NEET Previous Year Questions(2016-24): Anatomy of Flowering Plants | Biology Class 11 PDF Download

2024

Q1: Bulliform cells are responsible for     (NEET 2024)
(a) Inward curling of leaves in monocots.
(b) Protecting the plant from sall stress.
(c) Increased photosynthesis in monocots.
(d) Providing large spaces for storage of sugars.
Ans: (a)
Sol: Bulliform cells, which are specialized cells found in the leaves of many monocot plants such as grasses, play a crucial role in responding to environmental stress conditions like water scarcity. Their primary function is associated with the mechanism of leaf folding or rolling during drought or high temperature conditions. This adaptive feature helps in reducing the leaf surface exposed to the air, thereby minimizing water loss through transpiration.
Now, let’s evaluate each option in relation to the role of bulliform cells:

Option A: Inward curling of leaves in monocots.
This option is correct. Bulliform cells are large, thin-walled, and filled with water. When these cells lose water under dry conditions, they collapse, causing the leaf to fold or roll inward. This curling mechanism helps to reduce the exposure of the surface area of the leaf to the harsh environment, thus reducing water loss and protecting the plant during drought.

Option B: Protecting the plant from salt stress.
This option is not correct. While bulliform cells are involved in protecting the plant by reducing transpiration, their role specifically in protecting from salt stress isn't well-documented. Salt stress protection involves other physiological and biochemical responses in plants.

Option C: Increased photosynthesis in monocots.
This is also incorrect. Bulliform cells do not directly influence photosynthesis rates. Their function is mainly related to the mechanical folding of the leaf, which indirectly may influence photosynthetic efficiency under stress conditions but is not their primary role.

Option D: Providing large spaces for storage of sugars.
This option is incorrect. Bulliform cells are not involved in the storage of sugars. Their structure and function are geared towards managing water content for leaf folding mechanisms, rather than nutrient storage.

Therefore, the correct answer is Option A: Inward curling of leaves in monocots.

Q2: In the given figure, which component has thin outer walls and highly thickened inner walls?       (NEET 2024)
(a) C
(b) D
(c) A
(d) B
Ans: (a)
Guard cells to stomata have thin outer wall and highly thickened inner walls.

2023

Q1: Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R :           (NEET 2023)
Assertion A : Late wood has fewer xylary elements with narrow vessels.
Reason R : Cambium is less active in winters.
In the light of the above statements, choose the correct answer from the options given below :
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is NOT the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Ans: (a)

Assertion A is true: Late wood, also known as "summer wood," is the portion of a tree ring that is formed during the later part of the growing season. It typically has fewer xylary (wood-forming) elements and narrower vessels compared to early wood.

Reason R is true and provides the correct explanation for Assertion A: The cambium, a layer of actively dividing cells between the xylem and phloem, is responsible for the formation of new xylem cells. During winters, the cambium becomes less active due to the colder temperatures and reduced metabolic activity. This reduced cambial activity leads to the formation of narrower vessels and fewer xylary elements in the late wood.

Q2:  Given below are two statements :          (NEET 2023)
Statement I : Endarch and exarch are the terms often used for describing the position of secondary xylem in the plant body.
Statement II : Exarch condition is the most common feature of the root system.
In the light of the above statements, choose the correct answer from the options given below:
(a) Both Statement I and Statement II are true
(b) Both Statement I and Statement II are false
(c) Statement I is correct but Statement II is false
(d) Statement I is incorrect but Statement II is true
Ans: (d)

• Statement I : Endarch and exarch are the terms often used for describing the position of secondary xylem in the plant body.
• This statement is incorrect. Endarch and exarch are used to describe the developmental sequence of primary xylem, not secondary xylem. In endarch condition, the first formed xylem is towards the centre (protoxylem) and the last formed xylem is towards the periphery (metaxylem), which is typical of stems. In the exarch condition, the first formed xylem is towards the periphery and the last formed xylem is towards the centre, which is typical of roots.
• Statement II : Exarch condition is the most common feature of the root system.
• This statement is true. The exarch condition, where the first-formed xylem is towards the periphery and the last-formed xylem is towards the centre, is indeed the most common feature of the root system.

2022

Q1: Read the following statements about the vascular bundles:            (NEET 2022 Phase 1)
(a) In roots, the xylem and phloem in a vascular bundle are arranged in an alternate manner along the different radii. 
(b) Conjoint closed vascular bundles do not possess cambium. 
(c) In open vascular bundles, cambium is present in between xylem and phloem 
(d) The vascular bundles of dicotyledonous stem possess endarch protoxylem 
(e) In the monocotyledonous root, usually there are more than six xylem bundles present
Choose the correct answer from the options given below:
(a) (b), (c), (d) and (e) Only
(b) (a), (b), (c), (d) and (e)
(c) (a), (c), (d) and (e) Only
(d) (a), (b) and (d) Only
Ans: (d)
All the statements are correct regarding vascular bundles but none of the options with such combination is given.

Q2: In old trees the greater part of secondary xylem is dark brown and resistant to insect attack due to:           (NEET 2022 Phase 1)
(a) secretion of secondary metabolities and their deposition in the lumen of vessels.
(b) deposition of organic compounds like tannins and resins in the central layers of stem.
(c) deposition of suberin and aromatic substances in the outer layer of stem.
(d) deposition of tannins, gum, resin and aromatic substances in the peripheral layers of stem.
(e) presence of parenchyma cells, functionally active xylem elements and essential oils.
Choose the correct answer from the options given below:
(a) (c) and (d) Only
(b) (d) and (e) Only
(c) (b) and (d) Only
(d) (a) and (b) Only
Ans: (d)
In old trees, the greater part of secondary xylem is dark brown due to deposition of organic compounds like tannins, resins, oils, gums, aromatic substances and essential oils in the central or innermost layers of the stem. These substances make it hard, durable and resistant to the attacks of micro-organisms and insects.

Q3: Initiation of lateral roots and vascular cambium during secondary growth takes place in cells of     (NEET 2022 Phase 2)

(a) Pericycle
(b) Epiblema
(c) Cortex
(d) Endodermis
Ans: (a)
Initiation of lateral roots and vascular cambium during secondary growth takes place in pericycle cells of dicot roots. Epiblema, endodermis and cortex do not dedifferentiate.

2021

Q1: Match List I with List II            (NEET 2021)

Select the correct answer from the options given below.
     (a)      (b)     (c)     (d)
(a) (i)      (ii)     (iii)     (iv)
(b) (iii)    (ii)     (iv)     (i)
(c) (ii)     (iv)     (i)      (iii)
(d) (iv)    (iii)    (ii)      (i)

Ans: (c)
(a) Meristematic tissues are those tissues which have cells with active cell division capacity.
(b) Simple tissues are those tissues which have all the cells similar in structure and function.
(c) Vascular tissues are complex permanent tissues hence they have different types of cells.
(d) Sclereids are sclerenchymatous cells which are dead with highly thickened walls and narrow lumen.

Q2: Select the correct pair.            (NEET 2021)
(a) Cells of medullary rays that form part of a cambial ring - Interfascicular cambium
(b) Loose parenchyma cells rupturing the epidermis and forming a lens-shaped opening in the bark - Spongy parenchyma
(c) Large colourless empty cells in the epidermis of grass leaf - Subsidiary cells
(d) In dicot leaves, vascular bundles are surrounded tissue by large thick-walled cells - Conjunctive tissue
Ans: (a) 

• When the cells of medullary rays differentiated, they give rise to the new cambium called interfascicular cambium.
• Loose parenchyma cells rupturing the epidermis and forming a lens-shaped opening in bark are called complementary cells.
• Large colorless empty cells in the epidermis of grass leaves are called bulliform cells.
• In dicot leave, vascular bundles are surrounded by large thick walled cells called bundle sheath cells.

2020

Q1: The transverse section of a plant shows the following anatomical features:    
(i) a Large number of scattered vascular bundles surrounded by bundle sheath. 
(ii) Large conspicuous parenchymatous ground tissue. 
(iii) Vascular bundles conjoint and closed. 
(iv) Phloem parenchyma absent.
Identify the category of plant and its part:            (NEET 2020)
(a) Dicotyledonous stem
(b) Dicotyledonous root
(c) Monocotyledonous stem
(d) Monocotyledonous root
Ans: (c) 
The monocot stem is characterised by conjoint, collateral, and closed vascular bundles, scattered in the ground tissue containing the parenchyma. Each vascular bundle is surrounded by sclerenchymatous bundle-sheath cells. Phloem parenchyma and medullary rays are absent in monocot stems.

2018

Q1: Stomata in grass leaf are          (NEET 2018)   
(a) Dumb-bell shaped
(b) Kidney-shaped
(c) Rectangular
(d) Barrel-shaped
Ans: (a)
Grass being a monocot, has Dumb-bell shaped stomata in their leaves.

Q2: Secondary xylem and phloem in dicot stem are produced by          (NEET 2018)   
(a) Apical meristems
(b) Vascular cambium
(c) Phellogen
(d) Axillary meristems
Ans: (b)

The cells of vascular cambium cut off towards pith, mature into secondary xylem and the cells cut off towards periphery mature into secondary phloem during secondary growth in dicot stem.

Q3: Casparian strips occur in          (NEET 2018)   
(a) Epidermis
(b) Pericycle
(c) Cortex
(d) Endodermis.
Ans: (d)
Endodermis have casparian strips on radial and inner tangential wall. It is rich in suberin.

Q4: Plants having little or no secondary growth are          (NEET 2018)
(a) Grasses
(b) Deciduous angiosperms
(c) Conifers
(d) Cycads.
Ans: (a)
Grasses are monocots and monocots usually do not have secondary growth.
Palm like monocots have anomalous secondary growth

2017

Q1: The vascular cambium normally gives rise to          (NEET 2017)
(a) Primary phloem
(b) Secondary xylem
(c) Periderm
(d) Phelloderm.
Ans: (b)
Cells of vascular cambium divide periclinally both on the outer and inner sides to form secondary permanent tissues, i.e., secondary xylem and secondary phloem.

Q2: Root hair develops from the region of          (NEET 2017)
(a) Elongation
(b) Root cap
(c) Meristematic activity
(d) Maturation.
Ans: (a)
In roots, the root hairs develops from zone of maturation. This zone is differentiated zone thus bearing root hairs.

2016

Q1: Cortex is the region found between          (NEET 2016)
(a) Epidermis and stele
(b) Pericycle and endodermis
(c) Endodermis and pith
(d) Endodermis and vascular bundle.
Ans: (a)
In botanical terms, the cortex of a plant is the region found between the epidermis and the stele. Therefore, the correct answer is:
Option (a) : Epidermis and stele.
To clarify:

• Epidermis: This is the outermost layer of cells in the plant stem and root. It serves as a protective barrier against the external environment.
• Stele: This is the central part of the root or stem, containing the vascular tissue (xylem and phloem), pith, and often a pericycle. The stele is located inside the endodermis.
• The cortex lies between these two layers, functioning mainly in storage and transport of nutrients and water. It is composed primarily of parenchyma cells and is a significant part of the root and stem where it often stores starch.

The other options refer to different parts of the plant anatomy:

• Option C: "Endodermis and pith" - The pith is located in the center of the stem, surrounded by the vascular tissue, which is inside the endodermis. The cortex is not between these two.
• Option D: "Endodermis and vascular bundle" - The endodermis is a single layer of cells forming a boundary between the cortex and the stele; it doesn't define the boundaries of the cortex.
• Option B: "Pericycle and endodermis" - The pericycle is a layer of cells found just inside the endodermis, and it is part of the stele. This option does not correctly describe the position of the cortex.

Thus, Option A is the most accurate in describing the location of the cortex in a plant.

Q2: Specialized epidermal cells surrounding the guard cells are called          (NEET 2016)
(a) Bulliform cells
(b) Lenticels
(c) Complementary cells
(d) Subsidiary cells.
Ans: (d)
Specialized epidermal cells surrounding the guard cells are known as Subsidiary or accessory cell.

2015

Q1: Vascular bundles in monocotyledons are considered closed because:          (NEET 2015)
(a) Cambium is absent
(b) There are no vessels with perforations
(c) Xylem is surrounded all around by phloem
(d) A bundle sheath surrounds each bundle
Ans: (a)
Vascular bundles in monocotyledons are considered as closed because cambium is absent in the vascular system and thus they lack secondary growth in the thickness.

2014

Q1: You are given a fairly old piece of dicot stem and a dicot root. Which of the following anatomical structures will you use to distinguish between the two?          (NEET 2014)
(a) Secondary xylem
(b) Secondary phloem
(c) Protoxylem
(d) Cortical cells
Ans: (c)
The anatomically fairly old dicotyledonous root is distinguished from the dicotyledonous stem by position of protoxylem. In dicot root the protoxylem is located near the periphery of the vascular cylinder while in dicot stem the protoxylem is located near the centre of vascular bundle i.e., the xylem is endarch.