Cell-ebrity Status
What structure is found in plant cells but not animal cells and provides additional support and protection?
Cell wall
What is the main function of the cell membrane?
Regulates what enters and leaves the cell.
What type of transport moves substances across a membrane without requiring cellular energy (ATP)? Show answer
Passive transport
What type of transport requires cellular energy to move substances against their concentration gradient?
Active transport
What is the movement of water across a selectively permeable membrane called?
Osmosis
Which organelle is responsible for producing proteins?
ribosomes
What organelle allows plant cells to convert light energy into chemical energy?
Chloroplast
What does it mean when a cell membrane is described as selectively permeable?
Selectively permeable means allowing some substances to pass through more readily than others.
In which direction does net diffusion occur?
From high concentration to low concentration.
What energy-carrying molecule directly powers many forms of active transport?
ATP
What term describes a solution with the same effective concentration of nonpenetrating solutes as the inside of a cell?
Isotonic
Which organelle produces most of the ATP used by a eukaryotic cell?
mitochondria
Which organelle is typically much larger in mature plant cells and stores water and dissolved substances?
Large central vacuole
What are the two main parts of a phospholipid bilayer?
Hydrophilic (water-attracting) head and hydrophobic (water-repelling) tails.
What is the term for the difference in concentration of a substance between two areas?
Concentration gradient
What is the process called when a cell brings large materials inside by surrounding them with its membrane and forming a vesicle?
Endocytosis
What happens to an animal cell placed in a hypotonic solution?
Water enters the animal cell, causing it to swell and possibly burst.
Which organelle modifies, sorts, and packages proteins for transport?
Golgi apparatus
Name two structures found in both plant and animal cells.
Any two: nucleus, cell membrane, cytoplasm, mitochondria, ribosomes, endoplasmic reticulum, or Golgi apparatus.
Why do phospholipids arrange themselves into a bilayer when surrounded by water?
Hydrophilic heads face the watery environments inside and outside the cell, while hydrophobic tails face inward, away from water.
What type of passive transport uses a membrane protein to move substances down their concentration gradient?
Facilitated diffusion
What is the process called when a vesicle fuses with the cell membrane to release materials outside the cell?
Exocytosis
What happens to an animal cell placed in a hypertonic solution?
Water leaves the animal cell, causing it to shrink.
A cell contains an unusually large number of mitochondria. What can you infer about this cell's energy requirements?
The cell requires a large amount of energy (ATP) to carry out its functions.
A plant cell is placed in a hypotonic solution. Explain why it generally does not burst like an animal cell might.
Water enters the plant cell, but the rigid cell wall prevents excessive expansion and generally keeps the cell from bursting.
Why can small nonpolar molecules, such as oxygen, cross the phospholipid bilayer more easily than charged ions?
Oxygen is small and nonpolar, allowing it to pass through the phospholipid bilayer. Charged ions generally require transport proteins.
A substance is at a higher concentration outside a cell than inside. If the membrane is permeable to it, predict the direction of its net movement and explain why.
The substance moves into the cell by diffusion because its concentration is higher outside than inside, assuming the membrane is permeable to it.
A cell moves sodium ions from an area of lower sodium concentration to an area of higher sodium concentration using ATP. Identify the type of transport and explain why ATP is necessary.
Active transport. ATP provides energy to move sodium ions against their concentration gradient, from low to high concentration.
An animal cell contains 10% nonpenetrating solute and is placed in a solution containing 5% of the same solute. Identify the surrounding solution and predict the direction of net water movement.
Hypotonic solution. Water moves into the cell because the surrounding solution has a lower concentration of nonpenetrating solutes (5%) than the cell (10%). The cell swells.
A mutation prevents ribosomes from functioning properly. Explain how this could affect other structures and processes in the cell.
The cell would be unable to produce proteins normally, disrupting enzyme activity, cell structures, transport proteins, and other essential functions.
A scientist discovers a cell with a nucleus, mitochondria, a cell wall made of cellulose, and chloroplasts. Identify the type of cell and explain how two of its structures support its survival.
Plant cell. Chloroplasts perform photosynthesis to produce sugars, while the cellulose cell wall provides support and protection.
A toxin damages the transport proteins embedded in a cell membrane without destroying the phospholipid bilayer. Predict how this could affect the movement of substances into and out of the cell. Show answer
Substances that require transport proteins may no longer enter or leave normally, disrupting nutrient uptake, ion balance, and homeostasis.
Two solutions are separated by a membrane permeable to glucose. Initially, one side contains more glucose than the other. After equilibrium is reached, do glucose molecules stop moving? Explain.
No. Molecules continue moving randomly in both directions, but there is no net movement because equilibrium has been reached.
A cell is treated with a chemical that greatly reduces ATP production. Predict what would happen to ATP-powered ion pumps and explain how this could affect homeostasis.
ATP-powered ion pumps would slow down or stop, disrupting ion concentration gradients, water balance, and normal cellular functions.
Two identical animal cells are placed in different solutions. Cell A is placed in a 20% nonpenetrating solute solution, while Cell B is placed in a 5% solution. Both cells initially contain 10% of that solute. Predict what happens to each cell and explain why.
Cell A: Water leaves the cell, causing it to shrink because the 20% solution is hypertonic. Cell B: Water enters the cell, causing it to swell because the 5% solution is hypotonic.