Monthly archives: April, 2012

Distinguishing characters of Pteridophytes

Pteridophytes: 1. The life cycle shows distinct heteromorphic alternation of generation. 2. Plant body of Sporophyte is dominant phase. 3. Sporophyte is differentiated into true root, stem and leaves. 4. Vascular tissue i.e xylem and phloem are present. Xylem lacks vessels but tracheids are present. In phloem sieve tubes and companion cells are absent. 5. …

Pteridophytes

This division includes club mosses, horsetails and ferns. The oldest known pteridophytes are fossils from the end of the silurian period, 380 million years ago. Pteridophyta constitutes the earliest known vascular plants. Vascular plants are those plants that contain the vascular tissue that is the conducting tissues of xylem and phloem. Sometimes all vascular plants …

Bryophytes

There are fossil records of blue green algae (Cyanobacteria) living 3000 million years ago and many eukaryotic organisms have existed for more than 1000 million years. However the first organisms to colonize the land, primitive plants did so only 420 millions years ago. The greatest simple problem to overcome in making the transition from water …

Algae

In Algae the plant body shows no differentiation into root, stem or leaf or true tissues. Such a plant body is called thallus. They do not have vascular tissues. The sex organs of this group of kingdom plantae are not surrounded by a layer of sterile cells. Algae are autotrophic organisms and they have chlorophyll. …

Economic importance of Fungi

Fungi are useful to mankind in many ways. These organisms play an important role in medicine, agriculture and industry. They have harmful effects also. Useful aspects of fungi The antibiotic Penicillin was discovered in 1928 by Alexander Fleming of Britain from the fungus Penicillium notatum, which in 1940s emerged as a ‘wonder drug’ for the …

Ascocarps

The ascomycetes or sac fungi are identified by the presence of spores called ascospores, which are enclosed in a sac like structure. These ascocarps are of three types: 1.Cleistothecium: These are closed and spherical ascocarps. eg. Eurotium 2. Perithecium: These are flask shaped ascocarps. eg. Neurospora. 3. Apothecium : These are cup shaped ascocarps. eg.Peziza.

Classification of Fungi

Traditionally fungi have been regarded as plants. At one time fungi were given the status of a class and together with the class algae formed the division Thallophyta of the Plant Kingdom. The thallophyta were those plants whose bodies could be described as thalli. A thallus is a body, often flat, which is not differentiated …

Nutrition in Fungi

Fungi are heterotrophic in their mode of nutrition that is they require an organic source of carbon. In addition they require a source of nitrogen, usually organic substances such as amino acids. The nutrition of fungi can be described as absorptive because they absorb nutrients directly from outside their bodies. This is in contrast to …

Fungi

Conventionally Fungi have been included in plant kingdom. But in pursuance of Whittaker’s five kingdom classification Fungi and Plants (Algae, Bryophytes, Pteridophytes Gymmosperms and Angiosperms) are described here as two separate kingdoms. Angiosperms are not described in detail here. Salient Features Fungi are non chlorophyllous, eukaryotic, organisms. They are a large and successful group. They …

Significance of Viruses

1. Viruses are a kind of biological puzzle to biologists since they are at the threshold of living and non-living things showing the characteristics of both. 2. They are very much used as biological research tools due to their simplicity of structure and rapid multiplication. They are widely used in research especially in the field …

Tyrannosaur Found in China

Finding by American Museum of Natural History Paleontologists and Others Underscores Evolutionary Links among Living Birds and Non-Avian Dinosaurs Yutyrannus huali, was covered from head to tail in downy feathers, which is assumed to be an ancestor of Tyrannosaur rex. It is found to be 30 feet large and 3000 pounds in weight, but was …