Homeostasis
What is homeostasis?
Maintaining relatively stable internal conditions despite changes inside or outside the organism.
Which type of feedback counteracts a change and moves conditions back toward a stable range?
Negative feedback
According to cell theory, what are living things made of?
One or more cells
Which organelle contains most of a eukaryotic cell's DNA and helps direct cellular activities?
Nucleus
Why is homeostasis important to cells?
Cells function properly only within suitable ranges of conditions such as temperature, water balance, pH, and concentrations of substances.
Which type of feedback amplifies the original change?
Positive feedback
What is the basic unit of structure in living things?
Cells
What structures build proteins?
Ribosomes
Body temperature rises and sweating begins. How does this help maintain homeostasis?
Evaporation of sweat helps transfer thermal energy away from the body, helping temperature move back toward its normal range.
Sweating in response to rising body temperature is what kind of feedback? *You're trying to return back to homeostasis*
Negative feedback
Where do new cells come from?
Pre-existing cells
Which organelle modifies, sorts, and packages many proteins?
Golgi apparatus
A dehydrated body begins conserving water. Explain why this is a homeostatic response.
The response helps counter water loss and maintain a more stable internal water balance.
During childbirth, contractions trigger signals that strengthen contractions. What kind of feedback is this?
Positive feedback
State the three major things in cell theory
Living things are made of cells; cells are the basic units of structure/function; new cells arise from existing cells.
Which organelle is strongly associated with producing ATP for cellular work? *Powerhouse
Mitochondria
Why would losing the ability to maintain homeostasis eventually threaten cell survival?
Internal conditions could move outside the ranges needed for enzymes, membranes, and other cellular processes to function properly.
Define both positive and negative feedback
Positive amplifies the initial change, negative returns back to normal
Scientists discover something that reproduces but is not made of cells. Why would cell theory make its classification as a living organism scientifically complicated?
Classical cell theory identifies cells as the fundamental units of living organisms, so something acellular does not satisfy that criterion even if it has some life-like characteristics.
What do plant cells have that animal cells do not?
Cell wall