Biology : Taxonomy Part-IV

Total Questions: 40

1. Desert plants have longer root systems because: [U.P.P.C.S. (Pre) 1996]

(a) High temperature of the soil stimulates the growth of roots
(b) Roots grow in search of water
(c) Soil does not contain water, hence becomes compact and presses the roots to grow longer
(d) Roots move opposite to the solar heat

Correct Answer: (b) Roots grow in search of water

Solution:Desert plants have the capability to complete their life-cycle even in a dry atmosphere. The root system of these plants becomes longer in search of water from the soil and their stems are small, adapted and underground sometimes. Plant varieties that have adapted by developing very long roots are collectively known as phreatophytes.

2. Deserts have phreatophytes, i.e., plants that have: [R.A.S./R.T.S. (Re. Exam) (Pre) 2013]

(a) Succulent stem (100-200 mm thick)
(b) Lipid accumulation (20-30 mm) in leaves
(c) Long (20-30 ft) tap roots
(d) Small (2-3 mm) or spine-like leaves

Correct Answer: (c) Long (20-30 ft) tap roots

Solution:Phreatophyte is a deep-rooted plant that obtains a significant portion of water that it needs from the phreatic zone or the capillary fringe above the phreatic zone. These plants maintain water status which is largely independent of soil water. Their long tap roots (up to 25-30 meters length) reach the underground water level to take water.

3. Plants adapted to dry climates are known as: [R.A.S./R.T.S. (Pre) 1993]

(a) Epiphyte
(b) Xerophyte
(c) Hydrophytes
(d) Mean plants

Correct Answer: (b) Xerophyte

Solution:

Xerophytes:

These are plants that have evolved to survive in dry, arid conditions, often with limited water availability. They exhibit various adaptations like reduced leaf surface area, storage of water, or deep root systems to access water from the ground.

Hydrophytes:

These are aquatic plants that have adapted to live in water environments, often with specialized structures like aerenchyma for buoyancy and gas exchange.

Epiphytes:

These are plants that grow on other plants, typically for physical support, but not for obtaining nutrients or water from the host plant.

Mean plants:

There isn't a specific scientific term "mean plants". This phrase is not used in botany or ecology.

4. Desert plants are generally — [U.P. Lower Sub. (Pre) 2013]

(a) Viviparous
(b) Succulent
(c) Herbaceous
(d) Heterophyllous

Correct Answer: (b) Succulent

Solution:A succulent is a plant that stores water for times when water is not available to it. Succulent plants are generally found in arid environments such as deserts and semi-deserts.

Vivipary is a type of seed germination where the seed germinates while still attached to the parent plant, and the embryo develops inside the fruit,
Herbaceous plants are characterized by their non-woody stems and are not a type of seed germination. They are categorized by their stem structure.

Heterophylly refers to the presence of different types of leaves on the same plant, which can be due to environmental conditions or developmental stages. It's not a type of seed germination.

5. Epiphytes are plants which depend on other plants for: [I.A.S. (Pre) 2001]

(a) Food
(b) Mechanical support
(c) Shade
(d) Water

Correct Answer: (b) Mechanical support

Solution:An epiphyte is a plant that grows harmlessly upon another plant (such as a tree), fulfilling moisture and nutrients from the air, rain, and sometimes from debris accumulating around it, instead of the structure to which it is fastened. Epiphytic organisms usually derive only physical support and not nutrition from their host, though they may sometimes damage the host.

6. Plants which grow on saline soils are: [53rd to 55th B.P.S.C. (Pre) 2011]

(a) Xerophytes
(b) Hydrophytes
(c) Halophytes
(d) Succulents

Correct Answer: (c) Halophytes

Solution:Halophytes or aquatic plants are plants that have adapted to live in an aquatic environment. Plants growing on saline soils or water are called halophytes (salt-loving plants). They grow in saline semi-deserts, mangrove swamps, marshes and sloughs and seashores.

Xerophytes:

Hydrophytes:

These are aquatic plants that have adapted to live in water environments, often with specialized structures like aerenchyma for buoyancy and gas exchange.

Succulent:

A succulent is a plant that stores water for times when water is not available to it. Succulent plants are generally found in arid environments such as deserts and semi-deserts.

7. What are salt-loving plants called? [67th B.P.S.C. (Pre) (Re. Exam) 2022]

(a) Xerophytes
(b) Mesophytes
(c) Glycophytes
(d) Halophytes
(e) None of the above/More than one of the above

Correct Answer: (d) Halophytes

8. A hydrophyte is : [U.P.P.C.S. (Pre) 1994,R.A.S./R.T.S. (Pre) 1999]

(a) A marine animal
(b) An aquatic plant
(c) A plant disease
(d) A rootless plant

Correct Answer: (b) An aquatic plant

9. Plants growing on rocks are called : [R.A.S./R.T.S. (Pre) 2010]

(a) Epiphytes
(b) Halophytes
(c) Xerophytes
(d) Lithophytes

Correct Answer: (d) Lithophytes

Solution:Lithophytes are plants that grow in or on rocks. Those that grow on rocks are also known as epilithic or epiphytic plants. Lithophytes feed off nutrients from rainwater and nearby decaying plants, including their own dead tissues.

10. Which one of the following pairs is not correctly matched? [U.P. R.O./A.R.O. (Pre) 2017]

(a) Cuscuta - Stem parasite
(b) Chandan - Root parasite
(c) Orchids - Epiphyte
(d) Nepenthes - Hydrophyte

Correct Answer: (d) Nepenthes - Hydrophyte

Solution:Nepenthes are not hydrophytes. They are tropical pitcher plants and a genus of carnivorous plant. Other pairs are correctly matched.

Cuscuta (Dodder):

Cuscuta is a parasitic vine that lacks chlorophyll and cannot photosynthesize. It derives its nutrients from the host plant by attaching itself to the host's stem and forming specialized structures called haustoria, which allow it to draw nutrients from the host's vascular system. It's known as amarbel in India.

Chandan (Sandalwood):

Chandan is a root parasite, meaning it derives its nutrients from the roots of its host plant. It has adapted to parasitic lifestyles, often growing on the roots of other trees and plants.

Orchids:

Orchids are epiphytes, not parasites or root parasites. They grow on other plants (like trees) for support, but they don't take nutrients from their host. They are known for their diverse and beautiful flowers.

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