science: chpt. 7 test Flashcards
In the mid _____ there was a lot of new _______ about cells because of the new ____________.
1800s; theories; microscopes
___________ prevents fatty-acid tails from sticking together
Cholesterol
What did scientist observe using early microscopes?
Tiny organisms
Electron microscopes have about ____ more magnification than compound light microscopes
500x
What king of images can be seen with a scanning electron microscopes (SEM)
3D images
What is the cell theory?
(1) All living organisms are composed of one or more cells
(2) Cells are the basic unit of structure and organization of all living organisms
(3) Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cells.
What decade did the cell theory become a living thing?
1850
Do bacteria cells have nuclei? Why?
No, because they are prokaryotic
What is present in eukaryotic cells?
Nucleus
Is cholesterol polar or non-polar?
Non polar
What substance in the plasma membrane identify chemical signals?
Carbohydrate chain
What converts sugars into energy (also called the powerhouse of the cell)?
Mitochondria
What organelles are only found in animals?
Lysosome
The condition of continuous, random movement of particles but no overall change in concentration of materials
Dynamic Equilibrium
Does active transport move substances with or against the concentration gradient?
Against
What will happen to a cell in a hypotonic solution solution?
- Plant cells will swell but because of the cell wall it won’t burst.
- Animal cells will swell and possibly burst.
What kind of molecules are expelled during exocytosis?
Large molecules
Is facilitated diffusion active or passive?
Passive
Compare and contrast exocytosis and endocytosis.
Both exocytosis and endocytosis are energy-requiring processes. However, exocytosis expels wastes and secretes substances at the plasma membrane and endocytosis is when large substances from the outside environment enter the cell.
Use principles of osmosis to explain wilting.
Osmosis regulates the movement of water across the plasma membrane. This helps maintain homeostasis. If a plant cell is in a hypertonic solution the loss of water causes wilting.
