Which lateral meristem is responsible for the increase in girth (thickness) of the plant?
- Apical cambium
- Ground meristem
- Intercalary meristem
- Vascular cambium
Explanation: Vascular cambium and cork cambium are lateral meristems responsible for secondary growth, which increases the girth of the plant.
Which tissue layer in dicot stems consists of a few layers of collenchyma to provide mechanical strength?
- Pericycle
- Pith
- Hypodermis
- Endodermis
Explanation: In dicot stems, the hypodermis is collenchymatous. In monocot stems, the hypodermis is sclerenchymatous.
Which of the following is true regarding 'Annual Rings'?
- Formed in tropics
- Lack xylem
- Seen in roots
- Indicate age
Explanation: Annual rings are formed by the differential activity of cambium in spring and autumn. They can be used to estimate the age of a tree (Dendrochronology).
In dicot roots, the vascular cambium originates from tissues located:
- Inside pith
- Below epidermis
- Below phloem
- Above protoxylem
Explanation: In dicot roots, the vascular cambium is completely secondary. It originates from the pericycle tissue located just below the phloem bundles.
In 'Isobilateral' leaves, the stomata are typically present:
- Only on upper
- Only on lower
- Only on margins
- On both sides
Explanation: In isobilateral (monocot) leaves, stomata are present on both the upper and lower surfaces of the epidermis.
The primary function of the 'Pericycle' in dicot roots is to initiate:
- Gas exchange
- Food storage
- Lateral roots
- Vertical growth
Explanation: In roots, the initiation of lateral roots and vascular cambium during secondary growth takes place in the pericycle cells.
In a 'Conjoint' vascular bundle, the arrangement of xylem and phloem is typically:
- Scattered randomly
- Same radius
- Different radii
- Circular rings
Explanation: In conjoint bundles, xylem and phloem are situated on the same radius of the vascular bundle, common in stems and leaves.
The 'Dumb-bell shaped' guard cells are a unique diagnostic feature of the stomata found in:
- Grasses
- Hibiscus
- Peepal trees
- Sunflowers
Explanation: In monocots like grasses, guard cells are dumb-bell shaped, whereas in dicots, they are typically bean-shaped or kidney-shaped.
Which of the following is a result of the 'differential activity' of the vascular cambium in temperate regions?
- Root hairs
- Casparian strips
- Stomatal pores
- Annual rings
Explanation: The change in cambial activity between spring and autumn produces distinct early and late wood, forming visible annual rings.
Lenticels, which permit gas exchange between the atmosphere and internal tissues, are found on:
- Leaf surfaces
- Woody stems
- Root tips
- Floral buds
Explanation: Lenticels are lens-shaped openings in the bark of woody trees that facilitate the exchange of gases.
In Gymnosperms, the absence of sieve tubes and companion cells is compensated by which specific cells?
- Sclereids
- Albuminous cells
- Vessels
- Tracheids
Explanation: Gymnosperms lack sieve tubes and companion cells. Instead, they possess sieve cells and albuminous cells for nutrient transport.
In a mature Dicot stem, the 'Pith' and 'Medullary rays' are composed of which tissue?
- Chlorenchyma
- Sclerenchyma
- Collenchyma
- Parenchyma
Explanation: The central pith and the medullary rays (which separate vascular bundles) are made of thin-walled parenchymatous cells.
In the phloem of angiosperms, the functions of sieve tubes are controlled by the nucleus of:
- Bast fibres
- Sieve cells
- Companion cells
- Phloem parenchyma
Explanation: Mature sieve tube elements lack a nucleus. Their functions are regulated by the nucleus of adjacent companion cells.
The presence of thickened corners due to cellulose, hemicellulose, and pectin is characteristic of which tissue?
- Sclerenchyma
- Collenchyma
- Parenchyma
- Aerenchyma
Explanation: Collenchyma consists of cells thickened at the corners. It provides mechanical support to growing parts like young stems.
The wood formed during the spring season, characterized by wider vessels, is called:
- Autumn wood
- Hard wood
- Early wood
- Late wood
Explanation: Spring wood (early wood) is formed when the cambium is more active, producing xylem elements with wider vessels.
The central 'Pith' region is characteristically well-developed and large in which of the following plant structures?
- Monocot stem
- Monocot leaf
- Dicot stem
- Dicot root
Explanation: In dicot stems and monocot roots, the central pith is conspicuously large and well-developed, consisting of parenchymatous cells with intercellular spaces. Conversely, dicot roots and monocot stems have a very small, inconspicuous, or absent pith.
What happens to the 'Primary xylem' as the secondary xylem continues to form in a woody stem?
- Becomes phloem
- Crushed completely
- Pushed toward center
- Pushed toward outside
Explanation: As the vascular cambium adds new secondary xylem to the outside of the old xylem, the primary xylem is pushed and crushed towards the center.
The 'Bark' of a tree includes all tissues located outside of the:
- Vascular cambium
- Pith
- Endodermis
- Pericycle
Explanation: Bark is a non-technical term for all tissues exterior to the vascular cambium, including secondary phloem and the periderm.
Where does the initiation of lateral roots take place in a dicotyledonous plant?
- Pericycle
- Cortex
- Endodermis
- Epidermis
Explanation: In roots, lateral roots originate from the pericycle, which is a layer of thick-walled parenchymatous cells inside the endodermis.
The 'complementary cells' associated with lenticels are produced by the activity of:
- Phellogen
- Apical meristem
- Vascular cambium
- Endodermis
Explanation: The phellogen (cork cambium) sometimes produces loosely arranged parenchymatous cells instead of cork, known as complementary cells.
The 'Trichomes' found on the stem surface are primarily involved in:
- Preventing water loss
- Secondary growth
- Absorption
- Sugar transport
Explanation: Trichomes are epidermal hairs that help reduce transpiration and can also protect the plant from pests.
The process of 'Secondary growth' is typically observed in which group of plants?
- Bryophytes
- Pteridophytes
- Monocots
- Dicots/Gymnosperms
Explanation: Secondary growth, which increases girth, is a characteristic of dicotyledons and gymnosperms due to the presence of lateral meristems.
The 'Bulliform cells', which help in leaf rolling during water stress, are found in the epidermis of:
- Dicot roots
- Dicot leaves
- Monocot roots
- Monocot leaves
Explanation: In grasses (monocots), large, empty, colorless bulliform cells are found in the epidermis. They cause leaf rolling to minimize water loss.
The 'Mesophyll' of a leaf is primarily made of which type of cells?
- Sclerenchyma
- Chlorenchyma
- Sieve tubes
- Collenchyma
Explanation: Mesophyll is the ground tissue of the leaf containing chloroplasts (chlorenchyma) and is responsible for photosynthesis.
Regarding 'Dendrochronology', which anatomical feature is used to estimate the age of a tree?
- Pith size
- Xylem vessels
- Bark thickness
- Annual rings
Explanation: Dendrochronology is the science of dating tree growth rings to understand past climates and determine the age of the tree.
The epidermal hairs on the stem that help in preventing water loss are called:
- Root hairs
- Stomata
- Trichomes
- Lenticels
Explanation: Trichomes are multicellular epidermal hairs on the stem. They help in reducing water loss due to transpiration.
Which of the following is a characteristic feature of monocotyledonous stems?
- Distinct pith
- Scattered bundles
- Ringed bundles
- Open bundles
Explanation: Monocot stems have numerous scattered vascular bundles, each surrounded by a sclerenchymatous bundle sheath.
In which plant group is the 'Vascular bundle' described as being 'open'?
- Mosses
- Dicots
- Monocots
- Algae
Explanation: Dicot vascular bundles are 'open' because they possess cambium between the xylem and phloem, enabling secondary growth.
In a dorsiventral (dicot) leaf, the 'Palisade parenchyma' is primarily located towards which surface?
- Leaf margin
- Adaxial surface
- Abaxial surface
- Vascular bundle
Explanation: Palisade parenchyma is situated towards the adaxial (upper) epidermis, while spongy parenchyma is towards the abaxial (lower) epidermis.
Which of the following components is considered the only 'non-living' element of the Phloem tissue?
- Sieve tubes
- Phloem parenchyma
- Companion cells
- Phloem fibres
Explanation: Phloem fibres (bast fibres) are made of sclerenchyma and are dead at maturity. Other phloem elements are generally living cells.
The primary function of the 'Aerenchyma' tissue in aquatic plants like Hydrilla is to provide:
- Mechanical support
- Food storage
- Water transport
- Buoyancy
Explanation: Aerenchyma is a type of parenchyma with large air cavities that helps aquatic plants float by providing buoyancy.
The 'Bundle sheath' cells in the leaves of plants like Maize are typically:
- Lacking chloroplasts
- Thin-walled
- Full of air
- Thick-walled
Explanation: In C4 plants like maize, vascular bundles are surrounded by large, thick-walled bundle sheath cells, a feature of Kranz anatomy.
In an 'Isobilateral' leaf, the mesophyll tissue is characteristically:
- Differentiated into layers
- Undifferentiated throughout
- Highly lignified
- Completely avascular
Explanation: In isobilateral leaves (typically found in monocots), the mesophyll is undifferentiated. It is not divided into the palisade and spongy parenchyma layers that are characteristic of dorsiventral (dicot) leaves, giving it a uniform appearance.
Which tissue provides the majority of mechanical strength to the 'husk' of a coconut?
- Xylem parenchyma
- Companion cells
- Collenchyma
- Sclerenchyma fibres
Explanation: The coconut husk is composed of sclerenchyma fibres, which are dead, thick-walled cells providing extreme structural rigidity.
Which of the following is true for 'Lenticels' found in woody trees?
- Control water
- Store starch
- Perform photosynthesis
- Permit gas exchange
Explanation: Lenticels are lens-shaped openings in the bark that allow for gas exchange between the atmosphere and the internal tissues of the stem.
Which of the following lacks 'Vessels' in its xylem?
- Gymnosperms
- Sunflowers
- Mango
- Peepal
Explanation: Xylem vessels are a characteristic feature of Angiosperms. Most Gymnosperms lack vessels and rely on tracheids.
Which of the following best describes the 'radial' arrangement of vascular bundles in plants?
- Arranged in a continuous ring
- Arranged on the same radius
- Scattered in ground tissue
- Arranged on different radii
Explanation: A radial vascular bundle arrangement is characterized by the xylem and phloem strands alternating with each other on different radii. This arrangement is a distinct anatomical feature of root structures.
The term 'Bark' refers to all tissues located external to the:
- Pericycle
- Epidermis
- Endodermis
- Vascular cambium
Explanation: Bark is a non-technical term that includes all tissues outside the vascular cambium, including secondary phloem and periderm.
In an 'endarch' xylem, which is characteristic of stems, the protoxylem is located towards:
- The phloem
- The periphery
- The center
- The epidermis
Explanation: In endarch arrangement (stems), the protoxylem lies toward the pith (center) and the metaxylem lies toward the periphery.
The 'Interfascicular cambium' in a dicot stem is formed by the meristematic activity of which cells?
- Medullary rays
- Pith
- Cortex
- Endodermis
Explanation: Cells of medullary rays adjoining the intrafascicular cambium become meristematic to form the interfascicular cambium, completing the cambial ring.
Vascular bundles surrounded by a prominent 'bundle sheath' are found in:
- Leaves
- Dicot roots
- Banyan roots
- Dicot stems
Explanation: In leaves, vascular bundles are surrounded by a layer of thick-walled cells called bundle sheath cells.
Which primary tissue provides the ability for a young plant stem to bend without breaking?
- Phellem
- Xylem vessels
- Sclerenchyma
- Collenchyma
Explanation: Collenchyma cells are living and have pectin-thickened corners, providing both mechanical support and flexibility to young stems.
Which specific part of the secondary xylem remains functional for water and mineral conduction in old trees?
- Heartwood
- Duramen
- Sapwood
- Phellem
Explanation: Sapwood (alburnum) is the peripheral, light-colored region of secondary xylem that remains functional in water transport, unlike the central heartwood.
The 'Phelloderm' formed during secondary growth is more commonly known as the:
- Cork
- Bark
- Secondary phloem
- Secondary cortex
Explanation: The cork cambium (phellogen) cuts off cells on the inner side to form the phelloderm, also known as the secondary cortex.
In the context of root anatomy, the 'Casparian strips' prevent the movement of water through the:
- Symplast pathway
- Apoplast pathway
- Transmembrane pathway
- Vacuolar pathway
Explanation: Suberin in Casparian strips blocks the apoplastic movement (through cell walls), forcing water to enter the symplast (living cytoplasm) of the endodermis.
The 'gritty' texture felt while eating fruits like pear and sapota is due to the presence of:
- Parenchyma
- Sclereids
- Tracheids
- Collenchyma
Explanation: Sclereids are spherical, thick-walled dead sclerenchyma cells that provide the gritty texture in the pulp of certain fruits.
Which of the following tissues constitutes the 'Stele' of the plant?
- Cortex and Pith
- Outside endodermis
- Inside endodermis
- Epidermis and Cortex
Explanation: The stele includes all tissues on the inner side of the endodermis, such as the pericycle, vascular bundles, and pith.
Which specific cells regulate the opening and closing of stomata?
- Guard cells
- Subsidiary cells
- Mesophyll cells
- Epidermal cells
Explanation: Guard cells enclose the stomatal pore. Their turgidity changes to control the opening and closing of the pore.
Which part of the secondary xylem is dark brown, durable, and resistant to pests due to tannin deposition?
- Sapwood
- Softwood
- Alburnum
- Heartwood
Explanation: Heartwood is the central, non-functional part of the secondary xylem. It is durable due to the deposition of organic compounds like tannins and resins.
Which component of the xylem is uniquely composed of living cells?
- Xylem parenchyma
- Xylem fibres
- Xylem tracheids
- Xylem vessels
Explanation: In xylem, vessels, tracheids, and fibres are dead. Only xylem parenchyma consists of living cells used for storage.
The innermost layer of the root cortex, characterized by the presence of Casparian strips, is the:
- Endodermis
- Hypodermis
- Pericycle
- Epidermis
Explanation: The endodermis is the innermost layer of the cortex. Its radial and tangential walls have water-impermeable suberin deposits called Casparian strips.
Which tissue in the leaf is responsible for most of the photosynthesis?
- Mesophyll
- Pericycle
- Epidermis
- Endodermis
Explanation: The mesophyll contains chlorenchyma cells packed with chloroplasts, making it the primary site for photosynthesis.
The 'Dorsiventral' leaf is a typical characteristic of which group of plants?
- Monocotyledons
- Gymnosperms
- Dicotyledons
- Pteridophytes
Explanation: Dicot leaves are usually dorsiventral (different upper and lower surfaces), whereas monocot leaves are usually isobilateral.
In which plant part is the vascular bundle 'conjoint' and 'closed'?
- Monocot root
- Dicot root
- Monocot stem
- Dicot stem
Explanation: Conjoint closed bundles lack cambium and cannot undergo secondary growth, which is a feature of monocot stems.
Which tissue is known as the 'Packing tissue' of the plant body?
- Phloem
- Xylem
- Sclerenchyma
- Parenchyma
Explanation: Parenchyma is the most common and basic tissue that fills spaces between other tissues, often referred to as packing tissue.
The 'Phellogen', involved in the formation of bark, is also known as:
- Cork cambium
- Secondary phloem
- Vascular cambium
- Primary cortex
Explanation: Phellogen is the cork cambium. It produces phellem (cork) on the outer side and phelloderm (secondary cortex) on the inner side.
Which of the following tissues is characteristically absent in the primary plant body of most Monocots?
- Vascular cambium
- Phloem
- Xylem
- Parenchyma
Explanation: Monocots lack vascular cambium in their vascular bundles, which is why they generally do not undergo secondary growth.
In the stem of a plant, the first-formed primary xylem is known as:
- Protoxylem
- Metaxylem
- Heartwood
- Secondary xylem
Explanation: The first-formed primary xylem elements are called protoxylem, and the later-formed ones are called metaxylem.
Which anatomical feature helps in distinguishing a Dicot root from a Monocot root?
- Number of xylem
- Presence of epidermis
- Exarch xylem
- Radial bundles
Explanation: Dicot roots usually have 2â4 xylem bundles (diarch to tetrarch), while monocot roots have more than six (polyarch).
Which specific meristem is responsible for the regeneration of parts removed by grazing herbivores in grasses?
- Secondary meristem
- Intercalary meristem
- Apical meristem
- Lateral meristem
Explanation: Intercalary meristems occur between mature tissues. They are common in grasses and help regenerate parts eaten by herbivores.