ATI TEAS VII Online Practice A – Science Questions & Answers

Vitamin B12 is converted to methyl-cobalamin, which is consumed in a reaction where methionine synthase produces the amino acid methionine. Which of the following molecules is the catalyst in this reaction? Vitamin B12 Methyl-cobalamin Methionine synthase Methionine - ANSWERSMethionine synthase Methionine synthase has the suffix -ase, which is a standard nomenclature for enzymes. Its name further indicates that it helps to make methionine, so it is a catalyst. Which of the following classes of chemical messengers is able to easily diffuse across the cell membrane? Steroids Interleukins Catecholamines Histamines - ANSWERSSteroids Steroids are lipid-soluble. Therefore, they are able to diffuse across the hydrophobic cell membrane. A gene is being copied into a molecule that contains ribose and uracil. Which of the following cellular processes does this describe? DNA replication Translation Gene splicing Transcription - ANSWERSTranscription Transcription is the process by which a gene, encoded in DNA, is copied into a messenger RNA. RNA contains ribose sugar and uracil base. Which of the following statements are true regarding the lymphatic system? - ANSWERSThe lymph flows from the interstitial spaces toward the heart is correct. ^ The lymphatic system contains a clear fluid called lymph that flows in one direction from the interstitial spaces toward the lymph ducts that then empty into the veins to enter the circulatory system and travel toward the heart. The lymphatic system helps the body to absorb lipids is correct. ^ Lymphatic vessels, called lacteals, absorb dietary lipids from the small intestine. Which of the following will occur in the absence of melanocytes in the skin? - ANSWERSThe skin will not have pigmentation. Melanocytes produce the pigment called melanin, which gives skin its color. In the absence of melanocytes, the skin will not be able to produce the pigment melanin and will have a pale and white appearance. Which of the following hormones requires iodine for its production? Thyroid hormones Melatonin Parathyroid hormone Calcitonin - ANSWERSThyroid hormones The human body needs iodine, a naturally occurring element (food), to produce the thyroid hormones thyroxine and triiodothyronine. Melatonin- sleep inducing hormone produced by the pineal gland in response to low light levels. Parathyroid hormone- regulates calcium levels in the blood by releasing parathormone. Calcitonin- hormone that regulates calcium in the blood. Which of the following is the role of the urethra? - ANSWERSTo transport urine out of the body The urethra connects the bladder to the opening of the body and allows the urine to exit the body. Which of the following terms describes the bonding together of smaller molecules to form larger molecules? - ANSWERSAnabolism Anabolism describes the endothermic process by which bonds are formed between molecules to make larger molecules. Catabolism- break down complex large molecules to simple molecules and release heat Anaphylaxis- body's immune system overreacting to a harmless substance Which of the following is a characteristic feature of the adaptive immune system? -It uses phagocytes for the ingestion of foreign particles. -It produces antibodies against a specific antigen in the body. -It exerts the first response of the immune system against an infection. -It is comprised of non-specific barriers against a pathogen. - ANSWERSIt produces antibodies against a specific antigen in the body. The adaptive immune system contains B cells, which differentiate into plasma cells, which produce antibodies against specific antigens. innate immune system -uses phagocytes for the ingestion of foreign particles. - first response of the immune system against an infection. -non-specific barriers against a pathogen. after doing a belly flop into a swimming pool, a child says, " the water slapped me." what is the property of water that causes the slap? Irregular expansion Hydrogen bonding Capillary action Hydrophobic exclusion - ANSWERSHydrogen bonding Hydrogen bonding holds the water molecules tightly together so they cannot disperse easily, increasing surface tension and causing the slap. Which of the following is true of centromeres of mitotic chromosomes prior to anaphase? It is the region where sister chromatids are most closely attached. It is the region where crossing over occurs. It is the region where replication begins. It is the region where histones are made. - ANSWERSIt is the region where sister chromatids are most closely attached. A centromere is a specialized region where two chromatids are most closely attached. Which of the following occurs when a skeletal muscle is in a relaxed state? Tropomyosin covers myosin-binding sites. Myosin forms cross bridges with actin filaments. Ca2+ is released into the cytosol of the muscle cell. ATP binds to myosin heads. - ANSWERSTropomyosin covers myosin-binding sites. When a muscle is in a relaxed state, tropomyosin covers myosin-binding sites on actin. Which of the following cell organelles are abundant in nerve and muscle cells to help meet their ATP requirements? Endoplasmic reticulum Mitochondria Golgi bodies Nucleus - ANSWERSMitochondria Mitochondria play a role in cellular respiration and help generate ATP, which provides cellular energy to carry out different functions. Which of the following is the function of the spleen in a healthy adult human? It stores bile produced in the liver. It synthesizes platelets. It is a vestigial organ. It degrades aged red blood cells. - ANSWERSIt "degrades" aged red blood cells. A healthy spleen has narrow tubes that cause aged red blood cells to rupture as they try to squeeze through. bile- stores in gall bladder. platelets- synthesize in bone marrow and stored in spleen. vestigial organ- no function and are from the past ancestors (wisdom tooth, tonsils, Coccyx) Which of the following correctly describes the color change and substance properties for acid-base indicator testing? Blue litmus turns red, indicating the presence of a base with a pH > 7. Red litmus turns blue, showing the presence of an acid with a pH > 7. Blue litmus turns red, indicating the presence of an acid with a pH < 7. Red litmus turns blue, showing the presence of a base with a pH < 7. - ANSWERSBlue litmus turns red, indicating the presence of an acid with a pH < 7. Blue litmus would turn red with an acid, and acids have a pH less than 7. Which of the following molecules present in blood has the ability to buffer changes in pH? Cholesterol Bicarbonate Plasma sugars Circulating salts - ANSWERSBicarbonate Bicarbonate is the conjugate base of carbonic acid, which is made from water and carbon dioxide, both of which are present in abundance in blood. Therefore, bicarbonate is a buffer in conjunction with carbonic acid.