GATE Life Science Mock Test- 1 (Botany & Zoology) - GATE Life Sciences MCQ

The radial wave function of hydrogen atom for 3s orbital is given by the relationship

The oxide of alkali and alkaline metals are more basic than transition metal oxides because basic character of the oxides decreases across the period. Among transition of metal oxides, the acidic character increases with increase in oxidation state of the transition metal. The order of increasing basic character of the oxides is

CrO₃ < Cr₂O₃ < MnO < MgO
+6 +3 +2 +2

Percent change in energy 

The dwarf pea mutant as used by Mendel in his experiment had a defect in BA3β-hydroxylase involved in the biosynthesis of gibberellins.

Here the recessive allele in homogenous condition marks the effect of dominant allele. For e.g. In mice, the wild body colour is known as agouti (greyish) and is controlled by gene say A which is hypostatic to recessive allele C. The dominant allele C in the presence of 'a' gives coloured mice. In the presence of dominant allele C, A gives rise to agouti. So, ccaa will be coloured and ccAA will be albino. When coloured mice (CCaa) are crossed with albino (ccAA), agouti mice (CcAa) appear in F1. Small cc mask the effect of AA and is therefore epistatic. Consequently, ccAA is albino. The ratio 9 : 3 : 3 : 1 is modified to 9 : 3 : 4. The combination ccAA is also albino due to the absence of both the dominant alleles.

Geological time scale shows the ages of various eras and periods together with the major groups of plants and animals that are believed to have existed during that period. It has been divided into 6 major era. An era may be further divided into periods and periods into epoch. Mesozoic era is divided into 3 period namely cretaceous, jurassic and triassic. First bird archaeopteryx appeared in jurassic period. Archaeopteryx is a link between reptile and bird, having reptilian long tail, teeth and avian feathers and beak. In cretaceous period, the first modern bird appeared and the previous archaeopteryx became extinct.

Wuchereria bancroftii passes its life cycle in 2 hosts: man (definitive host) and mosquito (intermediate host). The embryonic stage of Wuchereria bancroftii is known as microfilariae. Sheathed microfilariae are ingested by the mosquito during its blood meal. They cast off the sheath quickly, penetrate the gut wall within an hour or two, and migrate to the thoracic muscle. Here they rest and begin to metamorphose. Within 2 weeks, the microfilariae develop into infective larvae inside the mosquito thoracic muscle through 3 larval stages. The infective stage of microfilariae then enters the proboscis sheath of mosquito.

The sickle-cell allele causes a change in the structure of blood cells that does not allow the malarial parasite to reproduce. Thus, there is some advantage to heterozygotes where malaria is a danger. Homozygotes for non-sickled blood cells would be more likely to suffer from malaria and thus less likely to reproduce. Homozygotes for sickled blood cells do not have enough oxygen carrying capacity and thus are less likely to survive to reproduce. Heterozygotes are likely to survive better than either alternative. Thus, they are more likely to survive and transfer either allele to their offspring. This will allow the sickle allele to remain at high frequency in the population. In populations where malaria is not a danger, there is no advantage of carrying the sickle allele. Thus, it will gradually decrease in frequency in the population.

Mitotic cyclin ubiquitination is performed by APC (Anaphase Promoting Complex), which is activated in late mitosis by the association of Cdc20. The destruction of cyclin B (Mitotic cyclin) is required for exit from mitosis, and is mediated by the ubiquitin pathway. Recently, a 20S complex, termed the anaphase-promoting complex (APC) or the cyclosome, has been genetically and biochemically identified as the cyclin-specific ubiquitin ligase (E3). In addition, a ubiquitin-conjugating enzyme (E2), UBC4, was shown to be involved in cyclin ubiquitination in xenopus egg extracts. Another E2 activity, designated UBCx, can independently support cyclin ubiquitination in xenopus. A similar activity (E2 - C) has also been observed in clams.

Bacterial chemotaxis is the most widely studied two component sensory system. Chemotaxis is the cell's response to a stress environment. It is controlled by more than 40 genes in over 14 operons that produce proteins for the structural components of the flagella, the flagellar motor, transmembrane receptors, and signal transduction. In a typical two component system, a receptor protein transduces environmental signals into metabolic changes though phosyphorylation of a second protein. The signal cascade requires the transfer of a phosphate group from an autophosphorylating protein kinase to a regulator protein. In bacterial chemotaxis, transmembrane chemoreceptors, the CheA histidine kinase, and the CheW coupling protein assembles into signalling complexes that allow bacteria to modulate their swimming behaviour in response to environmental stimuli. The rate of autophosphorylation of the protein CheA is controlled by the transmembrane receptor proteins. CheA then in turn transfers the phosphate group at aspartate residues to another protein, CheY, which interacts directly with the flagellar switch to affect a change in swimming pattern.

Oxidation of glyceraldehyde - 3 - phosphate to 1, 3 - bisphosphoglycerate is catalysed by glyceraldehyde - 3 - phosphate dehydrogenase. The aldehyde group of glyceraldehyde - 3 - phosphate first reacts with the – SH group of an essential Cys residue in the active site of the enzyme. Iodoacetate reacts with the – SH group of Cys residue in glyceraldehyde - 3 - phosphate dehydrogenase. Hence, iodoacetate is a potent inhibitor of glyceraldehyde - 3 - phosphate dehydrogenase.

From the given data, we can calculate that the expected double crossover if there is no interference.
(0.1 x 0.2) = 0.02 or 2%
Coefficient of coincidence is the ratio of the observed to the expected double crossovers.
Therefore, coefficient of coincidence = 1.6/2.0 = 0.8