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Short & Long Question Answers with Solution: Anatomy of flowering plants | Biology Class 11 - NEET PDF Download

Short & Long Type Questions


Q.1. Is Pinus an evergreen tree?
Ans:
Evergreen plants maintain their green leaves year-round. Pinus is a member of the gymnosperm category, characterized by its thick bark and needle-like leaves that minimize transpiration. This adaptation allows Pinus to thrive in cold temperatures, as it sustains photosynthesis even in frigid conditions without shedding its leaves.


Q2. How would you distinguish between them if you are provided with a microscopic preparation of a transverse section of meristematic tissue and permanent Tissue?
Ans: Meristematic tissues are composed of cells that can divide, and these cells exist in different shapes without intercellular space between them. These cells are thin-walled and rich in protoplasm. They do not contain vacuoles. While permanent tissues are derived from meristematic Tissue, their cells have a definite shape, size, and function. These cells can be thin-walled (living) or thick-walled (dead).


Q3. Why are phloem and xylem complex tissues?
Ans: Xylem and phloem consist of multiple cell types that work together in harmony to execute various functions.

  • Xylem facilitates the transport of water and minerals while offering structural support to the plant. Its components include tracheids, xylem parenchyma, and xylem fibers.
  • Phloem, on the other hand, transports nutrients throughout the plant and consists of sieve tubes, phloem parenchyma, companion cells, and phloem fibers. This intricate arrangement classifies them as complex tissues.


Q4. Are there any elements of phloem which are comparable to those of Xylem? Explain. 
Ans:
(a) The phloem sieve elements are comparable to the Xylem vessel because of both tack nuclei.
(b) Phloem and xylem fibre are similar because both provide tensile strength to the Tissue.
(c) Phloem parenchyma and Xylem parenchyma are the living components of phloem and Xylem, respectively. 


Q.5. Name the modifications of epidermal cells and the functions performed by them.
Ans:  Here are the alterations observed in epidermal cells:

Root Hair:

  • Root hairs are single-cell extensions originating from epidermal cells. They serve to enhance the surface area for water and material absorption.

Epidermal Appendages (Trichomes):

  • Epidermal appendages, known as trichomes, can be single or multiple cells in structure. They provide defense against insects, aid in temperature regulation, and minimize water loss for the plant.


Q6. What is the epidermal cell modification in plants which prevents water loss?
Ans:
In grasses, certain adaxial epidermal cells along the veins modify themselves into large, empty, colourless cells. These are called bulliform cells or motor cells. Bulliform cells help in the folding and unfolding of grass leaves.
The leaf surface is exposed when the bulliform cells in the leaves have absorbed water and are turgid. When flaccid due to water stress, the leaves curl inwards (inrolling) to minimise water loss (transpiration).


Q.7. What are guard cells?
Ans: Guard cells, specialized plant cells found in the epidermis of various plant organs, have a crucial role in enabling gas exchange and regulating transpiration. They achieve this by controlling the opening and closing of stomata.


Q8. PaIm is a monocotyledonous plant, yet it increases in girth. How is it possible? 
Ans: A pain louse is not a plant, hence does not have primary cambium in the vascular bundles of the stem. However, the tree grows in diameter. A secondary cambium may be found in the hypodermal region of the stem. The latter forms the conjunctive Tissue and patches of met cells. The activity of meristematic cells results in the formation of secondary vascular bundles. 


Q9. How do open vascular bundles differ from closed vascular bundles?
Ans:
Open vascular bundles are vascular structures in plants that allow for secondary growth, which means these plants can grow in girth over time. In contrast, closed vascular bundles do not permit secondary growth, meaning they remain fixed in size and do not expand in girth. This distinction arises from the presence or absence of cambium tissue, a meristematic tissue responsible for secondary growth. Open vascular bundles contain cambium, while closed vascular bundles lack cambium, restricting their ability to increase in size. This variation in vascular bundle structure impacts a plant's overall growth and development.


Q10. What are the reproductive parts of a flower?
Ans: The primary reproductive components of a flower are the stamen and pistil. The stamen, also called the Androecium, serves as the male reproductive organ, composed of the anther and filaments. On the other hand, the pistil, known as the gynoecium, functions as the female reproductive organ, featuring three essential parts: the stigma, style, and ovary. These reproductive structures play pivotal roles in pollination, fertilization, and the production of seeds, ensuring the plant's reproductive success.

Q11. What are the three tissues systems classified in flowering plants? Name the tissues under every system.
Ans: 
In flowering plants, there are three basic tissue systems:

  • Dermal tissue system: It is composed of the epidermis layer, which helps in protection. But during secondary growth, it is replaced by periderm.
  • Vascular tissue system: It consists of Xylem and phloem, found in the stele. In the root system, the vascular bundles are renal and found in exarch conditions, whereas, in the stems, these vascular bundles are collateral.
  • Ground or Fundamental Tissue: It includes all the tissues except dermal and vascular, which act as parenchyma and sclerenchyma cells. It is found mainly between the epidermis layer and vascular cylinder and is formed of thin-walled cells that include intercellular spaces between them. Collenchyma cells are usually thickened at the corners , whereas Sclerenchyma c is dead Tissue, without protoplast and provide mechanical support.


Q12. What is wood? What are Its different types?
Ans:  Botanically, the secondary Xylem is called Wood. It is generated by the plant’s metabolism, which includes secondary growth by cambium that constitutes the bulk of the plant body in both the dicot stem & dicot root. Wood is classified into main categories.

  • Hardwood: – Hardwood is the Wood produced by angiosperms. It consists mainly of xylem vessels, also called porous Wood. 
  • Soft Wood: – Softwood is the Wood produced by gymnosperms. It consists mainly of xylem tracheids & hence it is called a non-porous Wood. 
  • Heartwood: Heartwood is the central core of Wood formed during secondary growth. It consists of dead cells. The cells are dark in colour due to extractives like gums, resins, tannins, etc. 
  • Sap Wood: – It is the peripheral part of Wood formed during the secondary growth process. It consists of living cells, which are lighter in colour as the extractives are not present. 
  • Early Wood: – Earlywood is the Wood formed during a favourable season. It mainly consists of vessels and tracheids. 
  • Late Wood: – Latewood is the Wood formed during unfavourable seasons. It mainly consists of vessels & tracheids.


Q13. Explain  the phloem of an angiosperm with its components briefly.
Ans: Phloem is food and mineral conducting Tissue which consists of –

  • Sieve elements: Sieve elements occur as a single cell in pteridophytes, gymnosperms and longitudinal files of cells in angiosperms. The morphological specialisation includes developing a sieve area on the walls bearing sieve plates. Also, the sieve plate bears many perforations.

The protoplasmic strands are continuous through these perforations within the adjacent sieve tubes. A thin layer of parietal cytoplasm and a large central vacuole is formed in a mature sieve element. One of the major important features of sieve elements is that they lack a nucleus at maturity.

  • Companion cells: Companion cells are thin-walled, containing living narrow parenchyma cells closely associated with the sieve tube elements. They appear rounded or polygonal, containing dense granular cytoplasm, a prominent nucleus, and numerous small vacuoles. These companion cells lack starch.

The nuclei of the companion cells serve as the common nucleus of sieve tubes because they lack them. The companion cells mainly occur in angiosperms, accompanying the sieve tube elements.

  • Phloem fibres: Phloem fibres form a prominent part of the primary and secondary phloem. They contain elongated cells with lignified walls having simple pits. These cells provide support and help in the transportation of food material. They are also used for making cords and ropes etc.
  • Phloem parenchyma: Phloem parenchyma are the living parenchyma cells associated with sieve tube cells. These cells are elongated along with sieve tube cells. These cells are elongated and pointed in shape and store starch, fat, and other organic substances. The tannins and resins are also found in these cells, and They too are elongated like the sieve elements.

The sieve element is considered a living component which lacks a nucleus at maturity.


Q14.  Distinguish between:

  1. Phellem and Phelloderm
  2. Open Bundle and closed Bundle
  3. Fascicular cambium and inter fascicular cambium
  4. Conjoint vascular bundles and Radial vascular bundles
  5. Periderm and Bark

Ans: 

1. Phellem and Phelloderm

  • Philem: Philem is a dead tissue formed by the cork cambium’s activity in the cortex’s outer regions during secondary growth. It is protective in function.
  • Phelloderm: On the other hand, phelloderm is a living tissue formed by the cork cambium’s activity in the cortex’s inner side. It regains and regrows during secondary growth. It performs the function of storage.

2. Open Bundle and closed Bundle

  • Open Bundles are classified as avascular bundles containing cambium between Xylem and phloem. Like in a dicot stem.
  • Closed Bundles are classified as avascular handles lacking cambium between Xylem and phloem. Like in a monocot stem.

3. Fascicular cambium and inter fascicular cambium

  • The fascicular cambium is a cambium strip found between the Xylem and phloem of each vascular Bundle of a dicot stem.
  • Interfascicular cambium is a cambium strip formed from the cells of medullary rays adjoining the fascicular cambium. Dining secondary growth occurs.

4. Conjoint vascular bundles and Radial vascular bundles

  • Conjoint vascular bundles contain Xylem and phloem, which lie in the same bundles. They also lie on different radii alternating with each other. The most common example is dicot and monocot root.

5. Periderm and Bark

  • Periderm: It includes three tissues consisting of phellogen, phellem and phelloderm. These cells are formed in the peripheral region of the axis.
  • On the other hand, bark includes all the Tissue external to the secondary Xylem formed during secondary growth. These are cambium and secondary phloem.

Q15. Describe the internal structure of a dorsiventral leaf.
Ans: Dicots exhibit dorsiventral leaves. When examined under a microscope, the vertical section of a dorsiventral leaf consists of three main parts, they are:

  1. Epidermis: The epidermis is the outermost root layer with no intercellular spaces, stomata, or cuticles. It also bears unicellular root hairs. 
  2. Mesophyll: it is a tissue found in between the abaxial and adaxial epidermises. This Tissue is differentiated into the palisade parenchyma and the spongy parenchyma. The palisade parenchyma comprises tall, compactly arranged cells, while the spongy parenchyma comprises round or oval, loosely-arranged cells possessing intercellular spaces. Mesophyll comprises chloroplasts that carry out photosynthesis.
  3. Vascular system: The vascular bundles found in leaves are closed and conjoint, engirdled by thick layers of bundle-sheath cells.
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