Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Cell Theory: All living organisms are composed of one or more cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.
The Nucleus: Often called the 'control center' of the cell, it contains the genetic material in the form of (deoxyribonucleic acid).
Mitochondria: The site of aerobic cellular respiration, where glucose is broken down to release energy in the form of (Adenosine Triphosphate).
Chloroplasts: Found only in plant cells and some protists; they contain the green pigment chlorophyll and are the site of photosynthesis, converting light energy into chemical energy stored in .
Cell Wall: A rigid outer layer made of cellulose found in plant cells that provides structural support and protection, maintaining a fixed shape.
Cell Membrane: A semi-permeable lipid bilayer that controls the movement of substances such as , , and into and out of the cell.
Vacuoles: Plant cells typically have one large central vacuole that maintains turgor pressure, while animal cells have small, temporary vacuoles used for storage or transport.
Cytoplasm: The jelly-like substance where most chemical reactions occur and which contains the organelles.
📐Formulae
💡Examples
Problem 1:
A student observes a plant cell under a microscope. The image of the cell measures in length. If the actual length of the cell is , calculate the magnification used.
Solution:
Explanation:
To find magnification, divide the measured image size by the actual size of the specimen. Ensure both units are the same before dividing.
Problem 2:
Identify which organelle would be more abundant in a human heart muscle cell compared to a skin cell and explain why using chemical requirements.
Solution:
Mitochondria would be more abundant.
Explanation:
Muscle cells require a high amount of energy () for contraction. Mitochondria are responsible for cellular respiration (); therefore, cells with high metabolic demands contain more mitochondria.
Problem 3:
Why does a plant cell not burst when placed in a solution with a high concentration of , whereas an animal cell might?
Solution:
The presence of the Cell Wall in plant cells.
Explanation:
When water enters a cell via osmosis, the internal pressure increases. The plant cell has a rigid cell wall made of cellulose that exerts an opposing pressure, preventing the cell from lysing (bursting). Animal cells lack this wall and only have a flexible cell membrane.