← Previous 1 2 3 4 5 6 7 8 Next →
All of the following are known to be components of cell walls except which one? Possible Answers:
Explanation: Actin is what makes up microfilaments. Chitin is indeed in cell walls of fungi. Cellulose is the main ingredient to plant cell walls and peptidoglycan are found in the cell walls of cyanobacteria and bacteria. Also, cellulose is made of polysaccharides, therefore, this is also an incorrect answer because it is a component of the cell wall.
Which of the following best describes the fluid mosaic model of membranes? Possible Answers:
The membrane consists of a phospholipid bilayer with proteins of various lengths and sizes located on the exterior portions of the membrane.
The membrane contains a phospholipid bilayer with proteins of various lengths and sizes interspersed among the phospholipids.
The membrane consists of a phospholipid bilayer with proteins of uniform lengths and sizes located on the interior portions of the membrane.
The membrane contains a phospholipid bilayer with proteins of uniform lengths and sizes interspersed among the phospholipids.
The membrane consists of a phospholipid bilayer with proteins of various lengths and sizes located on the interior portions of the membrane.
Correct answer: The membrane contains a phospholipid bilayer with proteins of various lengths and sizes interspersed among the phospholipids. Explanation: The fluid mosaic model says that proteins can extend all the way through the phospholipid bilayer of the membrane. There are peripherial, integral, and transitional proteins. Therefore, these proteins are various sizes and lengths.
Which one of the following can be easily diffused across the cell membrane? Possible Answers:
Explanation: Lipids can diffuse freely across the cell membrane, because the cell membrane is made up of lipids. Ions will not be able to pass through the hydrophobic section of the membrane, because it is polar. Chloride is an ion. Water is polar and also won't be able to pass through the hydrophobic section of the membrane. Sucrose is too big to freely diffuse into the cell.
In regard to cellular membranes, what does it mean to be selectively permeable? Possible Answers:
Polarization of the cell membrane allows for passive transport of all foreign molecules or ions
Molecules and ions outside the cell are selected to enter the cell via active or passive transport through the phospholipid bilayer
Molecules and ions are always kept to the exterior of the phospholipid bilayer
Molecules and ions can pass freely through the phospholipid bilayer
Polarization of the cell membrane allows for no entrance of foreign molecules or ions
Correct answer: Molecules and ions outside the cell are selected to enter the cell via active or passive transport through the phospholipid bilayer Explanation: A cell must exchange molecules and ions with its surroundings. This process is controlled by the selective permeability of the plasma membrane. Passive transport requires no energy from the cell; molecules like water can diffuse into and out of the cell through the phospholipid bilayer freely by way of osmosis. Other molecules and ions, like sodium, are actively transported across the phospholipid bilayer. This requires ATP created by the cell. Active transport moves solutes against their concentration gradients, which is why it requires energy.
Which of the following is NOT true of the cytoplasmic protein structures known as tonofibrils? Possible Answers:
They are primarily made of kertain tonofilaments.
They are most typically anchored to the cytoskeleton.
They are primarily found in endocrine tissues.
The protein filaggrin is thought to hold them together.
They converge at desmosomes and hemidesmosomes.
Correct answer: They are primarily found in endocrine tissues. Explanation: Tonofibrils are groups of keratin tonofilaments (intermediate filaments) most commonly found in the epithelial tissues, not endocrine tissues, and which play an important structural role in cell makeup.
← Previous 1 2 3 4 5 6 7 8 Next →
Andrew
University of South Florida-Main Campus, Bachelors, Biomedical Sciences. New York Medical College, PHD, Doctor of Medicine.
Laura
Athens State University, Bachelor of Science, Psychology.
Anagha
University of Central Florida, Bachelor of Science, Biomedical Sciences.
If you've found an issue with this question, please let us know. With the help of the community we can continue to improve our educational resources.
If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one or more of your copyrights, please notify us by providing a written notice (“Infringement Notice”) containing the information described below to the designated agent listed below. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors. Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as ChillingEffects.org. Please be advised that you will be liable for damages (including costs and attorneys’ fees) if you materially misrepresent that a product or activity is infringing your copyrights. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney. Please follow these steps to file a notice: You must include the following: A physical or electronic signature of the copyright owner or a person authorized to act on their behalf; An identification of the copyright claimed to have been infringed; A description of the nature and exact location of the content that you claim to infringe your copyright, in \ sufficient detail to permit Varsity Tutors to find and positively identify that content; for example we require a link to the specific question (not just the name of the question) that contains the content and a description of which specific portion of the question – an image, a link, the text, etc – your complaint refers to; Your name, address, telephone number and email address; and A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe your copyright is not authorized by law, or by the copyright owner or such owner’s agent; (b) that all of the information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are either the copyright owner or a person authorized to act on their behalf. Send your complaint to our designated agent at: Charles Cohn Varsity Tutors LLC 101 S. Hanley Rd, Suite 300 St. Louis, MO 63105 Or fill out the form below: |