Plant Kingdom: Class 11 Biology Q&A · Page 2
59 free answers on Plant Kingdom (Biology) for Class 11 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- BiologyClass 11All
Which phloem element closely associates with the sieve tube elements?
Companion cells Mechanistic Insight: Companion cells are specialized parenchymatous cells connected to sieve tube elements via plasmodesmata (cytoplasmic bridges). Since mature sieve tubes lack nuclei, companion cells: Control sieve tube metabolism Maintain pressure gradients for translocation Regulate loading/unloading of photoassimilates</s
- BiologyClass 11All
What is the location of protoxylem in a dicot stem?
Protoxylem lies towards the centre (pith) in dicot stems. Advanced Explanation: This arrangement is called endarch condition (proto = first; endo = inside). The sequence of xylem differentiation is: Protoxylem (innermost, smaller vessels) → Metaxylem (outermost, larger vessels) Contrast with Roots: In roots, protoxylem is exarch (
- BiologyClass 11All
In which two forms does sclerenchyma exist in the body of plants?
Solution: Sclerenchyma fibres (elongated, pointed cells) Sclereids (short, isodiametric stone cells) Detailed Comparison: Feature Sclerenchyma Fibres Sclereids <st
- BiologyClass 11All
What is the name given to the specialised regions of active cell division in plants?
Solution:Meristems (or meristematic tissues) Expanded Explanation: Meristems are regions of undifferentiated cells capable of continuous division (mitosis). Based on position, they are classified as: Apical meristems: At root and shoot tips (primary growth) Intercalary meristems: At leaf bases and internodes (grasses) Lateral
- BiologyClass 11All
Distinguish between families Solanaceae, Liliaceae and Fabaceae on the basis of gynoecium characteristics. Also write economic importance of any one of the above family.
Solution: Family Gynoecium Solanaceae Bicarpellary, syncarpous, superior ovary, bilocular, oblique septum, axile placentation, many ovules <stro
- BiologyClass 11All
a) What is fruit? (b) Define parthenocarpic fruit. (c) Describe various zones of fruit by taking any fleshy fruit.
Solution: (a)Fruit: A mature, ripened ovary developed after fertilization, containing seeds. (b)Parthenocarpic fruit: A fruit that develops without fertilization, hence seedless. Examples: Banana, seedless grapes, pineapple (induced parthenocarpy) (c)Zones of a Fleshy Fruit (Mango&mdash
- BiologyClass 11All
Mention three economic importance of the first terrestrial plants having vascular tissues.
Soil binding: Prevents erosion on slopes Medicinal value: Dryopteris provides anthelmintic drugs Ornamental use: Ferns cultivated for decorative foliage
- BiologyClass 11All
Write the names of any three classes of pteridophytes. Give one example for each.
Class Example Psilopsida Psilotum Lycopsida Lycopodium Sphenopsida Equ
- BiologyClass 11All
What type of sexual reproduction is shown by Volvox?
Oogamous reproduction (fusion of large non-motile egg with small motile sperm)
- BiologyClass 11All
What are gymnosperms?
Gymnosperms are vascular seed plants characterized by naked seeds—ovules and seeds not enclosed within ovary or fruit tissue.
- BiologyClass 11All
Name the characteristic red pigment of red algae.
r-Phycoerythrin (phycobiliprotein)
- BiologyClass 11All
Name the structure that fixes brown algae to the substratum.
Holdfast
- BiologyClass 11All
What is meant by a thallus?
A thallus is a plant body lacking differentiation into true roots, stems, and leaves. This simple organization characterizes algae and primitive bryophytes
- BiologyClass 11All
Represent schematically the life cycle of a gymnosperm.
Gymnosperm life cycle (heterosporous, with alternation of generations): Sporophyte (2n) → Male/Female Cones ↓ Male cone: Microsporophylls → Microsporangia → Microspore mother cells → Meiosis → Microspores → Pollen grains (male gametophyte) Female cone: Megasporophylls → Megasporangia (ovules) → Megaspore mother cells → Meiosis → Megaspores → Female gametophyte → Ar
- BiologyClass 11All
Discuss the economic importance of bryophytes.
(a) Soil erosion prevention: Dense mats protect soil from rain impact (b) Soil formation: Pioneer species (Sphagnum) fill ponds/lakes, creating peat soil (c) Water retention: Sphagnum absorbs large water volumes—used for plant transport (d) Peat production: Compressed, fossilized Sphagnum forms peat: Fuel source Soil amendment (
- BiologyClass 11All
Discuss major pigments and cell wall composition of different classes of algae.
Class Pigments Cell Wall Composition Chlorophyceae Chlorophyll a, b Inner cellulose + outer pectose layer Phaeophyceae <td
- BiologyClass 11All
What are the functions of following structures in algae? (b) Mention the pigments and reserve food material.
(a) Functions: Holdfast: Anchors alga to substratum Frond: Leaf-like photosynthetic structure Air bladder: Provides buoyancy for optimal light exposure (b) Brown algae characteristics: Pigments: Chlorophyll a & c, carotenoids, fucoxanthin Reserve food: Laminarin, m
- BiologyClass 11All
Discuss the economic importance of pteridophytes.
(a) Soil conservation: Bind soil on slopes, preventing erosion (b) Medicinal applications: Dryopteris yields anthelmintic (anti-parasitic) compounds (c) Ornamental value: Ferns cultivated for aesthetic foliage (d) Food source: Marsilea provides edible starch for some communities (e) Industrial use: Equisetum stems used for scouring ut
- BiologyClass 11All
What is the dominant phase of pteridophytes and how is it formed?
The sporophyte is dominant in pteridophytes: Formation sequence: Spore mother cells in sporangia undergo meiosis → haploid spores Spores germinate → prothallus (small gametophyte) Prothallus bears antheridia and archegonia Flagellated antherozoids swim to archegonia (requires water) Fertilization
- BiologyClass 11All
Give five main characteristics of brown algae.
Pigmentation: Chlorophyll a & c, fucoxanthin (xanthophyll) imparts brown coloration Habitat: Predominantly marine; abundant in temperate and cold waters Morphological diversity: Range from simple filaments (Ectocarpus) to massive kelps (>100 meters) Storage products: Laminarin (polysaccharide), mannitol (suga