AIPMT 2005 (Biology)

 Parkinson’s disease is caused by degeneration of brain neurons that are involved in movement control by making use of the neurotransmitter dopamine.

 Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on the 21st chromosome, either in whole (trisomy 21) or part (such as due to translocations). The effects of the extra copy varies greatly from individual to individual, depending on the extent of the extra copy, genetic background, environmental factors, and random chance.

  Centromeres appear as a constriction. They have a role in the separation of chromosomes into daughter cells during cell division (mitosis and meiosis).So,centromere is required for movement of chromosomes toward poles 

 Protein synthesis in an animal cell occurs in ribosomes present in cytoplasm as well as in mitochondria.

Endonuclease hydrolyses internal phosphodiester bonds in a polynucleotide chain. Restriction endonucleases (restriction enzymes) are divided into three categories:
Type I, Type II, and Type III

 Prevalence of pesticide resistant insects supports Darwin's concept of natural selection in organic evolution.Natural selection is the preservation of a functional advantage that enables a species to compete better in the wild. Natural selection is the naturalistic equivalent to domestic breeding.

 Carbohydrates, the most abundant biomolecules on Earth, are produced by some bacteria, algae and green plant cells.

 Most large proteins do not flip-flop due to their extensive polar regions, which are unfavorable in the hydrophobic core of a membrane bilayer. This allows the asymmetry of membranes to be retained for long periods, which is an important aspect of cell regulation.

 G2 phase is a period of rapid cell growth and protein synthesis during which the cell readies itself for mitosis. So, during G–2 stage of interphase histone proteins synthesized in a eukaryotic cell.

 The main organelle involved in modification and routing of newly synthesized proteins to their destinations is endoplasmic reticulum.The endoplasmic reticulum serves many general functions, including the folding of protein molecules in sacs called cisternae and the transport of synthesized proteins in vesicles to the Golgi apparatus.

 E.coli cells with a mutated z gene of the lac operon cannot grow in medium containing only lactose as the source of the energy because they cannot synthesise functional betagalactosidase.

 Synergid cells are two specialized cells that lie adjacent to the egg cell in the female gametophyte of angiosperms and play an essential role in pollen tube guidance and function.

The macronucleus controls non-reproductive cell functions, expressing the genes needed for daily functioning. The micronucleus is the generative or germline nucleus, containing the genetic material that is passed along from one generation to the next.

 In contrast to Annelids the Platyhelminths show absence of body cavity.
They are acoelomates (having no body cavity), and have no specialized circulatory and respiratory organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion.

 Barophilic prokaryotes grow slowly in highly alkaline frozen lakes at high altitudes.They are also known as Piezophiles.

  Animals belonging to Phylum Porifera are exclusively marine.This statement is wrong one as There is, however, one family of fresh water sponges (Family Spongillidae). 

 There exists a close association between the alga and the fungus within a lichen. The fungus provides protection, anchorage and absorption for the alga.This association is known as symbiosis.

 Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzymes. Most competitive inhibitors function by binding reversibly to the active site of the enzyme. As a result, many sources state that this is the defining feature of competitive inhibitors.

 
The ability of the Venus Flytrap to capture insects is due to rapid turgor pressure changes.Each side of the trap has three to four sensor hairs, each no longer than 0.2 inches (0.5 centimeters). An insect must trip a hair twice or two hairs within 20 seconds for the trap to respond; this allows it to avoid snapping shut on raindrops or other false alarms. 

 Golden rice is a transgenic crop of the future with the improved trait of high vitamin A content. Golden rice differs from its parental strain by the addition of three beta-carotene biosynthesis genes. The rice plant can naturally produce beta-carotene in its leaves, where it is involved in photosynthesis. However, the plant does not normally produce the pigment in the endosperm, where photosynthesis does not occur.

 Solar energy : greenhouse effect
This is a mis-matched pair.Solar energy is radiant light and heat from the Sun harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, solar thermal energy, solar architecture and artificial photosynthesis.

 In adventitious embryony (sporophytic apomixis), an embryo is formed directly (not from a gametophyte) from nucellus or integument tissue.Adventive embryony is important in several species of Citrus, in Garcinia, Euphorbia dulcis, Mangifera indica etc.

 To check resistance of mutants against streptomycin they must be grown on plates with streptomycin. Only those bacterial colonies will propagate from the master that are resistant to the antibiotic.

 Kyoto Protocol : Climatic change
This is the correct option among the all options provided.
Montreal Protocol was on Substances that Deplete the Ozone Layer.
The Basel Convention was on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal.
The Ramsar Convention was Convention on Wetlands of International Importance, especially as Waterfowl Habitat.

 Gamma–rays (from Cobalt 60) generally used for induced mutagenesis in crop plants. They were employed to develop 64% of the radiation-induced mutant varieties, followed by X-rays (22%).

 Auxospores and hormocysts are form, respectively, by several diatoms and a few cyanobacteria. Auxospores typically play a role in growth processes, sexual reproduction or dormancy in some species of diatoms. Hormocysts are the specialised structures found in cyanobacteria which help in reproduction.

Botanical gardens serve as ex-situ conservation sites, maintaining living collections of plant species outside their natural habitats. This preserves genetic diversity (germplasm) for research, education, and potential reintroduction. They do not provide natural habitat for wild plants (that's in-situ conservation), and while they may have tropical plants and recreational areas, these are not their 'most important' scientific function.

 A polar ice cap or polar cap is a high-latitude region of a planet, dwarf planet, or natural satellite that is covered in ice.Around 70% of the fresh water on Earth is contained in this ice sheet.

 I - C, II - A, III - D, IV - E, V - B
I. Peritrichous flagellation      (C) Escherichia coli
II. Living fossil                          (A) Ginkgo
III. Rhizophore                         (D) Selaginella
IV. Smallest flowering plant (E) Wolffia
V. Largest perennial alga     (B) Macrocystes

 Enlargement of body size by swallowing air in puffer fish.This statement is wrong. All the other options help in deception from predation.

 HIV infection is associated with the progressive loss of CD4(+) T cells through their destruction or decreased production.

 The world's highly prized wool yielding 'Pashmina' breed is goat. The goat  most known for its fine cashmere is Himalayan goats, often referred to as Cashmere goats. The name Cashmere derives from the Indian region Kashmir, where the first Cashmere clothing was appreciated. Another very well known word for Cashmere is Pashmina. This derives from the Persian word for "wool".

 Vivipary is the condition whereby the embryo (the young plant within the seed) grows first to break through the seed coat then out of the fruit wall while still attached to the parent plant. It is an undesirable character for annual crop plants as the seeds cannot be stored under normal conditions for the next season.

 An important step in the manufacture of pulp for paper industry from the woody tissues of plants is the preparation of pure cellulose by removing lignin.

 Butyric acid producing anerobic bacteria is used for retting of jute.
Retting is a process employing the action of microorganisms and moisture on plants to dissolve or rot away much of the cellular tissues and pectins surrounding bast-fibre bundles, and so facilitating separation of the fibre from the stem.

 Three crops that contribute maximum to global foodgrain production are wheat, rice and maize. They are grown maximally as they form one of the staple diets of largest population of the world.

 An electron transport chain (ETC) is a series of compounds that transfer electrons from electron donors to electron acceptors via redox reactions, and couples this electron transfer with the transfer of protons (H+ ions) across a membrane. This creates an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP), a molecule that stores energy chemically in the form of highly strained bonds. In most organisms the majority of ATP is generated in electron transport chains.

  At 22 ½o North and South Latitude heat gain through insulation approximately equals heat loss through terrestrial radiation.

 The edible white aril of Litchi chinensis is sometimes called an arillode. It grows partly from the funiculus and partly from the integument of the seed.

 Ectophloic siphonostele is a type of stele with pith that has the phloem only on the outside of the xylem. It is found in Marsilea and Botrychiun.

 Mn, Co, Ca these three elements affect both photosynthetic and mitochondrial electron transport.They are activally involved in both the processes.

 The Biological Diversity Act, 2002 is an Act of the Parliament of India for preservation of biological diversity in India, and provides mechanism for equitable sharing of benefits arising out use of traditional biological resources and knowledge. The Act was enacted to meet the obligations under Convention on Biological Diversity (CBD), to which India is a party.

  Phenyl is not used for disinfection of drinking water.Chlorine, chloramine and ozone are mainly used for disinfection of the water.

 As compared to a C₃^- plant, twelve additional molecules of ATP are needed for net production of one molecule of hexose sugar by C₄^- plants. 18 ATPs are required to synthesize one glucose molecule in C₃ plant and 30 ATPs are required to synthesize one glucose molecule in C₄ plants.

  Polytene Chromosomes (Salivary Chromosomes) were discovered by Balbiani (1881) in the salivary glands of Chironomus tantans. Later they were found in salivary glands of many insect larvae including Drosophila. Polytene chromosomes are formed by somatic pairing of homologous chromosomes followed by their repeated replication or endomitosis. They are in permanent prophase.

 Salinity from irrigation can occur over time wherever irrigation occurs, since almost all water (even natural rainfall) contains some dissolved salts. When the plants use the water, the salts are left behind in the soil and eventually begin to accumulate. Since soil salinity makes it more difficult for plants to absorb soil moisture, these salts must be leached out of the plant root zone by applying additional water.

 Chemiosmotic theory of ATP synthesis in the chloroplasts and mitochondria is based on proton gradient.Chemiosmosis is the movement of ions across a selectively permeable membrane, down their electrochemical gradient. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis.

 In a woody dicotyledonous tree,primary growth is tissue is present in Flowers, fruits and leaves because these are the active sites of growth.

 Potometer works on the principle that amount of water absorbed equals the amount transpired. There are two main types of potometers used - the bubble potometer and the mass potometer.

 A granum (plural grana) is a stack of thylakoid discs.A thylakoid is a membrane-bound compartment inside chloroplasts.They are the site of the light-dependent reactions of photosynthesis. Pyrenoids are sub-cellular micro-compartments found in chloroplasts of many algaeThe stroma of a plant is the region outside of the thylakoid space; most of the enzymes essential in the process of photosynthesis are generally embedded in the stroma and in the thylakoid membranes.

 Photosynthesis in C4- plants is relatively less limited by atmospheric CO2 levels because the primary fixation of CO2 is mediated via PEP carboxylase.

 Photosynthetically active radiation( PAR), designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more or less with the range of light visible to the human eye. Photons at shorter wavelengths tend to be so energetic that they can be damaging to cells and tissues, but are mostly filtered out by the ozone layer in the stratosphere. Photons at longer wavelengths do not carry enough energy to allow photosynthesis to take place.

Enzymes, vitamins and hormones can be classified into a single category of biological chemicals because all of these help in regulating metabolism.

 Glucose-6-phosphate dehydrogenase deficiency is a genetic disorder that occurs most often in males. This condition mainly affects red blood cells, which carry oxygen from the lungs to tissues throughout the body. In affected individuals, a defect in an enzyme called glucose-6-phosphate dehydrogenase causes red blood cells to break down prematurely. This destruction of red blood cells is called hemolysis.

 An acromion process is a type of bony process which articulates with the clavicle, or collar bone. It is characteristically found in the pectoral girdle of mammals.

 In ornithine cycle, CO₂ and ammonia wastes are removed from the blood. In mammals, this cycle takes place primarily in the liver, and to a lesser extent in the kidney.

 Secretin and cholecystokinin are digestive hormones. They are secreted in duodenum when acidic food enters there. Secretin stimulates release of bicarbonate rich fluid from the pancreas to counteract the acid. CCK stimulates pancreatic enzyme section like amylase and lipase, which aid in breaking down food. It also causes contraction of the gallbladder, which releases bile into the duodenum.

 There are 12 pairs of cranial nerves in class Mammalia.

 
Grey crescent is the area just opposite to the site of entry of sperm into ovum.Its establishment determines the location of the dorsal and ventral (up-down) axis, as well as of the anterior and posterior (front-back) axis and the dextro-sinistral (left-right) axis of the embryo.

Epiphytes are plants that live on other plants. They do not take nourishment from their host as parasitic plants do. As their roots do not reach the ground, they depend on the air to bring them moisture and inorganic nutrients. Many orchids and many bromeliads (members of the pineapple family like "Spanish moss") are epiphytes. Grasslands are also known as prairie or plains

 The net pressure gradient that causes the fluid to filter out of the glomeruli into the capsule is 20 mm Hg.
A glomerular hydrostatic pressure of 70 mm Hg develops in glomerulus. It is opposed by blood osmotic pressure (30 mm Hg) and capsular hydrostatic pressure (20 mm Hg ) inside the Bowman's capsule.

 From birth, the ovaries of the human female contain a number of immature, primordial follicles. These follicles each contain a similarly immature primary oocyte. After puberty and commencing with the first menstruation, a clutch of follicles begins folliculogenesis, entering a growth pattern that will end in death or in ovulation (the process where the oocyte leaves the follicle).

 Top-shaped multiciliate male gametes, and the mature seed which bears only one embryo with two cotyledons, are characteristic features of Cycads.In Cycas pollination is anemophilous (by wind). The 3-celled microspores liberate from mega-sporangia are blown away by wind. Finally microspores reach on ovules and get enlarged in the pollination drop (ooze) of micropyle. As the ooze dries up, the microspores are drawn into the pollen chamber.

 In amphitropous ovule, the embryo sac becomes horseshoe-shaped and the funiculus and micropyle are close to each other.

  Epithelial cells of the intestine involved in food absorption have on microvilli on their surface. Microvilli effectively increase the surface area of the cell and are useful for absorption and secretion functions.

 Thromboplastin is a plasma protein aiding blood coagulation through catalyzing the conversion of prothrombin to thrombin. So, if introduced into the blood stream, it would cause coagulation of blood at the site of its introduction.

 Autonomic nervous system is involved in peristalsis of intestine which is effected through mysentric plexus.Other options are examples of reflex actions.

 Thymus gland is associated with production T-lymphocytes ,which are important part of our immune system. They get matured in thymus gland .So,damage to thymus in a child may lead to loss of cell mediated immunity.

In a man, if abducens nerve is injured, then movement of the eyeball is affected as it controls the movement of a single muscle, the lateral rectus muscle of the eye.

 Kwashiorkor is a form of severe protein–energy malnutrition.Sufficient calorie intake, but with insufficient protein consumption, distinguishes it from marasmus. Kwashiorkor cases occur in areas of famine or poor food supply.So a patient suffering from Kwashiorkor is generally advised to specially consume more meat, lentils, milk and eggs in diet.

 Gliding joint is a type of joint allows for gliding movements between flat surfaces as the surfaces slide over one another. Only a limited amount of movement is allowed such as those between the articular processes (zygapophyses) of successive vertebrae.
Fibrous joint is present between skull bones. Cartilaginous joint is present between vertebrae. Hinge joint is present between knee and elbow.

 
A person is undergoing prolonged fasting. His urine will be found to contain abnormal quantities of ketones.
Ketones are metabolic end-products of fatty acid metabolism. In healthy individuals, ketones are formed in the liver and are completely metabolized so that only negligible amounts appear in the urine. However, when carbohydrates are unavailable or unable to be used as an energy source, fat becomes the predominant body fuel instead of carbohydrates and excessive amounts of ketones are formed as a metabolic byproduct. Higher levels of ketones in the urine indicate that the body is using fat as the major source of energy.

The simplest and smallest amino acid found in proteins is glycine, for which the R-group is a hydrogen (H).

 An Endangered (EN) species is a species which has been categorized by the International Union for Conservation of Nature (IUCN) Red List as likely to become extinct. "Endangered" is the second most severe conservation status for wild populations in the IUCN's schema after Critically Endangered (CR).
According to IUCN Red List of Red Panda (Ailurus fulgens) comes under Endangered species.

 The synthesis of DNA from an RNA template, via reverse transcription, produces complementary DNA (cDNA). Reverse transcriptases (RTs) use an RNA template and a short primer complementary to the 3' end of the RNA to direct the synthesis of the first strand cDNA, which can be used directly as a template for the Polymerase Chain Reaction (PCR).

  The genotype proportions p², 2pq, and q² are called the Hardy-Weinberg proportions.Two alleles denoted A and a with frequencies f(A) = p and f(a) = q, respectively,Expected genotype frequencies are-  f(AA) = p² for the AA homozygotes,  f(aa) = q² for the aa homozygotes, and f(Aa) = 2pq for the heterozygotes. So, the frequency of heterozygotes = 2pq= 2 X 0.6 X 0.4 = 0.48 

 A nucleotide is one of the structural components or building blocks of DNA and RNA. A nucleotide consists of a base (one of four chemicals: adenine, thymine, guanine, and cytosine) plus a molecule of sugar and one of phosphoric acid.

 Resolution of the microscope is inversely proportional to the wavelenth of the light used.The light with short wavelength have the higher resolution.Out of the given options, blue light have the minimum wavelength, hence have highest resolution.

 In order to find out the different types of gametes produced by a pea plant having the genotype AaBb, it should be crossed to a plant with the homozygous recessive genotype.It is called Test Cross.So, in above options, it should be crossed with aabb double recessive plant.

 During transcription holoenzyme RNA polymerase binds to a DNA sequence and the DNA assumes a saddle like structure at that point. This sequence is called TATA box. It is a type of promoter sequence, which specifies to other molecules where transcription begins.

 Sex-linked recessive traits typically occur only in males. Because the sex-linked trait is invariably X-linked, males transmit the trait only to their daughters, all of whom become carriers. Carrier (heterozygous) females can then transmit the trait to 50% of their male and female offspring. Affected males are hemizygous for the X-linked trait.

 Bryophyllum and Kalanchoe both the plants can be vegetatively propagated by leaf pieces.It is a type of asexual type of reproduction.

 A woman with normal vision, but whose father was colour blind, marries a colour blind man. Suppose that the fourth child of this couple was a boy. This boy may be colour blind or may be of normal vision.

 Telomerase, also called telomere terminal transferase,is a ribonucleoprotein that adds the polynucleotide "TTAGGG" to the 3' end of telomeres, which are found at the ends of eukaryotic chromosomes.

 In 1890 the Dutch geneticist Hugo de Vries discovered Oenothera lamarckiana or the evening primrose of Lamarck, growing as a parkland-escape on an abandoned field near Hilversum. In this plant de Vries believed he had found evidence that Charles Darwin was wrong.

 Genes for cytoplasmic male sterility in plants are generally located in
Mitochondrial genome. Mitochondrial DNA is only a small portion of the DNA in a eukaryotic cell; most of the DNA can be found in the cell nucleus and, in plants, in the chloroplast.

 Norman Ernest Borlaug was an American biologist, humanitarian and Nobel laureate who has been called "the father of the Green Revolution".He took up an agricultural research position in Mexico, where he developed semi-dwarf, high-yield, disease-resistant wheat varieties.

  Meat was not spoiled, when heated and kept sealed in a vessel, This experiment suggests that simplest living organisms could not have originated spontaneously from non-living matter.This  experiment was showing evidence against theory of spontanous generation.

 Cretinism is a condition of severely stunted physical and mental growth due to untreated congenital deficiency of thyroid hormones (congenital hypothyroidism) usually due to maternal hypothyroidism.

  Gene flow does occur between the populations of a species as they freely interbreed.so new genetic combinations occur.

 Potassium-argon method is the relatively most accurate method for dating of fossils.It is based on measurement of the product of the radioactive decay of an isotope of potassium (K) into argon (Ar). Potassium is a common element found in many materials, such as micas, clay minerals, tephra, and evaporites.

 Haemophilia is more commonly seen in human males than in human females because this disease is due to an X-linked recessive mutation.X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be expressed in males (who are necessarily hemizygous for the gene mutation because they have one X and one Y chromosome) and in females who are homozygous for the gene mutation.

 Neurons are least likely to regnerate when lost . They have least power of regeneration.

  Frankia cannot fix nitrogen in the free-living state.Frankia is a nitrogen-fixing bacterium that lives in the soil and has a symbiotic relationship with many plants.

 
Bacillus thuringiensis (Bt) strains have been used for designing novel
bio-insecticidal plants.During sporulation, many Bt strains produce crystal proteins (proteinaceous inclusions), called δ-endotoxins, that have insecticidal action. This has led to their use as insecticides, and more recently to genetically modified crops using Bt genes. Many crystal-producing Bt strains, though, do not have insecticidal properties.

 The catalytic efficiencies of two different enzymes can be compared by the Km value. Km is the Michaelis-Menten constant which shows the concentration of the substrate when the reaction velocity is equal to one half of the maximal velocity for the reaction.

 Production of a human protein in bacteria by genetic engineering is possible because the genetic code is universal.

 More the genetic (DNA) variationthe more is the age of Mankind.Therefore greater variation in Africa than in asia suggested African origin of modern man.

 Valium is a medication of the benzodiazepine family that typically produces a calming effect. It is commonly used to treat a range of conditions including anxiety, alcohol withdrawal syndrome, benzodiazepine withdrawal syndrome, muscle spasms, seizures, trouble sleeping and restless legs syndrome.

 Beriberi, nutritional disorder caused by a deficiency of thiamin (vitamin B1) and characterized by impairment of the nerves and heart. General symptoms include loss of appetite and overall lassitude, digestive irregularities, and a feeling of numbness and weakness in the limbs and extremities.In East Asian countries, where polished white rice is a dietary staple, beriberi has been a long-standing problem.