BIO QUIZ 2

Scientific explanation

Explains the cause of a phenomenon (why something happens)

Which of the following is an essential feature of a scientific explanation?

establishes cause(s) responsible for the phenomena being explained

What was the first hypothesized step in the evolution of the eukaryotic cell?

successive infolding of the plasma membrane

Archaea and Bacteria are both composed of prokaryotic organisms:

but these two groups are no more related to each other than to eukaryotic organisms.

Prokaryotic cells possess a nucleus but no other membrane-bound organelles.

False

Osmosis is a specialized case of diffusion that involves only the movement of water.

True

Creating an electrochemical gradient requires:

Energy

Hypothesis

A testable explanation that can be supported or rejected

Independent variable

The factor that is changed in an experiment

Dependent variable

The factor that is measured in an experiment

Diffusion

Movement of molecules from high to low concentration (no energy required)

Osmosis

Diffusion of water across a membrane

Electrochemical gradient

Difference in concentration and charge across a membrane that stores energy

Building a gradient

Requires energy because particles are moved against their natural flow

Passive transport

Movement of substances without energy (ex: diffusion, osmosis)

Active transport

Movement of substances using energy

Prokaryotic cells

Small cells with no nucleus and no membrane-bound organelles; DNA is in cytoplasm

Eukaryotic cells

Larger cells with a nucleus and membrane-bound organelles; DNA is inside nucleus

Nucleus

Membrane-bound organelle that contains DNA (only in eukaryotes)

Archaea

Prokaryotic organisms that are genetically different from bacteria

Bacteria

Prokaryotic organisms that are different from archaea

Three domains of life

Bacteria, Archaea, Eukarya

Origin of eukaryotic cells

Began with infolding of the plasma membrane

Membrane infolding

Process where the cell membrane folds inward to form internal structures like the nucleus

Cell membrane

A barrier that controls what enters and exits the cell and allows gradients to form

Energy in cells

Used to maintain order and build gradients

Thermodynamics (1st law)

Energy cannot be created or destroyed

Thermodynamics (2nd law

Entropy (disorder) increases unless energy is used