Bio unit 3
What is a light microscope?
light passes through the image to see it
In the figure below, working from the inside out, what would be the order of components observed? water filled bubble made of phospholipids
water, hydrophilic head, hydrophobic tail, hydrophobic tail, hydrophilic head, water
Water crosses the plasma membrane
Through facilitated diffusion or diffusion.
The plasma membrane is selectively permeable. Which of the following can pass freely through the membrane with no assistance?
oxygen and carbon dioxide
Diffusion across a biological membrane is called transport.
passive
Facilitated diffusion is a type of _____.
passive transport
A white blood cell engulfing a bacterium is an example of _____.
phagocytosis
When placed in a hypotonic environment, where the solute concentration is below that of the cell, a houseplant will _____.
ramain standing up straight
Which of the following enables a cell to pick up and concentrate a specific kind of molecule?
receptor-mediated endocytosis
You can recognize the process of pinocytosis when _____.
the cell is engulfing extracellular fluid
The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?
a hypertonic sucrose solution
What are the three principals of cell theory?
1.all living matter is composed by cells 2. all cells arise from other cells 3.cells only come from other cells
Which of the following is an accurate comparison of active transport and facilitated diffusion?
Active transport moves solutes against their concentration gradient; facilitated diffusion moves substances down their concentration gradient.
Which of the following is a difference between active transport and facilitated diffusion?
Active transport requires the expenditure of cellular energy, and facilitated diffusion does not.
What did Schleiden do?
All plants are made of cells
Frequently, transplanted organs are rejected by the recipient's body. How is this reaction related to plasma membranes?
Each person has a unique set of carbohydrate chains attached to his or her plasma membranes.
What is a scanning electron microscope?
Electrons move back and forth across a specimen, huge in size and (less detailed)
What is a transmission electron microscope?
Electrons pass through a sample of the specimen and will show an image of the internal details. Thin slices, (more detailed)
Which of these statements describes what occurs in facilitated diffusion?
Facilitated diffusion of solutes occurs through protein pores in the membrane.
What did Hooke discover?
He discovered cells and gave them their name
In active transport,
Molecules move across the plasma membrane against their concentration gradient.
What did Virchow do?
Proposed that all cells come from other cells
The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of
active transport
Utah's Great Salt Lake has an average salinity seven times higher than that of the oceans. Very few multicellular organisms live in this harsh environment. An example is the brine shrimp, which must devote a large portion of its metabolic energy to osmoregulation. These brine shrimp must _____.
actively pump water back into their cells to counter its loss due to osmosis
What did Schwann do?
all animals are made of cells
Which statements about the fluid mosaic structure of a membrane are correct? Select the three correct statements.
aqueous environment inside and outside of the cell and their hydrophobic tails clustered in the center,Because membranes are fluid, membrane proteins and phospholipids can drift about in the membrane, the diverse proteins found in and attached to membranes perform many important functions
What did Leeuwenhoek discover?
bacteria cells
What controls the net direction of molecules, such as oxygen, involved in passive transport?
c) the direction of the oxygen concentration gradient
Field of view
The area visible through the microscope eyepiece
Fluidity of an animal cell plasma membrane is enhanced by __________.
cholesterol molecules
Osmosis is often viewed incorrectly as a process driven directly by differences in solute concentration across a selectively permeable membrane. What really drives osmosis?
the difference in water concentration across a selectively permeable membrane
Resolution
the power to show details clearly in an image
Magnification
the ratio of an object's image size to its real size
A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of
facilitated diffuaion
Endocytosis moves materials _____ a cell via _____.
into ... membranous vesicles