Tag: leaf - external morphology

Questions Related to leaf - external morphology

The cuticle present above the epidermis is helpful in reducing 

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. Transpiration

  2. Respiration

  3. Photosynthesis

  4. None of the above

Show answer
Correct Option: A
Explanation:

The cuticle is comprised of polymers of wax. This layer is present on the surface of the epidermis of leaf and stem. This is the waxy and waterproof layer. This layer prevents the loss of water from the leaves and stem. This protective layer allows the retention of the water. This helps to reduce the loss of water in the form of water vapour by transpiration. 

Thus, the correct answer is option A. 

A Leaf of $20 \,cm^2$ grows $5 \,cm^2$ per hour and $B$ Leaf of $25 \,cm^2$ grows $5 \,cm^2$ per hour
The relative growth rate of leaf $A$ and $B$ respectively is

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. $25\%$ and $20\%$

  2. $20\%$ and $25\%$

  3. $50\%$ and $100\%$

  4. $25\%$ and $50\%$

Show answer
Correct Option: A
Explanation:

Relative growth is the increase in size relative to the size of the plant leaf present at the start of a given time interval. It can be also expressed as percentage increase.

Hence, for leaf A, relative growth = 5/20 × 100 = 25
For leaf B, relative growth = 5/25 × 100 = 20.
So, the correct option is '25 and 20'.

A modification of petiole is

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. Phyllode

  2. Phylloclade

  3. Cladode

  4. Corm

Show answer
Correct Option: A
Explanation:

Phyllode is a green, expanded structure formed by the modification of petiole or rachis of the leaf. In most of the xerophytes, leaves are reduced to prevent water loss in such plants phyllodes develop to carry out photosynthesis.

An example is Acacia.
So the correct option is 'Phyllode'

Swollen lower end of leaf stalk is

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. Petiole

  2. Pulvinus

  3. Thalamus

  4. Disc

Show answer
Correct Option: B
Explanation:

A swelling at the base of a petiole is known as pulvinus. It is a joint-like thickening at the base of a plant leaf or leaflet that facilitates growth-independent movement. For example, mango, pea and gram.
Therefore, the correct answer is option B.

Leaves develop from

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. Nodes

  2. Internodes

  3. Epidermis

  4. Endodermis

Show answer
Correct Option: A
Explanation:

Leaves develop from nodes. Apart from leaves, branches and aerial roots also develop from nodes from the stem. It also holds buds. Adventitious roots may also develop from it. Internodes are the intervals between the nodes. 

Thus, the correct answer is 'Nodes.'

Sometimes a few epidermal cells in the vicinity of guard cells become specialized in their shape and size are known as 

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. Stomatal aperture

  2. Trichomal cell

  3. Subsidiary cells

  4. Stomata

Show answer
Correct Option: C
Explanation:

The few epidermal cells surrounding the guard cells are modified to act as subsidiary cells. They lack chloroplasts and help in functioning of the guard cells by maintaining the water and solute balance with the guard cells.

A. Stomatal aperture is the opening of the stomata. It is also called stomatal pore.
B. Trichome cells give rise to the hair-like outgrowth called the trichomes.
C. Subsidiary cells are the modified epidermal cells near the guard cells.
D. Stomata are surrounded by the guard cells.
Hence, the correct answer is 'Subsidiary cells'

Go through the following matches.

(i) China rose Twisted aestivation
(ii) Calotropis Valvate aestivation
(iii) Gulmohur Ascending imbricate aestivation
(iv) Pea Descending imbricate aestivation

Which of these are correct?

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. (i), (ii) and (iii)

  2. (ii), (iii) and (iv)

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

  4. All are correct

Show answer
Correct Option: A
Explanation:
i) China rose - One margin of the appendage overlaps that of the next one (Twisted aestivation).
ii)Twisted aestivation -  The sepals or petals in whorl just touch one another at the margin (Valvate aestivation).
iii) Gulmohar botanical name is Delonix - Ascending imbricate aestivation.
iv) Tephrosia is a genus of flowering plants in the pea family - Descending imbricate aestivation.
So, the correct option is 'All are correct'. 

Leaf is _________ in origin.

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. Endogenous

  2. Exogenous

  3. Axillary

  4. Indefinite

Show answer
Correct Option: B
Explanation:

Leaves are exogenous (develop away from the plant body) in origin and develops from the swollen leaf primordium of the growing apex.

So, the correct option is 'Exogenous'.

A distinct endodermis is a constant feature of

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. Dicot leaves

  2. Monocot stems

  3. Monocot leaves

  4. Dicot stema

Show answer
Correct Option: A
Explanation:
The cells of the endodermis typically have their primary cell walls thickened on four sides radial and transverse with suberin, a water-impermeable waxy substance which in young endodermal cells is deposited in distinctive bands called Casparian strips.
So the correct option is 'Dicot leaves'.

Guard cells are kidney shaped in 

botany leaf - external morphology morphology of leaf structure of a leaf the leaf

  1. Rice

  2. Beans

  3. Grasses

  4. Maize

Show answer
Correct Option: A
Explanation:
  • Guard cells are specialized epidermal cells present on the surface of leaves and stems of plants that control the gaseous exchange in plants.
  • The guard cells form stomatal pores through which gaseous exchange and transpiration take place.
  • In monocots, the guard cells are dumbbell shape.
  • In dicots, they are kidney or bean shaped.
  • So, the correct answer is 'Beans'.