biology movement

Question 1

What are phospholipids?

Answer 1

Lipids containing a phosphate group, consisting of a hydrophilic phosphate head and two hydrophobic hydrocarbon tails.

Phospholipids are the most abundant lipids in biological membranes and are amphipathic.

Question 2

Define diffusion.

Answer 2

The net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient.

Diffusion can be classified into simple diffusion and facilitated diffusion.

Question 3

What is osmosis?

Answer 3

The net movement of water molecules from a region of higher water potential to a region of lower water potential through a selectively permeable membrane.

Water potential is influenced by solute concentration.

Question 4

What determines the rate of diffusion?

Answer 4

Factors include concentration gradient, diffusion distance, temperature, and surface area-to-volume ratio.

These factors can enhance or hinder the movement of particles.

Question 5

What is active transport?

Answer 5

The movement of ions or molecules across a membrane from lower to higher concentration against the concentration gradient, using energy (ATP).

Active transport allows cells to maintain concentrations of specific substances.

Question 6

What is the difference between a selectively permeable membrane and a partially permeable membrane?

Answer 6

A selectively permeable membrane regulates the movement of substances according to the cell’s needs; a partially permeable membrane allows smaller molecules to pass while excluding larger ones.

Visking tubing is an example of a partially permeable membrane.

Question 7

What are integral proteins?

Answer 7

Proteins embedded in the phospholipid bilayer with both hydrophilic and hydrophobic portions.

Integral proteins often facilitate transport across the membrane.

Question 8

What are peripheral proteins?

Answer 8

Proteins attached to the surface of the membrane, not embedded in the phospholipid bilayer.

Peripheral proteins are usually hydrophilic and can be easily dislodged.

Question 9

Describe simple diffusion.

Answer 9

The net movement of particles directly across the plasma membrane from a region of higher concentration to a region of lower concentration.

Simple diffusion does not require energy input.

Question 10

What is facilitated diffusion?

Answer 10

A special form of diffusion that allows charged particles and large molecules to cross membranes through transport proteins.

This process is passive and relies on the kinetic energy of particles.

Question 11

Compare simple diffusion and facilitated diffusion.

Answer 11

Similarities: Both move down a concentration gradient and do not require energy. Differences: Simple diffusion occurs directly across the membrane; facilitated diffusion requires transport proteins.

Simple diffusion is for hydrophobic and uncharged substances, while facilitated diffusion is for large and hydrophilic substances.

Question 12

What is the role of the plasma membrane?

Answer 12

It forms a boundary between the cytoplasm and the external environment, maintaining a constant internal environment.

The plasma membrane is crucial for regulating substance movement in and out of the cell.

Question 13

Define biological membrane.

Answer 13

A membrane found in living cells that encloses cell contents and regulates the passage of substances.

Biological membranes include plasma membranes and membranes surrounding organelles.

Question 14

What is turgor pressure?

Answer 14

The pressure exerted by the fluid inside the central vacuole of a plant cell against the cell wall, maintaining cell shape.

Turgor pressure is essential for plant tissue rigidity.

Question 15

What is the structure of biological membranes?

Answer 15

Biological membranes are composed mainly of lipids (primarily phospholipids), proteins, and a small amount of carbohydrates, typically 7-10 nm thick.

The arrangement of phospholipids in a bilayer is crucial for membrane function.

Question 16

What is the role of carbohydrates in membranes?

Answer 16

Carbohydrates are involved in cell recognition and signaling processes on the cell surface.

They often attach to proteins or lipids, forming glycoproteins and glycolipids.

Question 17

What is a concentration gradient?

Answer 17

The difference in concentration of the same particles in two regions.

Particles tend to move from areas of high concentration to low concentration.

Question 18

What are transport proteins needed for?

Answer 18

To carry particles of a substance across the plasma membrane.

Question 19

What types of substances are transported by these proteins?

Answer 19

Hydrophobic and uncharged substances; large and hydrophilic substances.

Question 20

Define osmosis.

Answer 20

The net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane.

Question 21

What is water potential?

Answer 21

The measure of the tendency of water molecules to move from a region of higher water potential to a region of lower water potential.

Question 22

How does solute concentration affect water potential?

Answer 22

Solute concentration affects water potential as solutes form weak (hydrogen) bonds with water molecules.

Question 23

What is the water potential of pure water?

Answer 23

Zero solute concentration and the highest water potential.

Question 24

What happens when a solute is added to pure water?

Answer 24

The solute concentration increases, causing its water potential to decrease.

Question 25

What occurs when a selectively permeable membrane separates two solutions of different water potentials?

Answer 25

A water potential gradient is established.

Question 26

What factors can affect the rate of osmosis?

Answer 26

* Water potential gradient * Distance over which water molecules need to move * Temperature * Surface area-to-volume ratio

Question 27

True or False: Osmosis requires additional energy input.

Answer 27

False.

Question 28

What happens to animal cells in a hypotonic solution?

Answer 28

Water enters the cell by osmosis, causing the cell to swell and potentially burst.

Question 29

What happens to animal cells in a hypertonic solution?

Answer 29

Water leaves the cell by osmosis, causing the cell to shrink or crenate.

Question 30

What happens to plant cells in a hypotonic solution?

Answer 30

Water enters the cell, the vacuole increases in size, and the cell swells without bursting due to the cell wall.

Question 31

What is turgor pressure?

Answer 31

The pressure exerted by the water in the vacuole against the cell wall.

Question 32

What happens to plant cells in a hypertonic solution?

Answer 32

Water leaves the cell, causing the vacuole and cytoplasm to decrease in size, leading to plasmolysis.

Question 33

Define plasmolysis.

Answer 33

The process where the plasma membrane pulls away from the cell wall due to loss of water.

Question 34

What role does turgor play in plants?

Answer 34

It maintains the shape of soft tissues in plants and is involved in movements of certain plant parts.

Question 35

What happens to a cell in a solution of the same water potential?

Answer 35

There is no change in size and shape; net movement of water molecules is equal in both directions.

Question 36

Define active transport.

Answer 36

The movement of ions or molecules across a membrane from lower concentration to higher concentration against a concentration gradient, using energy in the form of ATP.

Question 37

Why does active transport only occur in living cells?

Answer 37

Because living cells respire aerobically to produce ATP.

Question 38

What are some examples of active transport in living systems?

Answer 38

* Plants absorbing mineral salts and nitrate ions * Muscle fibers absorbing calcium ions

Question 39

What effect does a steeper concentration gradient have on the rate of diffusion?

Answer 39

The steeper the gradient, the faster the rate of diffusion.

Question 40

Fill in the blank: The rate of diffusion decreases rapidly with an increase in _______.

Answer 40

[distance].

Question 41

True or False: Passive transport requires energy in the form of ATP.

Answer 41

False.

Question 42

What is the direction of movement in active transport?

Answer 42

Against concentration gradient.

Question 43

What are the differences between passive and active transport?

Answer 43

* Passive transport: Net movement down a concentration gradient, no energy required * Active transport: Net movement against a concentration gradient, energy required.