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- Total number of questions : 20
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Zoology [ Question No: 1 To 20 ] :
Inclusive fitness refers to .............
Sarich and Wilson (1967) demonstrated that human, Gorilla and Chimpanzee were genetically equidistant and distinct for Orangutan and the divergence time is approximately :
Gastrulation in Drosophila begins with a change in cell shape and contraction of an epithelium sheet from the apical surface, this process is called as :
In the chick limb, the signal for condensation of mesenchymal cells to give rise to cartilage comes from the appearance of :
Which of the following groups of transcription factors (TFs) is responsible for maintaining the pluripotency of stem cells ?
The embryonic origin of squamous cell carcinoma is :
For long distance runner, the muscle needs increased O2 supply. At the muscle, this is formed by :
Which one of the following is not readily absorbed in the small intestine ?
Mark the most INCORRECT statement with respect to mammalian below :
A phenomenon in which animals adapted to temperate regions have shorter and poorly developed ears, eyes, hair and other phenotypic traits follow :
The nerve impulse :
..................... is involved in the specification of germ cells in all animals studied.
The Sewall Wright effect occurs because of :
Which one of the following electrodes will be a preferred choice for recording of transmembrane potential of a living cell ?
In which organ hydrochloric acid is secreted ?
Which organ is secondary lymphoid organ?
Digestion process occurring in higher animals is
Which of the following would not increase the stroke volume of the heart ?
The "foramen of Panizza" is found in which one of the following groups of animals?
Muscle performance is positively correlated with Darwinian fitness. The graph below describes the relationship between mean environmental temperature and muscle performance for two closely related lizard species, one living in temperate areas (solid line) and another living in tropical areas (dashed line). Current mean environmental temperatures are marked with vertical dotted lines at (i) for the temperate species and (ii) for the tropical species. If mean environmental temperatures at both locations increase at a steady rate over time, which one of the following is most likely to occur in the near future?
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20
Zoology [ Question No: 1 To 20 ] :
Inclusive fitness refers to .............
Your Answer : (Not Answered)
Correct Answer : C
Inclusive fitness is an individual's reproductive success together with its relatives' reproductive success.
W.D. Hamilton showed that a gene can spread not only through an individual's own offspring but also by helping relatives, who share copies of the same gene. Inclusive fitness adds this indirect component, weighted by relatedness, to direct fitness; Hamilton's rule, \(rB \gt C\), follows from it and explains kin-directed altruism.
An individual's own reproductive success alone is direct (classical) fitness. Neighbours and partners are not counted unless related, since only shared genes matter.
Sarich and Wilson (1967) demonstrated that human, Gorilla and Chimpanzee were genetically equidistant and distinct for Orangutan and the divergence time is approximately :
Your Answer : (Not Answered)
Correct Answer : B
Sarich and Wilson estimated the divergence at about 5 million years ago.
Using immunological distances between serum albumins, calibrated against a molecular clock, Sarich and Wilson found humans, chimpanzees and gorillas almost equidistant from one another, with the orangutan more distant. They placed the human-ape split at around 5 million years, far more recent than the 15 to 30 million years then favoured from fossils such as Ramapithecus.
Thirty and ten million years were the older palaeontological estimates their work challenged, and 100 million years is close to the age of the earliest placental mammals.
Gastrulation in Drosophila begins with a change in cell shape and contraction of an epithelium sheet from the apical surface, this process is called as :
Your Answer : (Not Answered)
Correct Answer : D
The process is invagination.
Drosophila gastrulation begins on the ventral side, where presumptive mesoderm cells constrict at their apical surfaces. The change in cell shape bends the epithelial sheet inward into a ventral furrow, which folds into the embryo: invagination.
Involution is the rolling of a sheet inward over a lip, as at the blastopore of amphibians. Convergent extension narrows and lengthens a tissue by cells intercalating, as in germ band extension. Epiboly is the spreading of an epithelial sheet over the embryo's surface.
In the chick limb, the signal for condensation of mesenchymal cells to give rise to cartilage comes from the appearance of :
Your Answer : (Not Answered)
Correct Answer : A
Condensation of limb mesenchyme into cartilage is signalled by N-cadherins.
In the developing chick limb bud, N-cadherin appears on the mesenchymal cells just as they aggregate into precartilage condensations. Antibodies that block N-cadherin prevent this condensation and the chondrogenesis that follows.
E-cadherin is the epithelial cadherin, found in the ectoderm, not the mesenchyme. B-cadherin and C-cadherin (in chick and Xenopus respectively) work in early embryonic cell adhesion, not in limb condensation.
Which of the following groups of transcription factors (TFs) is responsible for maintaining the pluripotency of stem cells ?
Your Answer : (Not Answered)
Correct Answer : B
Pluripotency is maintained by Oct 4, Nanog and SOX 2.
These three transcription factors form the core pluripotency network of embryonic stem cells. They bind together at many target genes, activate genes that keep the cells self-renewing and pluripotent, and repress genes of differentiation. Oct4 and Sox2 are also two of the four Yamanaka factors used to make induced pluripotent stem cells.
Stat3 carries the LIF signal in mouse ES cells but is not part of the core network. Cdx2 and Eomesodermin specify the trophectoderm lineage, so they mark the loss of pluripotency.
The embryonic origin of squamous cell carcinoma is :
Your Answer : (Not Answered)
Correct Answer : D
The keyed origin of squamous cell carcinoma is Ectoderm.
Squamous cell carcinoma is a malignant tumour of squamous (flat, stratified) epithelium. Its classic and commonest site is the skin, whose epidermis develops from surface ectoderm, and in that sense it is grouped with ectodermal tumours.
Carcinomas in general are tumours of epithelia, and squamous carcinoma can also arise in epithelia of other origins, such as the lungs after squamous metaplasia, but it is never a tumour of mesoderm or mesenchymal tissue: malignancies of those tissues are sarcomas. The key takes the skin tumour as the type case.
For long distance runner, the muscle needs increased O2 supply. At the muscle, this is formed by :
Your Answer : (Not Answered)
Correct Answer : D
The keyed answer is the accumulation of lactic acid lowering blood pH (printed 'causing demand blood pH').
During prolonged running, working muscle produces lactic acid and CO2. The fall in local blood pH lowers haemoglobin's affinity for oxygen, the Bohr effect, so more O2 is unloaded at the muscle exactly where it is needed. This chemical change is what makes extra oxygen available at the tissue.
Frequent contraction, the muscle's demand, and the squeezing action of muscles describe the need or help venous return, but they do not themselves free oxygen from haemoglobin at the muscle.
Which one of the following is not readily absorbed in the small intestine ?
Your Answer : (Not Answered)
Correct Answer : D
The ion not readily absorbed is \(Mg^{2+}\) (written Mg++ in the paper).
Only about a third of dietary magnesium is absorbed, slowly and largely in the distal small intestine and colon. This poor absorption is why magnesium salts, such as magnesium sulphate (Epsom salt) and milk of magnesia, act as osmotic laxatives: the unabsorbed ions hold water in the gut.
Sodium, chloride and potassium, by contrast, are absorbed efficiently along the small intestine. Sodium is taken up with glucose and amino acids by co-transporters and by exchangers, chloride follows it, and potassium is absorbed mostly passively as water is absorbed.
Mark the most INCORRECT statement with respect to mammalian below :
Your Answer : (Not Answered)
Correct Answer : D
The incorrect statement is Maximum carbon dioxide is transported as bound to hemoglobin.
In mammalian blood about 70 percent of carbon dioxide travels as bicarbonate ions in the plasma, formed inside red cells by carbonic anhydrase and moved out by the chloride shift. Only about 20 to 23 percent is carried as carbaminohaemoglobin, and about 7 percent is dissolved.
The other statements are correct. Oxygen is poorly soluble, so only about 1.5 to 3 percent of it is carried dissolved in plasma; dissolved carbon dioxide is the smallest of the three carbon dioxide fractions; and a rise in carbon dioxide lowers pH and shifts the oxygen dissociation curve to the right (the Bohr effect), favouring release of oxygen to the tissues.
A phenomenon in which animals adapted to temperate regions have shorter and poorly developed ears, eyes, hair and other phenotypic traits follow :
Your Answer : (Not Answered)
Correct Answer : C
The phenomenon follows Allen’s law.
Allen's rule states that warm-blooded animals of colder climates have shorter appendages (ears, tails, limbs) than related forms in warmer regions. Smaller extremities expose less surface for heat loss, so animals adapted to cooler, temperate regions have shorter ears and similar traits.
Bergmann's rule concerns overall body size, which increases in colder climates. Cope's rule says lineages tend to grow larger over evolutionary time, and Dollo's law says that evolution does not reverse to restore a lost structure exactly.
The nerve impulse :
Your Answer : (Not Answered)
Correct Answer : A
The nerve impulse can propagate in both the directions in an axon.
The axon membrane is the same along its length, so an action potential started at any point spreads to the excitable membrane on both sides. If an axon is stimulated in the middle, impulses run both towards the terminal and back towards the soma; such antidromic conduction is used routinely in experiments.
In the body, impulses normally start at the axon hillock and travel to the terminals because they are triggered there and because synapses pass signals one way; the refractory membrane behind an impulse only stops it turning back. So the one-way options describe the usual traffic, not a limit of the axon, and injury is not required.
..................... is involved in the specification of germ cells in all animals studied.
Your Answer : (Not Answered)
Correct Answer : D
The gene is Vasa.
Vasa encodes a DEAD-box RNA helicase found in the germ plasm and germ cells of every animal studied, from Drosophila and nematodes to fish, frogs and mammals. It is needed for germ cell specification and development, and its protein is the standard marker for identifying germ cells.
Sry is the mammalian Y-linked gene that starts testis development, Sox9 is its downstream target in Sertoli cells, and Wnt4 promotes ovary development. They are sex-determination genes acting on the somatic gonad, not on germ cell specification across animals.
The Sewall Wright effect occurs because of :
Your Answer : (Not Answered)
Correct Answer : B
The Sewall Wright effect occurs because of a decline in population.
The Sewall Wright effect is another name for genetic drift: random changes in allele frequencies from one generation to the next because only a sample of the gene pool is passed on. Its effect is strongest in small populations, so a decline in population size, as in a bottleneck or a founder event, makes drift important and can fix or eliminate alleles by chance alone.
Mutation creates new alleles but is not what drift means, a large or increasing population weakens drift, and variation is the raw material on which drift acts, not its cause.
Which one of the following electrodes will be a preferred choice for recording of transmembrane potential of a living cell ?
Your Answer : (Not Answered)
Correct Answer : A
The preferred choice is the electrolyte filled glass capillary electrode.
A glass micropipette pulled to a tip well under a micrometre wide and filled with a conducting salt solution, typically 3 M KCl, can pierce a cell membrane with little damage, which then seals around the glass. The electrolyte makes electrical contact with the cytoplasm through a silver/silver chloride wire, so the potential across the membrane can be recorded against an external reference. Patch-clamp pipettes are of the same kind.
Uninsulated steel microelectrodes are used for extracellular recording. A copper wire is toxic to cells and polarises, and solid uninsulated glass rods do not conduct, so none is used to record a transmembrane potential.
In which organ hydrochloric acid is secreted ?
Your Answer : (Not Answered)
Correct Answer : C
Hydrochloric acid is secreted in the Stomach.
The parietal (oxyntic) cells of the gastric glands in the stomach wall secrete hydrochloric acid. It makes the stomach strongly acidic, kills microbes in food, and converts pepsinogen into the protein-digesting enzyme pepsin.
The liver produces bile and the pancreas secretes digestive enzymes with alkaline bicarbonate, which neutralises the acid in the intestine. None of these secretes hydrochloric acid.
Which organ is secondary lymphoid organ?
Your Answer : (Not Answered)
Correct Answer : D
The secondary lymphoid organ is the spleen.
Secondary lymphoid organs are where mature lymphocytes meet antigens and immune responses begin: the spleen, lymph nodes, tonsils and Peyer's patches. The spleen filters the blood.
Bone marrow is a primary lymphoid organ, where lymphocytes are formed, as is the thymus, where T cells mature. The liver and the pancreas are not lymphoid organs: the liver is a metabolic and digestive gland, and the pancreas an endocrine and digestive gland.
Digestion process occurring in higher animals is
Your Answer : (Not Answered)
Correct Answer : B
Digestion in higher animals is extracellular.
In vertebrates and other higher animals, food is digested outside the cells, in the cavity of the alimentary canal, by enzymes secreted into it from glands such as the salivary glands, stomach, pancreas and intestine. Only the small digested molecules are then absorbed into the cells.
Intracellular digestion, inside food vacuoles, occurs in simple organisms such as Amoeba and Paramecium, and partly in sponges and cnidarians. 'Intercellular' means between cells and is not a type of digestion, so 'All of the above' is also wrong.
Which of the following would not increase the stroke volume of the heart ?
Your Answer : (Not Answered)
Correct Answer : C
The factor that would not increase stroke volume is increased K+ ions in interstitial fluid.
A high extracellular potassium concentration lowers the resting membrane potential of heart muscle cells, reducing their excitability and the force of contraction; severe hyperkalaemia can even stop the heart. So it decreases, rather than increases, stroke volume.
The other three increase it. More extracellular calcium strengthens contraction. Greater venous return stretches the ventricle more and, by the Frank-Starling mechanism, increases the force of the next beat. Epinephrine (adrenaline) increases contractility through beta-1 receptors.
The "foramen of Panizza" is found in which one of the following groups of animals?
Your Answer : (Not Answered)
Correct Answer : B
The foramen of Panizza is found in crocodiles.
Crocodilians have a fully four-chambered heart but keep two aortic arches: the left aorta leaves the right ventricle and the right aorta leaves the left ventricle. The foramen of Panizza is an opening that connects the two aortae just outside the heart, letting blood pass between them. Together with a valve at the base of the pulmonary outflow, it allows crocodiles to shunt blood away from the lungs during diving.
Fishes have a single circuit with a two-chambered heart, frogs a three-chambered heart without separate aortae from two ventricles, and dolphins, as mammals, a single (left) aortic arch, so none has this structure.
Muscle performance is positively correlated with Darwinian fitness. The graph below describes the relationship between mean environmental temperature and muscle performance for two closely related lizard species, one living in temperate areas (solid line) and another living in tropical areas (dashed line). Current mean environmental temperatures are marked with vertical dotted lines at (i) for the temperate species and (ii) for the tropical species. If mean environmental temperatures at both locations increase at a steady rate over time, which one of the following is most likely to occur in the near future?
Your Answer : (Not Answered)
Correct Answer : B
The likely outcome is that the temperate species may be positively impacted but the tropical species will be negatively impacted.
The temperate lizard's current temperature, mark (i), lies well below the peak of its broad performance curve. As temperatures rise it moves up the curve toward its optimum, so its muscle performance, and with it its fitness, may increase.
The tropical lizard's current temperature, mark (ii), is already at the peak of its narrow curve, and just beyond it the curve drops steeply. Any warming pushes it down that slope, so its performance falls sharply.
The two species therefore do not suffer to the same extent, the effects are not reversed, and saying neither is affected ignores the curves. This is the general point that tropical ectotherms, living near their thermal maximum, are the more vulnerable to warming.
Marks
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20