Cell Theory & Cell Types
What tool allowed scientists to observe cells and develop cell theory
Microscope
1. Which organelle contains most of a eukaryotic cell's DNA?
Nucleus
1. Which type of cell typically contains chloroplasts: plant or animal?
Plant cells
1. What is the movement of water across a selectively permeable membrane called?
Answer: Osmosis
1. What structure controls what enters and leaves a cell?
Answer: Plasma membrane (cell membrane)
What are the two major types of cells?
Prokaryotic and eukaryotic cells
2. Which organelle is responsible for making proteins?
Ribosomes
2. What rigid structure provides support and protection in plant cells but is absent in animal cells?
Answer: Cell wall
2. During diffusion, particles move from an area of ______ concentration to an area of ______ concentration.
Answer: High to low
2. What term describes an organism's ability to maintain a stable internal environment despite changes outside the body?
Answer: Homeostasis
What structure contains DNA in eukaryotic cells but is absent in prokaryotic cells?
Nucleus
3. A cell needs to package and ship proteins. Which organelle performs this job?
Answer: Golgi apparatus
3. Which organelle is typically much larger in plant cells and stores water and other materials?
Answer: Central vacuole
3. What do we call a solution that has approximately the same effective solute concentration as the inside of a cell?
Answer: Isotonic
3. A scientist observes a pond water organism moving using tiny hairlike structures. What are these structures called?
Cilia
A scientist discovers a single-celled organism with DNA, ribosomes, and a cell membrane, but no nucleus. What type of cell is it?
Prokaryotic cell
4. A cell needs to produce large amounts of usable energy through cellular respiration. Which organelle would be especially important?
Mitochondria
4. A scientist observes a cell containing a nucleus, mitochondria, cell wall, and chloroplasts. Identify the type of cell and provide two pieces of evidence.
Answer: Plant cell. The presence of a cell wall and chloroplasts indicates that it is a plant cell.
4. A cell is placed in a hypertonic solution. Which direction will water move, and what will happen to the cell?
Answer: Water moves out of the cell, causing it to shrink or lose mass.
4. A cell is placed in a hypotonic solution. Predict what will happen to the cell's mass and explain why.
Answer: The cell's mass will increase because water moves into the cell through osmosis.
A student claims that all single-celled organisms are prokaryotes. Explain why this statement is incorrect.
Some single-celled organisms are eukaryotes, such as paramecia. These organisms have a nucleus and membrane-bound organelles.
5. A cell produces a protein that needs to be transported outside the cell. Name three organelles involved in making, processing, and packaging that protein.
Answer: Ribosomes, rough endoplasmic reticulum, and Golgi apparatus.
5. A student claims that plant cells do not need mitochondria because they already have chloroplasts. Explain why this statement is incorrect.
Answer: Chloroplasts use sunlight to produce glucose through photosynthesis. Mitochondria break down glucose during cellular respiration to produce usable energy (ATP). Plant cells need both organelles.
5. Two identical cells are placed into different solutions. Cell A gains 20% mass, while Cell B loses 15% mass. Identify the type of solution each cell was placed in and explain the movement of water.
Answer: Cell A was placed in a hypotonic solution, causing water to enter the cell. Cell B was placed in a hypertonic solution, causing water to leave the cell.
5. Three identical model cells are placed into different solutions. After 24 hours, the following results are recorded:
Solution A: +35% mass
Solution B: +2% mass
Solution C: –22% mass
Identify which solution is hypotonic, hypertonic, and approximately isotonic. Explain how the data support your answers.
Solution A: Hypotonic — water entered the cell, increasing its mass.
Solution B: Approximately isotonic — very little net water movement occurred, so the mass remained nearly the same.
Solution C: Hypertonic — water left the cell, decreasing its mass.