Cell Theory & Types
What are the three main statements of cell theory?
All living things are made of cells; (2) The cell is the basic unit of life; (3) All cells come from pre-existing cells.
Which organelle is responsible for producing most of a cell’s ATP (energy)?
Mitochondrion.
What is diffusion? Give a simple everyday example.
Diffusion: movement of particles from high to low concentration (example: smell of perfume spreading across a room).
Give one example of a beneficial microbe and one example of a harmful microbe.
Beneficial: gut bacteria (e.g., Lactobacillus); Harmful: pathogenic bacteria (e.g., Streptococcus) or viruses (e.g., influenza).
Name two first-line physical or chemical defenses the human body uses against pathogens.
Skin, mucus, stomach acid, cilia in respiratory tract.
Identify one key structural difference between prokaryotic and eukaryotic cells.
Prokaryotes: no nucleus, typically smaller, no membrane-bound organelles. Eukaryotes: nucleus, membrane-bound organelles, generally larger/complex.
Name two organelles found in plant cells but not animal cells.
Chloroplast and cell wall (also large central vacuole).
Define osmosis in one sentence.
Osmosis: diffusion of water across a semi-permeable membrane.
How do bacteria reproduce? Name the process and give a brief description.
Binary fission: one bacterial cell divides into two identical daughter cells (DNA replicates, cell elongates, septum forms, cell splits).
Which cell type is primarily responsible for producing antibodies?
White blood cells or B lymphocytes (B cells).
If a scientist observes a single-celled organism with no nucleus but with a cell wall and ribosomes, this organism is most likely a ______.
Bacterium (prokaryote).
What is the function of ribosomes? Include where they can be found in the cell.
Ribosomes make (synthesize) proteins; found free in cytoplasm and attached to rough endoplasmic reticulum.
When placed in a hypertonic solution, plant cells typically ______ (gain/lose) water and may undergo ______ (plasmolysis/turgor).
Lose water; plasmolysis.
What is one major structural difference between viruses and bacteria?
Viruses lack cellular structure and organelles and require host cells to replicate; bacteria are cells with metabolic machinery.
Define “antibody” in one sentence and explain its role in immunity.
Antibody: a protein produced by B cells that specifically binds to an antigen on a pathogen to neutralize it or mark it for destruction.
Explain why multicellular organisms can have specialized cells while unicellular organisms cannot (brief, 2–3 sentences).
Multicellular organisms have many cells that can differentiate and carry out specialized functions; unicellular organisms perform all life functions within one cell.
Describe the role of the endoplasmic reticulum and Golgi apparatus in protein processing (short sequence: where made → processed → shipped).
Proteins are synthesized on ribosomes of the rough ER, then sent to the Golgi apparatus for modification, packaging, and shipping in vesicles to their destinations.
During microscope use, which objective lens do you start with and why? Also name two safety/handling rules for slides.
Start with the low-power (scanning) objective to locate the specimen; rules: handle slides by edges, start/finish with stage low and objective away from slide, clean lenses with lens paper only.
Explain why antibiotics treat bacterial infections but not viral infections (short, 2–3 sentences).
Antibiotics target bacterial structures or processes (cell wall synthesis, ribosomes) that viruses do not have; viruses replicate inside host cells and use host machinery, so antibiotics are ineffective.
Give one example of an innate immune response and one example of an adaptive immune response.
Innate: inflammation (e.g., redness and swelling that happens quickly); Adaptive: antibody production by B cells (specific response that develops after exposure).
A newly discovered cell has circular DNA in the cytoplasm, a plasma membrane, and a flagellum. Propose a classification (prokaryote/eukaryote) and justify using two specific features.
Classification: prokaryote; justification: circular DNA in cytoplasm (no nucleus) and flagellum common in many bacteria.
A cell has large central vacuole, chloroplasts, and a rigid cell wall. Explain how these organelles help the plant maintain structure and perform photosynthesis (2–3 sentences).
Central vacuole maintains turgor pressure (keeps plant rigid); chloroplasts conduct photosynthesis to make sugars; cell wall provides structural support and protection.
You observe cheek cells and onion skin cells under the microscope. List two observable differences you expect and explain why they occur.
Cheek cells: irregular shape, no cell wall, smaller nuclei visible; onion skin (plant) cells: rectangular shape, cell wall visible, larger central vacuole and sometimes chloroplasts (if from green tissue). Differences due to plant vs animal cell structures.
A class compares sizes: cell → bacterium → virus. Rank them from largest to smallest and give an approximate reason (one sentence) why size matters for how they interact with hosts or microscopes.
Largest to smallest: cell → bacterium → virus. Size affects detection (microscopes used), how they enter cells, and how immune system or treatments target them.
Put these adaptive immune steps in order: activation of B and T cells (white blood cells), pathogen enters body, antibodies are produced, memory cells form.
1) Pathogen enters body; 2) Activation of B and T cells; 3) Antibodies are produced; 4) Memory cells form.