Bio 2 U2S3: membrane structure and function homework

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Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment

is hypotonic to the protozoan

The ideal osmotic environment for an animal cell is a __________ environment.

isotonic

a plant cell surrounded by a __________ solution will be flaccid (limp)

isotonic

which of the following statements regarding membrane protein function is false?

membrane proteins produce phospholipids

The plasma membrane is selectively permeable. Which of the following can pass freely through the membrane w no assistance?

oxygen and carbon dioxide

Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of....

passive transport

the process of a white blood cell engulfing a bacterium is

phagocytosis

Most of the functions of a cell membrane, including transport and enzymatic function, are performed by

proteins

the molecules responsible for membrane transport are

proteins

which statement best describes phagocytosis?

a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a vacuole

which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer?

Na+

which of the following processes can move a solute against its concentration gradient?

active transport

which of the following statements regarding active transport is false?

active transport is driven by the concentration gradient

Membrane phospholipids

are able to drift about in the plasma membrane

a plant cell in a hypotonic solution

becomes turgid because of an inflow of water

how do fatty acids travel through a cell membrane?

carrier proteins

Fluidity of an animal cell plasma membrane is enhanced by __________.

cholesterol molecules

Osmosis can be defined as

diffusion of water

The fluid mosaic model describes the plasma membrane as consisting of ...

diverse proteins embedded in a phospholipid bilayer

what controls the net direction of molecules, such as oxygen, involved in passive transport?

the direction of the oxygen concentration gradient

Plasma membranes are selectively permeable. This means...

the plasma membrane allows some substances to enter or leave a cell more easily than others.

When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will

exhibit a net movement to the side with lower free water concentration

The cholesterol associated with animal cell membranes

helps to keep phospholipids from being too close to one another

A plant cell placed in a ___________ solution will lose water and plasmolyze

hypertonic

there is a net diffusion of water out of an animal cell when it is placed in a ___________ solution.

hypertonic

An animal cell placed in a ______________ solution will gain water, swell, and possibly burst

hypotonic

The ideal osmotic environment for a plant cell is a _________ environment

hypotonic

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.

transport proteins : down

In the figure below, working from the inside out, what would be the order of components observed?

water, hydrophilic head, hydrophobic tail, hydrophobic tail, hydrophilic head, water


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