Ecological Plant Groups (Short Questions and Answers)

Ecological Plant Groups

Short Questions and Answers

One Mark Questions with Answers

1. Swollen spongy petioles are present in

(a) Eichhornia

(b) Pistia

(c) Hydrilla

(d) Laminaria

Answer: (a) Eichhornia

 2. Typha is a

(a) submerged hydrophyte

(b) emerged hydrophyte

(c) floating hydrophytes

(d) attached hydrophyte with floating leaves

Answer: (a) submerged hydrophyte

3. Which of the plants is devoid of roots?

(a) Azolla

(b) Ceratophyllum

(c) Hydrilla

(d) Vallisneria

Answer: (c) Hydrilla

4. Sun loving plants are known as

(a) heliophytes

(b) sciophytes

(c) halophytes

(d) xerophytes

Answer: (a) heliophytes

5. An aquatic plant with floating leaves have

(a) stomata on both leaf surfaces

(b) stomata on petiole only

(c) stomata on upper surface

(d) stomata on lower surface

Answer: (c) stomata on upper surface

6. Plants such as Pandanus and Rhizophora are examples of

(a) xerophytes

(b) mesophytes

(c) hydrophytes

(d) halophytes

Answer: (d) halophytes

7. In general, a plant most likely to survive in area where temperature is high, relative humidity is low and wind prevalent, would have leaves

(a) large and broad

(b) large intercellular air spaces

(c) reduced palisade tissue

(d) small and narrow

Answer: (d) small and narrow

8. Hydrilla and Vallisneria are examples of

(a) submerged aquatic plants

(b) floating aquatic plants

(c) aquatic plants with floating leaves

(d) amphibious plants with dimorphic leaves

Answer: (a) submerged aquatic plants

 9. Which group of plants has to face physiological dryness?

(a) halophytes

(b) lithophytes

(c) hydrophytes

(d) epiphytes

Answer: (a) halophytes

 10. Desert plants have longer root system because

(a) high temperature of soil encourageous root growth

(b) low temperature at night encourageous root growth

(c) those plants adapted to produce long root system can survive better in a desert

(d) roots grow in search of water

Answer: (c) those plants adapted to produce long root system can survive better in a desert

 11. Which of the following is not the characteristic feature of the anatomy of xerophytes?

(a) spongy parenchyma

(b) well-developed conducting tissue

(c) well developed mechanical tissue

(d) thick cuticle

Answer: (a) spongy parenchyma

 12. In submerged hydrophytes the functional stomata are found

(a) on the upper surface of leaf

(b) on the lower surface of leaf

(c) on both surfaces of leaf

(d) no where

Answer: (d) no where

Two Marks Questions with Answers

1. Differentiate between free floating and floating plants.

Answer: Free floating plants float freely and independently on water surface.  Examples are, Eichhornia, Lemma, Pistia etc.  Floating (presence of roots) plants float on the surface of water.  These plants attach themselves to the bottom with the help of their roots.  Examples are, Nymphaea, Trapa etc.

2. What are submerged plants? Give examples.

Answer:  Submerged plants occur below the water surface, but are not attached.  Examples are, Ceratophyllum, Najas etc. Submerged (presence of roots plants occur below the water surface and also remain attached to the bottom of water reservoir.  Examples are, Hydrilla, Vallisneria etc.

3. Differentiate between amphibious and emergent plants.

Answer: Ambhibious (presence of roots) plants grow in waterlogged soils.  Examples are, Polygonum, Marsilea etc while emergent (presence of roots) plants grow in shallow waters and remain attached to the bottom.  A part of the plant is below the water surface and a part above it.  Examples are, Cyperus, Typha etc.

4. What are xerophytes?

Answer: Xerophytes are group of plants that survive in dry regions.  They grow in deserts, dry hilly regions.  They adapt themselves to dry and sandy or rocky soils having poor water content and extreme atmospheric conditions.  Xerophytes can withstand drought, intense light, extreme temperature and strong wind. Such a habitat is termed as xeric.

5. What is hydrochasy?

Answer:  In some desert grasses, the leaves roll due to the presence of motor or bulliform cells in the epidermis.  These cells are sensitive to changes in turgor and thus, contract when conditions are dry.  This results in upward rolling of leaves and cutting of the stomatal contact with external atmosphere.  This reduces the rate of transpiration.  This feature is termed as hydrochasy.

Three Marks Questions with Answers

1. Mention the anatomical characters common to all hydrophytes.

Answer: (1).  All hydrophytes show presence of large air chambers.  The tissue that forms air chambers is termed as aerenchyma.

(2).  Mechanical tissue, i.e., sclerenchyma is either poorly developed or absent.

(3).  Vascular tissue, particularly xylem is poorly developed.

(4).  Cuticle is absent.

(5).  Stomata are absent in submerged hydrophytes.

2. Mention some of the anatomical features of Eichhornia Petiole:

Answer: Transverse section of the petiole shows the following characters:

(1) Epidermis: This is a single layer of cells.  The cuticle is absent.

(2) Hypodermis: Parenchymatous tissue, present below the epidermis forms the hypodermis.

(3) Aerenchyma: The remaining part of the petiole is termed as ground tissue.  It has many air chambers or lacunae.  The size of the air chambers gradually increases towards the centre.

(4) Vascular tissues: Numerous vascular bundles are present here and there between the air chambers.  A distinct parenchymatous envelope surrounds each vascular bundle.  Phloem occurs in the peripheral part of the bundle and a single element of xylem is present in the centre.

3. Mention some of the morphological adaptation of xerophytes.

Answer: Following are some of the morphological characters of xerophytes.

(1).  The root system is well developed.

(2).  The plants usually have a long and stout tap root which branches profusely.

(3).  Presence of root hairs.

(4).  The roots go deep into the soil in search of water.

(5).  The shoot is generally hard and woody.

(6).  It is mostly covered with hairs, wax, and silica etc.

(7).  Stem may also be fleshy and growth remains stunted.

(8).  Some of the plants show modified stems; e.g., in Opuntia, the stem forms leaf-like structure termed as phylloclade.  In Asparagus and Ruscus, the leaf-like structure formed by the leaf is termed as cladode.

 4. What are the different types of xerophytes?

Answer: Depending on their ability to withstand drought condition of the soil, following are the different classes of xerophytes:

  1. Ephemeral annuals (drought escaping): Such xerophytes complete their life cycle before the arrival of dry condition; e.g., Argemone mexicana, Cassia, Solanum xanthocarpum etc.
  2. Succulents: These are drought resisting xerophytes.  Succulents grow in habitats with less or no water but store water whenever available.  They are perennial in habit and resist drought by accumulating water in leaves, stems and roots; e.g., Opuntia, Aloe, Cactus etc.
  3. Perennial non-succulents (drought-resistant): These are drought enduring xerophytes.  They grow in habitat with almost no water, they also cannot store water.  During drought growth of the plant stops and it takes place only during the brief period of plenty of water supply during rainfall; e.g., Nerium, Calotropis procera, Acacia arabica, etc.