In secretory phase during ovulation, the follicle breaks and collapses under the continuous influence of Luteinizing Hormone (LH). It begins to enlarge and forms a yellowish structure, called the corpus luteum. The corpus luteum plays an important role in the preparation of the endometrium for the implantation of the fertilised egg by secreting oestrogens and progesterone.

The plants obtained through genetic engineering contain a gene or genes usually from an unrelated organism, such genes are called transgenes and the plants containing transgenes are known as transgenic plants. These plants are often called as genetically modified or GM crops, eg, Flavor saur transgenic for identification, expressing the gene activity in time to produced several chemicals likes fatty acids sugars cellulose, rubber, etc.

Malignant tumour first grows slowly. No symptoms are noticed. This stage is called the latent stage. The tumour later grows quickly. The cancer cells go beyond adjacent tissue and enter the blood and lymph. Once this happens, they migrate to many other sites in the body, where the cancer cells continue to divide. It is metasis. Only maligant tumours are properly designated as cancer.

The general features of genetic code are:

(i) The genetic code is written in linear form, using the ribonuclotide bases that compose mRNA molecule as letters.

(ii) Each word of codon consists of three letters, ie, the codon triplet.

(iii) The genetic code inside the cell medium is said to be non-ambiguous.

(iv) The code is degenerate, ie, a given amino acid can be specified by more than one codons.
(v) The codon contains start and stops signals.

(vi) The code is said to be commaless.

(vii) The code is said to be commaless.

The seeds of castor (Ricinus communis, family -Euphorbiaceae) are endospermic dicot seeds. They possess  endosperm which acts at the food storgage tissue of seed. They also possess perisperm and cruncle.

The Montreal protocol on substances that deplete the ozone layer is a landmark international agreement designed to protect the stratospheric ozone layer.  The treaty was originally signed in 1987 and substantially amended in 1990 and 1992. The Montreal protocol stipulates that the production and consumption of compounds that deplete ozone in the stratosphere-chlorofluorocarbons (CFCs) halons, carbon tetrachloride, and methyl chloroform are to be phased out 2000 (2005 for methyl chloroform).

Biochemical Oxygen Demand (BOD) is the amount of oxygen used for biochemical oxidation by micro-organisms in a unit volume of water. Polluted water has high BOD. Thus, when sewage gets mixed with river water, BOD will increase.

Tonsil is a mass of lymphoid tissue, several of which are situated at the back of the mouth and throat in higher vertebrates.


The thymus is haemopoietic as well as an endocrine gland.The thymus is the seedbed of thymic lymphocytes (T-lymphocytes). Certain stem cells, originating in yolk sac and liver in the early embryo, migrate into the thymus and proliferate to form a large number of lymphocytes.

The thyroid is an endocrine gland.

Thalamus is the part forebrain in vertebrate lies above the hypothalamus.

The stools, which the infant passes out is quite yellowish due to bile pigments passed through bile juice.

Semiconservative replication of DNA was first demonstrated in E.coil. According to the semiconservative mode proposed by Waston and Crick, each strand of the two double helices formed would have one old and one new strand. The semiconservative nature of DNA of replication was proved by the experiment of Meselson and Stahl (1958).