substances be transported across a membrane against their concentration gradient?

What is the role of cholesterol in animal cell membranes? A. Blocks the association of the fatty acyl chains of phospholipids at high temperature. B. Is a receptor site for hormones on the surface of membranes. C. Broadens the temperature range of optimum membrane fluidity. D. Aids in the transport of small hydrophobic molecules across the membrane.    A fatty acid designated as 20:0 is ________, while one that is designated 20:3 delta ^5,8,11 is ________. A. complex; simple B. unsaturated; saturated C. saturated; unsaturated D. simple; complex E. monounsaturated; polyunsaturated

You find a membrane protein that moves molecules across a membrane. What type of transport could that protein be involved in?

In which situation would passive transport not use atransport protein for entry into a cell?a. water flowing into a hypertonic environmentb. glucose being absorbed from the bloodc. an ion flowing into a nerve cell to create anelectrical potentiald. oxygen moving into a cell after oxygen deprivation

Choose the processes from the list below which require active transport  A. Water moving through the membrane  B. Sodium moving out of a cell C. Potassium moving into a cell  D. Endocytosis  E. Oxygen moving from inhaled air into blood stream.