Biology CLEP Practice Questions
The shortest phase of cardiac cycle is Atrial systole Ventricular systole Atrial diastole Ventricular diastole Equal duration for A and B
Correct Answer: A. Atrial systole Explanation: Atrial systole is the shortest phase of cardiac cycle. Atrial systole gets completed in 0.1 seconds. Duration of atrial diastole is 0.7 seconds. Duration of ventricular systole and diastole is 0.3 seconds and 0.5 seconds respectively.
8. Required for the activity of DNA polymerase A) Okazaki fragments B) RNA primer C) Single-strand binding protein D) Leading strand E) Replication fork
B. DNA replication begins with a short segment of RNA (not DNA). DNA polymerase cannot begin adding nucleotides without an existing piece of DNA (a primer).
9. Substrate for DNA ligase A) Okazaki fragments B) RNA primer C) Single-strand binding protein D) Leading strand E) Replication fork
A. DNA synthesis on the lagging strand forms short segments called Okazaki fragments. Because DNA polymerase can only add nucleotides in the 5→3 direction, lagging strand synthesis is discontinuous. The final product is formed when DNA ligase joins Okazaki fragments together.
How many chromosomes does a human cell have after meiosis I? A) 92 B) 46 C) 23 D) 22 E) 12
B. The diploid chromosome number for humans is 46. After DNA duplication but before the first cell division of meiosis, there are 92 chromosomes (46 pairs). After meiosis I is completed, the chromosome number is halved and equals 46. Each daughter cell is haploid, but the chromosomes are still paired (sister chromatids). During meiosis II, the two sister chromatids of each chromosome separate, resulting in 23 haploid chromosomes per germ cell.
DNA replication occurs during which of the following phases? A) Prophase I B) Prophase II C) Interphase I D) Interphase II E) Telophase I
C. Although there are two cell divisions in meiosis, DNA replication occurs only once. It occurs in interphase I, before M phase begins.
Which photosynthetic pigment reflects yellow red light? A. Chlorophyll A B. Chlorophyll B C. Carotenoid D. Xanthophylls E. Phytochrome
C. Carotenoid Explanation: Carotenoids are the photosynthetic plant pigments which reflect yellow red light. They contribute to photosynthesis by transmitting the light energy which is absorbed from chlorophyll. They are also known as orange photosynthetic pigment.
5. A length of DNA coding for a particular protein is called a(n) A) Allele B) Genome C) Gene D) Transcript E) Codon
C. Genes code for proteins, and genes are discrete lengths of DNA on chromosomes. An allele is a variant of a gene (different DNA sequence). In diploid organisms, there may be two versions of each gene.
4. The synaptonemal complex is present in which of the following phases of the cell cycle? A) Metaphase of mitosis B) Metaphase of meiosis I C) Telophase of meiosis I D) Metaphase of meiosis II E) Telophase of meiosis II
C. The synaptonemal complex is the point of contact between homologous chromatids. It is formed when nonsister chromatids exchange genetic material through crossing over. Once meiosis I has completed, crossovers have resolved and the synaptonemal complex no longer exists. Rather, sister chromatids are held together at their centromeres prior to separation in anaphase II.
What is the inactivated X chromosome in females called? A. Barr body B. Heterochromatin C. Euchromatin D. Nucleosome E. None of the above
Correct Answer: A. Barr body Explanation: The inactivated X chromosome in females is called Barr body. Barr body was first discovered by Dr. Murray L. Barr. Inactivation of an X chromosome occurs due to dosage compensation.
Area where the movement of water is from the surface to the ground water system is called A. Catchment area B. Springs C. Aquifer D. Artesian well E. None of these
Correct Answer: A. Catchment area Explanation: Catchment area is the area where the net water movement is from the surface to the ground water system. Springs are the area where ground water reaches the surface and runs off. Aquifer is the rocky body through which ground water flows. Artesian well is a well drilled into an aquifier that has sufficient hydrostatic pressure to force water up into it.
An animal with two successive sets of teeth is called A. Diphyodont B. Monophyodont C. Heterodont D. Polyphodont E. None of the above
Correct Answer: A. Diphyodont Explanation: Diphyodonts have two sets of teeth namely deciduous teeth and permanent teeth. The deciduous teeth are replaced by permanent teeth. Monophyodonts are the organisms having one set of teeth which are not replaced at later stages of life. Heterodonts are the organisms which possess different types of teeth. Polyphodonts are the organisms whose teeth are continuously replaced.
Malleus, incus and stapes are collectively called Ear Ossicle Cranial bone Sternum bone Facial bone None of the above
Correct Answer: A. Ear Ossicle Explanation: Malleus, incus and stapes together form the ear ossicle. They are present in the middle ear space and are the smallest bone in human body. Sound-induced vibrations of the tympanic membrane (ear drum) are transmitted through malleus, incus and stapes respectively to the inner ear where it is interpreted as sound.
A measure of the disorder or randomness in a closed system is called Entropy Enthalpy Potential energy Kinetic energy None of the above
Correct Answer: A. Entropy Explanation: Entropy is the measure of the disorder or randomness which is derived from the second law of thermodynamics. Enthalpy is the sum of the internal energy of the system plus the product of its volume multiplied by the pressure. Potential energy is the ability of a system to do work due to its position or internal structure. Kinetic energy of an object is the energy it possesses due to its motion.
The word 'arthropod' means Jointed feet Jointed head Presence of eight legs Segmented body Bilateral symmetry
Correct Answer: A. Jointed feet Explanation: The word arthropod in Greek means jointed feet. Presence of jointed feet is the characteristic feature of arthropods.
Archaeopteryx belongs to the A. Jurassic era B. Deuonian era C. Cretaceous era D. Triassic era E. None of these
Correct Answer: A. Jurassic era Explanation: Archaeopteryx lived in the Jurassic era. Archaeopteryx shared some similarity with mesozoic dinosaurs. These include sharp teeth, long bony tail, three fingers with claws etc.
Heart develops from Lateral plate mesoderm Intermediate mesoderm Ectoderm Endoderm Paraxial mesoderm
Correct Answer: A. Lateral plate mesoderm Explanation: Lateral plate mesoderm is found at the periphery of the embryo. The circulatory system develops from the lateral plate mesoderm. Intermediate mesoderm develops into kidneys and gonads. Cartilage, skeletal muscles etc. develop from paraxial mesoderm.
Which of the following produces angiotensinogen? A. Liver B. Pancreas C. Kidney D. Thyroid gland E. Pituitary gland
Correct Answer: A. Liver Explanation: Angiotensinogen is a serum globulin produced by liver. Angiotensinogen is the precursor of angiotensin, an oligopeptide involved in regulating blood pressure. Angiotensin increases blood pressure by enhancing vasoconstriction. Angiotensinogen belongs to the serpin family
Rhizobium is a bacterium that lives in the root nodules of leguminous plants. This is an example for ________ A. Mutualism B. Commensalism C. Parasitism D. Predatism E. None of the above
Correct Answer: A. Mutualism Explanation: Mutualism is an association between organisms in which both organisms are benefited. Rhizobium lives in the root of legumes and forms nodule. Rhizobium helps to fix atmospheric nitrogen in leguminous plants. Commensalism is a type of association in which one organism benefits and the other is unaffected. Parasitism is a type of association in which one organism is benefited (parasite) and the other (host) is adversely affected. Predatism is a state of preying on other organisms.
To which of the following do ES cells belong? Pluripotent Oligopotent Multipotent Totipotent None of the above
Correct Answer: A. Pluripotent Explanation: ES cells or embryonic stem cells can develop into any of the cells belonging to the three germ layers. So they are pluripotent stem cells. ES cells will not develop extraembryonic cells. The differentiation of ES cells to different cells depends on specific factors.
The structure of a protein with linear sequence of amino acids is called A. Primary structure B. Secondary structure C. Tertiary structure D. Quaternary structure E. None of the above
Correct Answer: A. Primary structure Explanation: Proteins which have a linear sequence of amino acids in a polypeptide chain are primary structured proteins that are held together by peptide or covalent bonds. Secondary structure is the folding of primary sequence of amino acids into specific structures which are bound together by hydrogen bonds. Three-dimensional structure of a protein molecule is the tertiary structure and the three-dimensional structure and arrangement of more than one protein subunit is the quaternary structure.
Implantation is the process where The blastocyst becomes embedded in the endometrium. The sperm nuclei fuse with the egg nuclei Loss of the lining of endometrium takes place The gastrula becomes embedded in the endometrium None of the above
Correct Answer: A. The blastocyst becomes embedded in the endometrium. Explanation: The process of embedding of blastocyst to the endometrium is known as implantation. The fetus receives oxygen and nutrients from mother due to this adhesion. The blastula differentiates into three layers namely endoderm, mesoderm and ectoderm to form gastrula.
The term 'staminate' refers to Unisexual male flower bearing stamens Unisexual female flower bearing pistils Bisexual flower bearing stamens and pistils Unisexual male flower bearing pistils Unisexual female flower bearing stamens
Correct Answer: A. Unisexual male flower bearing stamens Explanation: Staminate refers to the male flowers that bear only stamens but lack pistils. Pistillate refers to the female flowers that bear only pistils but lack stamen.
Acceptor stem is present in tRNA rRNA siRNA mRNA hnRNA
Correct Answer: A. tRNA Explanation: tRNA consists of variable loop, TΨC loop, anticodon loop, D-loop and acceptor stem. The anticodon loop is needed for binding to the mRNA. Acceptor stem is needed for attaching the amino acid.
G protein receptors have A. 5 transmembrane ß helices B. 7 transmembrane a helices C. 5 transmembrane a helices D. 6 transmembrane a helices E. 7 transmembrane ß helices
Correct Answer: B. 7 transmembrane a helices Explanation: G protein receptors have 7 transmembrane a helices that traverse the plasma membrane and are connected by loops of varying length. The carboxy-terminus is located inside the cell and the amino terminus of the receptor is located outside the cell.
Glucocorticoid is produced by A. Adrenal medulla B. Adrenal cortex C. Pancreas D. Pineal gland E. Pituitary gland
Correct Answer: B. Adrenal cortex Explanation: Glucocorticoids are produced by the adrenal cortex. Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor. They stimulate gluconeogenesis and increase the blood glucose level.
Deposition of sediments or sediment accumulation is known as A. Profundation B. Aggradation C. Biocoenosis D. Trophic succession E. None of these
Correct Answer: B. Aggradation Explanation: Aggradation is the accumulation of sediments resulting in an elevation of land. Aggradation occurs when the deposition of sediments exceeds the amount of material the system can transport. Biocoenosis describes the interacting organisms in a habitat.
Which of the following glands secrete the FSH hormone? A. Islets of Langerhans B. Anterior pituitary gland C. Posterior pituitary gland D. Parathyroid gland E. Testis
Correct Answer: B. Anterior pituitary gland Explanation: The anterior pituitary gland secretes follicle stimulating hormone (FSH). In male, FSH stimulates spermatogenesis and in females it stimulates the growth of ovarian follicles. Anterior pituitary gland also secretes luteinising hormone, prolactin, thyroid stimulating hormone, adrenocorticotrophic hormone and growth hormone.
Which of the following metals is responsible for Itai-itai disease? A. Arsenic B. Cadmium C. Lead D. Mercury E. Uranium
Correct Answer: B. Cadmium Explanation: Itai-itai is a disease caused by cadmium poisoning. The symptoms of the disease include weak and brittle bones. The disease is initially characterized by spinal and leg bone pain. It also includes complications like kidney failure.
By which of the following processes, does the exchange of DNA occur due to pairing of two chromosomes? A. Mutation B. Crossing over C. Mitosis D. Transduction E. Transformation
Correct Answer: B. Crossing over Explanation: Crossing over which occurs during meiosis, is a process of exchange of genetic material from one chromosome to other when they pair with each other. Mitosis is somatic cell division, which takes place through phases. Mutation occurs by change in the nuclotide sequence. Transduction is the process of transfer of DNA from one bacterium to other by bacteriophages. Transformation refers to the alteration of DNA that results due to transfer of foreign DNA.
Which of the following is mixotropic? Yeast Dinoflagellates Amoeba Mushroom Blue- green algae
Correct Answer: B. Dinoflagellates Explanation: A mixotroph is an organism that can utilize different forms of energy. Dinoflagellates are flagellated mixotropic protists. They combine photosynthesis with ingestion of prey. Yeast, amoeba and mushroom are heterotrophic. Blue- green algae is autotrophic.
The adipose tissue plays role in Pigment storage Fat storage Stretching Binding organs None of the above
Correct Answer: B. Fat storage Explanation: Adipose is a type of connective tissue whose cells get expanded with fat droplets and hence the nucleus and cytoplasm of this cell are pushed towards edges to form ring like structure. Adipose tissue provides insulation, stores fat and gives protection. Pigmented connective tissue that is present in eyes and skin is meant to store pigments. Elastic connective tissue helps in stretching. Dense connective tissues bind the organs together.
The type of sex determination found in Crepidula fornicata is A. Temperature dependent B. Location dependent C. Chromosome dependent D. Water dependent E. Soil dependent
Correct Answer: B. Location dependent Explanation: There are certain species of animals whose sex is determined by environmental factors rather than the chromosomes. One such species is Crepidula fornicata in which location plays main role in determining their sex. Temperature dependent sex determination is seen in reptiles such as crocodiles and turtles.
In which part of the human body are Nissl's granules present? A. Osteoblasts B. Neuron C. Chondroblasts D. Goblet cell E. All of the above
Correct Answer: B. Neuron Explanation: Nissl's granules are present in the cell body of neuron. These are the site of protein synthesis in neurons and are made of rough endoplasmic reticulum and ribosome. It was named after Franz Nissl.
The passage of materials between the nucleus and the cytosol takes place through Vesicle Nuclear pore Nucleosome Cajal body Nuclear speckle
Correct Answer: B. Nuclear pore Explanation: Nuclear pores are small perforations on the nuclear envelope that allow transportation of substances across the nucleus and cytoplasm. Cajal body and nuclear speckle are small subnuclear organelles. Nucleosome is a chromosomal structure containing histones in DNA. Vesicles present in cytoplasm transport substances from one part of a cell to another part.
Engrailed proteins are Tethering proteins Transcription factors Ubiquitins Signaling molecules Carrier proteins
Correct Answer: B. Transcription factors Explanation: Engrailed proteins are transcription factors which play a major role in brain development in many species. They determine the midbrain/hindbrain border and aid in neuronal axon guidance.
The state of a neuron which inhibits the generation of action potential is said to be Depolarized Repolarized Hyperpolarized Resting potential A, B and D
Correct Answer: C. Hyperpolarized. Explanation: Resting potential is the state of a neuron which is not under any stimulus. The normal resting potential of human nerves is -70 mV. When a neuron receives stimulus, the cell's interior will be depolarized with influx of Na+ ions which will result in action potential. Immediately after the generation of action potential the cell is hyperpolarized; that makes the cell more negative and keeps the neuron in a refractory period so that the next action potential cannot generate. Next is the repolarization i.e. neuron will come to its original resting state.
Which of the following kinds of signalling occurs when the cells communicate with each other through direct contact? Endocrine signalling Paracrine signalling Juxtacrine signalling Intracrine signalling None of the above
Correct Answer: C. Juxtacrine signalling Explanation: Juxtacrine signalling is an example of intercellular communication where cells communicate through direct contact. Endocrine signalling occurs between cells that are present over large distance. Paracrine signalling occurs between cells that are present over short distance. In intracrine signalling the signals are produced inside the target cell.
In amphibian, vitellogenin is synthesized by Oocyte Uterus Liver Spleen Intestine
Correct Answer: C. Liver Explanation: Vitellogenin is a precursor protein that is expressed in the females of all oviparous species including amphibians, fishes, reptiles and birds. Vitellogenin is a glycolipoprotein secreted by the liver. Vitellogenin can be expressed by the male (in a few species) in the presence of estrogenic endocrine disruptive chemicals. Vitellogenin precursors provide the major egg yolk proteins which serves as nutrients.
The process of delivery of foetus is called Implantation Lactation Parturition Fertilization None of the above
Correct Answer: C. Parturition Explanation: The process in which the foetus is delivered is called as parturition. Oxytocin is released during parturition which is responsible for the contraction of uterus.
Presence of metameric segmentation is the characteristic of phylum Protista Porifera Cnidaria Annelida Platyhelminthes
Correct Answer: D. Annelida Explanation: Metameric segmentation is the division of body into a number of similar segments. Metameric segmentation is generally exhibited by phylum Annelida and phylum Arthropoda.
Lowest area of water body is called A. Littoral zone B. Aphotic zone C. Photic zone D. Benthic zone E. None of the above
Correct Answer: D. Benthic zone Explanation: Lowest area of water body such as ocean or lake is called as benthic zone. Organisms living in this zone are called as Benthos. Littoral zone is the region of lake, sea or ocean. Aphotic zone is the zone of water body which lacks sunlight. Photic zone is the upper part of water body to which enough sunlight penetrates and permits photosynthesis.
A region with high level of endemic species that is under threat from humans is called A. Botanical garden B. Wild life Sanctuaries C. Zoos D. Biodiversity hotspot E. None of these
Correct Answer: D. Biodiversity hotspot Explanation: Hotspots are the regions with significant reservoir of biodiversity and high level of endemic species that is under threat from humans. Botanical garden is a place where plants are cultivated for education, scientific and ornamental purposes. Wildlife sanctuaries are areas in natural conditions which are reserved for the conservation of animals within which human activity is inhibited. Zoo refers to an institution in which living animals are kept and usually exhibited to the public.
A process by which an egg undergoes a series of rapid cell divisions without cell growth or gene expression is called Apoptosis Acrosome reaction Cortical reaction Cleavage None of the above
Correct Answer: D. Cleavage Explanation: Cleavage is a series of rapid cell divisions without cell growth or gene expression. The organisms are formed by growth and development of these cells. The different cells formed from cleavage are called as blastomere. The compact mass of blastomere is called morula.
Nematocyst is a characteristic feature of Echinoderms Arthropods Molluscs Cnidarians Porifera
Correct Answer: D. Cnidarians Explanation: Nematocysts are sub-cellular organelle found in cnidocytes. They carry toxic substances. Nematocysts are powerful weapons and a single nematocyst is sufficient to paralyse smaller organisms. The box jellyfish has one of the most toxic nematocysts.
Which of the following reactions block polyspermy? A. Capacitation B. Spermatogenesis C. Acrosome reaction D. Cortical reaction E. Fertilization
Correct Answer: D. Cortical reaction Explanation: Cortical reaction can be defined as the reaction of egg cell to fertilization which results in the change of cell membrane. The cortical reaction is exocytosis of eggs' cortical granules. The calcium signal activates the egg to undergo cortical reaction. Cortical reaction prevents other sperms from entering the egg.
The type of petrification in which the organic matter of the dead body is replaced by double carbonates of calcium and magnesium is called A. Silicification B. Pyritization C .Carbonization D. Dolomitization E. None of these
Correct Answer: D. Dolomitization Explanation: In the process of fossil formation, the replacement of dead organic matter by the dissolved minerals is called petrification. It is of different types according to the mineral deposited. Silicification is the replacement of original dead matter by silica; Pyritization is the replacement by iron pyrites. When carbon compounds are deposited, it is called carbonization. In dolomitization, magnesium carbonate replaces the calcium carbonate that was already deposited in dead matter.
Lung is a derivative of ________ germ layer. Surface ectodermal Neuroectodermal Mesodermal Endodermal Both A and C
Correct Answer: D. Endodermal Explanation: During embryo development, the germ layers ectoderm, endoderm and mesoderm are differentiated from blastula in a process called gastrulation. Later organogenesis takes place from those germ layers. Lung is one of the foregut derivatives of endoderm.
In the process of animal development, gastrulation is represented as Gamete to zygote Zygote to blastula Blastula to gastrula Gastrula to neurula None of the above
Correct Answer: D. Gastrula to neurula Explanation: Gastrulation is the stage in development of an embryo, in which three distinct germ layers (ectoderm, endoderm and mesoderm) are formed. It takes place next to cleavage, in which blastula formation occurs from zygote. After gastrulation is neurulation which is the typical organogenesis.
Which among the following processes results in dark coloured amorphous substance during decomposition in soil? A. Mineralization B. Fragmentation C. Leaching D. Humification E. None of the above
Correct Answer: D. Humification Explanation: Decomposition in soil results in humification and mineralization. Humification refers to the accumulation of dark coloured amorphous substance called humus which serves as a reservoir of nutrients. It resists microbial action and so decomposition takes place very slowly. Further degradation of humus by microbes leads to mineralization.
The substance that inactivates an enzyme by denaturing it is called A. Feedback inhibitor B. Competitive inhibitor C. Allosteric inhibitor D. Irreversible inhibitor E. None of these
Correct Answer: D. Irreversible inhibitor Explanation: Irreversible inhibitors modify or denature the enzyme irreversibly. The other inhibitors will not denature the enzyme. DIFP can irreversibly inhibit serine proteases.
Which of the given organelles is not present in animal cells? Nucleus Golgi apparatus Lysosome Leucoplast Mitochondria
Correct Answer: D. Leucoplast Explanation: Among the given organelles, leucoplasts are present only in plant cells but not in animal cells. They are the sites responsible for storage of proteins, starch and lipid molecules.
Spleen is an organ of which of the following systems? A. Digestive system B. Endocrine system C. Excretory system D. Lymphatic system E. Respiratory system
Correct Answer: D. Lymphatic system Explanation: Lymphatic system helps in balancing the body's fluid level and it is closely associated with immune system to act against infection. Its components are thymus, bone marrow, spleen, lymph nodes and lymph. The B-lymphocytes that participate in defense mechanism get accumulated and get matured in spleen, a lymphatic organ.
Chains of sarcomeres in muscles are organized into Sarcolemma Sarcoplasm Myoblasts Myofibrils Fascia
Correct Answer: D. Myofibrils Explanation: Sarcolemma is the muscle cell membrane and the sarcoplasm is the cytoplasm of muscle cell. The connective tissue outside the epimysium (sheath of connective tissue that surrounds each muscle) that separates two muscles is called the fascia. The parallelly arranged filaments in the sarcoplasm, which are arranged by the chains of sarcomeres are called myofibrils. The embryonic cell that gives rise to muscle cell is called myoblast.
Which of the following blood components carries dissolved nutrients? A. Red blood cells B. White blood cells C. Platelets D. Plasma E. None of the above
Correct Answer: D. Plasma Explanation: Plasma is a straw-yellow colored fluid which constitutes 55% of blood. Plasma circulates dissolved nutrients such as glucose, amino acids, fatty acids etc. and it removes the waste products of metabolism. It is an aqueous solution consisting 90-93% of water.
Which of the following is included in aphotic zone? Bathypelagic Abyssopelgic Mesopelagic Hadopelagic All of the above
Correct Answer: E. All of the above Explanation: All the above mentioned zones are devoid or have little light and are called aphotic zones. Aphotic zone is the epipelagic zone. Very few organisms live in the hadopelagic (deepest) zone.
Which of the following fixes nitrogen? A. Azotobacter B. Anabaena C. Nostoc D. Calothrix E. All of the above
Correct Answer: E. All of the above Explanation: Azotobacter, anabaena, nostoc and calothrix are free living nitrogen fixing bacteria. Azotobacter can be found in the soil. Anabaena, nostoc and calothrixlives in water as well as on moist rocks.
Which of the following comes under the domain eukarya? Plantae Animalia Protista Fungi All of the above
Correct Answer: E. All of the above Explanation: Early biologists classified organisms into three major domains namely bacteria, archae and eukarya. Eukarya is a domain which consists of protists (unicellular or multicellular, colonial, diverse reproductive cycles) fungi (multicellular or unicellular, chemoheterotrophic, decomposers, unique reproductive cycles) plantae (photosynthetic autotrophs, multicellular, with cell wall) and animalia (chemoheterotrophs, without cell wall).
Which of the following is secreted by the pancreas? Elastase Carboxypeptidase Amylase Ribonuclease All of the above
Correct Answer: E. All of the above Explanation: Elastase, carboxypeptidase, ribonuclease and amylase are secreted by the pancreas. Elastase breaks down elastin. Carboxypeptidase cleaves peptide bond at the carboxyl terminal. Ribonuclease cleaves RNA molecules.
Which of the following is/are the characteristics of euglenoids? A. Autotrophic B. Heterotrophic C. Presence of pellicle D. Presence of flagella E. All the above
Correct Answer: E. All the above Explanation: Euglenoids are the protists which come under the group flagellates. They live in both fresh water and marine environment. They contain pellicle, a protein rich membrane which helps them in flexibility. They are mixotrophic which means that they are photosynthetic in the presence of sunlight and heterotrophic when they lack sunlight.
Which of the following develops from ectoderm? A. Liver B. Pancreas C. Kidney D. Stomach E. Brain
Correct Answer: E. Brain Explanation: Liver, pancreas and stomach develop from endoderm. Kidney develops from intermediate mesoderm. Brain develops from the neural tube of the ectoderm. Ectoderm generates the outer layer of the embryo. The ectoderm develops into the surface ectoderm, neural crest and neural tube.
Which of the following statements is false with respect to class Monocotyledoneae? Grass is an example of class Monocotyledonae. Embryo has one cotyledon Monocotyledons have a single cotyledon Vascular cambium usually absent Monocotyledons generally have reticulate venation
Correct Answer: E. Monocotyledons generally have reticulate venation Explanation: Monocotyledons generally have parallel venation. In parallel venation, the veins are present parallel to each other. Reticulate venation is a characteristic of dicot plant where the veins emerge from different parts of the main vein.
The semi fluid mass of partly digested food is called chyme. Formation of chyme takes place in Mouth Small intestine Large intestine Liver Stomach
Correct Answer: E. Stomach Explanation: The semifluid mass of partly digested food in stomach before entering duodenum is called as chyme. The food mixes thoroughly with the acidic gastric juice of the stomach by the churning movements of its muscular wall and results in the formation of chyme.
The word 'Savanna' refers to A. Temperate grasslands B. Tropical forests C. Deserts D. Artic region E. Tropical grasslands
Correct Answer: E. Tropical grasslands Explanation: Tropical grasslands are called as Savanna. It is located near the equator. It is scattered with shrubs and isolated trees. Savanna covers approximately 20% of earth's land area.
Which protein is targeted by cholera toxin? G proteins Actin Permease Vinculin Vitonectin
Correct Answer: G proteins Explanation: Cholera toxin inhibits the GTPase activity of the G protein. So the protein always remains in the activated state. This results in the constant activation of adenylate cyclase enzyme. cAMP level rises due to the activation of adenylate cyclase. This eventually leads to secretion of water, sodium ions etc to the intestinal lumen.
7. Which of the following chemical moieties forms the backbone of DNA? A) Nitrogenous bases B) Glycerol C) Amino groups D) Pentose and phosphate E) Glucose and phosphate
D. DNA is composed of nucleotides joined together in long chains. Nucleotides are composed of a pentose sugar, a phosphate group, and a nitrogenous base. The bases form the "rungs" of the ladder at the core of the DNA helix and the pentose-phosphates are on its outside, or backbone.
10. Which of the following is true of the enzyme telomerase? A) It is active on the leading strand during DNA synthesis B) It requires a chromosomal DNA template C) It acts in the 3→5 direction D) It adds a repetitive DNA sequence to the end of chromosomes E) It takes the place of primase at the ends of chromosomes
D. Each time a cell divides, a few base pairs of DNA at the end of each chromosome are lost. Telomerase is an enzyme that uses a built-in template to add a short sequence of DNA over and over at the end of chromosomes-a sort of protective "cap". This prevents the loss of genetic material with each round of DNA replication.
In plants and animals, genetic variation is introduced during A) Crossing over in mitosis B) Chromosome segregation in mitosis C) Cytokinesis of meiosis D) Anaphase I of meiosis E) Anaphase II of meiosis
D. In anaphase I, homologous chromosome pairs segregate randomly into daughter cells. This means that each daughter cell contains a unique combination of chromosomes that is different from the mother cell and different from its cognate daughter cell.
Which of the following is an example for denitrifying bacteria? A. Nitrosomonas sp B. Nitrobacter sp C. Rhizobium sp D. Pseodomonas sp E. All of the above
D. Pseodomonas sp Explanation: Denitrifiication is a process of reduction of nitrate to molecular nitrogen by microbial action. Pseodomonas sp is an example of denitrifying bacteria. Nitrosomonas sp and Nitrobacter sp are examples of nitrifying bacteria. Rhizobium sp is an example for nitrogen fixing bacteria.
6. In DNA replication, which of the following enzymes is required for separating the DNA molecule into two strands? A) DNA polymerase B) Single strand binding protein C) DNA gyrase D) Helicase E) Primase
D. The enzyme helicase unwinds DNA. It depends on several other proteins to make the unwinding run smoothly, however. Single-strand binding protein holds the single stranded DNA in place, and topoisomerase helps relieve tension at the replication fork.