Secretions of which one of the following structures does not help in maturation and motility of sperms?

All food chains begin with producers, except -

Identify the practices followed to avoid sexually transmitted infection
A. Avoiding sex with unknown partners/multiple partners
B. Using condom during coitus
C. Periodic Abstinence
D. Insertion of copper-T in the uterus
Choose the correct answer from the option given below:

Plants can capture only 2-10% of the PAR and this small amount of energy sustains the entire world. Here PAR stands for:

Fungi are also known to form symbiotic associations with plants. This is known as-

DNA recombinant technology involves the use of restriction endonucleases. After having cloned the gene of interest and having optimised the conditions to induce the expression of the target protein, one has to consider producing it on a large scale. The cells harbouring cloned genes of interest may be grown on a small scale in the laboratory. In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes. Presence of more than one recognition sites within the vector will generate several fragments, which will complicate the gene cloning. In Biolistics or gene gun method cells are bombarded with high velocity micro particles of gold or tungsten coated with DNA. The ligation of alien DNA is carried out at a restriction site present in one of the two antibiotic resistance genes. For example, you can ligate a foreign DNA at the BamH I site of tetracycline resistance gene in the vector pBR322. Since the DNA is enclosed within the membranes, we have to break the cell open to release DNA along with other macromolecules such as RNA, proteins, polysaccharides and also lipids. The RNA can be removed by treatment with ribonuclease whereas proteins can be removed by treatment with protease. Other molecules can be removed by appropriate treatments and purified DNA ultimately precipitates out after the addition of chilled ethanol.
Which one of the following enzymes should be used to break the bacterial cells for isolation of DNA?

About ______ the first cellular forms of life appeared on earth.

The flocculating power of \(\left[ Fe ( CN )_6\right]^{4-}\) is higher than \(PO _4^{3-}\) ion because :

Two charges, \(+ 20 \, μC\) and \(+ 40 \, μC\) are placed at a separation of 4 cm. The electric potential due to the pair at the middle point of the line joining the two charges is:

A compound is formed by two elements X and Y.
Atoms of 'Y' make ccp and those of element 'X' occupy tetrahedral voids.
The formula of the compound is:

A proton moves from south to north with a speed of \( 2 \times 10^7 \, \text{m/s} \). When a magnetic field is applied from west to east, the proton gets an acceleration of \( 10^{12} \, \text{m/s}^2 \). The mass of the proton is \( 1.6 \times 10^{-27} \, \text{kg} \). The value of the magnetic field is:

If \(A=\left[\begin{array}{cc}3 & 1 \\ 2 & -3\end{array}\right]\) be such that \(A^{-1}=K A\), then the value of \(K\) is :

Read the passage carefully to answer the questions given below
Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). In Bacillus thuringiensis the toxin is coded by a gene crylAc named cry. There are a number of them, for example, the proteins encoded by the genes crylAc and cryllAb control the cotton bollworms, that of crylAb controls corn borer. Using conventional methods of diagnosis (serum and urine analysis, etc.) early detection is not possible. Recombinant DNA technology, Polymerase Chain Reaction (PCR) and Enzyme Linked Immuno-sorbent Assay (ELISA) are some of the techniques that serve the purpose of early diagnosis. The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency. This enzyme is crucial for the immune system to function. The disorder is caused due to the deletion of the gene for adenosine deaminase. RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA.
RNAi involves involves silencing of a specific mRNA due to a complementary__________ molecule that binds to and prevents translation of the mRNA.