General Science - Biology: Diversity In Living Organisms (Notes)

Differentiation in Plants

(i) Thallophyta

- Plants that do not have well differentiated body design fall in this group.

- The plants in this group are commonly called algae. These plants are predominantly aquatic.

E.g. : Spirogyra, cladophora and chara.

(ii) Bryophyte

- These are called the amphibians of the plant kingdom. There is no specialized tissue for the conduction of water and other substances from one past of the plant body to another.

E.g. : moss (fumaria) and marchantia

(iii) Pteridopheysta

- In this group plant body is differentiated into roots, stem and leaves and has specialized tissue for the conduction of water and other substances from one plant of the plant body to another. Eg- marsilea, ferns, and horse tails.

(iv) Gymnosperms

- The plant of this group bear naked seeds and one usually perennial and evergreen and woody.

Eg- pines such as deodar.

(v) Angiosperms

- The seeds develop inside an organ which is modified to become a fruit.

These are also called flowering plants.

- Plant embryos in seeds have structures called cotyledons. Cotyledons are called seed leaves because in many instances they emerge and become green the seed germinates.

- The angiosperms are divided into two groups on the basis of the number of cotyledons present in the seed.

- Plants with seeds having a single cotyledon are called monocotyledons or monocots. Eg- paphiopedilum.

- Plants with seeds having two cotyledons are called dicots. Egipomoce.

Differentation of Animals

(i) Porifera

These are non mobile animals attached to some solid support. There are holes or pores all over the body. These lead to a canal system that helps in circulating water throughout the body to bring in food and O2. They are commonly called sponges mainly found in marine habitats.

(ii) Coelenterata

- These are animals living in water. The body is made up of two layers of cells.

One makes up cells on the outside of the body and the other makes the inner living of the body.

- Some of these species live in colonies while others have a solitary life e.g. span (Hydra) jellyfish are common example.

(iii) Platyhelminthes

- There are three layers of cells from which different tissues can be made.

This allow outside and inside body linings as well as some organs to be made.

- Thus there is some degree of tissues formation.

- They are either free living or parasitic. e.g. Planarians, liver flukes.

(iv) Nematode

- These are very familiar as parasitic worms causing diseases such as the worms causing elephantiasis (filaria worms) or the worms in the intestine (round or pin worms)

(v) Annelida

- They have true body cavity. This allows true organs to be packaged in the body structure. There is thus an extensive organ different ion. This differentiation occurs in a segmental fashion with the segment lined up one after the other from head to tail. Eg- Earthworms, leeches.

(vi) Arthropods

- There is an open circulatory system and so the blood does not flow in well defined blood vessels. They have joint legs.

Eg- prawns, butterflies, houseflies, spiders, scorpions and crabs.

(vii) Mollusca

- They have an open circulatory system and kidney like organs for excretion.

There is a little segmentation. There is a foot that is used for moving around. Egsnails, and mussels, octopus.

(viii) Echinodermate

- There are spiny skinned organisms.

These are exclusively free living marine animals. They have peculiar water driven tube system that they use for moving around. They have hard calcium carbonate structure that they use as skeleton.

Eg- starfish, sea cucumber.

(ix) Protochordats

- They are marine animals.

Eg- balanoglossus, hardemania and amphioxus.

(x) Vertebratia

- These animals have a true vertebral column & internal skeleton. These are grouped into five classes.

Pisces

- These are fish. They are cold blooded and their hearts have only two chambers unlike the four that human have.

- Some with skeletons made entirely of cartilage, such as shark.

- Some with skeleton made of both bones and cartilages such as tuna or rohu.

(xi) Amphibian

- They have mucus glands in the skin and a three chambered heart.

Respiration is through either gills or lungs.

Eg- frogs, toades, and salamanders.

(xii) Reptilia

- These animals are cold blooded have scales and breathe through lungs. While most of them have a three chamber heart while crocodile have four heart chambers.

Eg- snakes, turtles, lizards and crocodiles.

(xiii) Aves

- These are warm blooded animals and have a four chambered heart. They lay eggs. They breathe through lungs. All birds fall in this category. (xiv) Mamalia

- They are warm blooded animals with four chambered hearts.

- They have mammary glands for the production of milk to nourish their young. They produce live young ones.

- However a few of them like platypus and the echidna lay eggs.