Cell Membranes, Transport & Homeostasis... Practice Test

The cell membrane is a highly selective barrier that controls the movement of substances in and out of the cell.  In fact, polar molecules are unable to go across unless

• they are broken down into smaller pieces.
• they are enclosed in water-filled vesicles.
• they pass through channels in the cell membrane.
• they react with other substances to become nonpolar.

Organisms must be able to adapt to a changing external and internal environment.  An organism's ability to maintain a stable internal environment is known as homeostasis.  How does a cell's membrane help an organism maintain homeostasis?

• Cell membranes directly control the temperature of the cell.
• Cell membranes control the substances that enter or leave cells.
• Cell membranes use a large portion of the cell's energy supply.
• Cell membranes protect the cell organelles from large doses of radiation.

Tags

NGSS.HS-LS1-3

The cell membrane, or plasma membrane, is made up of a lipid bilayer in which hydrophilic heads face outward and hydrophobic tails face inward.
This arrangement within the cell membrane allows it to 

• fuse with ribosomes during DNA replication.
• absorb water from the cytoplasm whenever necessary.
• keep out all viral and bacterial infections.
• control the movement of substances in and out of the cell.

Tags

NGSS.MS-LS1-2

The fluid mosaic model shown above describes the structure and function of

• chloroplasts.
• chromosomes.
• nuclei.
• cell membranes.

Normal homeostatic conditions require potassium concentrations to be about 1000 times higher inside the cell than in the blood.
What mechanisms does a cell use to move these small potassium molecules into the cell against the concentration gradient?

• passive transport by osmosis
• passive transport by diffusion
• active transport by proteins
• active transport by endocytosis

Tags

NGSS.HS-LS1-3

Which of the following types of passive transport involves water molecules moving from a high concentration to a low concentration?

• osmosis
• simple diffusion
• filtration
• facilitated diffusion

Examine the diagrams of plant cells.  Each cell has been placed in a different solution.
The cell in diagram 2 has been placed in a solution that contains __________ the interior of the cell.

• water that is warmer than
• a lower concentration of water than
• the same concentration of water as
• water that is cooler than

Tags

NGSS.MS-LS1-5

NGSS.MS-LS2-1

Cells use __________ to take in large molecules or other cells.

• passive transport by osmosis
• passive transport by diffusion
• active transport by endocytosis
• active transport by carrier proteins

Cholesterol is an important component of the cell membrane because __________ .

• it makes the membrane more fluid and adds to its flexibility

• it aids in diffusion

• it aids in cell recognition

• it transports large, polar molecules

What will be the effect of placing a plant cell in a hypotonic solution?

• The plant will wilt.

• The cell will shrink in size.

• The cell will remain unaffected.

• The cell will expand and become turgid.

Tags

NGSS.HS-LS1-3