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1.1 The study of life Read Online
Viewed from space, Earth offers no clues about the diversity of life forms that reside there. The first forms of life on Earth are thought to have been microorganisms that existed for billions of years in the ocean before plants and animals appeared. The mammals, birds, and flowers so familiar to us are all relatively recent, originating 130 to 200 million years ago. Humans have inhabited this planet for only the last 2.5 million years, and only in the last 200,000 years have humans started looking like we do today.
Chapter 05: Structure and Function of Plasma Membranes
5.1 Components and Structure
5.2 Passive Transport
5.3 Active Transport
5.4 Bulk Transport
Download MCQ Quiz PDF eBook
Question: Active transport must function continuously because __________.
Choices:
plasma membranes wear out
not all membranes are amphiphilic
facilitated transport opposes active transport
diffusion is constantly moving solutes in opposite directions
Question: Water moves via osmosis _________.
Choices:
throughout the cytoplasm
from an area with a high concentration of other solutes to a lower one
from an area with a high concentration of water to one of lower concentration
from an area with a low concentration of water to one of higher concentration
Question: What is the combination of an electrical gradient and a concentration gradient called?
Choices:
potential gradient
electrical potential
concentration potential
electrochemical gradient
Question: Which plasma membrane component can be either found on its surface or embedded in the membrane structure?
Choices:
protein
cholesterol
carbohydrate
phospholipid
Question: What problem is faced by organisms that live in fresh water?
Choices:
Their bodies tend to take in too much water.
They have no way of controlling their tonicity.
Only salt water poses problems for animals that live in it.
Their bodies tend to lose too much water to their environment.
Question: What happens to the membrane of a vesicle after exocytosis?
Choices:
It leaves the cell.
It is disassembled by the cell.
It fuses with and becomes part of the plasma membrane.
It is used again in another exocytosis event.
Question: Which transport mechanism can bring whole cells into a cell?
Choices:
pinocytosis
phagocytosis
facilitated transport
primary active transport
Question: How does the sodium-potassium pump make the interior of the cell negatively charged?
Choices:
by expelling anions
by pulling in anions
by expelling more cations than are taken in
by taking in and expelling an equal number of cations
Question: The principal force driving movement in diffusion is the __________.
Choices:
temperature
particle size
concentration gradient
membrane surface area
Question: Which characteristic of a phospholipid contributes to the fluidity of the membrane?
Choices:
its head
cholesterol
a saturated fatty acid tail
double bonds in the fatty acid tail
Question: What is the primary function of carbohydrates attached to the exterior of cell membranes?
Choices:
identification of the cell
flexibility of the membrane
strengthening the membrane
channels through membrane
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