Test your comprehensive knowledge of the structural organisation of plants and animals, including morphology, anatomy, and physiological processes, based on NCERT Biology.
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Showing questions 81 - 100 of 128
81. The ground tissue in leaves, consisting of thin-walled chloroplast containing cells, is called:
In leaves, the ground tissue consists of thin-walled chloroplast containing cells and is called **mesophyll**.
82. Which of the following statements is true regarding vascular bundles in monocotyledons?
In the monocotyledons, the vascular bundles have **no cambium** present in them. Hence, since they do not form secondary tissues they are referred to as **closed**.
83. In roots, how are xylem and phloem arranged within the vascular bundles?
When xylem and phloem within a vascular bundle are arranged in an **alternate manner along the different radii**, the arrangement is called **radial** such as in roots.
84. In a dicotyledonous root, the innermost layer of the cortex is called the endodermis. What waxy material is deposited on its tangential and radial walls in the form of casparian strips?
The tangential as well as radial walls of the endodermal cells have a deposition of water-impermeable, waxy material **suberin** in the form of casparian strips.
85. In a dicotyledonous root, initiation of lateral roots and vascular cambium during secondary growth takes place in which layer?
Next to endodermis lies a few layers of thick-walled parenchyomatous cells referred to as **pericycle**. Initiation of lateral roots and vascular cambium during the secondary growth takes place in these cells.
86. What is the key anatomical difference between monocot and dicot roots regarding xylem bundles?
As compared to the dicot root which have fewer xylem bundles, there are usually **more than six (polyarch) xylem bundles in the monocot root**. Also, Monocotyledonous roots do not undergo any secondary growth.
87. In a young dicotyledonous stem, what is the outer hypodermis composed of, and what is its primary function?
The outer hypodermis, consists of a few layers of **collenchymatous cells** just below the epidermis, which provide **mechanical strength** to the young stem.
88. What is the innermost layer of the cortex in a dicot stem called, and what is it rich in?
The innermost layer of the cortex is called the **endodermis**. The cells of the endodermis are rich in **starch grains** and the layer is also referred to as the starch sheath.
89. A characteristic feature of dicot stems is the arrangement of vascular bundles in a ring. What type of vascular bundles are they?
A large number of vascular bundles are arranged in a ring; the ‘ring’ arrangement of vascular bundles is a characteristic of dicot stem. Each vascular bundle is **conjoint, open, and with endarch protoxylem**.
90. Which of the following anatomical features is characteristic of a monocotyledonous stem?
The monocot stem has a **sclerenchymatous hypodermis**, a large number of scattered vascular bundles... The **phloem parenchyma is absent**, and water-containing cavities are present.
91. In a dorsiventral (dicotyledonous) leaf, which epidermal surface generally bears more stomata?
The **abaxial epidermis generally bears more stomata** than the adaxial epidermis. The latter may even lack stomata.
92. The mesophyll in a dorsiventral leaf is differentiated into two types of parenchyma cells. What are they?
Mesophyll... has two types of cells – the **palisade parenchyma and the spongy parenchyma**.
93. What is a key difference in mesophyll structure between a dorsiventral (dicot) leaf and an isobilateral (monocot) leaf?
In an isobilateral leaf... the **mesophyll is not differentiated into palisade and spongy parenchyma**.
94. In grasses, certain adaxial epidermal cells along the veins modify into large, empty, colourless cells. What are these cells called, and what is their function?
These are called **bulliform cells**. When they are flaccid due to water stress, they make the leaves curl inwards to **minimise water loss**.
95. Which of the following is true regarding secondary growth in flowering plants?
The **secondary growth occurs in most of the dicotyledonous roots and stems**.
96. In unicellular organisms, all essential functions like digestion, respiration, and reproduction are performed by:
In unicellular organisms, all functions like digestion, respiration and reproduction are performed by a **single cell**.
97. A group of similar cells along with intercellular substances performing a specific function in multicellular animals is called a(n):
In multicellular animals, a group of similar cells alongwith intercellular substances perform a specific function. Such an organisation is called **tissue**.
98. How many basic types of tissues comprise all complex animals?
You may be surprised to know that all complex animals consist of only **four basic types of tissues**.
99. Which of the following statements correctly defines 'morphology' in the context of animals?
Morphology refers to study of form or externally visible features. In the case of animals this refers to the **external appearance of the organs or parts of the body**.
100. Frogs belong to which class and phylum?
Frogs can live both on land and in freshwater and belong to **class Amphibia of phylum Chordata**.