Revision Concepts
Morphology : The study of various external features, forms and relative position of different organs of the organism is known as morphology. It may be further divided into internal and external morphology.
External Morphology : It deals with external forms like shape, size, colour, structure and relative position of different organs.
Internal Morphology : Further divided into anatomy and histology.
Anatomy : It deals with the study of internal structure exposed after dissection and opening of various parts of an organ.
Histology : The study of tissues, their composition and structure.
Adaptation : Any alteration in the structure or function of an organism or any of its part that results from natural selection and by which the organism becomes better ®tted to survive and multiply in its environment.
The Root : The root is underground part of the plant and develops from elongation of radicle of t he embryo.
Characteristics : It ies inside the soild, chlorophyll is absent, absence of nodes and internodes, leaves and budgs; positive geotropic and hydrotropic and negative phototropic.
Main functions of root system :
1. Absorption of water and minerals from the soil.
2. Provides anchorage to plant parts.
3. Stores reserve food material and synthesises plant growth regulators (cytokinins)
Practice Questions
- Which part of a plant absorbs most of the water and minerals taken up from the soil?
(a) Taproots (b) root hairs (c) the thick parts of the roots near the base of the stem (d) storage roots - A plant with a fibrous root system, leaves with parallel venation, and a seed with a single cotyledon is probably a (a) corn plant (b) fern (c) fir tree (d) pine tree Explanation:- The characteristics described in the question are those of a monocot. Among the answers, only corn is a monocot.
- Ginger is an underground stem. It is distinguish from roots because it (a) lacks chlorophyll (b) stores food (c) has nodes and internodes (d) has xylem and vessels Explanation: – Ginger is an underground stem, it is distinguished from root because it has nodes and internodes.
- Match Column-I with Column-II and select the correct option from the codes given below.
Column-I Column-II
A. Marginal (i) Sunflower, marigold
B. Parietal (ii) Pea
C. Axile (iii) Mustard, Argemone
D. Free central (iv) Hibiscus, tomato, lemon
E. Basal (v) Dianthus, Primrose
(a) A-(ii), B-(iii), C-(iv), D-(v), E-(i)
(b) A-(i), B-(iii), C-(ii), D-(v), E-(iv)
(c) A-(i), B-(ii), C-(iii), D-(iv), E-(v)
(d) A-(iii), B-(ii), C-(iv), D-(v), E-(i)
5. Main difference between creepers and trailers is
(a) creepers are rooted at node while trailers don’t
(b) creepers are not rooted at node while trailers do
(c) creepers have internodes while trailers don’t
(d) creepers have node while trailers don’t
Explanation:- Sub-ariel Weak Stems : The weak stem take the support of ground for spreading and proper exposure of leaves and reproductive organs. They are of two categories-trailers and creepers. Creepers root at intervals while trailers do not do so. Breaking of the different rooted parts help in vegetative reproduction in creepers.
6. The fourth whorl of flower is of
(a) Petals
(b) Stamens
(c) Carpels
(d) Sepals
Explanation: – The fourth whorl of flower is of carpels.
7. Refer the given figure and select the incorrect statement regarding this.
(a) This type of root system develops from radicle of embryo.
(b) Lateral roots arising from the main root are exogenous in origin.
(c) Rootlets are the ultimate root branches that bear root hair for absorption.
(d) Secondary and tertiary roots are borne in acropetal succession.
Explanation :- Given figure represents tap roots system. Lateral branches of the roots develop from interior (usually pericycle) of the parent root. Such an origin is called endogenous.