GATE Life Science Mock Test - 4 (Biochemistry & Micro Biology) - GATE Life Sciences MCQ

'Before' and 'Back' are also used in reference to time; however, only 'ago' is in reference to present time, which is the context here.

Percentage of whisky in mixture = 75%
Percentage of whisky in water = 0%

Therefore, mixture and water should be mixed in the ratio of 2 : 1.
or,
We need to replace 1/3rd or  of the mixture with water.

Pipes P, Q, and R have rates of filling/emptying the tank as follows:

• P fills the tank at the rate of 1/6 per hour.
• Q fills the tank at the rate of 1/9 per hour.
• R empties the tank at the rate of 1/12 per hour.

Step 1: For the first 4 hours, pipes P and R are open:
Net rate = (1/6 - 1/12) = 1/12 per hour.
Volume filled in 4 hours = 4 x (1/12) = 1/3 of the tank.

Step 2: For the next 6 hours, pipes Q and R are open:
Net rate = (1/9 - 1/12) = 1/36 per hour.
Volume filled in 6 hours = 6 x (1/36) = 1/6 of the tank.

Total volume filled after 10 hours (4+6) = 1/3 + 1/6 = 1/2 of the tank.

Step 3: After 10 hours, only pipe Q is open (R is turned off).
Pipe Q fills the remaining half of the tank at the rate of 1/9 per hour.

Time taken to fill the remaining half = (1/2) / (1/9) = 4.5 hours.

Total time taken to fill the tank = 10 + 4.5 = 14.5 hours.

Dehydration of  in acidic condition gives stable conjugated alkene.

Since EMF of the cell is not additive, therefore we can use the Gibbs energy as:

Rate = K[CH₃Cl][H₂O]²   
When H₂O is taken in large excess, concentration of water remains constant with time.
∴ Rate = K[H₂O]² [CH₃Cl] = K'[CH₃Cl]

A and R both are correct but R is not the correct explanation of A.
Transposition starts by forming a strand transfer complex in which the transposon is connected to the target site through one strand at each end.
Replicative Transposition Proceeds through a Cointegrate. Replication of a strand transfer complex generates a cointegrate, which is a fusion of the donor and target replicons. The cointegrate has two copies of the transposon, which lie between the original replicons. Recombination between the transposon copies regenerates the original replicons, but the recipient has gained a copy of the transposon.

In delayed hypersensitivity, also known as Type IV hypersensitivity, the characteristic lesions typically appear after 48-72 hours of the second exposure to the antigen. This immune response is mediated by T-cells and does not involve antibodies.

Papain is a proteolytic enzyme belonging to cysteine protease family. Papain is found in unripe papaya and also in mountain papaya. Papain has a sulfhydryl group required for enzyme activity and a polypeptide chain accompanied by 3 disulfide bridges. Papain can digest protein substrates. Bromelain is a combination of proteolytic enzyme and small amounts of other substances like acid phosphatase, peroxidase, calcium and protease inhibitors. Bromelain is obtained from both stem and fruit of pineapples. Bromelain has anti-inflammatory effects and interferes with slow blood clotting.

It is a sphingolipid storage disease. It is an autosomal recessive disorder, which causes impairment of brain functions. It occurs when alarming level of ganlioside GM2 is stored in brain's nerve cells and leads to premature death of cells. Death results by the age of four. There is no known cure of this deadly disease.

Correct order of various steps of Variable Number of Tandem Repeats (VNTR) technique is: (i) → (iii) → (ii) → (v) → (iv)  → (vi)

Isolation of DNA → digestion of DNA by restriction endonucleases → separation of DNA fragments by electrophoresis → transferring (blotting) of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon → hybridisation using labelled VNTR probe → detection of hybridised DNA fragments by autoradiography.

Class-II MHC molecule is a transmembrane glycoprotein with cytoplasmic tails and extracellular Ig like domains; the domains are referred to as α₁, α₂, β₁ and β₂. In class I MHC molecule, α₁ and α₂ have antigenic peptide binding cleft. So, they are polymorphic. In Class II MHC, polymorphic domain is in α₁ and β₁.

Addition or elimination of a proton supplied by acid/base helps to increase the substrate's reactivity. Reaction involving two species can be accelerated by an enzyme by holding the substrate and enzyme close together. Thus, acid-base catalysis and catalysis by proximity decrease activation energy. A temporary covalent bond between substrate and enzyme is formed due to covalent catalysis. The chemical modification is temporary and the enzyme returns to the unmodified state on completion of the reaction. The substrate's binding to enzyme's active site weakens the target bond and make it susceptible to cleavage. Thus, covalent catalysis and catalysis by strain decrease the activation energy.

Enzyme glyceraldehyde-3-phosphate dehydrogenase catalyses the conversion of glyceraldehyde-3-phosphate into 1,3-bisphosphoglycerate. Iodoacetate is a potent inhibitor of glyceraldehyde-3-phosphate dehydrogenase because it forms a covalent derivative of essential –SH group of cysteine at enzyme's active site, rendering it inactive.

Among the various hormones that affect the expression of the PEPCK gene are insulin, thyroid hormone, glucagon and glucocorticoids, all of which act by means of specific transcription factors that bind to the DNA. The sites at which transcription factors bind to the region flanking the PEPCK gene are called response elements. GR is a member of a superfamily of nuclear receptors that are thought to have evolved from a common ancestral protein. The GRE consists of palindromic sequence. It is seen to consist of two defined stretches of nucleotides separated by three undefined nucleotides. The two-fold nature is important because pairs of GR polypeptides bind to DNA as dimers in which each subunit of the dimer binds to one-half of the DNA sequence.

It is a selective medium because it supports the growth of Gram-negative and inhibits Gram-positive bacteria due to the presence of crystal violet and bile salts. It is also differential medium because it differentiates between lactose fermenters and lactose non-fermenters.

Organic carbon is formed by conversion of atmospheric CO₂ or dissolved in water with the help of green plants, algae and some microorganisms (produce organic substance from inorganic carbon).

It is not true as Chaetomium atrobrunneum infects both animals and humans showing a proclivity for the tissues of the central nervous system. It causes fatal brain abscesses in immunologically impaired people.

Tetanus toxin tetanospasmin prevents the release of glycine. As a result, the opposite set of muscles often contracts simultaneously and in uncontrollable fashion, giving rise to characteristic tetanic spasms. Glycine is an inhibitory neurotransmitter that inhibits postsynaptic potential.