Cell Theory
This invention allowed scientists to discover cells for the first time.
Microscope.
Who first used the word “cell” after observing cork under a microscope?
Robert Hooke.
True or false: All living things are made of cells.
True — all living things are made of cells.
What is homeostasis in your own words
Homeostasis = keeping internal conditions stable despite external changes.
Statement: "Reproduction is required for an individual organism to be considered living." True or False?
False. Reproduction is a characteristic of life for species survival, but an individual can be alive without reproducing.
Name the three main ideas included in the Cell Theory (briefly list).
1) All living things are made of cells. 2) Cells are the basic units of life. 3) All cells come from pre-existing cells.
Who observed living single-celled organisms in pond water with a simple microscope?
Anton van Leeuwenhoek.
Give one example of a unicellular organism and one example of a multicellular organism.
Example answers: Unicellular — bacteria (E. coli), amoeba, yeast; Multicellular — human, oak tree, frog.
Why is maintaining a stable internal temperature important for organisms?
Maintaining temperature keeps enzymes and cell processes working correctly.
Statement: "Only animals show homeostasis." True or False?
False. All living organisms (including plants, animals, fungi, microbes) show homeostasis.
Which part of the Cell Theory explains how new cells are formed?
The idea "All cells come from pre-existing cells."
Which scientist concluded that all cells come from pre-existing cells?
Rudolf Virchow.
Which characteristic of life explains why organisms pass on DNA or RNA to offspring?
Heredity (genetic code: DNA/RNA).
Explain why sweating when you are hot is an example of homeostasis
Sweating cools the body as sweat evaporates, lowering body temperature to return to normal.
Statement: "Asexual reproduction leads to offspring with genetic variation." True or False?
False. Asexual reproduction produces genetically identical offspring (clones); sexual reproduction increases genetic variation.
Explain in one sentence why the Cell Theory is important for medicine or biology.
Example: Cell Theory helps doctors understand how cells divide and repair tissue, which informs treatments for injuries and diseases like cancer.
Schleiden and Schwann each contributed to Cell Theory. What did each discover?
Schleiden discovered plants are made of cells; Schwann discovered animals are made of cells.
Choose two characteristics of life and explain in two sentences how they work together in an organism (example: metabolism and growth).
Example: Metabolism provides energy for growth; growth uses that energy to build new cells and tissues.
Give three different examples of homeostasis
Examples: body temperature regulation, blood sugar regulation (insulin/glucagon), plant stomata opening/closing to control water loss.
Statement: "Metabolism includes both building up and breaking down molecules to get energy." True or False?
True. Metabolism includes anabolic (building) and catabolic (breaking down) reactions.
Give one piece of evidence (from historical observations) that supports the idea that all living things are made of cells.
Evidence examples: Hooke’s cork observations, Leeuwenhoek’s observations of living cells, Schleiden & Schwann’s observations that plants and animals are made of cells.
Describe how improvements in microscopes changed scientists’ understanding of life.
Improvements allowed viewing of smaller structures and living cells, leading to the Cell Theory and better understanding of growth, disease, and cell function.
Define adaptation and give a real example of an animal adaptation and how it helps survival.
Adaptation = a heritable trait that increases survival or reproduction; Example: Polar bears have thick fur and fat for insulation in cold Arctic climates.
Describe how homeostasis involves detection of a change and a response — use the example of being cold outside
Example: Cold detected by skin receptors → nervous system signals muscles to shiver → shivering generates heat to raise body temperature back toward normal.
Statement: "If an organism does not respond to any stimuli, it cannot be considered alive." True or False?
Generally True: responding to stimuli is a characteristic of life. Clarification: Some organisms may have slow or hard-to-detect responses (e.g., very slow-growing plants), but lack of obvious response does not alone prove non-life.