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What is the primary function of apical meristems in plants?
What is the primary function of apical meristems in plants?
Lateral meristems are involved in primary growth of plants.
Lateral meristems are involved in primary growth of plants.
False
What are the two main systems that acquire and transport resources for photosynthesis in a plant?
What are the two main systems that acquire and transport resources for photosynthesis in a plant?
Root and shoot systems
The vascular system carries water and minerals from roots to leaves through the _______.
The vascular system carries water and minerals from roots to leaves through the _______.
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Match the plant structures with their functions:
Match the plant structures with their functions:
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Which of the following statements best describes phenotypic plasticity in plants?
Which of the following statements best describes phenotypic plasticity in plants?
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Monocots and eudicots represent a major classification within the angiosperms.
Monocots and eudicots represent a major classification within the angiosperms.
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The _______ system is responsible for anchoring vascular plants in soil.
The _______ system is responsible for anchoring vascular plants in soil.
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What type of root system is characterized by roots that grow vertically and laterally?
What type of root system is characterized by roots that grow vertically and laterally?
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Phenotypic plasticity refers to the inability of a plant to change its structure in response to environmental conditions.
Phenotypic plasticity refers to the inability of a plant to change its structure in response to environmental conditions.
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What is the primary function of pneumatophores in mangroves?
What is the primary function of pneumatophores in mangroves?
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A swollen part of a rhizome that contains nodes with apical buds is known as a __________.
A swollen part of a rhizome that contains nodes with apical buds is known as a __________.
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Match the following plant structures with their characteristics:
Match the following plant structures with their characteristics:
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Which of the following leaf types is characterized by having multiple leaflets?
Which of the following leaf types is characterized by having multiple leaflets?
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Spines on plants serve primarily for attracting insects.
Spines on plants serve primarily for attracting insects.
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What part of the plant contains meristem tissue responsible for primary growth?
What part of the plant contains meristem tissue responsible for primary growth?
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What type of cells make up the xylem?
What type of cells make up the xylem?
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Sieve-tube elements in the phloem are dead at functional maturity.
Sieve-tube elements in the phloem are dead at functional maturity.
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What material strengthens the cell walls of tracheids and vessel elements?
What material strengthens the cell walls of tracheids and vessel elements?
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The _____ cells have pores between adjacent cells to facilitate the flow of phloem sap.
The _____ cells have pores between adjacent cells to facilitate the flow of phloem sap.
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Which of the following descriptions fits tracheids?
Which of the following descriptions fits tracheids?
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Match the type of vascular tissue with its function:
Match the type of vascular tissue with its function:
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Vessel elements are longer and narrower than tracheids.
Vessel elements are longer and narrower than tracheids.
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What are the two types of cells found in xylem tissue?
What are the two types of cells found in xylem tissue?
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In eudicots, how is vascular tissue arranged in stems?
In eudicots, how is vascular tissue arranged in stems?
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The primary function of stomata is to facilitate photosynthesis exclusively.
The primary function of stomata is to facilitate photosynthesis exclusively.
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What do root hairs increase in the root system?
What do root hairs increase in the root system?
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The _____ tissue in plants acts as a barrier against pathogens and regulates water loss.
The _____ tissue in plants acts as a barrier against pathogens and regulates water loss.
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Match the plant cell types with their primary functions:
Match the plant cell types with their primary functions:
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What is the role of the root cap?
What is the role of the root cap?
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Xylem and phloem are exclusive to leaves and not present in stems.
Xylem and phloem are exclusive to leaves and not present in stems.
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Which type of plant tissue is primarily responsible for the metabolic/storage functions?
Which type of plant tissue is primarily responsible for the metabolic/storage functions?
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In monocots, vascular bundles in stems are _____ throughout the stem.
In monocots, vascular bundles in stems are _____ throughout the stem.
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What is the main component of the cuticle found in epidermal tissue?
What is the main component of the cuticle found in epidermal tissue?
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What is the primary role of companion cells in plants?
What is the primary role of companion cells in plants?
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Sieve-tubes are primarily involved in the transportation of water in plants.
Sieve-tubes are primarily involved in the transportation of water in plants.
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What type of meristem is responsible for secondary growth in plants?
What type of meristem is responsible for secondary growth in plants?
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Bark is composed of ___, cork cambium, and secondary phloem.
Bark is composed of ___, cork cambium, and secondary phloem.
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Match the following plant structures with their functions:
Match the following plant structures with their functions:
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Which type of plant primarily exhibits secondary growth?
Which type of plant primarily exhibits secondary growth?
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The growth rings in a tree trunk indicate seasonal variations in growth conditions.
The growth rings in a tree trunk indicate seasonal variations in growth conditions.
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What cells do cork cambium produce, and what is their main function?
What cells do cork cambium produce, and what is their main function?
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The vascular cambium produces more secondary ___ than secondary phloem.
The vascular cambium produces more secondary ___ than secondary phloem.
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Which of the following tissues would you expect to find in a herbaceous plant?
Which of the following tissues would you expect to find in a herbaceous plant?
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Study Notes
Hierarchical organisation in plants
- Plants have an hierarchical organisation: specialised cells form tissues, which form organ systems
- Different specialised cells in plants include: tracheids, parenchyma cells
- Plant tissues include: vascular tissue, ground tissue
- Plant organ systems include: roots, shoots
Phenotypic plasticity
- Phenotypic plasticity is the ability of an organism to change its form or function in response to its environment
- Plants exhibit a great deal of phenotypic plasticity and have evolved a variety of forms adapted to specific environments
Meristems
- Meristems are stem cells that generate cells for growth
- Apical meristems are responsible for primary growth, which increases the length of roots and shoots
- Lateral meristems (including the vascular cambium and cork cambium) are responsible for secondary growth, which increases the width of roots and shoots
Monocots and eudicots
- Monocots and eudicots are the two main divisions in angiosperms
Root and shoot systems
- Root and shoot systems are the two major organ systems of vascular plants
- The shoot system consists of stems and leaves
- Shoots absorb light and CO2 needed for photosynthesis
- Reproductive shoots bear flowers, which aid angiosperms in sexual reproduction
- The root system absorbs water and nutrients from the soil via root hairs
- The root system anchors vascular plant in the soil
- The root system can act as a storage organ (e.g. tap root)
Vascular systems
- The vascular system connects the root and shoot systems, allowing for the transport of resources
- Xylem transports water and dissolved nutrients from the roots to the leaves
- Phloem transports sugars and other organic molecules in both directions between roots and shoots
Root growth
- Most parts of a plant are long and thin (e.g. roots) or flattened (e.g. leaves)
- Tap roots grow vertically
- Lateral roots grow horizontally
- Fibrous roots are very dense
- Pneumatophores grow above the surface of the soil, allowing roots to obtain oxygen in waterlogged environments (e.g. mangroves)
Phenotypic plasticity of shoot systems
- Shoots are repeating series of nodes, internodes, leaves and apical/axillary buds
- Buds contain meristematic tissue, which generates primary growth and lengthens the stem and branches
- Plants with short internodes and thickened leaves are adapted for storage (e.g. onion)
- Rhizomes are underground shoots that produce new individual plants from nodes (e.g. iris)
- Tubers are swollen tips of rhizomes that act as storage organs (e.g. potato)
Phenotypic plasticity of leaves
- Plants exhibit phenotypic plasticity in their leaves
- Leaf modifications include: simple or compound leaves, tendrils (for climbing), spines (for protection), leaves that are adapted to attract insects, leaves that trap and eat insects
- The shape of a leaf can be determined by the angle of branching and internode distance
Tissue systems in stems
- The tissue systems in stems have distinct arrangements in monocots and eudicots
- Epidermal tissue forms the outer layer of the stem and acts as a barrier against pathogens
- Vascular tissue (xylem + phloem) is arranged in vascular bundles that run the length of the stem (and root)
- In eudicots, vascular bundles are arranged in a ring near the perimeter of the stem
- In monocots, vascular bundles are scattered throughout the stem.
- Ground tissue (mainly parenchyma cells) forms the pith inside the vascular bundles and the cortex outside the vascular bundles (in eudicots)
Tissue systems in leaves
- The epidermis of leaves contains stomata, which regulate water loss and gas exchange
- Stomata are pores made up of two guard cells
- Guard cells regulate the opening and closing of stomata
- Ground tissue is made up of palisade mesophyll (elongated cells) and spongy mesophyll, which has loosely arranged cells and many air spaces
- Vascular tissue is arranged in veins, which contain xylem and phloem continous with the main plant. Veins are protected by a bundle sheath
Epidermis
- Epidermal cells protect the plant and regulate exchange with the environment
- Epidermal cells produce a lipid-based waxy cuticle that reduces water loss due to evaporation
- Epidermal cells can produce toxins or trichomes (hair-like outgrowths) to protect the plant
Primary growth
- Primary growth occurs at apical meristems, which lengthens roots and shoots
- Root growth occurs in three overlapping zones:
- Cell division (mitotic cells that express cyclin)
- Cell elongation (cells grow to 10x their original length and roots grow up to 4 cm/day)
- Cell differentiation (cells differentiate into vascular, ground and dermal tissue)
- The root cap protects the delicate apical meristem
- The root cap produces a polysaccharide slime (mucigel)
- The root cap detects gravity and determines the direction of growth
Lateral roots and root hairs
- Lateral roots emerge from the pericycle (outer ring of vascular cylinder)
- Lateral roots increase the size and surface area of the root system
- Root hairs increase the surface area of the root, facilitating water and mineral absorption
Ground tissue
- Parenchyma cells: have thin flexible primary cells, form large vacuoles; involved in metabolism and storage, primary site for photosynthesis
- Collenchyma cells: have thicker primary cell walls that provide support to parts of the plant shoot (e.g. celery strings)
- Sclerenchyma cells: have thickened secondary cell walls containing lignin. They form wood, the hard shells of nuts, and other rigid parts of the plants
Xylem
- Xylem transports water and dissolved minerals throughout the plant
- Two cell types form xylem: tracheids and vessel elements
- Xylem cells are elongated and tubular
- Xylem cells are dead at maturity
- Secondary cell walls are strengthened with lignin to prevent collapse during water transport
- Tracheids are long and slender with tapering ends and pits (primary cell walls) through which water can pass
- Vessels are shorter, thicker, and have thinner walls than tracheids. Vessels are stacked end-to-end with perforations between adjacent cells
Phloem
- Phloem transports sugars and other organic molecules throughout the plant
- Two types cells form phloem: Sieve-tube elements and companion cells
- Sieve-tube elements have sieve plates (pores) between adjacent cells
- Sieve-tube elements are alive at maturity but lack a nucleus, ribosomes, a vacuole, and a cytoskeleton, which enables phloem sap to flow more easily
- Companion cells are connected to sieve-tube cells by plasmodesmata
- Companion cells provide metabolic support for both themselves and adjacent sieve-tube cells. In some plants they assist in the loading of sugars into sieve-tube cells
Components of primary growth
- Primary meristem: gives rise to the primary tissue systems
- Protoderm: differentiates to form the dermal tissue system
- Ground meristem: differentiates to form the ground tissue system (parenchyma, collenchyma, sclerenchyma)
- Procambium: differentiates to form the vasular tissue system (xylem and phloem)
"Soft" vs "Hard" plants
- "Soft" plants e.g. herbs, forbs and grasses are mainly annuals and exhibit mostly primary growth
- "Hard" plants e.g. trees and shrubs are mainly perennials and exhibit both primary and secondary growth, secondary growth widens the roots and shoots and allows for the production of wood
Secondary growth
- Secondary growth increases the diameter of roots and shoots
- Secondary growth is driven by lateral meristems (vascular cambium and cork cambium)
- Secondary growth produces bark and wood
- The vascular cambium produces secondary xylem (towards the inside) and secondary phloem (towards the outside), increasing the diameter of the stem
- Cork cambium produces cork cells that provide protection and reduce water loss, forming the "skin layer" of the plant
Structure of a tree trunk
- Heartwood: xylem tissue that no longer transports water, usually dark in colour
- Sapwood: xylem cells that still transport water, usually light in colour
- Bark: cork cells, cork cambium and secondary phloem
- Annual growth rings: indicate the amount of secondary growth that occurs each year, which can be used to estimate the age of the tree, wider rings indicate better growth conditions
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Description
This quiz covers key concepts in plant biology, including hierarchical organization, phenotypic plasticity, meristems, and the classification of monocots and eudicots. Test your understanding of how specialized cells, tissues, and organ systems work together in plants and how they adapt to their environments.
