbon dioxide.
What supplies the mesophyll cells with water and minerals?
Vascular tissue called veins. The products of photosynthesis are also loaded into the phloem of the veins.
What covers the upper and lower leaf surfaces?
Non-photosynthetic epidermis with an overlying waxy cuticle (keeps water contained but also keeps CO2 out)
How is water retention and gas exchange balanced?
Guard cells (modified epidermal cells) change their shape to open and close pores called stomata.
How do C4 plants fix carbon dioxide efficiently when carbon dioxide levels drop?
They have modified leaf anatomy- photosynthetic cells are grouped around veins in concentric layers, forming an outer mesophyll layer and an inner bundle sheath. These contain different types of chloroplasts which leads to a biochemical division of labor.
