ATI TEAS VII Online Practice A - Science

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 - Methionine 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 - Steroids 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 - Transcription 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? It is a closed circulatory system.The lymph flows from the interstitial spaces toward the heart. The lymph transports carbon dioxide to the lungs for expiration. The lymphatic systems helps the body to absorb lipids. The lymphatic system contains more red blood cells than white blood cells. - The 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? The skin will have a thin dermis. The skin will not have pigmentation. The skin will get tanned on exposure to sunlight. The skin will not be able to maintain its temperature. - The 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 - Thyroid hormones The human body needs iodine, a naturally occurring element, to produce the thyroid hormones thyroxine and triiodothyronine. Which of the following is the role of the urethra? To transport urine out of the body To transport the egg to the uterusTo connect the kidneys to the bladder To connect the uterus to the outside of the body - To transport urine out of the body