Dat Biology Questions And Answers

Dat Biology Questions What are the seven components of the modern day cell theory? - ANS 1. All known living things are made up of one or more cells 2. All living cells arise from pre-existing cells by division. 3. The cell is the fundamental unit of structure and function in all living organisms. 4. The activity of an organism depends on the total activity of independent cells. 5. Energy flow (metabolism and biochemistry) occurs within cells. 6. Cells contain DNA which is found specifically in the chromosome and RNA found in the cell nucleus and cytoplasm. 7. All cells are basically the same in chemical composition in organisms of similar species A scientist wants to detach a peripheral membrane protein from the exterior of a cell membrane. Which is the best method to do so? A. change salt concentrations B. Perform a light centrifuge C. Add a detergent D. Change the temperature of a solution E. Run a small current through the solution - ANS A. change salt concentrations Peripheral membrane proteins are held in place by electrostatic interactions and hydrogen bonding. They are generally hydrophilic. Changing the salt concentration (a "salt wash") or the pH would disrupt both of these types of bonds and release the peripheral membrane protein from the cell membrane. A light centrifuge will precipitate cells and nuclei at most, only heavy centrifuges extract small soluble proteins. All of the following were observed by Miller-Urey in their classic experiment to check the hypothesis of the "chemical origins of life" EXCEPT for one. Which one is the EXCEPTION? A. Methane B. Amino acids C. Ammonia D. Organic compounds E. Nucleic acids - ANS Nucleic acids What was the Miller-Urey experiment - ANS The Miller-Urey experiment used ammonia, methane, water and hydrogen sealed in a sterile arrangement of tubes and flasks with connecting loops. One flask was half-filled with liquid water and the other with 2 electrodes (to simulate lighting in early earth). The flask with water was heated to simulate the temperature of early Earth, and sparks were fired from the electrodes to simulate lightning. After 2 weeks, they observed several organic compounds, amino acids (11 out of 20) and their base starting materials. However, no complete nucleic acids were observed. A toxin is released into the body that promotes the degeneration of microfilaments. Which of these structures is most likely to be directly affected? A. spindle fibers radiating from centrioles B. Lyosomes C. The extracellular matrix D. Chromosomes E. Muscles cells - ANS E. muscle cells Our muscles are made of long chains of cytoskeleton comprised of two filaments - actin and myosin. Of these, actin is a microfilament, while myosin is a motor protein. If actin degenerates, then our muscles would not contract, thus, our answer is E. The spindle fibers radiating from the centrioles are microtubules. A lysosome is an organelle that is involved in phagocytosis. The extracellular matrix consists of protein fibers and glycosaminoglycans. Chromosomes are made of nucleic acids What are Pilli - ANS Pili are small short "hairs" called fimbriae on the surface of bacteria that can be used in the exchange of genetic material between bacteria and in cell adhesion. Glycosis is best described as what type of process? A. Exergonic B. Endergonic C. Isotonic D. Hypertonic E. Hypotonic - ANS A. Exergonic Glycolysis requires the use of energy when the glucose molecule is broken into two pyruvates. The two steps in which ATP is used can be considered endergonic, however, overall glycolysis produces energy to be consumed by the cells. If energy is released, then the reaction is exergonic. The concentration terms, isotonic, hypertonic, and hypotonic refer to the relative concentrations of different environments and this is not related to cell thermodynamics or a cell's use or production of energy. Scanning Electron Microscope - ANS Transmission Electron Microscrope - ANS Compound Light Microscope - ANS Flourescence Microscope - ANS Oligodendrocytes are best associated with: A.Beta cells of the pancreas B. G cells of the stomach C. Nerves in the peripheral system D. White matter of the brain E. Spermagonia of the testes - ANS D. White matter of the brain The main extracellular buffer system in humans consists of: A amphipatic proteins. B. phosphate C sulfate D bicarbonate E histamines - ANS D. bicarbonate The main extracellular buffer is bicarbonate. This is how CO2 is transported throughout the body. Which of the following is a method marine fish use to maintain homeostasis? A. Swim towards freshwater B. Rarely drink water C. Absorb salt through gills D. Constantly urinate E. Constantly drink water - ANS E. Constantly drink water A human embryo is a deuterostome. In deuterostomes, the first opening that forms gives rise to what anatomical structure? A. Mouth B. Anus C. Head D. Back E. Genetalia - ANS B. Anus In mammals, which of the following structures aides the embryo in gas exchange and the disposal of liquid waste? A. YolkA. B. Amnion C. Allantois D. Chorinoic Villi E. Yolk sac - ANS C. Allatois A child is suspected to have Down Syndrome, or trisomy 21. Which of the following tests can substantiate this diagnosis? A. Gel electroporesis B. Polymerase Chain Reaction C. Dna Fingerprinting D. Northern Blotting E. Karyotyping - ANS E. Kayotyping All of the following processes result in genetic variation EXCEPT for one. Which one is the EXCEPTION? A. Mutation B. Crossing Over C. Meiosis D. Linked Genes E. Independent Assortment - ANS D. Linked Genes Nondisjunction occurring during meiosis II, followed by fertilization, would result in a zygote with which of the following chromosomal descriptions? A. Aneuplooid B. Diploid C. Haploid D. Tetraploid E. Disomic - ANS A. Aneuploid - extra or missing chromosome number A student observes a population of 100 eagles in Hardy-Weinberg equilibrium. The eagle's allele for a pointed beak is dominant, and the allele for a rounded beak is homozygous recessive. If 9 eagles were found to have a rounded beak in the population, what is the allele frequency of the pointed beak? A. 0.09 B. 0.30 C. 0.70 D. 0.81 E. 0.91 - ANS C. .70 The equation for the Hardy-Weinberg equilibrium is: p2 + 2pq + q2 = 1. We also know that p + q = 1, where p (pointed beak) and q (rounded beak) are the dominant allele and recessive allele frequencies, respectively. p2 = homozygous dominant (pointed beaks) 2pq = hybrids (pointed beaks) q2 = homozygous recessive (rounded beaks) 9 eagles display rounded beaks, which means they are homozygous recessive for the allele. q2 gives us the number for the homozygous recessive individuals, so if 9% of the population is recessive, then we know that: 0.09 = q2; q = 0.30. Thus, according to p + q = 1, the frequency of the dominant allele must be p = 1 - 0.30 = 0.70. Brackish water - ANS Brackish water means a mix between salt and fresh water, which would be found in an estuary Dino the dinosaur most likely live A 230 million years ago B 770 million years ago C 50 million years ago D 1 billion years ago - ANS A 230 million years ago Largest internal organ is the Liver Gall bladder Pacreas Stomach - ANS Liver Penicillians inhibit bacteria to? A replicate nucleic acids B synthesize cell walls C produce ATP D form spores E synthesize proteins - ANS synthesize cell walls Which of the below molecules exert its action within the target cell by only interacting with cell-surface receptors? A estrogen B testosterone C progesterone D insulin E more than one of these - ANS D insulin because steroid hormones bind to nuclear receptors Which germ layer is connective tissue derived from ? - ANS mesoderm The process which is common in both aerobic and anaerbic organisms? A Krebs cycle B Fermentation C Glycolysis D Electron Transport Chain - ANS Glycolysis - occurs in all living cells A biology student added I2-KI reagent to a unknown compound dissovled in water in a test tube. The solution turned blue-black. The unknown compound is most likely? A pure water B amylose (starch) C protein Dcellulose E glucose - ANS Amylose starch Consider the following ATP -- cyclic AMP The enzyme that catalyzes this reaction is also called adenyl cycalse. This enzyme is inactive until which hormone binds A Trypsin B Chymotripsin C Epinephrine D Thyroxin E Human Growth Hormone - ANS Epinephrine Which of the following is not a viral disease A Hepatitis B Small pox C Chickenpox D Rabies E Tuberculosis - ANS E Tuberculosis - bacterial Which of the following are true A marine fish rarely urinate, but constantly drink B Fresh water urinate constantly but rarely drink C many freshwater animals have very dilute urine D marine bony fish have isotonic urine, while freshwater bony fish have dilute urine E all the above are true - ANS E all the above are true A nucleoside consists of A phosphate and base B sugar and base C phosphate sugar and base D phosphate only - ANS sugar and base Platelets are derived from A Megakaryocytes B Leucocytes C Reticulocytes D Eosinophils E Monocytes - ANS Megakaryocytes Stem elongation and flowering in some plants is due to A Gibberellins B Cytokines C Abscisic acid D Ethylene E B and D - ANS A Gibberellins Birth control pills are most closely associated with what two hormones ? A Testosterone and estrogen B Estrogen and Progestin C Porgesterone and Enterogastrone D FSH and LH - ANS Estrogen and Progestin A situation in which different body cells express different genotypes and all the cells are derived from different fertilized eggs is called a A Morula B Mosaic C Chimera D Aneuploid E Polymorph - ANS Chimera- single organism that is made up of two or more genetically different populations Which is most involved in the slow block to polyspermy in the sea urcin? A myosin filaments B zona pellicuda C coritcal granules D acrosome E plasma membrane - ANS cortical granules - sperm proof fertilization membrane is formed when the cortical granules in the egg fuse with the plasma membrane Which hormone is found at highest levels during the secretory phase of the menstrual cycle? A LH B FSH C TSH D Estrogen E Progesterone - ANS Progesterone Secretory phase is the final phase of the cycle and the corpus luteceum produces progesterone Nitrogen fixation occurs in which structure? A anther B stamen C root nodule D xylem tissue E pistil - ANS Root nodule True or False Red tides are caused predominantly by red algae called rhodophyta? - ANS False. Red tides are primarly caused by dinoflagellates not red algae Which of the following is a mineralocorticoid A Aldosterone B Cortisol C Epinephrine D Insulin E Meletonin - ANS Aldosterone A protein of 210 amino acids is made from how many DNA nucleotides? - ANS 210 * 3 (3 codon)= 630 Where do sperm mature A epidymus B Semiferous tubules C Vas deferens D prostate - ANS Epidymus Which hormone stimulates the release of bile A Enterogastrone B Cholecystokinin C Bilease D Secretin E Gastrin - ANS Cholecytokinin Which of these is false about the liver A Albumin production B Bile production C Destruction of worn out red blood cells D Converts nitrogenous wastes into urea E Glucose storage - ANS E glucose storage- stores glycogen not glucose Where is urea made Kidneys Liver Lungs Gall bladder Thyroid - ANS Liver Which DNA sequence is a palidrome and could be a potential restriction enzyme site? GAATCG CCTAGG AAAAA GGGGG GGCCGG - ANS Palidrome= same when read left to right as it is right from left CCTAGG According to the Impact Hypothesis, an asteroid or comet struck the earth and caused mass extinction. A thin layer of which element separated Mesozoic and Cenozoic sediments? A Osmium B Iridium C Barium D Cerium E Promethium - ANS B Iridium asteroids and meteors have high levels of iridium Which structure is the link between the nervous and endocrine system? A Thalamus B Hypothalamus C Adrenal cortex D Medulla E Pineal gland - ANS B hypothalamus Bacteria derive energy from A Krebs cycle B Glycolysis C Electron Transport Chain D A and B E B and C - ANS E - glycolysis and electron transport chain Bill and Ann have normal vision, but their fathers are both colorblind. What is the probability that their first child will be a normal boy? - ANS 25% Xi X X XiX XX Y XiY XY How many DNA strands would be expected after 8 cycles of the PCR ? 8^2 2^8 2^16 2^8 x 2 10^8 x 2 - ANS 2^8 x 2 A egg cell will contain? A 23 chromosomes 46 chromatids B 23 chromosomes 23 chromatids C 46 chromosomes 46 chromatids D 46 chromosomes 23 chromatids - ANS Egg is haploid so it contains 23 chromosomes and 23 chromatids When O2 binds to hemoglobin we see an increased affinity for O2 binding in the remaining subunits. This is called A cooperativty B complement C Competitive inhibition D Allosteric Effect - ANS A cooperativity Cytochromes are with which of the following A TCA cycle B Glycolysis C Electron Transport Chain D Gluconeogenesis - ANS C Electron Transport Chain Cytochromes are a heme containing proteins found in the electron transport chain Which was most recent? A Cenozoic B Mesozoic C Paleozoic D Precambrian E Achaean - ANS A Cenozoic Cenozoic (most recent)Mesozoic (dinosaurs) Paleozoic (land plants, fish, alga) Precambrian (oldes, monera, fungi, invertebrates DNA is not found in A Erytrocytes B Lympocytews C Skin cells D Hair cells E Sperm cells - ANS A Erytrocytes because they lack a nucleus The phenomenon that occurs when one gene pair masks or modifies the expression of another gene pair is called? A peliotrophy B epistasis C modulation D cooperativity E mutation - ANS Epistasis Consider the cell life cycle which stage is normally the longest? A Go B G1 C G2 D M E S - ANS G1 - m phase is the shortest Which root contains cell bodies of the sensory neurons? A Ventral B Dorsal C Both contain sensory neurons - ANS Dorsal Which molecule participates in endocytosis by forming a polyhedral lattice around coated pits? A actin B myosin C Clathrin D Spectrin E tubulin - ANS Clathrin The energy source for chemoautotrophs comes from A. H20 B. ATP C. inorganic molecules D. organic molecules E. the sun - ANS C. inorganic molecules - comes from the oxidation of inorganic molecules Which of the following correctly describes cytokinesis in mammals A. molecular chaperones pull each cell to opposing ends B. Vesicles migrate and fuse to form cell plate C. Microfilaments encircle the center of the cell and shorten D. Microtubules pull apart the homologous chromosomes E. RNA is spliced out before it migrates to the cytoplasm - ANS C. Cytokinesis is the last stage of mitosis and actually begins occurring at the end of anaphase. It is the process of dividing the cytoplasm to form 2 cells. In mammals, a cleavage furrow develops from microfilaments encircling the cell and pulling the plasma membrane into the center. In plants, vesicles from the Golgi bodies migrate and fuse to form a cell plate to separate the two cells (Choice B). Choice [A] is incorrect, molecular chaperones are typically used in protein synthesis, not in cytokinesis. Choice [D] refers to anaphase directly where the microtubules shorten to pull apart chromosomes. Choice [E], while true, is not related to cytokinesis.