Which of the following does not belong with others? A) diffusion B) osmosis C) active transport D) passive transport 31. The movement of particles from an area of higher to lower concentration is called _ A) osmosis B) diffusion C) filtration D) active transport 32.Facilitated diffusion differs from ordinary diffusion in that a. facilitated diffusion expends no ATP b. facilitated diffusion moves molecules from an area of their higher concentration to their lower concentration c. the rate of molecular movement is limited by the number of available carrier molecules d. facilitated diffusion never eliminates the concentration gradient e. the rate of molecular movement is not limited by the number of available carrier molecules 33. A process that requires cellular energy to move a substance against its concentration gradient is called a. active transport b. passive transport c. facilitated transport d. osmosis e. diffusion 34. Tubulin is to microtubules as actin is to a. ribosomes b. microfilaments c. intermediate filaments d. flagella e. microvilli
The Correct Answer and Explanation is:
30. Correct answer: C) active transport
31. Correct answer: B) diffusion
32. Correct answer: C) the rate of molecular movement is limited by the number of available carrier molecules
33. Correct answer: A) active transport
34. Correct answer: B) microfilaments
Explanation:
Question 30: Active transport differs from the others because it requires energy from the cell to move substances across the membrane, usually against the concentration gradient. Diffusion, osmosis, and passive transport all move substances along the concentration gradient without using cellular energy.
Question 31: The movement of particles from an area of higher concentration to an area of lower concentration is called diffusion. It is a passive process where molecules spread out to reach equilibrium. This process occurs in gases and liquids and does not require cellular energy.
Question 32: Facilitated diffusion is similar to simple diffusion in that it moves substances from higher to lower concentration and does not require energy. However, it uses transport proteins or carriers embedded in the membrane. The correct answer is C because the speed of this process depends on how many carrier proteins are available, limiting the rate of transport.
Question 33: Active transport requires the input of cellular energy, usually in the form of ATP, to move substances against their concentration gradient. This is different from passive processes, which rely on natural kinetic energy and concentration differences. Examples include the sodium-potassium pump in cells.
Question 34: Tubulin is the protein subunit that makes up microtubules, which are part of the cell’s cytoskeleton. Similarly, actin is the protein that makes up microfilaments. Both microtubules and microfilaments provide structural support and help in cellular movement and shape, but they are composed of different proteins.
These topics are essential in understanding how cells transport substances and maintain their internal environment.
