NCERT Solutions for Class 9 Science Chapter 7

Gymnosperm have naked seeds whereas Angiosperms have seed inside their fruits.

(i) Phanerogams are higher plants that bear flower and seeds.
(ii) Seeds are the result of reproductive process.
(iii) They contain an embryo which store food.
(iv) They are further divided into Gymnosperms and Angiosperms.
(v) Angiosperm have seeds inside the fruits.

Whether the organism is prokaryotic or eukaryotic is the primary characteristic.

(i) It enables us to study living things more easily and understand them better.
(ii) It helps to identify and communicate about the large number of living organisms on earth.
(iii) It helps to trace the possible origins of different living organisms to determine any relationship.

Thallophytes body is not well differentiated, no vascular tissue present, usually contain green pigment and have cell wall made up of cellulose. Spirogyra, Ulva are thallophytes and are aquatic.

Aves:
(a)They lay eggs.
(b) Do not have mammary glands.
(c) Their body is covered with feathers.
Mammalia:
(a) They give birth to young ones.
(b) They have mammary glands.
(c) Their body is covered with hairs.

Carolus Linnaeus proposed the system of binomial nomenclature.

(a) Platyhelmintes:
(i) Their body is bilaterally symmetrical.
(ii) They are triploblastic
(iii) There is no coelom.
(b) Nematoda:
(i) Their body is cylindrical and bilaterally symmetrical.
(ii) Pseudocoelom is present.
(iii) They are triploblastic.

There are millions of species on this earth. For anybody, it is impossible to study about each of them in his lifetime. Classification makes it easy to study the organisms; on the basis of certain common characters.

We need to look at the fact if given character is present in a small number of organisms or a larger number of organisms. In the first case, the commonality of characters would represent a species. In the latter case, the commonality of characters would represent a higher taxa; like genus, family, order or phylum.

Following points explain the basis of grouping organisms into five kingdoms. Organization of nucleus: Organisms with unorganized nucleus are kept under the kingdom Monera. Those with organized nucleus are kept in other kingdoms. Number of cells: Unicellular eukaryotes are kept in the kingdom Protista, while multicellular eukaryotes are kept in other kingdoms. Mode of nutrition and presence of cell wall: Hetereotrophic organisms in which cell wall is present are taken under the kingdom fungi. Autotrophic organisms in which cell wall is present are taken in the kingdom Plantae. Organisms in which cell wall is absent are taken in the kingdom Animalia.

The major divisions of Plantae and the basis for these divisions are as follows: Thallophyta: Simple body design; with no differentiation into root, stem and leaves. Bryophyta: Body is differentiated into stem and leaf-like structures. Vascular system is absent. Pteridophyta: Body is differentiated into root, stem and leaves. Vascular system is present. Reproductive organs are inconspicuous. Seeds are not produced. Gymnosperms: Seeds are naked. Angiosperms: Seeds are covered.

In the plant kingdom, morphological characters are taken into consideration while deciding about the divisions. Morphology is the study of shapes and forms of various parts. In the animal kingdom, anatomical characters are taken into consideration while deciding about subgroups. Anatomy is the study of various organs’ design in animals.