Tag: morphology of the stem

Questions Related to morphology of the stem

Stems have played and important role in plant evolution. Their functions have changed and evolved over a period of time. From the list given below (i to iv), identify the functions performed by stems in different types of plants.
(i) Photosynthesis
(ii) Support
(iii) Storage
(iv) Spread and dispersal of plants

botany stem - external morphology morphology of the stem stem shoot system in plants

  1. (i) and (ii) only

  2. (i), (ii) and (iii) only

  3. (i), (ii), (iii) and (iv)

  4. (ii), (iii) and (iv) only

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Correct Option: C
Explanation:

In some plants, the stem has been modified to perform different functions. These are the adaptations shown by the plants due to adaptation and evolution. 

In dessert plants, the stem become green and flat to perform photosynthesis. 
In climbers, the stem tendrils cling or wound on the other plants to provide support. 
In rhizome and tubers, the food is stored in the stem. 
In plants like runners which spread on the land, the seeds or the spores are dispersed. This helps in the dispersed growth of the plants. 
Thus, the correct answer is option C. 

Waxy coating on epidermis of young stem is

botany stem - external morphology morphology of the stem stem shoot system in plants

  1. Suberin

  2. Periderm

  3. Phellem

  4. Cuticle

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Correct Option: D
Explanation:

Cuticle is a protecting film covering the epidermis of leaves, young shoots and other aerial plant organs without periderm. 

It consists of lipid and hydrocarbon polymers impregnated with wax and is synthesized exclusively by the epidermal cells. The cuticle is composed of an insoluble cuticular membrane impregnated by and covered with soluble waxes. Cutin, a polyester polymer composed of inter esterified omega hydroxy acids which are crosslinked by ester and epoxide bonds, is the best known structural component of the cuticular membrane.

Unbranched, erect, cylindrical stout axis with distinct nodes and internodes and with jointed appearance is called as

botany stem - external morphology morphology of the stem stem shoot system in plants

  1. Runner

  2. Sucker

  3. Culm

  4. Caudex

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Correct Option: C
Explanation:

Erect, unbranched stems with distinct nodes and internodes are called culms, nodes are swollen giving a jointed appearance. For example, bamboo.

Plants belonging to family Cactaceae  stores water in stems. It means, they are 

botany stem - external morphology morphology of the stem stem shoot system in plants

  1. Ephemerals

  2. Drought resistants

  3. Annuals

  4. Non-succulents

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Correct Option: B
Explanation:

Cactaceae have many adaptations that make them drought resistant in dry areas. They have a thick and hard-walled stem that helps in water storage. The stems of Cactaceae are fleshy and photosynthetic. A thick and waxy coating of it helps the cactus from evaporating excess water. Instead of leaves, most of them have spines or scales which are modified leaves. These spines and scales do not lose water through evaporation and protect the cactus from herbivores.

So, the correct answer is 'Drought resistants'

Shoot or stem develops from

botany stem - external morphology morphology of the stem stem shoot system in plants

  1. Plumule

  2. Radicle

  3. Bothof (A) and (B)

  4. None of the above

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Correct Option: A
Explanation:

Shoot or stem develops from plumule. Shoot or stem develops from plumule. Plumule is the future shoot of a plant as radicle is the future root of the plant. Plumule is positively phototrophic.
Thus, the correct answer is option A.

Lacunar collenchyma is specifically present in hypodermis of

botany stem - external morphology morphology of the stem stem shoot system in plants

  1. Cucurbita stem

  2. Sunflower stem

  3. Brinjal stem

  4. Maize stem

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Correct Option: A
Explanation:

Cucurbita stem has lacunar collenchyma or tubular collenchyma which is characterized by the presence of distinct intercellular spaces and deposition of pectocellulose is on the wall of intercellular spaces. Sunflower stem has lamellar or plate collenchyma which is characterized by cell wall thickening on the tangential walls giving the cell lamellar or plates like appearance. Brinjal stem has angular collenchyma which is characterized by deposition of pectocellulose are at the angles of the cell. Maize stem has sclerenchymatous hypodermis.
Therefore, the correct answer is option A.