life cycles of organisms

Why are Organisms Composed of Cells? - All living organisms are composed of structural and functional units called cells. The body of a living organism may be composed of a single cell - as in unicellular organisms or many cells - as in multicellular org..

Introduction - The term ecology is derived from two Greek words (oikos - means 'house' or place to live and logos means 'a discussion or study'). Literally, ecology is the study of organism 'at home' in their native environment. The term was first introduced by Reiter in 1868, but was ful..

Introduction - Alcohols, phenols, ethers, aldehydes, ketones and carboxylic acids are compounds with functional groups containing oxygen. An alcohol contains one or more hydroxyl (OH) groups(s) attached to aliphatic carbon atom(s). For e.g., ethyl alcohol formula CH 3 , CH 2 , OH is an alcohol. A p..

1) They produce food for all organisms 2) They provide beneficial substances like drugs, tannins, fibres, rubber, vegetable oils, fuel, condiments. 3) Some plants contain alkaloids which check growth of cancer cells. Example: Rosy periwinkle. 4) Plants release O 2 , cool environment by r..

Functional groups containing nitrogen are present in a variety of naturally occurring and man made organic compounds. These functional groups impart physico- chemical characteristics to these molecules. These groups are responsible for their unique chemical reactivity patterns and p..

"Biogeochemical cycles are the cyclic pathways through which chemical elements move from environment to organism and back to the environment". Since such movements of elements and inorganic compounds is essential for maintenance of life, they are also called 'nutrient..

Death - Death is the final termination of the life activities. Every living organism has a life cycle involving its birth, growth and death. The duration of life between the birth and death of an organism, represents its life spa..

. According to this theory, Each adult organism grows from a zygote. The zygote is a diploid cell having two sets of chromosomes - maternal and paternal. The zygote by mitotic divisions results in the formation of an adult and thus, all the vegetative or somatic cells of an organismh..

. The male sex organs are called antheridia and female sex organs are called archegonia. Antheridia produce antherozoids and archegonia enclose the egg cell. Fertilisation requires water. The diploid zygote is retained in the archegonial venter where it develops into an embryo. ..

On the basis of host- parasite relationship, there are different types of parasitism. a) Temporary parasitism and b) Permanent parasitism. Temporary parasitism is also referred as partial or intermittent parasitism. Here, the parasite spends most of its life cycle as indepen..